Characterization of a SHIV162P3 variant evolved in an infected rhesus macaque with persistent plasma viremia

Typically plasma viremia is controlled in macaques challenged with R5 tropic SHIV162P3 during the chronic phase of infection. However, in a few infected animals it sustains for a prolonged period. Persistent plasma viremia in two such macaques led to a rapid decline of CD4+ T-cells in blood leading to the induction of AIDS. A viral variant from one of these animals showed sensitivity to soluble CD4 and maraviroc similar to the challenge virus. However, it exhibited reduced sensitivity to anti-gp120 antibody b12 and to sera from SHIV162P3-infected macaques or HIV-1-infected humans. Molecular sequencing of the env gene from this virus revealed multiple mutations clustering on the V1 domain of gp120. These results demonstrate that evolution of the envelope in SHIV-infected macaques may lead to the emergence of a viral variant with altered immunological characteristics.