Novel anellovirus discovered from a mortality event of captive California sea lions

A viral metagenomic study was performed to investigate potential viral pathogens associated with a mortality event of three captive California sea lions (Zalophus californianus). This study identified a novel California sea lion anellovirus (ZcAV), with 35% amino acid identity in the ORF1 region to feline anelloviruses. The double-stranded replicative form of ZcAV was detected in lung tissue, suggesting that ZcAV replicates in sea lion lungs. Specific PCR revealed the presence of ZcAV in the lung tissue of all three sea lions involved in the mortality event, but not in three other sea lions from the same zoo. In addition, ZcAV was detected at low frequency (11%) in the lungs of wild sea lions. The higher prevalence of ZcAV and presence of the double-stranded replicative form in the lungs of sea lions from the mortality event suggest that ZcAV was associated with the death of these animals.