# Rev-RRE activity modulates HIV-1 replication and latency reactivation: Implications for viral persistence and cure strategies

## TL;DR

This study shows how the HIV-1 Rev-RRE system affects virus replication and reactivation from latency, suggesting that boosting this system could help cure HIV.

## Contribution

The study reveals how variations in Rev-RRE activity influence HIV replication and latency reactivation, offering new insights for cure strategies.

## Key findings

- Higher Rev-RRE activity increases HIV-1 replication capacity while maintaining Nef expression.
- Viruses with low Rev activity can acquire mutations to boost Rev-RRE activity and replication.
- Low Rev-RRE activity proviruses are harder to reactivate from latency, complicating cure strategies.

## Abstract

The HIV-1 Rev-RRE regulatory axis plays a crucial role in viral replication by facilitating the nucleo-cytoplasmic export and expression of viral mRNAs with retained introns. In this study, we investigated the impact of variation in Rev-RRE functional activity on HIV-1 replication kinetics and reactivation from latency. Using a novel HIV-1 viral vector with an interchangeable Rev cassette, we engineered viruses with two diverse Rev functional activities and demonstrated that higher Rev-RRE activity confers greater viral replication capacity while maintaining a constant level of Nef expression. In addition, a low Rev activity virus rapidly acquired a compensatory mutation in the RRE that significantly increased Rev-RRE activity and replication. In a latency model, proviruses with differing Rev-RRE activity levels varied in the efficiency of viral reactivation, affecting both initial viral release and subsequent replication kinetics. These results demonstrate that activity differences in the Rev-RRE axis among different viral isolates have important implications for HIV replication dynamics and persistence. Importantly, our findings indicate that bolstering Rev/RRE activity could be explored as part of latency reversal strategies in HIV cure efforts.

The activity of the HIV-1 Rev-RRE axis is essential for viral replication and varies among primary viral isolates. However, the role of this for viral fitness, evolution, and persistence has not previously been investigated. Our results show that during in vitro replication, there is a selective fitness advantage for a virus with higher Rev-RRE activity and that HIV has the ability to fine-tune this regulatory system with minimal sequence changes. Additionally, the maintenance of Nef expression in a low Rev activity virus suggests a potential mechanism for balancing immune evasion and replication capacity in different selection landscapes within a host. We also show that the virus with low Rev-RRE activity was more difficult to reverse from latency than the virus with higher Rev-RRE activity. Thus, differences in provirus Rev-RRE activity may be a barrier to developing effective latency reversal strategies. These findings provide new insights into the complex roles the Rev/RRE axis plays in functionality, viral fitness, evolution, and persistence.