Antigenic and genetic characterization of rabies viruses isolated from domestic and wild animals of Brazil identifies the hoary fox as a rabies reservoir

Abstract

Fifty Brazilian rabies viruses, collected from many different animal species and several regions of the country, were characterized by partial sequencing of the central, variable region of the P gene, a locus useful for sensitive molecular epidemiological studies. Phylogenetic analysis of the sequences, which included comparison with other rabies strains recovered from throughout the Americas, identified three main groups of Brazilian viruses, arbitrarily designated BRL-1 to BRL-3. BRL-1 was found in terrestrial carnivores and clusters with other American strains of the cosmopolitan lineage. BRL-2 comprised two distinct isolates, recovered from two species of non-haematophagous bats, that had evolutionary links to insectivorous-bat-derived strains of North America. BRL-3 consisted of isolates from vampire bats and from livestock species probably infected via contact with vampire bats. The terrestrial group was further subdivided into three subtypes: BRL-1a was associated exclusively with dogs and cats, while BRL-1b and BRL-1c were found exclusively in hoary foxes. These observations strongly support the role of the Brazilian hoary fox as a rabies reservoir. Screening of representative Brazilian rabies viruses against a collection of anti-rabies monoclonal antibodies (mAbs) identified a small panel of mAbs that could be used to discriminate between all Brazilian subgroups as defined by genetic classification in this study.