The within-host fitness of HIV-1 increases with age in ART-naïve HIV-1 subtype C infected children.

As the immune system develops with age, children combat infections better. HIV-1, however, targets an activated immune system, potentially rendering children increasingly permissive to HIV-1 infection as they grow. How HIV-1 fitness changes with age in children is unknown.

Viral Decay Dynamics and Mathematical Modeling of Treatment Response: Evidence of Lower in vivo Fitness of HIV-1 Subtype C.

Background: Despite the high prevalence of HIV-1 subtype C (HIV-1C) worldwide, information on HIV-1C viral dynamics and response to antiretroviral therapy (ART) is limited. We sought to measure viral load decay dynamics during treatment and estimate the within-host basic reproductive ratio, R0, and the critical efficacy, εc, for successful treatment of HIV-1C infection.

Methods: Individuals initiated on first-line ART in India and monitored for 6 months of treatment were considered.

Influence of recombination on acquisition and reversion of immune escape and compensatory mutations in HIV-1.

Following transmission, HIV-1 adapts in the new host by acquiring mutations that allow it to escape from the host immune response at multiple epitopes. It also reverts mutations associated with epitopes targeted in the transmitting host but not in the new host. Moreover, escape mutations are often associated with additional compensatory mutations that partially recover fitness costs.