CROI 2024 Abstract eBook

Abstract eBook

Poster Abstracts

uniquely recognizes different Env conformations, efficiently neutralizes 50% of the HIV-1 strains that were resistant to VRC01 and transmitted during the first-in-humans antibody-mediated prevention trial (HVTN 704). VRC01 resistant Envs are incompletely closed based on their sensitivity to cold and on partial sensitivity to antibodies targeting internal epitopes, which are typically occluded in tightly closed Envs. Most VRC01-resistant Envs retain the VRC01 epitope according to VRC01 binding to their gp120 subunit at concentrations that have no significant effect on virus entry, and they exhibit cross resistance to other CD4bs bnAbs that preferentially neutralize the closed Env conformation. Conclusion: Our findings refine current knowledge of Env conformational states and provide guidance for developing new strategies for bnAb immunotherapy and Env-based immunogen design. HIResist: A Database of HIV-1 Resistance to Broadly Neutralizing Antibodies Milind Misra 1 , Jeffy Jeffy 1 , Charis Liao 1 , Stepahnie Pickthorn 1 , Kshitij Wagh 2 , Alon Herschhorn 1 1 University of Minnesota, Minneapolis, MN, USA, 2 Los Alamos National Laboratory, Los Alamos, NM, USA Background: Changing the course of the human immunodeficiency virus type I (HIV-1) pandemic is a high public health priority with approximately 39 million people currently living with HIV-1 (PLWH) and about 1.5 million new infections annually worldwide. Broadly neutralizing antibodies (bnAbs) target vulnerable sites on HIV-1 envelope glycoproteins (Envs), which mediate viral entry, and block the infection of diverse HIV-1 strains. But different mechanics of HIV-1 resistance bnAbs prevent robust application of bnAbs therapeutics and preventative intervention. Here we have developed a specialized database, HIResist (HIV-1 Resistance to bnAbs), to analyze patterns of HIV-1 resistance to different bnAbs. HIResist is freely available online (at hiresist.umn.edu) and is a comprehensive online resource with analysis and visualization tools designed to support the HIV-1 research community, scientists, and the public. Methods: HIResist is a Flask web application with Gunicorn production server and Apache reverse proxy and is written in Python (50%) and HTML/ CSS/JavaScript (50%). Version control is achieved by using private GitHub repositories. The HIResist web server resides on a Linux virtual machine having eight 2.20 GHz Xeon E5-260 processors and 16 GB RAM. Data retrieved from the CATNAP database (www.hiv.lanl.gov) are stored in a periodically updated SQLite database. Results: HIResist is a bioinformatics tool that allows identification of patterns of resistance and mechanisms of HIV-1 escape; comparison of resistant and sensitive HIV-1 strains for each bnAb; identification of resistance and sensitivity signatures associated with specific bnAbs or groups of bnAbs; and visualization of antibody pairs on cross-sensitivity plots. Additionally, several graphical interfaces are available including heatmaps to cluster selected sets of HIV-1 strains and antibodies, and alignment tools with output displayed in a standard HIResist format, and visualization of resistance/sensitivity signatures of HIV-1 Envs. Conclusion: In addition to the tools mentioned previously, we continue to develop HIResist and plan to add several new interfaces including tools for comparison of bnAb resistance/sensitivity in HIV-1 strains from different populations of PLWH (e.g., drug users or elite controllers) and tools for assessment of emerging HIV-1 strains. HIResist is being developed to encourage engagement and exploration without the need for programming expertise of these highly relevant data by the broader scientific community.

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New HIV-1 Cell-Cell Transmission Assay Identifies Cell Type Dependency of PG9 And P16 Neutralization Dmitriy Mazurov , Alon Herschhorn University of Minnesota, Minneapolis, MN, USA Background: HIV-1 efficiently replicates in vivo by direct transmission from infected to uninfected CD4+ T cells, which is highly resistant to broadly neutralizing antibodies (bnAbs). But an accurate and sensitive measurement of HIV-1 transmission between cells remains challenging Methods: We developed an ultrasensitive HIV-1 cell-to-cell transmission assay that is based on a new vector, which triggers the expression nanoluciferase (nluc) reporter gene in target cells upon transmission and after reverse transcription of the HIV-1 RNA genome. The new vector is co-transfected with plasmids that express HIV-1 proteins, and the assay allows parallel measurements of free virus infection and cell-cell transmission. RT-qPCR was used to determine the efficiency of reporter RNA splicing and incorporation into HIV-1 virions Results: Optimization of our HIV-1 cell-cell transmission assay resulted in low background, >99% splicing efficiency, high sensitivity, and wide dynamic range for detection of cell-cell transmission in different T cell lines as well as in primary CD4+ T cells. The assay efficiently detects cell-cell transmission using single round viral vectors and HIV-1 molecular clones as sources of HIV-1 proteins in 96-well plate format. We used the new ultrasensitive assay to measure HIV-1 sensitivity to bnAbs and observed at least 10-fold less efficient neutralization of cell-cell transmission compared to free virus infection; VRC01 was the less efficient bnAb for neutralizing cell-cell transmission. Neutralization of HIV-1AD8 Env by PG9 and PG16 bnAbs, which target amino acids and glycans of the V1/V2 loop at the Env trimer apex, was depended on the type of virus producing cells. HIV-1AD8 pseudoviruses that were produced in lymphoid cell lines, and most importantly, in primary CD4+ T cells were resistant to PG9 and PG16 bnAbs, but pseudoviruses produced in 293T cells were still sensitive to these V1/V2 loop bnAbs Conclusion: A new ultrasensitive assay can measure HIV-1 cell-cell transmission in primary CD4+ T cells and accurately detect bnAb neutralization efficiency; the type of transmission and cell origin contribute to HIV-1 sensitivity to bnAbs. This assay is a valuable tool for monitoring and understanding bnAb resistance in HIV-1 patients Development of Individualized Antibody Treatment Regimens for Patients With Multidrug-Resistant HIV M A Rai , Jana Blazkova, Jesse S. Justement, Victoria Shi, Brooke D. Kennedy, Maegan R. Manning, Mary McLaughlin, Michael C. Sneller, Alice K. Pau, Susan Moir, Tae-Wook Chun National Institute of Allergy and Infectious Diseases, Bethesda, MD, USA Background: People living with HIV (PLWH) who harbor multidrug-resistant (MDR) viruses have limited therapeutic options and present extensive challenges in clinical management. We examined the capacity of HIV-specific broadly neutralizing antibodies (bNAbs) and anti-CD4 antibodies to suppress infectious viral isolates derived from PLWH with MDR viruses. Methods: We conducted immunologic and virologic analyses on 11 PLWH with MDR viruses. We measured the intact HIV proviral DNA burden and examined levels of immune activation and exhaustion markers by flow

Poster Abstracts

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