Cross-species transmission of host adaptation of feline leukemia virus between domestic cats and the wild felid Leopardus guigna.

Feline leukemia virus (FeLV) is widespread in domestic cats and frequently spills over into wild felid populations, causing severe outbreaks in nondomestic felid populations. Domestic cats carry both endogenous FeLV (enFeLV) and exogenous variants of FeLV (exFeLV), which can recombine to generate novel variants with alternate receptor usage. In contrast, most nondomestic felids, including the guigna, do not harbor enFeLV. This study applied amplification of the FeLV envelope gene combined with Illumina sequencing to characterize FeLV envelope gene diversity and transmission dynamics in guignas (Leopardus guigna), a small wild felid native to Chile and Argentina. Seven polymerase chain reaction (PCR )amplicons from five free-ranging guignas were sequenced. Illumina sequencing was successfully conducted, and subsequent phylogenetic analysis indicated that the detected infections were most closely related to strains circulating in Chilean domestic cats. However, a distinct guigna-specific cluster with unique sequence variations was identified, suggesting that FeLV transmission also occurs among guignas independent of domestic cats. Phylogenetic analysis showed that all guigna sequences formed a Chile-specific FeLV clade, closely related to domestic cat viruses but clearly separated from international FeLV-A strains.