Abstract
Orthohantaviruses are tightly linked to the ecology and evolutionary history of their mammalian hosts. We hypothesized that in regions with dramatic climate shifts throughout the Quaternary, orthohantavirus diversity and evolution are shaped by dynamic host responses to environmental change through processes such as host isolation, host switching, and reassortment. Jemez Springs virus (JMSV), an orthohantavirus harbored by the dusky shrew (Sorex monticola) and five close relatives distributed widely in western North America, was used to test this hypothesis. Total RNAs, extracted from liver or lung tissue from 164 shrews collected from western North America during 1983–2007, were analyzed for orthohantavirus RNA by reverse transcription polymerase chain reaction (RT-PCR). Phylogenies inferred from the L-, M-, and S-segment sequences of 30 JMSV strains were compared with host mitochondrial cytochrome b. Viral clades largely corresponded to host clades, which were primarily structured by geography and were consistent with hypothesized post-glacial expansion. Despite an overall congruence between host and viral gene phylogenies at deeper scales, phylogenetic signals were recovered that also suggested a complex pattern of host switching and at least one reassortment event in the evolutionary history of JMSV. A fundamental understanding of how orthohantaviruses respond to periods of host population expansion, contraction, and secondary host contact is the key to establishing a framework for both more comprehensive understanding of orthohantavirus evolutionary dynamics and broader insights into host–pathogen systems.
Highlights
Comparative phylogeographic study of parasites and their hosts can provide valuable insights into evolutionary history and processes of diversification for both host and parasite
The classic model of strict host–parasite codiversification as the leading process driving parasite evolution has been thrown into question over the past several decades with studies suggesting that host switching is more prevalent than originally thought, but that it may be the most common pattern throughout parasite evolutionary history [4,5]
Reassortment may be frequent in orthohantaviruses; research to date has mainly focused on reassortment within orthohantavirus strains hosted by single species [10]
Summary
Comparative phylogeographic study of parasites and their hosts can provide valuable insights into evolutionary history and processes of diversification for both host and parasite. These analyses provide a predictive framework for emerging disease under scenarios of changing environmental conditions [1,2,3]. These viruses have a complex history of both codiversification with their mammal hosts [7] and host switching across mammalian species [8,9]. Reassortment may be frequent in orthohantaviruses; research to date has mainly focused on reassortment within orthohantavirus strains hosted by single species [10]
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