G-102 Patients Infected with CRF07_BC Have Significantly Lower Viral Loads than Patients with HIV-1 Subtype B

Abstract

Background: The circulating recombinant form (CRF) 07_BC is the most prevalent HIV-1 strain among injection drug users in Taiwan. It contains a 7 amino-acid deletion (7d) in its p6gag. The objectives of this study were to conduct a cohort study to compare viral load and CD4 cell count changes between patients infected with subtype B and CRF07_BC and to elucidate its mechanism. Methods: Twenty-one patients infected with CRF07_BC and 59 patients with subtype B were selected from a cohort of 667 HIV-1/AIDS patients whom have been followed up for more than 3 years. Generalized estimated equation was used for statistical analysis. The replicative kinetics, tropism and cytopathic effects were determined. HIV-1 NL4-3 which containing a 7 amino-acid deletion in p6gag (7d virus) was generated and its virological properties were compared with the wild-type. Results: Patients infected with CRF07_BC had significantly lower viral load than patients with subtype B. CRF07_BC isolates had lower replicative capacity than subtype B isolates although they were all CCR5 tropic. 7d virus had significantly lower gag processing efficiency and slower viral life cycle. Electronic microscopy showed 7d virus had poorer viral maturation processes: more viruses attached to the cell membrane and less mature virions. The interaction between p6gag and Alix protein was less efficient in cells infected with 7d virus. Conclusions: Patients infected with CRF07_BC had significantly slower disease progression. The differences of virological characteristics between CRF07_BC and subtype B were due to its 7 amino-acid deletion in p6gag.