Mutations in simian immunodeficiency virus protease cleavage sites 2 and12 impair in vitro virus production

Abstract

The global disease burden due to the HIV/AIDS epidemic continues to rise as efforts to prevent or treat the virus are met with more and more challenges. The advent of potent antiretroviral treatment options that appear to reduce viral loads to undetectable levels in infected patients, are thwarted by HIV’s ability to establish latency and a long term persistent virus reservoir. A preventative approach that can establish persistent immunity against HIV-1 is urgently needed. This study seeks to examine the in vitro effect of a candidate vaccine targeted against highly conserved amino acid sequences, known as Protease Cleavage Sites (PCS), in HIV-1. Preliminary testing of the vaccine consisting of 20mer PCS overlapping peptides was conducted in Cynomolgus macaques and revealed that the highest frequency of mutation in two of the twelve sites, were located in the PCS2 and PCS12 regions. Sequencing of these mutants isolated from the peripheral blood of vaccinated monkeys facilitated the creation, by molecular cloning, of a library viral clones harboring the same mutations. These viral clones were then characterized in vitro by determining their replicative abilities as compared to wild type virus. While more work is required to determine the mechanisms by which these mutations impair viral fitness, the results thus far, are informative towards the continued development of this candidate vaccine.