Between roost contact is essential for maintenance of European bat lyssavirus type-2 in Myotis daubentonii bat reservoir: ‘The Swarming Hypothesis’

Abstract

Many high-consequence human and animal pathogens persist in wildlife reservoirs. An understanding of the dynamics of these pathogens in their reservoir hosts is crucial to inform the risk of spill-over events, yet our understanding of these dynamics is frequently insufficient. Viral persistence in a wild bat population was investigated by combining empirical data and in-silico analyses to test hypotheses on mechanisms for viral persistence. A fatal zoonotic virus, European Bat lyssavirus type 2 (EBLV-2), in Daubenton's bats (Myotis daubentonii) was used as a model system. A total of 1839 M. daubentonii were sampled for evidence of virus exposure and excretion during a prospective nine year serial cross-sectional survey. Multivariable statistical models demonstrated age-related differences in seroprevalence, with significant variation in seropositivity over time and among roosts. An Approximate Bayesian Computation approach was used to model the infection dynamics incorporating the known host ecology. The results demonstrate that EBLV-2 is endemic in the study population, and suggest that mixing between roosts during seasonal swarming events is necessary to maintain EBLV-2 in the population. These findings contribute to understanding how bat viruses can persist despite low prevalence of infection, and why infection is constrained to certain bat species in multispecies roosts and ecosystems. Bats have been implicated as reservoirs for multiple viral, bacterial and protozoal pathogens of human and animal health importance, including Ebola virus, Bartonella spp., and rabies virus 1,2. Aspects of the ecology and demography of bats such as forming high-density aggregations, and flight permitting long-distance movement, may play a role in this ability to maintain a variety of pathogens 2. Mechanisms of pathogen persistence at the population level are often poorly understood, particularly when infection elicits a long lasting protective immune response 3. Rabies virus is one of a growing number of recognised lyssavirus species that are all capable of causing fatal encephalitis 4. The majority of these lyssaviruses are associated with bats 5. Although the full public and animal

Combining host genetic structure and serology to investigate rabies-related lyssaviruses in the greater mouse-eared bat (Myotis myotis)

“…Indeed, higher antibody titers were found during late summer, which could be a sign of seroconversion due to viral exposure. This result differs from recent evidences determined for EBLV-2 in Myotis daubentonii, for which it was suggested a peak in virus transmission later during the autumnal swarming, when males and females aggregate for mating (Horton et al, 2020). However, this is rather predictable, considering that bats are highly variable in their ecology, so that differences in life history traits including hibernation, colony formation, parturition and mating are likely to determine peculiarities in virus dynamics as well (D. T S Hayman et al, 2013).…”

“…In this context, the meta-population structure seen in our sampling area as opposed to the close population model in the Balearic Islands could explain virus maintenance in M. myotis even in the absence of M. schreibersii . Indeed, several studies suggest that the exchange of individuals between roosts may be one of the main factors favoring the persistence of viruses across the whole population, sometimes allowing for local fade out of infection with subsequent reintroduction (Blackwood, Streicker, Altizer, & Rohani, 2013;Colombi et al, 2019;Horton et al, 2020;Pons-Salort et al, 2014).…”

Bat Flies of the Family Streblidae (Diptera: Hippoboscoidea) Host Relatives of Medically and Agriculturally Important “Bat-Associated” Viruses

“…The imperfect specificity of viruses for bat flies and of bat flies for bats in México was surprising ( Figure 6 ; Table S1 ). Our study sites in México and Uganda are both biodiversity “hot spots” where host switching by bat flies may occur due, for example, to multispecies bat roosting [ 14 , 63 , 64 ], perhaps explaining these observations.…”

Incursion of European Bat Lyssavirus 1 (EBLV-1) in Serotine Bats in the United Kingdom

“…This is likely a consequence of the local disease prevalence and the association of serotine bat roosts with buildings, e.g., homes and offices as well as accommodation for livestock [26]. Definitive mechanisms for the maintenance of EBLV-1 in serotine bat populations have not been established, but the species does form relatively large (n = 20-100 individuals) maternity colonies and a network of infection and or transmission nodes may exist across populations, similar to that seen in Daubenton's bats which are thought to contribute to the maintenance of EBLV-2 in that system [27,28]. The interconnectivity of these infection nodes may contribute to disease maintenance in bat populations and are also potential pathways supporting natural spread (i.e., emergence into new areas).…”