Title: Infection and replication of retroviruses
Funder: The Francis Crick Institute

Abstract: Over 36 million people are infected with HIV and there is no cure, no vaccine and increasing resistance to current drugs. Hence, retroviral infection is a major global health issue. The early stages of the retroviral life cycle are particularly attractive therapeutic targets, with several anti-retroviral drugs and cellular anti-viral factors inhibiting these steps. However, numerous events that occur during these stages are still poorly understood. The overall aim of my research is to characterise the molecular events that occur once a retrovirus has entered a cell in order to fully understand the early stages of retroviral replication. As well as discovering how viruses exploit cellular processes, I believe our studies will also allow us to learn more about the cellular factors themselves. Additionally, we hope to provide potential ways in which to manipulate viral interactions with the host for the benefit of human health. Focusing on early replication events, we are specifically interested in (i) elucidating the function and cellular interactions of viral proteins that are essential for retroviral replication and (ii) identifying and characterizing the action of cellular proteins that restrict infection during early replication. Within this theme, my research programme is divided into three separate but inter-related projects: Project 1: Investigating the function of the p12 protein of murine leukaemia virus (MLV) in early replication We have found that p12 interacts with and stabilises the MLV capsid (CA) shell. Retroviral infection depends on having a CA shell with appropriate stability. We are therefore investigating p12-CA binding and comparing it to HIV CA interactions to understand CA stability and breakdown. MLV p12 is also involved in tethering the viral pre-integration complexes (PIC) to mitotic chromatin prior to integration, and it seems that CA binding is also necessary for this function. We are examining how p12 interacts with chromatin and the role this plays in retroviral integration. Project 2: Investigating the role of capsid in HIV-1 early replication The relationship between uncoating (breakdown of the viral core), reverse transcription, trafficking the core to the nucleus and nuclear entry and integration of HIV DNA remain unclear. However, recent evidence suggest that CA is central to all these replication steps. Using a panel of HIV-1 mutants with altered CA shell stabilities and fluorescent microscopy, we are exploring the localisation of CA and the interactions between CA and cellular factors. Project 3: Investigating how Vpx and Vpr enhance HIV replication Vpr and Vpx are HIV accessory proteins that are not absolutely required for infection but seem to play an important role in vivo. Both bind the substrate-adaptor protein DCAF1, and likely target cellular proteins for degradation that would otherwise inhibit viral replication. Vpx induces degradation of the cellular protein SAMHD1 and we have investigated the mechanism of SAMHD1 restriction of HIV infection and how Vpx overcomes SAMHD1. Continuing on from this work, we are now focusing on deducing the cellular target and function of the HIV-1 Vpr protein.


Research activity codes: 2.1 BIOLOGICAL AND ENDOGENOUS FACTORS;4.1 DISCOVERY AND PRECLINICAL TESTING OF MARKERS AND TECHNOLOGIES
Health categories: INFECTION