Alex Sigal

Professor Alex Sigal is member of faculty at the Africa Health Research Institute and associate professor at the University of KwaZulu-Natal. Alex’s core research direction is understanding SARS-CoV-2 evolution, and long term-persistence in the presence and absence of HIV co-infection. He is particularly interested in SARS-CoV-2 variants, the effects, antibody neutralisation, and cellular transmission of SARS-CoV-2. Alex’s laboratory was the first to isolate the live beta variant, which was made available for research worldwide.

Alex has a PhD in systems biology from the Weizmann Institute and was a postdoctoral fellow with David Baltimore at the California Institute of Technology, where he worked on HIV cell-to-cell spread and its effects on antiretroviral therapy. He established his laboratory at AHRI in collaboration with the Max Planck Institute for Infection Biology in Berlin, where his interests included neuro HIV, HIV evolution, and TB. After the start of the Covid-19 pandemic, his group at AHRI pivoted to SARS-CoV-2 research, establishing a longitudinal observational cohort to investigate the effects of HIV co-infection on Covid-19 outcomes and the virological and serological techniques for isolating and testing SARS-CoV-2 variants.

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Click here for a full list of publications.

Alex Sigal

Sigal Group

The Sigal group was the first globally to isolate, characterize, and report on the Omicron variant and its escape from previous immunity.

The group works on emerging pathogens and their interaction with immune suppression caused by poorly controlled HIV infection. In their work on SARS-CoV-2, the Sigal group investigated the evolution and immune escape of variants of concern first detected in South Africa. This included the first isolation of the live Beta variant virus and the first description globally of Omicron variant escape from previous immunity.

The group continues to investigate evolution of SARS-CoV-2 and was the first to show the evolution of immune escape in long-term SARS-CoV-2 infection in immunosuppression because of advanced HIV disease.

Meet the Team

Khadija Khan - Sigal Group

Khadija Khan

Laboratory manager

Khadija holds a masters degree in Applied Sciences from Durban University of Technology. Khadija previously managed the AHRI Biorepository before moving to the Sigal Lab. Her current work focuses largely on the SARS-CoV-2 longitudinal study. This includes managing a team dedicated to testing vaccine samples, performing live virus neutralization assays (LVNA) of SARS-CoV-2 as well as other high-throughput experimental pipelines for SARS-CoV-2 application.

Yashica Ganga - Sigal Group

Yashica Ganga

Laboratory supervisor

Yashica Ganga holds a Masters degree in Medical Science (Physiology) from UKZN. Her work is in the field of HIV and HIV Associated Neurocognitive Diseases, namely HIV Associated Dementia. She is currently working on drug sensitivity in HIV cell-to-cell spread in primary cell lines. Her other duties include processing and storage of clinical samples, administrative duties, general lab duties and routine BSL3 and BSL2 maintenance and upkeep.

Mallory Bernstein  - Sigal Group

Mallory Bernstein

Laboratory data supervisor

Mallory is a former US Fulbright Scholar and holds a Master’s degree in African Studies with Health from University College London. Previous work at AHRI consisted of time-lapse microscopy image analysis of Mtb-infected human macrophages and HIV ART adherence in dried blood spots by LC-MS/MS. Her current work in Sigal Lab focuses on data analysis for the SARS-CoV-2 longitudinal cohort study. Her other duties include statistical analysis, data management, computer processing, general lab duties, maintenance, and upkeep.

Zesuliwe Jule  - Sigal Group

Zesuliwe Jule

Laboratory technologist

Zesuliwe completed her masters degree in Medical Science, cum laude (Immunology and Virology) from University of KwaZulu-Natal. Her research focused on immune response to HIV-1 infection in people with low neutrophil counts and Duffy antigen receptor for chemokine (DARC) polymorphism. Zesuliwe previously worked as a research intern at South African Medical Research Council and as Laboratory Technologist at HIV Pathogenesis Programme. Her current work includes processing and storage of specimens, maintenance of BSL2 and BSL3 and performing laboratory experiments pertaining to neutralisation of SARS-CoV-2

Kajal Reedoy  - Sigal Group

Kajal Reedoy

Laboratory technologist

Kajal completed her masters degree in Medical Microbiology at the University of KwaZulu-Natal, focusing on Mycobacterium tuberculosis metabolomics. Her current duties include the processing and storing of clinical samples, propagation of host cell lines, SARS-CoV-2 sample processing and live virus neutralisation assays, as well as general BSL2 and BSL3 maintenance.

Selected Recent Publications

Cele, S., Jackson, L., Khoury, D. S., Khan, K., Moyo-Gwete, T., Tegally, H., San, J. E., Cromer, D., Scheepers, C., Amoako, D. G., Karim, F., Bernstein, M., Lustig, G., Archary, D., Smith, M., Ganga, Y., Jule, Z., Reedoy, K., Hwa, S. H., Giandhari, J., Blackburn, J. M., Gosnell, B. I., Abdool Karim, S. S., Hanekom, W., von Gottberg, A., Bhiman, J. N., Lessells, R. J., Moosa, M. S., Davenport, M. P., de Oliveira, T., Moore, P. L. & Sigal, A. (2022). Omicron extensively but incompletely escapes Pfizer BNT162b2 neutralization. Nature 602, 654–656 .

Cele, S., Karim, F., Lustig, G., San, J. E., Hermanus, T., Tegally, H., Snyman, J., Moyo-Gwete, T., Wilkinson, E., Bernstein, M., Khan, K., Hwa, S. H., Tilles, S. W., Singh, L., Giandhari, J., Mthabela, N., Mazibuko, M., Ganga, Y., Gosnell, B. I., Karim, S. S. A., Hanekom, W., Van Voorhis, W. C., Ndung’u, T., Lessells, R. J., Moore, P. L., Moosa, M. S., de Oliveira, T. & Sigal, A. (2022) . SARS-CoV-2 prolonged infection during advanced HIV disease evolves extensive immune escape. Cell Host & Microbe, Volume 30, Issue 2, 154 - 162.e5.

Khan, K., Karim, F., Cele, S., Reedoy, K., San, J. E., Lustig, G., Tegally, H., Rosenberg, Y., Bernstein, M., Jule, Z., Ganga, Y., Ngcobo, N., Mazibuko, M., Mthabela, N., Mhlane, Z., Mbatha, N., Miya, Y., Giandhari, J., Ramphal, Y., Naidoo, T., Sivro, A., Samsunder, N., Kharsany, A. B. M., Amoako, D., Bhiman, J. N., Manickchund, N., Karim, Q. A., Magula, N., Abdool Karim, S. S., Gray, G., Hanekom, W., von Gottberg, A., Milo, R., Gosnell, B. I., Lessells, R. J., Moore, P. L., de Olveira, T., Moosa, M. S. & Sigal, A. (2022) . Omicron infection enhances Delta antibody immunity in vaccinated persons. Nature 607, 356–359 .

Khan, K., Karim, F., Ganga, Y., Bernstein, M., Jule, Z., Reedoy, K., Cele, S., Lustig, G., Amoako, D., Wolter, N., Samsunder, N., Sivro, A., San, J. E., Giandhari, J., Tegally, H., Pillay, S., Naidoo, Y., Mazibuko, M., Miya, Y., Ngcobo, N., Manickchund, N., Magula, N., Karim, Q. A., von Gottberg, A., Abdool Karim, S. S., Hanekom, W., Gosnell, B. I., Lessells, R. J., de Oliveira, T., Moosa, M. S. & Sigal, A. (2022). Omicron BA.4/BA.5 escape neutralizing immunity elicited by BA.1 infection. Nature Communications 13, 4686.

Cele, S., Gazy, I., Jackson, L., Hwa, S.-H., Tegally, H., Lustig, G., Giandhari, J., Pillay, S., Wilkinson, E., Naidoo, Y., Karim, F., Ganga, Y., Khan, K., Bernstein, M., Balazs, A. B., Gosnell, B. I., Hanekom, W., Moosa, M.-Y. S., Abrahams, S., … de Oliveira, T. & Sigal, A. (2021). Escape of SARS-CoV-2 501Y.V2 from neutralization by convalescent plasma. Nature 593, 142–146.