Tissue distribution study of Flying fox retrovirus (FFRV) infection in the endangered Spectacled flying fox (Pteropus conspicillatus)

This study investigated tissue distribution and host-associated factors of Flying fox retrovirus (FFRV) infection in the endangered Spectacled flying fox (Pteropus conspicillatus). Blood, lymph node, spleen and liver samples from 100 wild bats were initially screened for FFRV proviral DNA by multiplex real-time PCR, with positives confirmed by conventional/nested PCR, Sanger sequencing and BLAST analysis. Screening for viral RNA then was performed in all tissues from provirus-positive bats. FFRV proviral DNA was detected in 22% of bats, with the highest detection frequencies in lymph nodes, spleen and blood, and lowest detection in liver; overall tissue differences were not significant (Cochran's Q p = 0.07), but lymph nodes showed higher detection than liver (McNemar p = 0.021). Paired analysis of provirus-positive tissues and their corresponding RNA demonstrated a significant discordance between proviral DNA and viral RNA positivity (McNemar p < 0.05), indicating that integrated FFRV provirus is not a reliable predictor of the presence of viral RNA at the tissue level. Sex was the only significant host factor, with males more frequently FFRV provirus-positive than females (p < 0.05), while age category and body condition score showed no association with infection status.