Seroprevalence of Toscana Virus and Sandfly Fever Sicilian Virus in European Bat Colonies Measured Using a Neutralization Test

Abstract

Toscana phlebovirus (TOSV) and Sicilian phlebovirus (SFSV) are endemic in the Mediterranean area where they are transmitted to humans by infected sandflies. Vertebrates of several species have been postulated to act as reservoirs of these viruses, but convincing evidence is still awaited. Among them, bats have been suggested, however documented evidence is lacking. Here we tested a total of 329 bats belonging to eight species collected from twelve localities in southern Spain for the presence of neutralizing antibodies specific to TOSV and SFSV. Positive sera were detected in Schreiber’s long-fingered bat (Miniopterus schreibersii), mouse-eared Myotis (Myotis myotis), European free-tailed bat (Tadarida teniotis), and common serotine (Eptesicus serotinus) with the latter showing the highest prevalence rates for SFSV (22.6%) and TOSV (10%). There was no difference between females and males. Results suggest that bats are not likely to play a major role in the natural cycle of these two sandfly-borne phleboviruses. However, large breeding colonies of bats can be used as sentinels for surveillance of the presence of such viruses in a given locality. In addition, capture–recapture studies should be initiated in order to understand better the dynamics of TOSV and SFSV in bat populations.

High rates of antibodies against Toscana and Sicilian phleboviruses in common quail Coturnix coturnix birds

“…In this study, we found for the first time SFSV and TOSV neutralizing antibodies in wild birds. Our results show rates of neutralizing antibodies that were among the highest ever detected in vertebrates (Alwassouf et al, 2016b;Ayhan et al, 2021). Moreover, if the cut-off is decreased and moved from 40 to 20, NT Abs against SFSV and TOSV would be observed in 59% and 58.5% of quails, respectively.…”

“…After 5 days (for TOSV) and 6 days (for SFSV), the microplates were read under an inverted microscope, and the presence (neutralization titer at 20, 40, 80, and 160) or absence (no neutralization) of the cytopathic effect was noted. Cutoff value for positivity was set at titer ≥40 as in previous studies ( Alwassouf et al, 2016b ; Ayhan et al, 2021 ).…”

“…Although antibodies against TOSV and SFSV were found in horses, cats, dogs, cattle, goat and bats ( Alwassouf et al, 2016a , b ; Ayhan et al, 2017a , 2021 ), the amplifying host (if any) remains undiscovered. Since dogs are the reservoir host for certain species of Leishmania , it has been hypothesized that they could also play this role for TOSV and/or SFSV.…”

“…Bats also have been suggested as a reservoir of phleboviruses. However, a study carried out in eight European bat species suggests that bats are not likely to play a major role in the natural cycle of these two viruses ( Ayhan et al, 2021 ).…”

New Isolation of Ponticelli III Virus (Bunyavirales: Phenuiviridae) in Emilia-Romagna Region, Italy

“…In the Old World, at least 250 million people have been exposed to Phlebovirus infections [ 9 , 10 ]. One of the main examples is TOSV, which is known as an emerging pathogen causing meningitis in the Mediterranean region, for which defined reservoirs have not yet been identified.…”