Thottapalayam virus, a prototype shrewborne hantavirus

Abstract

Thottapalayam virus (TPMV) has been placed in the genus Hantavirus of the family Bunyaviridae by virtue of its morphologic features and overall genetic similarities to well-characterized rodentborne hantaviruses. This virus has been isolated from the Asian house shrew (Suncus murinus); however, whether TPMV is naturally harbored by an insectivore host or represents spillover from a rodent reservoir host is unknown. Our analysis of published and unpublished data on the experimental host range, genetics, and molecular phylogeny of TPMV supports coevolution of TPMV with its nonrodent reservoir host. Future studies on the epizootiology of TPMV and investigations of new shrewborne hantaviruses will provide additional insights into the evolutionary origin of hantaviruses in their rodent and insectivore reservoir hosts. Such investigations may also provide clues about determinants of hantavirus pathogenicity and virulence.

Figure 1

Intracytoplasmic virus-specific fluorescence in brain tissues of an 11-day-old Mongolian gerbil (A) and a 10-day-old NIH Swiss mouse (B) injected intracerebrally with 6,000 PFU of Thottapalayam virus (TPMV) strain VRC-66412 from serum of an adult rat injected intramuscularly with TPMV (original magnification, x400).

Figure 2

Phylogenetic relationship between Thottapalayam virus (TPMV) and other hantaviruses based on the nucleotide sequences of the full-length small (S) genomic segment, determined by using the neighbor-joining method. Numbers at each node are bootstrap probabilities (expressed as percentages) determined for 1,000 iterations. Branch lengths are proportional to number of nucleotide substitutions per site. Sequences used for comparison were those of Hantaan (HTNV/76–118, NC 005218), Seoul (SEOV/SR-11, M34881), Dobrava (DOBV/3970, L41916), Bayou (BAYV, L36929), Black Creek Canal (BCCV, L39949), Sin Nombre (SNV/CC107, L33683; SNV/CC74, L33816; and SNV/NMH10, L25784), El Moro Canyon (ELMCV/Rm-97, U11427), Puumala (PUUV/K27, L08804 and PUUV/Sotkamo, NC 005224), Prospect Hill (PHV/PH1, Z49098), and Tula (TULV/T23, Z30945) viruses. Strain designations are unavailable for BAYV and BCCV. The full-length S-segment sequence of TPMV has been deposited into GenBank (accession no. AY526097).

Figure 3

Phylogenetic relationship between Suncus murinus and other insectivores and rodents in a 401-nt cytochrome b region of mitochondrial DNA determined by using the neighbor-joining method. Numbers at each node are bootstrap probabilities determined for 1,000 iterations. Members of the genus Crocidura (white-toothed shrews) belong to the subfamily Crocidurinae. They are distinguished from members of the subfamily Soricinae (red-toothed shrews) by their unpigmented teeth, 3 upper unicuspids, and more prominent ears than either the genera Sorex or Neomys.