Circulation of rabies-related lyssaviruses
Serological analyses performed in 2016 showed neutralization of EBLV-1b
in 119 out of 270 (44%) individual blood samples from South TyroleanM. myotis, with serological titers ranging from 2 to 2.4
LogD50/ml (Table 4). In addition, 46 samples (17%) from
different roosts and seasons showed viral inhibition below the
determined cutoff for the method. Observed sero-prevalence and specific
antibody titers increased after the birth pulse, occurring at the end of
May across the whole population (Table 4). Despite the percentage of
seropositive individuals varied from 0 to 26.5% among colonies in early
May, the seasonal increasing trend was confirmed in all colonies (Table
4, Figure 4). Overall, animals under 1 year of age showed a higher
percentage of positivity and higher titers compared to adults; however,
this result might be confounded by the fact that we found only few adult
animals in September, when sero-prevalence has been proven considerably
higher in all colonies (Table 4, Figure S1). Indeed, taking into account
the correlation among bats within the same colony, results from
multivariable analyses suggest that the influence of seasonality alone
might explain the qualitative (QIC=173.1630, AUC=90.57) and quantitative
(AIC=-104.9) serological pattern found in the dataset (Supplementary
methods). Overall, these analyses confirmed the higher probability to
find sero-positive bats in autumn as compared to spring (94.17% vs
9.55%), also showing a mean significantly higher serological titer
(2.32 vs 2.11 LogD50/ml) (Table 5, Figure 5) and regardless of the age
category. Indeed, we found no significant difference in serological
titers between youngsters and adults in September (Figure 5).