Feline leukemia virus (FeLV) is a transmissible gammaretrovirus of felids. While domestic cats are the principal reservoir for FeLV, the virus has been documented in many unrelated species. Animals that develop progressive infections are responsible for the vast majority of transmission and have high case fatality rates. Since this has considerable implications for conservation, we conducted an extensive survey of FeLV infections from archived pumas and domestic cats samples from CA, CO, and FL. We also paid particular attention to known FeLV outbreaks in the endangered Florida panther (2003-2007; 2010-2016). In total, samples from 651 puma and 307 domestic cats were tested for the presence of FeLV using a quantitative PCR assay. An FeLV env genome segment was amplified by PCR, cloned, and sequenced to assess unique identity of individual infections. Full genome sequencing was completed in a subset of Florida samples to assess the degree of intraspecific transmission.
Results/Conclusions
We identified 39 positive samples in pumas (6.0% prevalence) and 23 positive samples in domestic cats (7.5% prevalence). Regional differences were detected, with the highest prevalence in both cats and puma occurring in Florida. Genomic analysis of the env region of the viral genome demonstrates variation between viral sequences in different samples. Our national dataset provides evidence that FeLV is relatively common in pumas, potentially indicating interactions with domestic cats which may vary by region. In the Florida panthers phylogenetic analyses document at least two circulating FeLV strains in panthers, representing separate introductions from domestic cats. The original FeLV panther outbreak strain is either still circulating or another domestic cat transmission event has occurred with a closely related variant. We additionally report the first documented case of a cross-species transmission event of an oncogenic FeLV recombinant (FeLV-B). Evidence of multiple FeLV strains and detection of FeLV-B indicate Florida panthers are at high risk for FeLV infection. Future studies will assess genotypic relationships of FeLV in the two species and further characterize the relationship of infection outcomes to demographic and ecological conditions.