Unlocking the Role of a Genital Herpesvirus Otarine Herpesvirus 1 in California Sea Lion Cervical Cancer

摘要

Wild California sea lions (Zalophus californianus) have a high prevalence of urogenital carcinoma. The cancer starts in the sea lion’s genital tract then spreads aggressively to other organs resulting in death. Previous research has identified a herpesvirus, otarine herpesvirus 1 (OtHV1), in the genital tract of most sea lions with urogenital carcinoma, however, this virus has also been found in the genital tracts of sea lions without cancer making its role in urogenital carcinoma ambiguous. Here, tissues from 95 sea lions with and 163 without cancer were tested for OtHV1, the amount of virus was quantified, and viral gene expression was measured. OtHV1 was found in 100% of the sea lions with urogenital carcinoma and there were exceptionally high viral loads and viral gene expression within the genital tumors. Of the sea lions that did not have cancer, 36% tested positive for herpesvirus and they had much lower viral load and no detectable viral gene expression, indicating the herpesvirus was dormant. These findings support that genital herpesvirus plays an integral role in sea lion urogenital carcinoma and suggests there is an underlying trigger or event that causes the virus to induce cancer in some infected sea lions and not others.