Modeling Hantavirus Maintenance and Transmission in Rodent Communities

Abstract

Analysis of the phylogenetic relationships among hantaviruses suggests that hantaviruses have had a longstanding co-evolutionary history with their predominant rodent carriers (Schmaljohn and Hjelle 1997; Nichol, in press). Closely related hantaviruses are generally derived from rodents that are themselves closely related, while deeper evolutionary branches in the virus phylogenetic tree are associated with deeper branches in the rodent phylogenetic tree. As a first approximation, hantavirus evolution resembles that of an extrachromosomal genetic element of murid rodents more than it does that of an autonomous, horizontally transmitted agent. Those hantaviruses that have a clearly identified reservoir host are associated with rodents of the family Muridae, subfamilies Murinae, Arvicolinae, and Sigmodontinae. A single hantavirus isolate, Thottapalayam, was obtained from a non-murid host, the shrew Suncus murinus (Carey et al. 1971). It is unclear whether insectivores are truly reservoirs for hantaviruses,or rare incidental hosts. If the former were true then these viruses would most likely represent ancient relatives of those found in murid rodents, given the temporal depth of the divergence between Insectivora and Rodentia. It appears to us to be somewhat more likely that Thottapalayam represents a recent host-switching event, since even the high divergence of that virus from other hantaviruses is not as large as is the divergence between Insectivora and Rodentia.