Hantavirus - Evolution

Evolution

Findings of significant congruence between phylogenies of hantaviruses and phylogenies of their rodent reservoirs have led to the theory – well-accepted until recently – of long-standing hantavirus-rodent host coevolution. However, recent findings have led to scientific debate and new hypotheses regarding hantavirus evolution.

Various hantaviruses have been found to infect multiple rodent species, and cases of cross-species transmission (host switching) have been recorded. Additionally, rates of substitution based on nucleotide sequence data reveal that hantavirus clades and rodent subfamilies may not have diverged at the same time. Furthermore, hantaviruses have been found in multiple species of shrews and moles.

Taking into account the inconsistencies in the theory of coevolution, Ramsden et al. (2009) have proposed that the patterns seen in hantaviruses in relation to their reservoirs could be attributed to preferential host switching directed by geographical proximity and adaptation to specific host types. Ulrich et al. (2010) have proposed that the observed geographical clustering of hantavirus sequences may have been caused by an isolation-by-distance mechanism. Upon comparison of the hantaviruses found in hosts of orders Rodentia and Soricomorpha, Yanagihara et al. (2011) have proposed that the evolutionary history of the hantavirus consists of a complex mix of both host switching and codivergence and suggest that ancestral shrews or moles rather than rodents may have been the early original hosts of ancient hantaviruses.