Identification of a novel herpesvirus from a California desert tortoise (Gopherus agassizii)

Herpesviruses are significant pathogens of tortoises, causing upper respiratory tract disease and necrotizing stomatitis, with infections often associated with high mortality rates. Herpesvirus infection in a captive California desert tortoise (Gopherus agassizii) was detected by light microscopic observation of intranuclear inclusion bodies in various tissues followed by transmission electron microscopic observation of herpesvirus-like particles, and amplification of herpesvirus nucleic acid sequences using polymerase chain reaction. Using an indirect enzyme linked immunosorbent assay, anti-tortoise herpesvirus antibodies were detected one month after initial onset of clinical signs. This novel herpesvirus is distinct from the previously described tortoise herpesvirus (tortoise herpesvirus-1, THV-1) sharing 83% sequence identity of 60 amino acids of a portion of the DNA polymerase gene and 79% sequence identity across 120 amino acids of a portion of the ribonucleotide reductase gene. Similar to THV-1, this novel herpesvirus, tortoise herpesvirus-2 (THV-2), also clusters with the alphaherpesviruses.