2026

What is the title of your project, and what is its primary focus?

Title of the project: “Emerging cellular targets of Vif and its interaction with host HUWE1”

HIV accessory protein Vif is essential for HIV-1 replication in vivo, best known for antagonizing host APOBEC3 family restriction factors that hypermutate the HIV genome in the absence of Vif. Although the past 20 years of research on Vif have been primarily focused on Vif-APOBEC3 interactions, emerging proteomic and genetic studies indicate that Vif engages a broader network of host proteins, including regulators of cell cycle and innate immunity. Prior work from the HARC Center investigators identified approximately two dozen high-confidence Vif-interacting host proteins. Among these, the HECT-type E3 ubiquitin ligase HUWE1 emerged as a compelling candidate restriction factor, as CRISPR-mediated knockout of HUWE1 in primary CD4⁺ T cells enhances HIV replication. 

In this HARC CDA project, we will determine and map the molecular basis of the interactions between Vif and emerging host factors beyond conventional APOBEC3s, such as HUWE1. We expect that Vif engages multiple host pathways through structurally distinct interfaces to modulate cellular processes and enhance viral replication. To test this hypothesis, we will combine single particle cryo-EM, structural proteomics, functional biochemistry, and HIV virology. These studies will offer extended view of the Vif-mediated host remodeling during HIV infection and molecular basis for the crucial virus-host interactions that could be targeted for future therapeutics.

How does your project align with the Center’s objectives?

Our research is directly aligned with the HARC Center's core mission to define HIV accessory and regulatory protein complexes, and it will complement the center's existing systems-to-structure pipeline. Our work will provide mechanistic insights into HIV-1 Vif interaction networks beyond host APOBEC3 anti-HIV factors, including its interaction with HUWE1, a host interactor originally identified by HARC Center members. I am particularly excited about collaborating with the lab of Dr. Judd Hultquist, a HARC investigator and also my departmental colleague at Northwestern, to leverage their expertise in HIV genetics and virology.

What is the most inspiring aspect of your research?

The most inspiring and exciting aspect of our research is our ability to determine atomic structures of macromolecular complexes directly isolated from human cells. Traditionally, structural studies of Vif complexes have relied on time-consuming in vitro reconstitution with heterologously expressed recombinant proteins. In contrast, advances in cryo-EM now enable us to enrich near-native protein complexes from cells and analyze them in their near-physiological context. This approach allows us to work with heterogeneous samples and resolve multiple structurally distinct complexes from a single preparation. As a result, we can capture the dynamic landscape of Vif-associated host interactions in a way that was previously not possible.

What are your thoughts on the importance of advancing our understanding of HIV–host protein complexes and expanding therapeutic targets and treatment strategies for HIV/AIDS?

Currently, neither a cure nor a vaccine can treat and protect people currently living with or at risk of HIV. Existing anti-retroviral therapeutics (ART) typically combine two or more drugs targeting key processes of the HIV viral lifecycle, such as viral genome replication, virion maturation, and host cell entry of the virus. The long-acting capsid inhibitor Lenacapavir, a biannual injectable for HIV pre-exposure prophylaxis (PrEP), was approved by FDA recently, which highlighs the potential of targeting previously underexplored viral components to prevent the infection. We think it remains critical to expand the scope of drug targets to enhance the flexibility and durability of ART and PrEP, and effectively counter emerging drug-resistant strains. Currently, there are no approved drugs targeting HIV accessory proteins. I believe that targeting virus-host molecular interactions within the infected cells represents an open avenue for the future development of versatile and adaptable therapeutics and prophylaxis.