Arousal from hibernation and reactivation ofEptesicus fuscusgammaherpesvirus (EfHV) in big brown bats

Abstract

Many viruses that cause serious and often fatal disease in humans have spilled over from bats. Recent evidence suggests that stress may enhance virus shedding by bats increasing the possibility of transmission to other species. To understand the reasons for spillover is therefore important to determine the molecular pathways that link stress to virus reactivation and shedding in bats. We recently isolated and characterized a gammaherpesvirus (Eptesicus fuscus herpesvirus, EfHV) autochthonous to North American big brown bats. Since herpesviruses are known to reactivate from latent infections in response to a wide variety of stressors, EfHV presents us with an opportunity to study how physiological, behavioural or environmental changes may influence the big brown bats’ relationship with EfHV. To understand the biology of the virus and how the extended periods of torpor experienced by these bats during hibernation along with the stress of arousal might influence the virus‐host relationship, we attempted to detect the virus in the blood of wild‐caught non‐hibernating bats as well as captive bats arising from hibernation. We compared the prevalence of EfHV in the blood (using PCR) and EfHV‐specific antibodies (using ELISA) between captive hibernating bats and wild‐caught non‐hibernating bats. We detected EfHV only in the blood of captive hibernating bats (27.8% = 10/36) and not in wild‐caught non‐hibernating bats (0.0% = 0/43). In contrast, the EfHV‐specific antibody titres were higher in the non‐hibernating bats compared to the hibernating bats. Our study suggests that: (a) viral DNA in blood indicates reactivation from latency, (b) long periods of hibernation lead to suppression of immunity, (c) stress of arousal from hibernation reactivates the virus in bats with lower levels of anti‐viral immunity (indicated by humoral immune response), and (d) levels of anti‐viral immunity increase in non‐hibernating bats following reactivation.

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

“…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.…”

Bat‐borne viruses in Africa: a critical review

“…Echolocation has been postulated as a mechanism for potential viral spread (Calisher et al , ), representing a sneeze and expulsion of droplets of oropharyngeal fluids, mucus or saliva that could act as a transmission route. Hibernation and torpor are hypothesized to aid in viral persistence and subsequent viral reactivation due to decreased metabolic and immunological activity (Gerow et al , ). There are currently few reports of torpor in African bat species; however, it may be more common than currently documented (Geiser & Stawski, ).…”

Artificial light at night amplifies seasonal relapse of haemosporidian parasites in a widespread songbird

“…More generally, our study highlights the reactivation of chronic or latent infection as a novel mechanism by which urbanization can affect infectious disease dynamics. Examining how ALAN affects cycles of latency and reactivation in other host and parasite systems, such as Borrelia burgdorferi and arboviruses in songbirds [64,65] or henipaviruses and herpesviruses in bats [66,67], could inform disease risks relevant for wildlife conservation, domestic animal health, and human health. Such work could be especially informative for synanthropic wildlife and migratory species that are increasingly becoming sedentary in anthropogenic habitats [68].…”