Large-scale amplification, cloning and sequencing of near full-length HIV-1 subtype C genomes

Full-length HIV-1 genome sequencing provides important data needed to address several vaccine design, molecular epidemiologic and pathogenesis questions. A protocol is presented for obtaining near full-length genomes (NFLGs) from subjects infected with HIV-1 subtype C. This protocol was used to amplify NFLGs from 244 of 366 (67%) samples collected at two clinics in Durban, South Africa (SK and PS). Viral load was directly associated with frequency of successful NFLG amplification for both cohorts (PS; p = 0.005 and SK; p < 0.001). Seventeen of 38 initially NFLG-negative SK samples had variation within the PCR primer binding sites, however only 3 of these were successfully re-amplified using re-designed primers homologous to the target viruses. NFLGs were obtained from 7 of 24 PBMC samples processed from subjects whose plasma did not yield a NFLG. Stable plasmid clones were obtained from all 244 NFLG-positive PCR products, and both strands of each genome were sequenced, using a primary set of 46 primers. These methods thus allow the large-scale collection of HIV-1 NFLGs from populations infected primarily with subtype C. The methods are readily adaptable to other HIV-1 subtypes, and provide materials for viral functional analyses and population-based molecular epidemiology studies that include analysis of viral genome chimerization.