This hypothesis is strengthened by two findings: one, a relative decrease in lymphocyte counts was observed in herpesvirus-infected sea lions compared to sea lions with papillomavirus or those with no apparent infections (see Figure S7); and two, when comparing levels of transcription of genes related to cytotoxicity among apparently uninfected sea lions, sea lions infected by OtHV-1, ZcPV-1, and by both viruses simulaneously, levels of Eomes, perforin, and tbx21 of sea lions infected by OtHV-1 were equal to or lower than uninfected sea lions. This evidence concerns the gene PRF1 and infection.