Evolutionary potential of HIV-1 capsid: mechanisms and consequences

PROJECT SUMMARY The viral capsid, a cone-shaped protein shell, plays multiple roles during HIV-1 replication and has emerged as a promising antiviral target. It has been widely accepted that structural and functional constraints limit the mutational tolerance of the capsid. However, there is growing appreciation that HIV-1 accommodates phenotypic variability in nearly every capsid-mediated function without compromising viral replicative fitness. These observations raise the possibility that the capability of HIV-1 capsid to adapt is likely underestimated and substantial. The evolutionary potential of HIV-1 capsid has direct implications for drug resistance and serves as the molecular basis for host factor utilization and evasion. In this application, building upon our previous and preliminary studies, we propose to study the mechanisms and consequences of HIV-1 capsid variability using a multi-pronged strategy with special focus on the use of large-scale genetic approaches. In Aim 1, high-throughput mutational analysis of HIV-1 capsid will be conducted to generate comprehensive resistance profiles of various capsid inhibitors. We will also explore how combinatorial use of different types of capsid inhibitors can improve antiviral activity through synergistic interactions and/or by restricting resistance pathways. In Aim 2, to elucidate how HIV-1 exploits multiple host factors via highly charged pores at the center of each CA multimer, we will study the requirement for these cellular factors in capsid stability and other post-entry steps among diverse lentiviruses. Additionally, deep mutational scanning and detailed phenotyping will be applied to the central pore of HIV-1 capsid. In Aim 3, leveraging the availability of HIV-1 variants with varying uncoating kinetics, we will study the role of the capsid in shielding viral DNA from innate sensors in the context of cell-to-cell transmission of HIV-1. Second, to determine how the impacts of the capsid on viral DNA sensing can define the fate of viral infection, we will develop novel experimental assays that enable quantification of viral latency and competitions in a co-culture system. These studies will increase our understanding of the molecular basis for capsid-mediated functions. New findings will provide valuable insights into the evolutionary potential of HIV-1 capsid and may be harnessed to aid in the discovery and design of novel capsid targeting antivirals.