Figure 2. Amino acid comparison of sequences from cat FIV-Pcenv-1 and virus inoculum with parental clones (PPR and C36), another clade A domestic cat sequence (Petaluma), and nondomestic feline species (FIV-Oma = Pallas cat; FIV-Ple = lion; FIV-Pco-puma).

FIV-Fca defective isolate indicates replication-deficient strain from a domestic cat. Highlighted cysteines are conserved among domestic cat, but variation is noted at this site between and among felid species, and in prototypic HIV-1 lab strain NL4-3. Initial viral inoculum had an arginine incorporated at this site, which was replaced by histidine following infection of cat # FIV-PCenv-1.