CROI 2019 Abstract eBook

Abstract eBook

Oral Abstracts


passive and active immunization strategies provide renewed hope for ending the HIV-1 epidemic at the earliest stages of life. 68 HUGGING PHYLOGENETIC TREES: USE OF MOLECULAR ANALYSIS FOR PUBLIC HEALTH INTERVENTION Alexandra M. Oster , CDC, Atlanta, GA, USA New tools have made it possible to identify clusters of ongoing HIV transmission through the analysis of HIV molecular data. Although analysis of molecular data to understand transmission clusters has become more widespread in recent years, such analysis has typically been retrospective. Now, public health agencies are beginning to use data routinely collected through surveillance to prospectively identify clusters for public health response aimed at strengthening prevention efforts and ensuring that people with and at risk for HIV have access to the services they need. Cluster detection efforts can be used to prompt public health action, but this work must be done in a way that maximizes benefit and minimizes potential harms. This presentation will describe this new strategy and the promise it holds for HIV prevention. 69 A VIRUS-PACKAGEABLE CRISPR SCREEN IDENTIFIES HIV RESTRICTION AND DEPENDENCY FACTORS Molly Ohainle , Louisa Pendergast, Jolien Vermeire, Ferdinand Roesch, Daryl Humes, Julie M. Overbaugh, Michael Emerman Fred Hutchinson Cancer Research Center, Seattle, WA, USA Background: HIV relies on host-encoded factors to complete its life cycle inside the host cell but also must evade recognition by host-encoded factors that have evolved to defend cells against viral invasion. We developed a powerful screening technology to identify HIV restriction and dependency factors in a system that is flexible to cell type and HIV strains. Methods: HIV-CRISPR screening is a novel CRISPR/Cas9-mediated functional screening method to find HIV restriction factors. The HIV-CRISPR approach takes advantage of the packaging system of HIV to rescue HIV-CRISPR vectors encoding Cas9 and single-guideRNAs (sgRNAs) from cells. sgRNA-encoding HIV-CRISPR genomes are packaged in trans into budding HIV-1 particles. Release of HIV-CRISPR genomes into the supernatant is dependent on the extent of HIV replication within each cell in the population, thus revealing genes that restrict HIV replication within cells. We assembled an sgRNA library specific for Interferon Stimulated Genes (ISGs) into HIV-CRISPR to create PIKAHIV, the HIV- Packageable ISG Knockout Assembly. We then screened PIKAHIV-transduced THP-1 cells to find HIV-1 restriction and dependency factors. Results: We find that the antiviral effects of a small panel of genes, including MxB, IFITM1, Tetherin and TRIM5, together account for the 8-fold inhibition of HIV-1LAI replication by IFN in THP-1 cells. Many, but not all of these same factors were identified in a parallel screen with an R5-tropic, clade A primary isolate. However, Tetherin does restrict the primary isolate, suggesting that Vpu- mediated antagonism of Tetherin varies significantly across viral strains. Further we find that potent IFITM-mediated inhibition of VSV-G pseudotyped HIV-1 is a major block to infection and masks the effects of other antiviral effectors. We also identify novel factors, including SEC62 and TLR2/MYD88, to be important dependency factors for replication for both viruses. Screens with viral mutants reveal additional restriction factors that may be masked by binding of host cell factors to wildtype HIV. Conclusion: Highlighting the strength of the HIV-CRISPR approach, we have identified in one screen in one cell type with one virus, many key players in genetic resistance to HIV including TRIM5, Tetherin, IFITM, and MxB. The ability of IFN-induced restriction factors to inhibit HIV replication in human cells suggests that these human restriction factors are incompletely antagonized and that this antagonism varies from virus to virus. 70 A FUNCTIONAL MAP OF HIV-HOST INTERACTIONS IN PRIMARY HUMAN CD4+ T CELLS Judd F. Hultquist 1 , Joe Hiatt 2 , Lara Rheinemann 3 , Ryan Leenay 4 , Andrew May 4 , Wesley I. Sundquist 3 , Alexander Marson 2 , Nevan J. Krogan 2 1 Northwestern University, Chicago, IL, USA, 2 University of California San Francisco, San Francisco, CA, USA, 3 University of Utah, Salt Lake City, UT, USA, 4 Chan Zuckerberg Biohub, San Francisco, CA, USA Background: The limited coding capacity of the HIV genome necessitates a heavy reliance on the host molecular architecture for optimal replication. Attempts to biochemically identify host factors that physically interact with HIV proteins have yielded hundreds of candidates, but it is unknown which

Lene Ryom , Centre of Excellence for Health, Immunity and Infections, Copenhagen, Denmark The smoking epidemic in people living with HIV (PLWHV) differs significantly from that in the HIV-negative general population (GP). Firstly, smoking rates in PLWHV are disproportionally high (2-3 times higher than in the GP) with a roughly even distribution of smoking men and women. Smoking further impacts the health of PLWHV much more severely than that of the GP. As such, the excess risk of mortality in smoking PLWHV is three times higher compared to the GP with up to twelve life years lost due to smoking. Tobacco smoke contains several thousand substances of which multiple are considered poisonous or carcinogenic. Nicotine may enhance viral replication and several studies suggest a lower proportion of smoking PLWHV are virally suppressed. Smoking also changes the innate and adaptive immune response by causing inflammation and immune suppression- effects similar to that of HIV itself causing a state of double trouble for smoking PLWHV. Smoking further increases risks of several AIDS-defining conditions including esophageal candidiasis and tuberculosis, thereby directly counteracting the effects of antiretroviral treatment. For non-AIDS conditions the risk of bacterial pneumonia is 73% higher among smoking PLWHV compared to never-smokers. An estimated 70% of all myocardial infarctions in PLWHV are attributed to smoking, making smoking a more important individual risk factor than hypertension and HIV itself. In NA-ACCORD almost 20% of all cancers and over 90% of lung cancers were directly attributed to smoking. While smoking cessation in PLWHV may already after one-year lower risks of cardiovascular events, lung cancer risks remain elevated even several years after cessation in the DAD study. PLWHV are almost 20% less likely to quit smoking than the GP, possibly related to greater sociodemographic challenges. HIV guidelines recommend regular assessment of smoking status and motivation to quit, followed by cessation advice and combined behavioral counselling and pharmaceutical substitution therapy. As smoking is a leading cause of preventable morbidity and mortality in PLWHV it is imperative to design studies to clarify the complex needs of different groups of smoking PLWHV. Such studies should address effectiveness of different smoking cessation interventions and safety profiles of pharmaceutical substitutions. Smoking cessation should further become a top priority in the clinical management of PLWHV to break the silence of the killing smoke. Despite the highly-successful use of antiretroviral (ART)-based prevention for reduction of mother to child transmission (MTCT), as of 2017, 180,000 children continue to become infected with HIV-1 annually. Moreover, the fetal toxicities and prematurity associated with combination ART use in pregnancy are continuing to come to light. Pregnancy and the postpartum period are high risk for acute HIV acquisition, which translates into to high risk for HIV transmission to the developing fetus and breastfeeding infant. HIV variants transmitted perinatally have been demonstrated to be resistant to neutralization by concurrently circulating maternal antibodies, Thus, strategies that could synergize with ART to further reduce HIV MTCT during pregnancy may include temporary enhancement of autologous virus neutralization and targeted induction of functional antibodies that efficiently cross the placental barrier, which may be achievable with currently available HIV-1 vaccines. Furthermore, the pediatric HIV epidemic is bi-modal, with a peak in the neonatal period and a renewed high-risk period in adolescence following sexual debut. Therefore, vaccines that will eliminate the HIV epidemic will require administration during childhood. The early life immune system represents a unique immune landscape that could potentially be harnessed for qualities that are needed for the elicitation of protective immunity. In fact, recent reports have demonstrated that HIV-infected children develop broadly-neutralizing antibodies at a higher frequency and faster pace than that of HIV-infected adults. Intriguingly, the broadly-neutralizing antibodies identified in HIV-infected children have lower levels of somatic mutation than that of adults. Moreover, immunization strategies that aim for long-term development of protective immunity are well-suited for integration with the pediatric vaccine schedule, while immediate protection in the breastfeeding period can be achieved through concurrent passive administration of a potent broadly-neutralizing antibody. Therefore, enhancing and leveraging maternal and infant HIV immunity through novel

Oral Abstracts

67 RAISING THE WALL IN MATERNAL/FETAL IMMUNITY Sallie Permar , Duke Human Vaccine Institute, Durham, NC, USA


CROI 2019

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