Otariid gammaherpesvirus 1 in South American fur seals (Arctocephalus australis) and a novel related herpesvirus in free-ranging South American sea lions (Otaria byronia): Prevalence and effects of age, sex, and sample type
Introduction Worldwide, many ecosystems have undergone unprecedented change over the past 150 years due to anthropogenic activity. South American pinniped populations have experienced declines related to hunting, habitat encroachment, overfishing, and pollution.1–3 Coastal development reduces available habitat and subsequently increases intra- and inter-specific contact between animals, a setting that creates the potential for increased disease transmission.4–6 The Punta San Juan marine protected area (PSJ) guards critical rookeries for two pinniped species considered endangered by the Peruvian government: the South American sea lion (Otaria byronia, SASL) and the South American fur seal (Arctocephalus australis, SAFS). Commercial hunting in the early 1900s decimated SAFS and SASL populations, and subsequent depletion of fish stocks by commercial fisheries and alterations in prey availability from El Niño Southern Oscillation (ENSO) events have limited population recovery.7, 8
Herpesviruses Herpesviruses, a family of large DNA viruses with intranuclear replication, usually display high host fidelity and appear to have often codiverged with the evolution of their host species.17, 18 Disease is typically relatively mild in the absence of immunosuppression, with latency being a characteristic of endemic herpesviral infection. When endemic hosts are immunosuppressed, herpesviruses can be oncogenic.19 Host jumps are generally within the same host superorder, and more rapid, severe disease may be a significant barrier to establishment of a herpesvirus in a novel host species.20, 21
Otariid Herpesviruses There are eight described otariid herpesviruses, seven in the subfamily Gammaherpesvirinae, and one in the subfamily Alphaherpesvirinae.Otariid Alphaherpesvirus 1 was described in a SASL with no associated viral lesions.24 Otariid gammaherpesvirus 1 (OtGHV1) is well documented in California sea lions (Zalophus californianus, CSL) and has been closely associated with development of urogenital carcinoma.25, 26 OtGHV2, 3, 4, 5, 6, and 7 have also been identified in otariid species, but their impact on health is not well understood.27–33 These seven gammaherpesviruses form three clades, one containing OtGHV1 and 4 from CSL and NFS, respectively, one containing OtGHV3 from CSL in a clade utilizing hosts in the Caniformia including several phocids, and one in the genus Percavirus containing OtGHV2, 5, 6, and 7.34–36 While OtGHV2 is described in CSL, OtHV5 and 6 were initially sequenced from SAFS in Brazil. These viruses have also been detected in subantarctic fur