Experimental study of European bat lyssavirus type-2 infection in Daubenton's bats (Myotis daubentonii)

Abstract

European bat lyssavirus type 2 (EBLV-2) can be transmitted from Daubenton's bats to humans and cause rabies. EBLV-2 has been repeatedly isolated from Daubenton's bats in the UK but appears to be present at a low level within the native bat population. This has prompted us to investigate the disease in its natural host under experimental conditions, to assess its virulence, dissemination and likely means of transmission between insectivorous bats. With the exception of direct intracranial inoculation, only one of seven Daubenton's bats inoculated by subdermal inoculation became infected with EBLV-2. Both intramuscular and intranasal inoculation failed to infect the bats. No animal inoculated with EBLV-2 seroconverted during the study period. During infection, virus excretion in saliva (both viral RNA and live virus) was confirmed up to 3 days before the development of rabies. Disease was manifested as a gradual loss of weight prior to the development of paralysis and then death. The highest levels of virus were measured in the brain, with much lower levels of viral genomic RNA detected in the tongue, salivary glands, kidney, lung and heart. These observations are similar to those made in naturally infected Daubenton's bats and this is the first documented report of isolation of EBLV-2 in bat saliva. We conclude that EBLV-2 is most likely transmitted in saliva by a shallow bite.

Twenty years of active bat rabies surveillance in Germany: a detailed analysis and future perspectives

“…This supports findings from serological studies on Lagos bat virus which postulated that acute transmission of bat lyssaviruses in adapted bat hosts occurs at a far higher rate than the occurrence of disease [47]. Our results further support previous experimental studies that although lyssaviruses have the ability to cause clinical disease in bats, they may not necessarily be fatal [41,42,44]. Unlike in other mammalian species where antibodies against RABV are only detectable in the final stage of infection, shortly before the animal's death, we were able to observe seroconversion in repeatedly captured bats (Table 2).…”

“…The low number of RT-PCR-positive animals corroborates results obtained in experimental studies of EBLV infection in European bats (E. serotinus, M. daubentonii) and in North American big brown bats (E. fuscus), in which virus shedding was rarely detected [41,42,44]. However, active bat rabies surveillance studies are considerably biased by random sampling, and samples do not necessarily represent the entire populations of each indigenous bat species.…”

Susceptibility and Pathogenesis of Little Brown Bats (Myotis lucifugus) to Heterologous and Homologous Rabies Viruses

“…Virus was detected up to 18 days before clinical signs compatible with RABV infection were first noted. This is considerably longer than the length of time in previous studies, in which RABV was detected in saliva within 10 days of the appearance of clinical signs (14,18,26).…”

“…Although i.m. inoculation is believed to be the most common route of RABV transmission between terrestrial mammals, it may be different among chiropterans (17,18) On the basis of our data, i.m. inoculation is more likely to result in clinical infection yet is less likely to result in dissemination of the virus to the salivary glands.…”

Pathobiology of rabies virus and the European bat lyssaviruses in experimentally infected mice

“…In the rare human cases associated with these bat lyssaviruses (Anonymous, 1986;Selimov et al, 1989;Fooks et al, 2003) symptoms included adymania, dizziness, anisocoria, ptosis and ambulatory difficulties (Favi et al, 2002), limb paresthesia and tightness, behavioural changes, aggression and agitation followed by coma and death, usually due to circulatory insufficiency (Fooks et al, 2003;Hemachudha et al, 2002). In experimental animals, studies have been undertaken in various species to elucidate the pathogenesis of both EBLV-1 and EBLV-2 (Freuling et al, 2009;Vos et al, 2004a,b;Tjørnehøj et al, 2006;Picard-Meyer et al, 2008;Brookes et al, 2007;Johnson et al, 2008). EBLV-2 appears less pathogenic when inoculated peripherally in vivo (Vos et al, 2004a;Picard-Meyer et al, 2008).…”