Experimental infection of big brown bats (Eptesicus fuscus) with Eurasian bat lyssaviruses Aravan, Khujand, and Irkut virus

Here we describe the results of experimental infections of captive big brown bats (Eptesicus fuscus) with three newly isolated bat lyssaviruses from Eurasia (Aravan, Khujand, and Irkut viruses). Infection of E. fuscus was moderate (total, 55-75%). There was no evidence of transmission to in-contact cage mates. Incubation periods for Irkut virus infection were significantly shorter (p < 0.05) than for either Aravan or Khujand virus infections. In turn, quantification of viral RNA by TaqMan PCR suggests that the dynamics of Irkut virus infection may differ from those of Aravan/Khujand virus infection. Although infectious virus and viral RNA were detected in the brain of every rabid animal, dissemination to non-neuronal tissues was limited. Levels of viral RNA in brain of Aravan/Khujand virus-infected bats was significantly correlated with the number of other tissues positive by TaqMan PCR (p < 0.05), whereas no such relationship was observed for Irkut virus infection (where viral RNA was consistently detected in all tissues other than kidney). Infectious virus was isolated sporadically from salivary glands, and both infectious virus and viral RNA were obtained from oral swabs. The detection of viral RNA in oral swabs suggests that viral shedding in saliva occurred < 5 days before the onset of clinical disease.