Continuing Orthohantavirus Circulation in Deer Mice in Western Montana

Abstract

Hantavirus pulmonary syndrome (HPS) is an often-fatal disease caused by New World hantaviruses, such as Sin Nombre orthohantavirus (SNV). In the US, >800 cases of HPS have been confirmed since it was first discovered in 1993, of which 43 were reported from the state of Montana. The primary cause of HPS in the US is SNV, which is primarily found in the reservoir host Peromyscus maniculatus (deer mouse). The reservoir host covers most of the US, including Montana, where multiple studies found SNV in local deer mouse populations. This study aimed to check the prevalence of SNV in the deer mice at popular recreation sites throughout the Bitterroot Valley in Western Montana as compared to previous studies in western Montana. We found high prevalence (up to 20%) of deer mice positive for SNV RNA in the lungs. We were unable to obtain a SNV tissue culture isolate from the lungs but could passage SNV from lung tissue into naïve deer mice. Our findings demonstrate continuing circulation of SNV in western Montana.

Keywords: Bitterroot Valley; Montana; Peromyscus maniculatus; Sin Nombre orthohantavirus; genome detection; lung.

Figure 1

Map of field sites and capture data for 2017 and 2018 trapping seasons. The number of deer mice per total number animal capture is listed next to symbols for the trapping month (May, June, July, or August) per field site (Lake Como, Alta, or Hogan Cabin).

Figure 2

(a) Phylogenetic tree of 1121 bp of the L segment, (b) tree of 2088 bp of the M segment, and (c) tree of 1641 bp of the S segment of Bitterroot Valley Sin Nombre orthohantavirus (SNV) sequences compared to other SNV sequences throughout the western United States. The trees were inferred using the neighbor-joining method based on the Tamura-Nei model. Bootstrap percentages (1000 replicates) above 70% are shown next to the branches. The branch lengths are the number of base substitutions per site. GenBank submission numbers are listed in parentheses. Analyses were conducted in Geneious Prime 11. HNTV = Hantaan virus, PHV = Prospect Hill virus.