Hindawi Publishing Corporation ISRN Virology Volume 2013, Article ID 861912, 22 pages http://dx.doi.org/10.5402/2013/861912 Review Article The Pathogenesis of Alphaviruses Gregory J. Atkins Department of Microbiology, Moyne Institute, Trinity College, Dublin 2, Ireland Correspondence should be addressed to Gregory J. Atkins;
[email protected] Received 27 September 2012; Accepted 19 October 2012 Academic Editors: B. Kim and J. S. Lee Copyright © 2013 Gregory J. Atkins. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Alphaviruses are enveloped single-stranded positive sense RNA viruses of the family Togaviridae. e genus alphavirus contains nine viruses, which are of medical, theoretical, or economic importance, and which will be considered. Sindbis virus (SINV) and Semliki Forest (SFV), although of some medical importance, have largely been studied as models of viral pathogenicity. In mice, SINV and SFV infect neurons in the central nervous system and virulent strains induce lethal encephalitis, whereas avirulent strains of SFV induce demyelination. SFV infects the developing foetus and can be teratogenic. Venezuelan Equine Encephalitis virus, Eastern Equine Encephalitis virus, and Western Equine Encephalitis virus can induce encephalitis in horses and humans. ey are prevalent in the Americas and are mosquito transmitted. Ross River virus, Chikungunya virus (CHIKV), and O’nyong-nyong virus (ONNV) are prevalent in Australasia, Africa and Asia, and Africa, respectively. ONNV virus is transmitted by Anopheles mosquitoes, while the other alphaviruses are transmitted by culicine mosquitoes. CHIKV has undergone adaptation to a new mosquito host which has increased its host range beyond Africa.