Fig. 5

Problems in identifying proviruses from sequenced env transcripts or proteoforms. Hypothetical unique alleles in single nucleotide polymorphisms (SNPs) or single amino acid variants (SAAVs) are represented as coloured vertical bars (absence of the coloured bar denotes presence of the alternate variant) and premature stop codons represented as an asterisk. The figure shows possible difficulties that may arise in attempting to determine which proviruses gave rise to the Env protein in a patient or cell line. See Additional file 7 for further explanation of the mechanisms