Cross reactive antigenicity in orally vaccinated foxes and raccoon dogs against European Bat Lyssavirus type 1 and 2.

For the first time, the effectiveness of oral rabies vaccines against European Bat Lyssaviruses Type 1 (EBLV-1) and Type 2 (EBLV-2) by means of cross-neutralization assays was investigated. Sera from orally vaccinated red foxes (Vulpes vulpes) and raccoon dogs (Nyctereutes procyonoides) with the Street Alabama Dufferin (SAD) B19 and SAD P5/88 live-modified vaccine viruses were used to study the cross reactive antigenicity against CVS-11 (genotype 1), EBLV-1 (genotype 5) and EBLV-2 (genotype 6). For comparison, similar crossneutralization assays with sera from EBLV-1 and EBLV-2 infected ferrets (Mustela putorius furo) and/or foxes were conducted. Sera from animals vaccinated with the two oral rabies vaccines were reactive against CVS-11 (homologous virus), EBLV-1 and EBLV-2 (heterologous virus). There was a positive relationship among the virus neutralising antibody titres (VNA); high VNA titres against CVS-11 also resulted in high VNA titres against each EBLV, whereas in general, the VNA-titres obtained with homologous virus were statistically higher than those with the heterologous virus except for SAD P5/88 vaccinated raccoon dogs. No significant difference was found between EBLV-1 and EBLV-2 VNA titres. A similar trend was observed when the results of the cross-neutralization data of the foxes and ferrets inoculated i.m. with EBLV-1 and/or EBLV-2 was analysed. Based on the similarity of the EBLV-VNA titres obtained in our study questions were raised on whether the genetic distance of genotype 5 & 6 within phylogroup 1 really does reflect their antigenetic characteristics or whether this is a feature of attenuated live vaccine viruses. This broad cross protection, however, demonstrated that the representatives of attenuated SAD strains of oral rabies vaccines currently used in Germany are most likely able to protect the reservoir species, red fox and raccoon dog, against EBLV-1 and EBLV-2 infection.