Current Role at Stanford

Research Scientist

Honors & Awards

  • Gene Technology Research Fellow, German Academic Exchange Service (DAAD) (1986-89)

Education & Certifications

  • Sc.D., Harvard University, School of Public Health, Boston, MA, Virology (1996)
  •, J.W. Goethe University, Frankfurt/Main, Germany, Medicine / Biochemistry (1986)
  • M.D., J. Gutenberg University, Mainz, Germany, Medicine (1985)

Service, Volunteer and Community Work

  • Board Member, Committee of 100 for Tibet (9/1/1996)


    San Francisco


Professional Interests

Topics of interest: Cancer, Tumor immunology, Transplantation, Molecular Immunology, HIV/AIDS pathogenesis

One of the hallmarks of cancer cells is that they escape from being surveyed and eliminated by the immune system. My goal is to investigate the genetic basis of tumor immune escape using mouse models of human cancer, and, conversely, the gene network that confers on cells, in particular stem cells and their derivatives, immune privilege so that they are tolerated by a reactive (allogeneic and/or autoimmune) immune system.

To approach these challenging questions, I have designed a positive genetic screen, in which cells are modified with immunomodulatory genes and then transferred into living mice. The subsequent survival of the gene-modified cells is determined with highly sensitive In vivo bioluminescence imaging. The phenotype of cell survival can therefore be connected causally to any of the transferred immunomodulatory genes.
Our initial data show that no single immunomodulatory gene or two gene combination is able to achieve tumor immune escape and transplant tolerance, Rather, these phenotypes are quite complex and must require the cooperative expression of multiple genes. Genetic screens of higher order complexity are therefore needed and currently being developed. The results of this endeavor will help us in the design and development of more effective cancer immunotherapies and in the improved induction of operational transplant tolerance.

My second area of interest is HIV/AIDS, in particular its molecular evolution, epidemiology, drug resistance, and vaccine development. For this, I have been collaborating for several years now with Dr. Robert Shafter and members of his lab to accelerate and refine HIV molecular diagnostics.


All Publications

  • Signaling by Extracellular Vesicles Advances Cancer Hallmarks Trends in Cancer Kanada, M., Bachmann, M. H., Contag, C. H. 2016; 2 (2): 84–94
  • Breast Cancer Cell Colonization of the Human Bone Marrow Adipose Tissue Niche NEOPLASIA Templeton, Z. S., Lie, W., Wang, W., Rosenberg-Hasson, Y., Alluri, R. V., Tamaresis, J. S., Bachmann, M. H., Lee, K., Maloney, W. J., Contag, C. H., King, B. L. 2015; 17 (12): 849-861
  • Differential fates of biomolecules delivered to target cells via extracellular vesicles. Proceedings of the National Academy of Sciences of the United States of America Kanada, M., Bachmann, M. H., Hardy, J. W., Frimannson, D. O., Bronsart, L., Wang, A., Sylvester, M. D., Schmidt, T. L., Kaspar, R. L., Butte, M. J., Matin, A. C., Contag, C. H. 2015; 112 (12): E1433-42


    Extracellular vesicles (EVs), specifically exosomes and microvesicles (MVs), are presumed to play key roles in cell-cell communication via transfer of biomolecules between cells. The biogenesis of these two types of EVs differs as they originate from either the endosomal (exosomes) or plasma (MVs) membranes. To elucidate the primary means through which EVs mediate intercellular communication, we characterized their ability to encapsulate and deliver different types of macromolecules from transiently transfected cells. Both EV types encapsulated reporter proteins and mRNA but only MVs transferred the reporter function to recipient cells. De novo reporter protein expression in recipient cells resulted only from plasmid DNA (pDNA) after delivery via MVs. Reporter mRNA was delivered to recipient cells by both EV types, but was rapidly degraded without being translated. MVs also mediated delivery of functional pDNA encoding Cre recombinase in vivo to tissues in transgenic Cre-lox reporter mice. Within the parameters of this study, MVs delivered functional pDNA, but not RNA, whereas exosomes from the same source did not deliver functional nucleic acids. These results have significant implications for understanding the role of EVs in cellular communication and for development of EVs as delivery tools. Moreover, studies using EVs from transiently transfected cells may be confounded by a predominance of pDNA transfer.

    View details for DOI 10.1073/pnas.1418401112

    View details for PubMedID 25713383

  • Methods for Culturing Human Femur Tissue Explants to Study Breast Cancer Cell Colonization of the Metastatic Niche JOVE-JOURNAL OF VISUALIZED EXPERIMENTS Templeton, Z. S., Bachmann, M. H., Alluri, R. V., Maloney, W. J., Contag, C. H., King, B. L. 2015


    Bone is the most common site of breast cancer metastasis. Although it is widely accepted that the microenvironment influences cancer cell behavior, little is known about breast cancer cell properties and behaviors within the native microenvironment of human bone tissue.We have developed approaches to track, quantify and modulate human breast cancer cells within the microenvironment of cultured human bone tissue fragments isolated from discarded femoral heads following total hip replacement surgeries. Using breast cancer cells engineered for luciferase and enhanced green fluorescent protein (EGFP) expression, we are able to reproducibly quantitate migration and proliferation patterns using bioluminescence imaging (BLI), track cell interactions within the bone fragments using fluorescence microscopy, and evaluate breast cells after colonization with flow cytometry. The key advantages of this model include: 1) a native, architecturally intact tissue microenvironment that includes relevant human cell types, and 2) direct access to the microenvironment, which facilitates rapid quantitative and qualitative monitoring and perturbation of breast and bone cell properties, behaviors and interactions. A primary limitation, at present, is the finite viability of the tissue fragments, which confines the window of study to short-term culture. Applications of the model system include studying the basic biology of breast cancer and other bone-seeking malignancies within the metastatic niche, and developing therapeutic strategies to effectively target breast cancer cells in bone tissues.

    View details for DOI 10.3791/52656

    View details for Web of Science ID 000361534300067

    View details for PubMedID 25867136

  • A Truncated Human NKG2D Splice Isoform Negatively Regulates NKG2D-Mediated Function JOURNAL OF IMMUNOLOGY Karimi, M. A., Aguilar, O. A., Zou, B., Bachmann, M. H., Carlyle, J. R., Baldwin, C. L., Kambayashi, T. 2014; 193 (6): 2764-2771


    NKG2D is a stimulatory receptor expressed by NK cells and a subset of T cells. NKG2D is crucial in diverse aspects of innate and adaptive immune functions. In this study, we characterize a novel splice variant of human NKG2D that encodes a truncated receptor lacking the ligand-binding ectodomain. This truncated NKG2D (NKG2D(TR)) isoform was detected in primary human NK and CD8(+) T cells. Overexpression of NKG2D(TR) severely attenuated cell killing and IFN-γ release mediated by full-length NKG2D (NKG2D(FL)). In contrast, specific knockdown of endogenously expressed NKG2D(TR) enhanced NKG2D-mediated cytotoxicity, suggesting that NKG2D(TR) is a negative regulator of NKG2D(FL). Biochemical studies demonstrated that NKG2D(TR) was bound to DNAX-activated protein of 10 kDa (DAP10) and interfered with the interaction of DAP10 with NKG2D(FL). In addition, NKG2D(TR) associated with NKG2D(FL), which led to forced intracellular retention, resulting in decreased surface NKG2D expression. Taken together, these data suggest that competitive interference of NKG2D/DAP10 complexes by NKG2D(TR) constitutes a novel mechanism for regulation of NKG2D-mediated function in human CD8(+) T cells and NK cells.

    View details for DOI 10.4049/jimmunol.1400920

    View details for Web of Science ID 000341859700016

    View details for PubMedID 25092887

  • Measuring Cytotoxicity by Bioluminescence Imaging Outperforms the Standard Chromium-51 Release Assay PLOS ONE Karimi, M. A., Lee, E., Bachmann, M. H., Salicioni, A. M., Behrens, E. M., Kambayashi, T., Baldwin, C. L. 2014; 9 (2)


    The chromium-release assay developed in 1968 is still the most commonly used method to measure cytotoxicity by T cells and by natural killer cells. Target cells are loaded in vitro with radioactive chromium and lysis is determined by measuring chromium in the supernatant released by dying cells. Since then, alternative methods have been developed using different markers of target cell viability that do not involve radioactivity. Here, we compared and contrasted a bioluminescence (BLI)-based cytotoxicity assay to the standard radioactive chromium-release assay using an identical set of effector cells and tumor target cells. For this, we stably transduced several human and murine tumor cell lines to express luciferase. When co-cultured with cytotoxic effector cells, highly reproducible decreases in BLI were seen in an effector to target cell dose-dependent manner. When compared to results obtained from the chromium release assay, the performance of the BLI-based assay was superior, because of its robustness, increased signal-to-noise ratio, and faster kinetics. The reduced/delayed detection of cytotoxicity by the chromium release method was attributable to the association of chromium with structural components of the cell, which are released quickly by detergent solubilization but not by hypotonic lysis. We conclude that the (BLI)-based measurement of cytotoxicity offers a superior non-radioactive alternative to the chromium-release assay that is more robust and quicker to perform.

    View details for DOI 10.1371/journal.pone.0089357

    View details for Web of Science ID 000331711900132

    View details for PubMedID 24586714

  • Functional Imaging of Legumain in Cancer Using a New Quenched Activity-Based Probe JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Edgington, L. E., Verdoes, M., Ortega, A., Withana, N. P., Lee, J., Syed, S., Bachmann, M. H., Blum, G., Bogyo, M. 2013; 135 (1): 174-182


    Legumain is a lysosomal cysteine protease whose biological function remains poorly defined. Legumain activity is up-regulated in most human cancers and inflammatory diseases most likely as the result of high expression in populations of activated macrophages. Within the tumor microenvironment, legumain activity is thought to promote tumorigenesis. To obtain a greater understanding of the role of legumain activity during cancer progression and inflammation, we developed an activity-based probe that becomes fluorescent only upon binding active legumain. This probe is highly selective for legumain, even in the context of whole cells and tissues, and is also a more effective label of legumain than previously reported probes. Here we present the synthesis and application of our probe to the analysis of legumain activity in primary macrophages and in two mouse models of cancer. We find that legumain activity is highly correlated with macrophage activation and furthermore that it is an ideal marker for primary tumor inflammation and early stage metastatic lesions.

    View details for DOI 10.1021/ja307083b

    View details for Web of Science ID 000313143000036

  • A Nonpeptidic Cathepsin S Activity-Based Probe for Noninvasive Optical Imaging of Tumor-Associated Macrophages CHEMISTRY & BIOLOGY Verdoes, M., Edgington, L. E., Scheeren, F. A., Leyva, M., Blum, G., Weiskopf, K., Bachmann, M. H., Ellman, J. A., Bogyo, M. 2012; 19 (5): 619-628


    Macrophage infiltration into tumors has been correlated with poor clinical outcome in multiple cancer types. Therefore, tools to image tumor-associated macrophages could be valuable for diagnosis and prognosis of cancer. Herein, we describe the synthesis and characterization of a cathepsin S-directed, quenched activity-based probe (qABP), BMV083. This probe makes use of an optimized nonpeptidic scaffold leading to enhanced in vivo properties relative to previously reported peptide-based probes. In a syngeneic breast cancer model, BMV083 provides high tumor-specific fluorescence that can be visualized using noninvasive optical imaging methods. Furthermore, analysis of probe-labeled cells demonstrates that the probe primarily targets macrophages with an M2 phenotype. Thus, BMV083 is a potential valuable in vivo reporter for tumor-associated macrophages that could greatly facilitate the future studies of macrophage function in the process of tumorigenesis.

    View details for DOI 10.1016/j.chembiol.2012.03.012

    View details for Web of Science ID 000304794600013

    View details for PubMedID 22633413

  • Longitudinal, Noninvasive Imaging of T-Cell Effector Function and Proliferation in Living Subjects CANCER RESEARCH Patel, M. R., Chang, Y., Chen, I. Y., Bachmann, M. H., Yan, X., Contag, C. H., Gambhir, S. S. 2010; 70 (24): 10141-10149


    Adoptive immunotherapy is evolving to assume an increasing role in treating cancer. Most imaging studies in adoptive immunotherapy to date have focused primarily on locating tumor-specific T cells rather than understanding their effector functions. In this study, we report the development of a noninvasive imaging strategy to monitor T-cell activation in living subjects by linking a reporter gene to the Granzyme B promoter (pGB), whose transcriptional activity is known to increase during T-cell activation. Because pGB is relatively weak and does not lead to sufficient reporter gene expression for noninvasive imaging, we specifically employed 2 signal amplification strategies, namely the Two Step Transcription Amplification (TSTA) strategy and the cytomegalovirus enhancer (CMVe) strategy, to maximize firefly luciferase reporter gene expression. Although both amplification strategies were capable of increasing pGB activity in activated primary murine splenocytes, only the level of bioluminescence activity achieved with the CMVe strategy was adequate for noninvasive imaging in mice. Using T cells transduced with a reporter vector containing the hybrid pGB-CMVe promoter, we were able to optically image T-cell effector function longitudinally in response to tumor antigens in living mice. This methodology has the potential to accelerate the study of adoptive immunotherapy in preclinical cancer models.

    View details for DOI 10.1158/0008-5472.CAN-10-1843

    View details for Web of Science ID 000285334200016

    View details for PubMedID 21159636

  • Cancer stem cells from human breast tumors are involved in spontaneous metastases in orthotopic mouse models PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Liu, H., Patel, M. R., Prescher, J. A., Patsialou, A., Qian, D., Lin, J., Wen, S., Chang, Y., Bachmann, M. H., Shimono, Y., Dalerba, P., Adorno, M., Lobo, N., Bueno, J., Dirbas, F. M., Goswami, S., Somlo, G., Condeelis, J., Contag, C. H., Gambhir, S. S., Clarke, M. F. 2010; 107 (42): 18115-18120


    To examine the role of breast cancer stem cells (BCSCs) in metastasis, we generated human-in-mouse breast cancer orthotopic models using patient tumor specimens, labeled with optical reporter fusion genes. These models recapitulate human cancer features not captured with previous models, including spontaneous metastasis in particular, and provide a useful platform for studies of breast tumor initiation and progression. With noninvasive imaging approaches, as few as 10 cells of stably labeled BCSCs could be tracked in vivo, enabling studies of early tumor growth and spontaneous metastasis. These advances in BCSC imaging revealed that CD44(+) cells from both primary tumors and lung metastases are highly enriched for tumor-initiating cells. Our metastatic cancer models, combined with noninvasive imaging techniques, constitute an integrated approach that could be applied to dissect the molecular mechanisms underlying the dissemination of metastatic CSCs (MCSCs) and to explore therapeutic strategies targeting MCSCs in general or to evaluate individual patient tumor cells and predict response to therapy.

    View details for DOI 10.1073/pnas.1006732107

    View details for Web of Science ID 000283184800050

    View details for PubMedID 20921380

  • Nucleic Acid Template and the Risk of a PCR-Induced HIV-1 Drug Resistance Mutation PLOS ONE Varghese, V., Wang, E., Babrzadeh, F., Bachmann, M. H., Shahriar, R., Liu, T., Mappala, S. J., Gharizadeh, B., Fessel, W. J., Katzenstein, D., Kassaye, S., Shafer, R. W. 2010; 5 (6)


    The HIV-1 nucleoside RT inhibitor (NRTI)-resistance mutation, K65R confers intermediate to high-level resistance to the NRTIs abacavir, didanosine, emtricitabine, lamivudine, and tenofovir; and low-level resistance to stavudine. Several lines of evidence suggest that K65R is more common in HIV-1 subtype C than subtype B viruses.We performed ultra-deep pyrosequencing (UDPS) and clonal dideoxynucleotide sequencing of plasma virus samples to assess the prevalence of minority K65R variants in subtype B and C viruses from untreated individuals. Although UDPS of plasma samples from 18 subtype C and 27 subtype B viruses showed that a higher proportion of subtype C viruses contain K65R (1.04% vs. 0.25%; p<0.001), limiting dilution clonal sequencing failed to corroborate its presence in two of the samples in which K65R was present in >1.5% of UDPS reads. We therefore performed UDPS on clones and site-directed mutants containing subtype B- and C-specific patterns of silent mutations in the conserved KKK motif encompassing RT codons 64 to 66 and found that subtype-specific nucleotide differences were responsible for increased PCR-induced K65R mutation in subtype C viruses.This study shows that the RT KKK nucleotide template in subtype C viruses can lead to the spurious detection of K65R by highly sensitive PCR-dependent sequencing techniques. However, the study is also consistent with the subtype C nucleotide template being inherently responsible for increased polymerization-induced K65R mutations in vivo.

    View details for DOI 10.1371/journal.pone.0010992

    View details for Web of Science ID 000278465900010

    View details for PubMedID 20539818

  • Panel of Prototypical Raltegravir-Resistant Infectious Molecular Clones in a Novel Integrase-Deleted Cloning Vector ANTIMICROBIAL AGENTS AND CHEMOTHERAPY Reuman, E. C., Bachmann, M. H., Varghese, V., Fessel, W. J., Shafer, R. W. 2010; 54 (2): 934-936


    We created an HIV-1 cloning vector, pNL4.3DeltaIN, to generate recombinant infectious molecular clones for analysis of patient-derived HIV-1 integrase coding regions. Using this vector, we constructed a panel of clinically derived viruses with the canonical patterns of raltegravir resistance mutations and submitted the panel to the NIH AIDS Research and Reference Reagent Program. Investigational integrase inhibitors with activity against these clones are likely to retain activity against the most clinically relevant raltegravir-resistant variants.

    View details for DOI 10.1128/AAC.01345-09

    View details for Web of Science ID 000273860600051

    View details for PubMedID 19917747

  • Minority Variants Associated with Transmitted and Acquired HIV-1 Nonnucleoside Reverse Transcriptase Inhibitor Resistance: Implications for the Use of Second-Generation Nonnucleoside Reverse Transcriptase Inhibitors JAIDS-JOURNAL OF ACQUIRED IMMUNE DEFICIENCY SYNDROMES Varghese, V., Shahriar, R., Rhee, S., Liu, T., Simen, B. B., Egholm, M., Hanczaruk, B., Blake, L. A., Gharizadeh, B., Babrzadeh, F., Bachmann, M. H., Fessel, W. J., Shafer, R. W. 2009; 52 (3): 309-315


    K103N, the most common nonnucleoside reverse transcriptase inhibitor (NNRTI)-resistant mutation in patients with transmitted resistance and in patients receiving a failing NNRTI-containing regimen, is fully susceptible to the new NNRTI, etravirine. Therefore, we sought to determine how often NNRTI-resistant mutations other than K103N occur as minority variants in plasma samples for which standard genotypic resistance testing detects K103N alone.We performed ultradeep pyrosequencing (UDPS; 454 Life Sciences a Roche Company, Branford, CT) of plasma virus samples from 13 treatment-naive and 20 NNRTI-experienced patients in whom standard genotypic resistance testing revealed K103N but no other major NNRTI-resistance mutations.Samples from 0 of 13 treatment-naive patients vs. 7 of 20 patients failing an NNRTI-containing regimen had minority variants with major etravirine-associated NNRTI-resistant mutations (P = 0.03, Fisher exact test): Y181C (7.0%), Y181C (3.6%) + G190A (3.2%), L100I (14%), L100I (32%) + 190A (5.4%), K101E (3.8%) + G190A (4.9%), K101E (4.0%) + G190S (4.8%), and G190S (3.1%).In treatment-naive patients, UDPS did not detect additional major NNRTI-resistant mutations suggesting that etravirine may be effective in patients with transmitted K103N. In NNRTI-experienced patients, UDPS often detected additional major NNRTI-resistant mutations suggesting that etravirine may not be fully active in patients with acquired K103N.

    View details for Web of Science ID 000271202900002

    View details for PubMedID 19734799

  • Human Immunodeficiency Virus Type 1 Isolates with the Reverse Transcriptase (RT) Mutation Q145M Retain Nucleoside and Nonnucleoside RT Inhibitor Susceptibility ANTIMICROBIAL AGENTS AND CHEMOTHERAPY Varghese, V., Mitsuya, Y., Shahriar, R., Bachmann, M. H., Fessel, W. J., Kagan, R. M., Shafer, R. W. 2009; 53 (5): 2196-2198


    Q145M, a mutation in a conserved human immunodeficiency virus type 1 reverse transcriptase (RT) region, was reported to decrease susceptibility to multiple RT inhibitors. We report that Q145M and other Q145 mutations do not emerge with RT inhibitors nor decrease RT inhibitor susceptibility. Q145M should not, therefore, be considered an RT inhibitor resistance mutation.

    View details for DOI 10.1128/AAC.01593-08

    View details for Web of Science ID 000265528700072

    View details for PubMedID 19223644

  • CNOB/ChrR6, a new prodrug enzyme cancer chemotherapy MOLECULAR CANCER THERAPEUTICS Thorne, S. H., Barak, Y., Liang, W., Bachmann, M. H., Rao, J., Contag, C. H., Matin, A. 2009; 8 (2): 333-341


    We report the discovery of a new prodrug, 6-chloro-9-nitro-5-oxo-5H-benzo(a)phenoxazine (CNOB). This prodrug is efficiently activated by ChrR6, the highly active prodrug activating bacterial enzyme we have previously developed. The CNOB/ChrR6 therapy was effective in killing several cancer cell lines in vitro. It also efficiently treated tumors in mice with up to 40% complete remission. 9-Amino-6-chloro-5H-benzo(a)phenoxazine-5-one (MCHB) was the only product of CNOB reduction by ChrR6. MCHB binds DNA; at nonlethal concentration, it causes cell accumulation in the S phase, and at lethal dose, it induces cell surface Annexin V and caspase-3 and caspase-9 activities. Further, MCHB colocalizes with mitochondria and disrupts their electrochemical potential. Thus, killing by CNOB involves MCHB, which likely induces apoptosis through the mitochondrial pathway. An attractive feature of the CNOB/ChrR6 regimen is that its toxic product, MCHB, is fluorescent. This feature proved helpful in in vitro studies because simple fluorescence measurements provided information on the kinetics of CNOB activation within the cells, MCHB killing mechanism, its generally efficient bystander effect in cells and cell spheroids, and its biodistribution. The emission wavelength of MCHB also permitted its visualization in live animals, allowing noninvasive qualitative imaging of MCHB in mice and the tumor microenvironment. This feature may simplify exploration of barriers to the penetration of MCHB in tumors and their amelioration.

    View details for DOI 10.1158/1535-7163.MCT-08-0707

    View details for Web of Science ID 000263397300008

    View details for PubMedID 19190118

  • In vivo analysis of heat-shock-protein-70 induction following pulsed laser irradiation in a transgenic reporter mouse JOURNAL OF BIOMEDICAL OPTICS O'Connell-Rodwell, C. E., Mackanos, M. A., Simanovskii, D., Cao, Y., Bachmann, M. H., Schwettman, H. A., Contag, C. H. 2008; 13 (3)


    Induction of heat shock protein (Hsp) expression appears to correlate with a cytoprotective effect in cultured cells and with improved healing of damaged tissues in animal models and in humans. This family of proteins can also serve as indicators of thermal stress in cases of burn injury or surgical procedures that produce heat. Thus, a rapid in vivo readout for induction of Hsp transcription would facilitate studies of Hsp genes and their encoded proteins as mediators of therapeutic effects and as reporters of thermal damage to tissues. We created a transgenic reporter mouse where expression of luciferase is controlled by the regulatory region of the inducible 70 kDa Hsp, and assessed activation of Hsp70 transcription in live animals in response to rapid, high temperature stresses using in vivo bioluminescence imaging (BLI). This model can be used to noninvasively reveal levels of Hsp70 transcription in living tissues, and has utility in studies of the predictive and protective effects of Hsp70 expression, and of various stress responses in tissues.

    View details for DOI 10.1117/1.2904665

    View details for Web of Science ID 000257951200001

    View details for PubMedID 18601518

  • The impact of regulatory T cells on T-cell immunity following hematopoietic cell transplantation BLOOD Nguyen, V. H., Shashidhar, S., Chang, D. S., Ho, L., Kambham, N., Bachmann, M., Brown, J. M., Negrin, R. S. 2008; 111 (2): 945-953


    Regulatory T cells (Tregs) prevent graft-versus-host disease (GvHD) by inhibiting the proliferation and function of conventional T cells (Tcons). However, the impact of Tregs on T-cell development and immunity following hematopoietic cell transplantation (HCT) is unknown. Using a murine GvHD model induced by Tcons, we demonstrate that adoptive transfer of Tregs leads to (1) abrogration of GvHD, (2) preservation of thymic and peripheral lymph node architecture, and (3) an accelerated donor lymphoid reconstitution of a diverse TCR-Vbeta repertoire. The resultant enhanced lymphoid reconstitution in Treg recipients protects them from lethal cytomegalovirus (MCMV) infection. By contrast, mice that receive Tcons alone have disrupted lymphoid organs from GvHD and remain lymphopenic with a restricted TCR-Vbeta repertoire and rapid death on MCMV challenge. Lymphocytes from previously infected Treg recipients generate secondary response specific to MCMV, indicating long-term protective immunity with transferred Tregs. Thymectomy significantly reduces survival after MCMV challenge in Treg recipients compared with euthymic controls. Our results indicate that Tregs enhance immune reconstitution by preventing GvHD-induced damage of the thymic and secondary lymphoid microenvironment. These findings provide new insights into the role of Tregs in affording protection to lymphoid stromal elements important for T-cell immunity.

    View details for DOI 10.1182/blood-2007-07-103895

    View details for Web of Science ID 000252458700071

    View details for PubMedID 17916743

  • Social support and maladaptive coping as predictors of the change in physical health symptoms among persons living with HIV/AIDS AIDS PATIENT CARE AND STDS Ashton, E., Vosvick, M., Chesney, M., Gore-Felton, C., Koopman, C., O'Shea, K., Maldonado, J., Bachmann, M. H., Israelski, D., Flamm, J., Spiegel, D. 2005; 19 (9): 587-598


    This study examined social support and maladaptive coping as predictors of HIV-related health symptoms. Sixty-five men and women living with HIV/AIDS completed baseline measures assessing coping strategies, social support, and HIV-related health symptoms. The sample was primarily low-income and diverse with respect to gender, ethnicity, and sexual orientation. Three, 6, and 12 months after completing baseline assessments, physical health symptoms associated with HIV disease were assessed. After controlling for demographic characteristics, CD4 T-cell count, and baseline HIV-related health symptoms, individuals reporting lower increase in HIV-related health symptoms used less venting (expressing emotional distress) as a strategy for coping with HIV. However, when satisfaction with social support was added to the model, the use of this coping strategy was no longer significant, and individuals reporting more satisfying social support were more likely to report lower increase in their HIV-related health symptoms, suggesting that social support is a robust predictor of health outcomes over time independent of coping style and baseline medical status. These findings provide further evidence that social support can buffer deleterious health outcomes among individuals with a chronic illness. Future research needs to examine mediating pathways that can explain this relationship.

    View details for Web of Science ID 000232058300006

    View details for PubMedID 16164385

  • Molecular imaging using labeled donor tissues reveals patterns of engraftment, rejection, and survival in transplantation TRANSPLANTATION Cao, Y. A., Bachmann, M. H., Beilhack, A., Yang, Y., Tanaka, M., Swijnenburg, R. J., Reeves, R., Taylor-Edwards, C., Schulz, S., Doyle, T. C., Fathman, C. G., Robbins, R. C., Herzenberg, L. A., Negrin, R. S., Contag, C. H. 2005; 80 (1): 134-139


    Tissue regeneration and transplantation of solid organs involve complex processes that can only be studied in the context of the living organism, and methods of analyzing these processes in vivo are essential for development of effective transplantation and regeneration procedures. We utilized in vivo bioluminescence imaging (BLI) to noninvasively visualize engraftment, survival, and rejection of transplanted tissues from a transgenic donor mouse that constitutively expresses luciferase. Dynamic early events of hematopoietic reconstitution were accessible and engraftment from as few as 200 transplanted whole bone marrow (BM) cells resulted in bioluminescent foci in lethally irradiated, syngeneic recipients. The transplantation of autologous pancreatic Langerhans islets and of allogeneic heart revealed the tempo of transplant degeneration or immune rejection over time. This imaging approach is sensitive and reproducible, permits study of the dynamic range of the entire process of transplantation, and will greatly enhance studies across various disciplines involving transplantation.

    View details for DOI 10.1097/01.TP.0000164347.50559.A3

    View details for Web of Science ID 000230473800023

    View details for PubMedID 16003245

  • MYC inactivation uncovers pluripotent differentiation and tumour dormancy in hepatocellular cancer NATURE Shachaf, C. M., Kopelman, A. M., Arvanitis, C., Karlsson, A., Beer, S., Mandl, S., Bachmann, M. H., Borowsky, A. D., Ruebner, B., Cardiff, R. D., Yang, Q. W., BISHOP, J. M., Contag, C. H., Felsher, D. W. 2004; 431 (7012): 1112-1117


    Hepatocellular carcinoma is generally refractory to clinical treatment. Here, we report that inactivation of the MYC oncogene is sufficient to induce sustained regression of invasive liver cancers. MYC inactivation resulted en masse in tumour cells differentiating into hepatocytes and biliary cells forming bile duct structures, and this was associated with rapid loss of expression of the tumour marker alpha-fetoprotein, the increase in expression of liver cell markers cytokeratin 8 and carcinoembryonic antigen, and in some cells the liver stem cell marker cytokeratin 19. Using in vivo bioluminescence imaging we found that many of these tumour cells remained dormant as long as MYC remain inactivated; however, MYC reactivation immediately restored their neoplastic features. Using array comparative genomic hybridization we confirmed that these dormant liver cells and the restored tumour retained the identical molecular signature and hence were clonally derived from the tumour cells. Our results show how oncogene inactivation may reverse tumorigenesis in the most clinically difficult cancers. Oncogene inactivation uncovers the pluripotent capacity of tumours to differentiate into normal cellular lineages and tissue structures, while retaining their latent potential to become cancerous, and hence existing in a state of tumour dormancy.

    View details for DOI 10.1038/nature03043

    View details for Web of Science ID 000224730800044

    View details for PubMedID 15475948

  • A genetic reporter of thermal stress defines physiologic zones over a defined temperature range FASEB JOURNAL O'Connell-Rodwell, C. E., Shriver, D., Simanovskii, D. M., Mcclure, C., Cao, Y. A., Zhang, W. S., Bachmann, M. H., Beckham, J. T., Jansen, E. D., Palanker, D., Schwettman, H. A., Contag, C. H. 2004; 18 (2): 264-271


    We define five unique cellular responses to thermal stress using a reporter construct generated using the stress-inducible promoter from the gene encoding a murine 70 kDa heat shock protein (Hsp70A.1) to express luciferase (luc). Thermal stress was delivered over a range of temperatures (42-68 degrees C) for 5 s to 20 min and luciferase activity was measured in live cells using a cooled CCD camera as a measure of reporter gene transcription. Reporter gene expression was assessed every 2 h for 10 h, and at 24 h post-stress. Expression patterns were validated for selected temperatures. A transition zone where cells lose the ability to produce light and beyond which >50% of cells die was observed to occur within a narrow (2.5 degrees C) temperature window. Although luc and hsp70 mRNA levels in this transition zone were high, there were reduced levels of Luc and Hsp70 protein and ATP levels. Cells treated at these temperatures recovered the ability to produce light in response to a secondary stress at 30 h. This Hsp70-luc reporter gene construct may be useful for defining zones of physiologic responses and assessing collateral thermal damage generated during treatment of biological tissue with lasers and other sources of heat.

    View details for DOI 10.1096/fj.03-0585com

    View details for Web of Science ID 000220425000006

    View details for PubMedID 14769820

  • Shifting foci of hematopoiesis during reconstitution from single stem cells PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Cao, Y. A., Wagers, A. J., Beilhack, A., Dusich, J., Bachmann, M. H., Negrin, R. S., Weissman, I. L., Contag, C. H. 2004; 101 (1): 221-226


    To reveal the early events and dynamics of hematopoietic reconstitution in living animals in real-time, we used bioluminescence imaging to monitor engraftment from single luciferase-labeled hematopoietic stem cells (HSC) in irradiated recipients. Transplanted HSC generated discrete foci in the spleen and bone marrow (BM), at a frequency that correlated with BM compartment size. Initially detected foci could expand locally, seed other sites in BM or spleen, and/or recede with different kinetics. These studies reveal dynamic and variable patterns of engraftment from highly purified HSC and indicate that the final overall contribution of individual HSC to hematopoietic chimerism does not depend on the specific site of initial engraftment and expansion.

    View details for Web of Science ID 000187937200042

    View details for PubMedID 14688412

  • In vivo dynamics of hematopoietic reconstitution from purified stem and progenitor cells. Wagers, A. J., Cao, Y. A., Beilhack, A., Dusich, J., Bachmann, M. H., Negrin, R. S., Weissman, I. L., Contag, C. H. AMER SOC HEMATOLOGY. 2003: 332A-332A
  • Alternative therapies: a common practice among men and women living with HIV. journal of the Association of Nurses in AIDS Care : JANAC Gore-Felton, C., Vosvick, M., Power, R., Koopman, C., Ashton, E., Bachmann, M. H., Israelski, D., Spiegel, D. 2003; 14 (3): 17-27


    This study examined the prevalence and factors associated with alternative therapy use in an ethnically diverse, gender-balanced sample of persons living with HIV/AIDS. More than two thirds (67%) of the participants who were taking HIV-related medications were also taking an alternative supplement. Half of the sample (50%) reported that they took one or more multivitamins, 17% reported using mineral supplements, 12% reported using Chinese herbs, and 12% reported using botanicals. Substantial proportions of the sample also reported using acupuncture (31%), massage (23%), and meditation (28%) to specifically treat HIV-related symptoms. Women were four times more likely to use alternative therapies than men. Also, Caucasians were nearly four times more likely to use alternative treatments compared to other ethnic groups. The results of this study indicate a strong need to assess individual patients' use of alternative treatment approaches as well as to further investigate their efficacy among HIV-positive patients.

    View details for PubMedID 12800809

  • Revealing lymphoma growth and the efficacy of immune cell therapies using in vivo bioluminescence imaging BLOOD Edinger, M., Cao, Y. A., Verneris, M. R., Bachmann, M. H., Contag, C. H., Negrin, R. S. 2003; 101 (2): 640-648


    Cancer therapeutics have achieved success in the treatment of a variety of malignancies, however, relapse of disease from small numbers of persistent tumor cells remains a major obstacle. Advancement of treatment regimens that effectively control minimal residual disease and prevent relapse would be greatly accelerated if sensitive and noninvasive assays were used to quantitatively assess tumor burden in animal models of minimal residual disease that are predictive of the human response. In vivo bioluminescence imaging (BLI) is an assay for the detection of small numbers of cells noninvasively and enables the quantification of tumor growth within internal organs. Fusion genes that encode bioluminescent and fluorescent reporter proteins effectively couple the powerful in vivo capabilities of BLI with the subset-discriminating capabilities of fluorescence-activated cell sorting. We labeled 2 murine lymphoma cell lines with dual function reporter genes and monitored radiation and chemotherapy as well as immune-based strategies that employ the tumorcidal activity of ex vivo-expanded CD8(+) natural killer (NK)-T cells. Using BLI we were able to visualize the entire course of malignant disease including engraftment, expansion, metastasis, response to therapy, and unique patterns of relapse. We also labeled the effector NK-T cells and monitored their homing to the sites of tumor growth followed by tumor eradication. These studies reveal the efficacy of immune cell therapies and the tempo of NK-T cell trafficking in vivo. The complex cellular processes in bone marrow transplantation and antitumor immunotherapy, previously inaccessible to investigation, can now be revealed in real time in living animals.

    View details for DOI 10.1182/blood-2002-06-1751

    View details for Web of Science ID 000180384800039

    View details for PubMedID 12393519

  • Sleep disturbances in women with metastatic breast cancer. breast journal Koopman, C., Nouriani, B., Erickson, V., Anupindi, R., Butler, L. D., Bachmann, M. H., Sephton, S. E., Spiegel, D. 2002; 8 (6): 362-370


    We examined sleeping problems in women with metastatic breast cancer in relation to depression, social support, and salivary cortisol. Ninety-seven women with metastatic breast cancer were drawn from a larger study on the effects of group therapy on quality of life and survival. This study is based on the baseline assessments conducted prior to randomization into treatment conditions. Sleep, depression symptoms, and social support were assessed by self-reporting. Cortisol was assessed from saliva samples taken over a 3-day period. Medical status and demographic characteristics were also examined in relation to each sleep variable in multiple regression analysis. Most women (63%) reported one or more types of sleep disturbance and 37% reported using sleeping pills in the previous 30 days. Problems with falling to sleep were significantly related to greater pain and depressive symptoms. Problems of waking during the night were significantly associated with greater depression and less education. Problems in waking/getting up were significantly associated with greater depressive symptoms and less social support. Sleepiness during the day was not significantly related to the variables in the regression model. Fewer hours of sleep were significantly associated with metastases to the bone, higher depressive symptoms, and more social support. Women who reported sleeping 9 or more hours per night, compared to those who reported a moderate amount of sleep (6.5-8.5 hours), had significantly lower 9 p.m. cortisol levels. Use of sleeping pills was more frequent among women reporting greater pain and depressive symptoms. These results suggest that women with metastatic breast cancer who are at higher risk for having sleeping problems are those who are less educated, in pain, depressed, have bony metastases, or lack social support.

    View details for PubMedID 12390359

  • Advancing animal models of neoplasia through in vivo bioluminescence imaging EUROPEAN JOURNAL OF CANCER Edinger, M., Cao, Y. A., Hornig, Y. S., Jenkins, D. E., Verneris, M. R., Bachmann, M. H., Negrin, R. S., Contag, C. H. 2002; 38 (16): 2128-2136


    Malignant disease is the final manifestation of complex molecular and cellular events leading to uncontrolled cellular proliferation and eventually tissue destruction and metastases. While the in vitro examination of cultured tumour cells permits the molecular dissection of early pathways in tumorigenesis on cellular and subcellular levels, only interrogation of these processes within the complexity of organ systems of the living animal can reveal the full range of pathophysiological changes that occur in neoplastic disease. Such analyses require technologies that facilitate the study of biological processes in vivo, and several approaches have been developed over the last few years. These strategies, in the nascent field of in vivo molecular and cellular imaging, combine molecular biology with imaging modalities as a means to real-time acquisition of functional information about disease processes in living systems. In this review, we will summarise recent developments in in vivo bioluminescence imaging (BLI) and discuss the potential of this imaging strategy for the future of cancer research.

    View details for Web of Science ID 000179242500008

    View details for PubMedID 12387838

  • Bioluminescent indicators for in vivo measurements of gene expression TRENDS IN BIOTECHNOLOGY O'Connell-Rodwell, C. E., Burns, S. M., Bachmann, M. H., Contag, C. H. 2002; 20 (8): S19-S23
  • Visualization of tumor and effector cell trafficking in hematologic malignancies Negrin, R., Edinger, M., Verneris, M., Cao, Y. A., Bachmann, M., Contag, C. ELSEVIER SCIENCE INC. 2002: 105-105
  • Visualization of tumor growth and response to NK-T cell based immunotherapy using bioluminescence ANNALS OF HEMATOLOGY Negrin, R. S., Edinger, M., Verneris, M., Cao, Y. A., Bachmann, M., Contag, C. H. 2002; 81: S44-S45

    View details for Web of Science ID 000178591900015

    View details for PubMedID 12611073

  • Advances in vivo bioluminescence imaging of gene expression ANNUAL REVIEW OF BIOMEDICAL ENGINEERING Contag, C. H., Bachmann, M. H. 2002; 4: 235-260


    To advance our understanding of biological processes as they occur in living animals, imaging strategies have been developed and refined that reveal cellular and molecular features of biology and disease in real time. One rapid and accessible technology for in vivo analysis employs internal biological sources of light emitted from luminescent enzymes, luciferases, to label genes and cells. Combining this reporter system with the new generation of charge coupled device (CCD) cameras that detect the light transmitted through the animal's tissues has opened the door to sensitive in vivo measurements of mammalian gene expression in living animals. Here, we review the development and application of this imaging strategy, in vivo bioluminescence imaging (BLI), together with in vivo fluorescence imaging methods, which has enabled the real-time study of immune cell trafficking, of various genetic regulatory elements in transgenic mice, and of in vivo gene transfer. BLI has been combined with fluorescence methods that together offer access to in vivo measurements that were not previously available. Such studies will greatly facilitate the functional analysis of a wide range of genes for their roles in health and disease.

    View details for DOI 10.1146/annurev.bioeng.4.111901.093336

    View details for Web of Science ID 000177827800011

    View details for PubMedID 12117758

  • Bioluminescence imaging of lymphocyte trafficking in vivo EXPERIMENTAL HEMATOLOGY Hardy, J., Edinger, M., Bachmann, M. H., Negrin, R. S., Fathman, C. G., Contag, C. H. 2001; 29 (12): 1353-1360


    Lymphocytes are highly mobile cells that travel throughout the body in response to a tremendous variety of stimuli. Revealing lymphocyte trafficking patterns in vivo is necessary for a complete understanding of immune function, as well as cell-cell and cell-tissue interactions in immune development and in response to insult. Although the location of cell populations in various tissues at any given point in time may be revealed by techniques such as flow cytometry and immunofluorescence, these methods are not readily amenable to the assessment of dynamic cell migration patterns in vivo. In the past 5 years, technologies for imaging molecular and cellular changes in living animals have advanced to a point where it is possible to reveal the migratory paths of these vitally important cells. Here, we review one advancement in cellular imaging, in vivo bioluminescence imaging, which addresses the problem of lymphocyte tracking. This imaging strategy has the potential to elucidate the temporal patterns of immune responses and the spatial distribution of lymphocytes within the body.

    View details for Web of Science ID 000172949100001

    View details for PubMedID 11750093

  • Real time in vivo imaging of syngeneic and allogeneic T cells after bone marrow transplantation. Edinger, M., Verneris, M. R., Cao, Y., Bachmann, M., Contag, C. H., Negrin, R. S. AMER SOC HEMATOLOGY. 2001: 384A-384A
  • Monitoring the anti tumor activity of expanded CD8(+) NKT cells after allogeneic bone marrow transplantation using bioluminescent imaging. Edinger, M., Verneris, M. R., Cao, Y., Bachmann, M., Contag, C. H., Negrin, R. S. AMER SOC HEMATOLOGY. 2001: 433A-433A
  • Antigen-specific T cell-mediated gene therapy in collagen-induced arthritis JOURNAL OF CLINICAL INVESTIGATION Nakajima, A., Seroogy, C. M., Sandora, M. R., Tarner, I. H., Costa, G. L., Taylor-Edwards, C., Bachmann, M. H., Contag, C. H., Fathman, C. G. 2001; 107 (10): 1293-1301


    Autoantigen-specific T cells have tissue-specific homing properties, suggesting that these cells may be ideal vehicles for the local delivery of immunoregulatory molecules. We tested this hypothesis by using type II collagen-specific (CII-specific) CD4(+) T hybridomas or primary CD4(+) T cells after gene transfer, as vehicles to deliver an immunoregulatory protein for the treatment of collagen-induced arthritis (CIA), a mouse model of rheumatoid arthritis (RA). CII-specific T cells or hybridomas were transduced using retroviral vectors to constitutively express the IL-12 antagonist, IL-12 p40. Transfer of engineered CD4(+) T cells after immunization significantly inhibited the development of CIA, while cells transduced with vector control had no effect. The beneficial effect on CIA of IL-12 p40-transduced T cells required TCR specificity against CII, since transfer of T cells specific for another antigen producing equivalent amounts of IL-12 p40 had no effect. In vivo cell detection using bioluminescent labels and RT-PCR showed that transferred CII-reactive T-cell hybridomas accumulated in inflamed joints in mice with CIA. These results indicate that the local delivery of IL-12 p40 by T cells inhibited CIA by suppressing autoimmune responses at the site of inflammation. Modifying antigen-specific T cells by retroviral transduction for local expression of immunoregulatory proteins thus offers a promising strategy for treating RA.

    View details for Web of Science ID 000168867400014

    View details for PubMedID 11375419

  • Visualizing leukemia & lymphoma cell homing and quantification of tumor burden in response to therapy in living animals. Edinger, M., Verneris, M. R., Cao, Y., Bachmann, M. H., Costa, G. L., Contag, C. H., Negrin, R. S. AMER SOC HEMATOLOGY. 2000: 123A-123A
  • CONSERVED V3 LOOP SEQUENCES AND TRANSMISSION OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 AIDS RESEARCH AND HUMAN RETROVIRUSES Shpaer, E. G., Delwart, E. L., Kuiken, C. L., Goudsmit, J., Bachmann, M. H., Mullins, J. I. 1994; 10 (12): 1679-1684


    The third variable region (V3) of the surface glycoprotein (gp120) of envelope sequence subtype B, type 1 human immunodeficiency virus (HIV-1B), is highly variable among T cell line-adapted viruses and syncytium-inducing HIV-1-B isolates. Here we analyze the V3 region sequences from 93 individuals close to the time of seroconversion and show that the cysteine-bridged V3 loop, which also encompasses a major neutralizing determinant, is highly conserved, whereas sequences immediately surrounding the loop are similarly divergent in all HIV-1-B strains. Viruses with this conserved V3 loop have been reported to be more resistant to antibody-mediated neutralization than T cell-adapted viruses with divergent V3 sequences. We hypothesize, therefore, that on transmission from a donor to a recipient, virions inherently more resistant to neutralization by donor antibodies have a greater chance of initiating infection than those more sensitive to neutralization. This might explain the conservation of V3 early in infection and has implications for the design of HIV vaccines.

    View details for Web of Science ID A1994PZ08800013

    View details for PubMedID 7888227



    To identify HIV-1 envelope sequence subtypes in infected individuals from the Russian Federation and Belarus.A cohort of children infected after exposure to non-sterile needles during the 1988-1989 HIV-1 epidemic in southern Russia (n = 20) and HIV-1-seropositive individuals from Russia (n = 1) and Belarus (n = 7) infected via sexual transmission.DNA samples derived from peripheral blood mononuclear cells were analysed for their HIV-1 genotypes by the heteroduplex mobility assay (HMA). The 1.3 kilobase-pair env gene fragments encoding a portion of gp120 were amplified by nested polymerase chain reaction, cloned and sequenced. The env sequences derived from these patients were aligned and phylogenetic neighbour-joining and maximum parsimony-derived trees generated.The env sequences derived from eight individuals infected in Russia and Belarus belong to subtype A (one), B (four), C (two), and D (one). Sequences derived from children, infected during parenteral manipulations in southern Russia, and one mother were closely related, but highly divergent, as a group, from all prototypic strains (genetic divergence, 17.2-22.9%). However, they clustered together with env sequences of the V1525 and LBV21-7 isolates from Gabon, recently described to be members of a new HIV-1 env subtype G.Extensive heterogeneity of HIV-1 subtypes was evident in the Russian Federation and Belarus. Our data also support the existence of an HIV-1 env genetic subtype G, and such isolates are now apparently present on both the African and European continents. These variants were identified through V3 peptide enzyme-linked immunosorbent assay screening and subsequent HMA analysis. The combination of these techniques represents a model for screening HIV variants within a large population.

    View details for Web of Science ID A1994PU18500002

    View details for PubMedID 7888112

  • RAPID GENETIC-CHARACTERIZATION OF HIV TYPE-1 STRAINS FROM 4 WORLD-HEALTH-ORGANIZATION-SPONSORED VACCINE EVALUATION SITES USING A HETERODUPLEX MOBILITY ASSAY AIDS RESEARCH AND HUMAN RETROVIRUSES Bachmann, M. H., Delwart, E. L., Shpaer, E. G., Lingenfelter, P., Singal, R., Mullins, J. I., Osmanov, S., Belsey, E. M., Heyward, W., Esparza, J., GALVAOCASTRO, B., VANDEPERRE, P., Karita, E., Wasi, C., SEMPALA, S., Tugume, B., Biryahwaho, B., RUBSAMENWAIGMANN, H., VONBRIESEN, H., Esser, R., Grez, M., Holmes, H., Newberry, A., Ranjbar, S., Tomlinson, P., BRADAC, J., MCCUTCHAN, F., LOUWAGIE, J., Hegerich, P., LOPEZGALINDEZ, C., Olivares, I., Dopazo, J., Goudsmit, J., deWolf, F., Hahn, B. H., Gao, F., Yue, L., Saragosti, S., Schochetman, G., Kalish, M., LUO, C. C., George, R., Pau, C. P., Weber, J., CHEINGSONGPOPOV, R., Kaleebu, P., Nara, P., FENYO, E. M., Albert, J., Myers, G., Korber, B. 1994; 10 (11): 1345-1353


    To assist in the preparation for the testing of vaccines against human immunodeficiency virus (HIV) we, as part of the World Health Organization Network for HIV Isolation and Characterization (WHO-NHIC), evaluated the genotypic variation of HIV-1 in cohorts from Brazil, Rwanda, Thailand, and Uganda. Here we report the results from a pilot study of 65 HIV-1-infected individuals. In all cases in which viral envelope gene fragments could be amplified by polymerase chain reaction, subtypes could be assigned using a heteroduplex mobility assay (HMA)1 by comparison with HIV-1 strains representing six HIV-1 envelope subtypes. All subtype classifications matched those found by envelope gene sequencing. Phylogenetic relationships were further clarified by heteroduplex formation between samples within each subtype. A relatively homogeneous subtype E virus population predominated over subtype B viruses in the sample set from Thailand. Viruses from the other countries were also limited to one or two subtypes but were more divergent within each subtype. All samples from Rwanda (13/13) and some from Uganda (3/16) were of subtype A; all Brazilian samples were of subtype B, except for one belonging to subtype C; most samples from Uganda (13/16) clustered with the subtype D. Analysis by HMA is therefore applicable for screening of HIV-1 genotypes in countries under consideration for large-scale vaccine trials. It should be generally useful when samples containing at least one variable genetic locus need to be rapidly classified by genotype and/or analyzed for epidemiological clustering.

    View details for Web of Science ID A1994PV99600004



    Retrovirus infection is initiated by the binding of virus envelope glycoprotein to a receptor molecule present on cell membranes. To characterize a receptor for feline leukemia virus (FeLV), we extensively purified the viral envelope glycoprotein, gp70, from culture supernatants of FeLV-61E (subgroup A)-infected cells by immunoaffinity chromatography. Binding of purified 125I-labeled gp70 to the feline T-cell line 3201 was specific and saturable, and Scatchard analysis revealed a single class of receptor binding sites with an average number of 1.6 x 10(5) receptors per cell and an apparent affinity constant (Ka) of 1.15 x 10(9) M-1. Cross-linking experiments identified a putative gp70-receptor complex of 135 to 140 kDa. Similarly, coprecipitation of 125I-labeled cell surface proteins with purified gp70 and a neutralizing but noninterfering anti-gp70 monoclonal antibody revealed a single cell surface protein of approximately 70 kDa. These results indicate that FeLV-A binds to feline T cells via a 70-kDa cell surface protein, its presumptive receptor.

    View details for Web of Science ID A1992HU59900052

    View details for PubMedID 1316477