Alphavirus - Host Interactions
Kate D. Ryman and William B. Klimstra
from: Arboviruses: Molecular Biology, Evolution and Control (Edited by: Nikos Vasilakis and Duane J. Gubler). Caister Academic Press, U.K. (2016) Pages: 89-106.
Members of the genus Alphavirus, family Togaviridae, are arthropod-borne viruses, mostly vectored in nature by specific mosquito species between various vertebrate reservoir hosts including birds, rodents, equids and non-human primates (NHPs) in classical arbovirus transmission cycles. The exceptions are the so-called salmonid alphaviruses, salmon pancreatic disease virus and its subtype, sleeping disease virus, which infect fish, causing mortality in farmed salmon and trout, and the southern elephant seal virus (SESV). The presence of SESV within lice suggests an arthropod-borne cycle, but the vector-host relationships have yet to be confirmed. The second genus in the family is Rubivirus, containing only the rubella virus, which shares genomic and structural features with the alphaviruses but is not an arbovirus and so not discussed further. Within the Alphavirus genus, viruses are grouped into four major subgroups by antibody cross-reactivity: the Semliki Forest (SF), Venezuelan equine encephalitis (VEE), eastern equine encephalitis (EEE) and western equine encephalitis (WEE) serocomplexes. Fascinatingly, recent phylogenetic evidence suggests that the salmonid alphaviruses may be the progenitors of the entire genus. As a consequence of their transmission cycle, the alphaviruses must be replication-competent in their mosquito vectors and reservoir hosts, which vary between viruses. It has become increasingly clear that these highly divergent hosts each exert strongly selective pressures on the viruses that constrain viral genetic variation but may also drive particular aspects of host interaction that result in disease. In this chapter, we will describe recent advances in our understanding of the characteristics of alphavirus interaction with vertebrate hosts, focusing upon the relationship of particular infection/replication characteristics to disease manifestations and immune responses read more ...