Abstract
Rabies virus kills tens of thousands of people globally each year, especially in resource-limited countries. Yet, there are genetically- and antigenically-related lyssaviruses, all capable of causing the disease rabies, circulating globally among bats without causing conspicuous disease outbreaks. The species richness and greater genetic diversity of African lyssaviruses, along with the lack of antibody cross-reactivity among them, has led to the hypothesis that Africa is the origin of lyssaviruses. This hypothesis was tested using a probabilistic phylogeographical approach. The nucleoprotein gene sequences from 153 representatives of 16 lyssavirus species, collected between 1956 and 2015, were used to develop a phylogenetic tree which incorporated relevant geographic and temporal data relating to the viruses. In addition, complete genome sequences from all 16 (putative) species were analysed. The most probable ancestral distribution for the internal nodes was inferred using three different approaches and was confirmed by analysis of complete genomes. These results support a Palearctic origin for lyssaviruses (posterior probability = 0.85), challenging the ‘out of Africa’ hypothesis, and suggest three independent transmission events to the Afrotropical region, representing the three phylogroups that form the three major lyssavirus clades.
Highlights
Determining the evolutionary history of viruses is fundamental to our understanding of the patterns and processes occurring during viral emergence and spread
In much of the world there are related viruses, called lyssaviruses, which circulate among bats without causing conspicuous outbreaks
The greater diversity of African lyssaviruses has led to the hypothesis that Africa is the origin of these viruses
Summary
Determining the evolutionary history of viruses is fundamental to our understanding of the patterns and processes occurring during viral emergence and spread. Emergence and spread of viral diseases is a permanent threat in animal and public health and special attention has been given to fast-evolving RNA viruses due to the high mortality rates recorded worldwide. The family Rhabdoviridae contains a diverse variety of RNA viruses that replicate in vertebrates, invertebrates and plants. The lyssaviruses, which cause the disease rabies, are unique within these negative-sense, single-stranded RNA viruses because they do not require arthropod vectors and are well-adapted to their mammalian hosts [1]. Well-established wildlife Carnivora reservoirs for RABV are apparently absent in South America and Australasia. Lyssaviruses are present in both of these regions and throughout the rest of the world in bat hosts (Chiroptera)
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