Two-step evolution of HIV-1 budding system leading to pandemic in the human population.

The pandemic HIV-1, HIV-1 group M, emerged from a single spillover event of its ancestral lentivirus from a chimpanzee. During human-to-human spread worldwide, HIV-1 diversified into multiple subtypes. Here, our interdisciplinary investigation mainly sheds light on the evolutionary scenario of the viral budding system of HIV-1 subtype C (HIV-1C), a most successfully spread subtype. Of the two amino acid motifs for HIV-1 budding, the P(T/S)AP and YPxL motifs, HIV-1C loses the YPxL motif. Our data imply that HIV-1C might lose this motif to evade immune pressure. Additionally, the P(T/S)AP motif is duplicated dependently of the level of HIV-1 spread in the human population, and >20% of HIV-1C harbored the duplicated P(T/S)AP motif. We further show that the duplication of the P(T/S)AP motif is caused by the expansion of the CTG triplet repeat. Altogether, our results suggest that HIV-1 has experienced a two-step evolution of the viral budding process during human-to-human spread worldwide.

A widely distributed HIV-1 provirus elimination assay to evaluate latency-reversing agents in vitro.

Persistence of HIV-1 latent reservoir cells during antiretroviral therapy (ART) is a major obstacle for curing HIV-1. Even though latency-reversing agents (LRAs) are under development to reactivate and eradicate latently infected cells, there are few useful models for evaluating LRA activity in vitro. Here, we establish a long-term cell culture system called the "widely distributed intact provirus elimination" (WIPE) assay. It harbors thousands of different HIV-1-infected cell clones with a wide distribution of HIV-1 provirus similar to that observed in vivo. Mathematical modeling and experimental results from this in vitro infection model demonstrates that the addition of an LRA to ART shows a latency-reversing effect and contributes to the eradication of replication-competent HIV-1. The WIPE assay can be used to optimize therapeutics against HIV-1 latency and investigate mechanistic insights into the clonal selection of heterogeneous HIV-1-infected cells.