Immune System Modulation and Viral Persistence in Bats: Understanding Viral Spillover

Subudhi, Sonu; Rapin, Noreen; Misra, Vikram

Viruses 2019, 11, x 6 of 10 HSV-specific CD8 + T cells capable of producing IFN-γ. This contributes to reactivation of the virus [51] . Studies on murine gammaherpesvirus-68 (MHV-68) in mice have shown that latent gammaherpesviruses are sequestered in cells in the spleen and can be reactivated by stress [52, 53] . Stressors, such as unfolded protein responses and hypoxia, can induce the expression of viral immediate early genes that help in initiating the lytic cycle of virus thereby reactivating it [54] . Arousal from hibernation is a stressful event for bats [55] . Many big brown bats are latently infected with a gammaherpesvirus [56] . Gerow et al. [57] demonstrated that the virus reactivates from latency when big brown bats arouse from hibernation, leading to detection of the virus in blood. This reactivation was also associated with a low level of antibodies against the virus. Following hibernation the antibody levels increase, which subsequently drives the virus into latency.