Molecular study of rabies virus in slaughtered dogs in Billiri and Kaltungo local government areas of Gombe state, Nigeria

Rabies is one of the most dreadful diseases and a major viral zoonosis which has been shown to cause an almost 100% fatality rate in infected victims. It is characterized by acute progressive encephalitis in mammals. This study determined the genotypic characteristics of rabies virus in dogs slaughtered for human consumption based on sequence of a fragment of nucleoprotein gene. Brain tissues were collected from 50 dogs slaughtered in Billiri and Kaltungo Local Government Areas of Gombe State, Nigeria. Direct fluorescent antibody test (DFAT) was used to screen for the presence of rabies virus antigen. Viral RNA isolated from DFAT positive brain tissues were subjected to the reverse transcription polymerase chain reaction (RT-PCR) followed by sequencing of the amplicons. Maximum Likelihood (ML) was used to construct a phylogenetic tree for sequences obtained with 1000 bootstrap replicates. The DFAT detected rabies antigen in 3 (6%) of the 50 dog brain tissues, from which 1 (2%) was positive by RT-PCR. ML phylogeny approach of the nucleotide sequences inferred members as originating lyssavirus genus and dog species. Essentially, MK234794 in this study displayed 99.3% sequence similarity with other related rabies viruses in the Africa 2 cluster (Nigeria, Cameroon, Chad and Niger). Interestingly, MK234794 showed no cluster relation with the Africa 1a, 1b, 3 and Africa 4 clades, respectively. This indicates there is in-country and trans-boundary circulation of the rabies viruses with no co-circulation between the Africa lineages, especially as dogs are continuously being traded due to consumption of dog meat in West Africa. This finding has given additional insight into the molecular epidemiology of rabies virus in Nigeria, therefore providing more baseline information for future design of rabies control programs in the country.