[Source: Journal of Virology, full page: (LINK). Abstract, edited.]
The introduction and dispersal of Sindbis virus from central Africa to Europe
Jiaxin Ling, Teemu Smura, Jan O. Lundström, John H.-O. Pettersson, Tarja Sironen, Olli Vapalahti, Åke Lundkvist, Jenny C. Hesson
Bird-hosted viruses have the potential to be transported over large areas of the world and to be transmitted in distant geographical regions. Sindbis virus (SINV) is a mosquito-borne alphavirus that is locally amplified in a bird-mosquito enzootic cycle and distributed all over the Old World and Australia/Oceania. Sindbis virus genotype I (SINV-I) is the cause of disease outbreaks in humans in South Africa as well as in northern Europe. To trace the evolutionary history and potential strain-disease association of SINV-I, we sequenced 36 complete genomes isolated from field material in Europe as well as in Africa and the Middle-East, collected over 58 years. These were analysed together with 30 additional published whole SINV-I genomes using Bayesisan analysis. Our results suggested that SINV-I was introduced only once to northern Europe from central Africa, in the 1920s. After its first introduction to Sweden, it spread east and southwards on two separate occasions in the 1960s and 1970s. Another introduction from central Africa seems to have occurred to southern/central Europe, and where these two introductions meet, one recombination event was detected in central Europe. In addition, another recombinant strain was found in central Africa, where also the most divergent SINV-I viruses originated.
This study shows that only a single introduction of SINV into a new geographical area is required for the spread and establishment, provided that the requisite vector(s) and reservoir(s) of epizootological and epidemiological importance, are present. Further, we present the first report of recombination between two strains of SINV in nature. Our study increases the knowledge on new introductions and dispersal of arboviruses in general, and on SINV in particular.
Copyright © 2019 Ling et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license.
Keywords: Arbovirus; Alphavirus; Sindbis virus; Wild Birds; Africa; Europe.