Summary auto-generated
This study analyzes the evolutionary relationships of 47 European bat lyssaviruses (EBL) and 2 Duvenhage viruses from Africa by sequencing a 400-nucleotide region of the nucleoprotein gene. Using phylogenetic analysis, the researchers identified three distinct genetic clusters: genotype 4 (Duvenhage), genotype 5 (EBL1), and genotype 6 (EBL2). Both EBL1 and EBL2 further subdivided into two lineages (a and b). EBL1, found primarily in the serotine bat (Eptesicus serotinus), shows low genetic variability with two geographically distinct lineages: EBL1a widespread across northern and eastern Europe, and EBL1b in western Europe. The authors hypothesize that EBL1b was introduced from North Africa, while EBL1a arrived from another direction. EBL2 is less frequently detected and appears associated with Myotis species. The viruses exhibit minimal intrinsic heterogeneity, with mutations occurring primarily at synonymous sites, suggesting strong selective constraints and close viral adaptation to their bat hosts. This geographic distribution pattern and genetic organization has important implications for public health concerns, particularly regarding vaccine efficacy against these divergent lyssavirus genotypes.
Key findings
- European bat lyssaviruses form three distinct genetic clusters (genotypes 4, 5, and 6), with EBL1 and EBL2 each subdividing into two geographically separated lineages
- EBL1a and EBL1b show distinct geographic distributions, with EBL1b displaying a north-south pattern consistent with introduction from North Africa via Spain
- Eptesicus serotinus is the principal reservoir for EBL1, while Myotis species (M. dasycneme and M. daubentonii) are reservoirs for EBL2
- The viruses exhibit remarkably low genetic variability (less than 3.3% nucleotide divergence) with mutations occurring primarily at silent sites, indicating strong host adaptation
- Conventional rabies vaccines show weak efficacy against EBL genotypes, raising public health concerns for specialized vaccine development
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Abstract
Forty-seven European bat lyssaviruses (EBL) and two African insectivorous bat lyssaviruses (Duvenhage viruses) were selected for a comparison to be made of their evolutionary relationships. Studies were based on direct sequencing of the PCR-amplified products of the 400 nucleotides coding for the amino terminus of the nucleoprotein. Phylogenetic relationships were analysed after bootstrap resampling using the maximum parsimony and the neighbour-joining methods. Analyses of both the nucleotide and amino acid sequences placed these viruses in three separate clusters, namely genotype 4 (Duvenhage), genotype 5 (EBL1) and genotype 6 (EBL2). Evolutionary analysis of the nucleoprotein gene of EBL1 and EBL2 indicated low intrinsic heterogeneity mainly due to synonymous substitutions. In addition, both EBL1 and EBL2 evolved into at least two genetically distinguishable lineages (a and b) following geographical drifting. We can speculate that subsequently the lineages EBL1a and EBL1b were introduced into parts of northern Europe from two different geographical directions; EBL1b was probably introduced most recently and was from North Africa. Eptesicus serotinus appears to be the principal reservoir for EBL1 and Myotis dasycneme and M. daubentonii the reservoirs for EBL2.