Session 59Poster Presentations Viral Genetic Diversity Session Day and Time: Thursday 1:30 - 3:30 pm Room: Hall A
500 High Diversity of Cell-associated Reservoirs of HIV-1 May Contribute to Viral Genetic Shifts in the Plasma T. Liegler*1, J. Harris2, M. Warmerdam1, J. Barbour1, L. J. Montaner3, J. M. McCune1, R. M. Grant1 1J D Gladstone Inst of Virology and Immunology, San Francisco, CA; 2Univ of California at San Francisco; and 3Wistar Inst, Philadelphia, PA
Background: Viral variants that appear in blood plasma during STI are not always representative of those isolated from peripheral blood cells. We hypothesized that genetic diversity in replication-competent HIV-1 populations associated with blood cells is high, thereby requiring multiple isolates for characterization.
Methods: Thirteen (13) adults with chronic infection underwent up to 3 cycles of STI, typically 8 wks off and > 12 wks on therapy. CD4 T-cell counts, plasma VL, and genotypic drug resistance were assayed throughout the study. Independently derived isolates of a replication-competent virus derived by limiting dilution of PBMC co-cultures were generated during periods of viral suppression. CD8 cells were depleted from cultures. Phylogenetic trees were inferred from nucleotide sequences using PAUP v4.0.
Results: All patients had rebound viremia during all cycles off therapy. Five (5) out of 13 cases showed genotypic drug resistance during the first or subsequent cycles; 3/3 cases showed resistance in biological clones isolated from blood cells. Distinct patterns of resistance were seen at different points during a single 8-wk off cycle. Early rebound plasma viremia was not necessarily represented in viral quasispecies from cultures at proximal off cycles, but emergence did occur at distant cycles of interruption. Viruses independently isolated from blood cells were typically diverse, with some but not all lineages clustering with viral variants appearing in the plasma.
Conclusions: Replication-competent virus populations in peripheral blood cells are diverse, indicating that single isolates, or multiple clones from single isolates, are insufficient to characterize this reservoir of HIV-1. Even with up to 8 biological clones of HIV-1 per time point, the rebounding virus in plasma could not always be identified. These data suggest that HIV-1 infection is compartmentalized, leading to diversity in reservoirs that contribute to viral genetic shifts over time.
