Taxonomy and evolutionary studies on lyssaviruses with special reference to Africa.

Currently, the Lyssavirus genus is composed of four serotypes and the ungrouped European bat lyssaviruses (EBL). Using previously described PCR amplification and direct sequencing methods, the N genes of 70 representative lyssaviruses collected from 40 different countries were examined. From the results, a phylogenetic tree with six branches (genotypes) was constructed: genotypes 1-4 correlated with the classification of serotypes 1-4 and in addition EBL 1 and EBL 2 were identified as two further genotypes (5 and 6). Analysis of the 51 rabies (genotype 1) viruses in the study identified nine distinct groups which could be correlated with their geographical origins. A comparison of the six genotypes with four principal Vesiculovirus serotypes showed that their relationship was closer than that of even the two most closely related Vesiculovirus serotypes. Antigenic site sequences of isolates from vaccine/treatment failures were similar to vaccine and field strains, suggesting that failures were not due to genetic variation at the N protein level.