Dynamics of HIV Core Interactions

ABSTRACT, PROJECT 1 The overarching goals of the proposed studies are to i) elucidate dynamic, multifaceted interplay between HIV-1 and host cell that regulates infection and ii) define the virus-host interactions as therapeutic targets. The post-fusion journey of HIV-1 across the cytoplasm and via nuclear pore complex (NPC) is regulated by dynamic interactions of the conically shaped virus capsid shell with variety host proteins that either aid (dependency factors) or inhibit (restriction factors) infection. However, full identity and definitions of mechanisms of action of the cellular binding partners of HIV-1 capsid remain largely unknown. Furthermore, it is not clear how HIV-1 has evolved so that its capsid shell can bind selectively to diverse and seemingly unrelated regulatory host proteins that dictate the outcome of infection. In Aim 1, we will discover and characterize novel, dynamic interactions between HIV-1 capsid and host cell during virus ingress. Specifically, our efforts will focus on uncovering previously unrecognized, dynamic networks of cellular proteins that regulate HIV-1’s journey across the cytoplasm and through the NPC. Furthermore, we will elucidate structural determinants for selective and avid binding of these proteins to HIV-1 capsid. The hydrophobic capsid pocket, which engages several HIV-1 host dependency factors, has been successfully targeted by small molecule inhibitors. However, a relatively low barrier to resistance to current capsid targeting antivirals is a serious concern. In Aim 2, we will characterize interactions of existing and novel small molecule inhibitors with distinct sites on HIV-1 capsid. Specifically, we will define how known HIV-1 capsid inhibitors influence a dynamic structure of the conical HIV-1 capsid shell. Moreover, we will discover novel small molecules that bind at distinct sites on HIV-1 capsid and retain activity against viral variants resistant to current inhibitors. To accomplish above two aims we have assembled a highly collaborative B-HIVE team with complementary, multidisciplinary expertise in cryo-ET, cryo-EM, X-ray crystallography, HDX-MS, native MS, molecular modeling, live cell microscopy, virology, molecular biology, biochemistry, and medicinal chemistry. Our research will generate unprecedented insight into virus-host interactions that regulate HIV1’s journey during the virus ingress and define these interactions as the principal therapeutic target. Moreover, our structural and mechanistic characterization of multiple, distinct small molecule binding sites on the conical capsid surface will provide powerful means for ongoing efforts in pharmaceutical industry to rationally develop next generation of long-acting capsid inhibitors with enhanced barrier to resistance to transform care of the people living with HIV-1.