The invention provides a process for the selection of HIV-1 subtype (clade) C isolates, selected HIV-1 subtype C isolates, their genes and modifications and derivatives thereof for use in prophylactic and therapeutic vaccines to produce proteins and polypeptides for the purpose of eliciting protection against HIV infection or disease. The process for the selection of HIV subtype isolates comprises the steps of isolating viruses from recently infected subjects; generating a consensus sequence for at least part of at least one HIV gene by identifying the most common codon or amino acid among the isolated viruses; and selecting the isolated virus or viruses with a high sequence identity to the consensus sequence. HIV-1 subtype C isolates, designated Du422, Du 151 and Du 179 (assigned Accession Numbers 01032114, 00072724 and 00072725, respectively, by the European Collection of Cell Cultures) are also provided.