RESUMO
Orthohantaviruses are mainly carried and transmitted by wild rodents, although during the last decade, they have also been identified in multiple species of shrews and moles. Orthohantavirus, Orthohantavirus seewisense (Seewis virus, SWSV), first detected in Switzerland in a single Sorex araneus (Eurasian common shrew) specimen, has been further described in several European countries, including Croatia's neighboring Slovenia and Hungary. Croatia is a well-known endemic region for several zoonotic agents including three different orthohantaviruses: Orthohantavirus puumalaense (PUUV), Orthohantavirus dobravaense (DOBV), and Orthohantavirus tulaense (TULV). In this study, nine shrews were tested and SWSV RNA was detected in liver, lung, and kidney belonging to two shrews (22.22%), one collected on Medvednica mountain in Zagreb County, and the other in the Stara Gradiska area in lowland Croatia. The phylogenetic analysis of the complete S segment's open reading frame (ORF) and partial L-segment revealed that the Croatian sequences, when compared to sequences from the adjacent geographic regions, form a specific genetic lineage. Two SWSV-positive shrew species-Sorex araneus and Neomys milleri (Mediterranean water shrew)-were identified using barcode-based sequence analysis. Therefore, the SWSV detection in N. milleri throughout the course of this study is seen as a rare find in this shrew species. To our knowledge, this is the first molecular and phylogenetic analysis of SWSV in Croatia.
RESUMO
Murid and cricetid rodents were previously believed to be the principal reservoir hosts of hantaviruses. Recently, however, multiple newfound hantaviruses have been discovered in shrews, moles, and bats, suggesting a complex evolutionary history. Little is known about the genetic diversity and geographic distribution of the prototype shrew-borne hantavirus, Thottapalayam thottimvirus (TPMV), carried by the Asian house shrew (Suncus murinus), which is widespread in Asia, Africa, and the Middle East. Comparison of TPMV genomic sequences from two Asian house shrews captured in Myanmar and Pakistan with TPMV strains in GenBank revealed that the Myanmar TPMV strain (H2763) was closely related to the prototype TPMV strain (VRC66412) from India. In the L-segment tree, on the other hand, the Pakistan TPMV strain (PK3629) appeared to be the most divergent, followed by TPMV strains from Nepal, then the Indian-Myanmar strains, and finally TPMV strains from China. The Myanmar strain of TPMV showed sequence similarity of 79.3-96.1% at the nucleotide level, but the deduced amino acid sequences showed a high degree of conservation of more than 94% with TPMV strains from Nepal, India, Pakistan, and China. Cophylogenetic analysis of host cytochrome b and TPMV strains suggested that the Pakistan TPMV strain was mismatched. Phylogenetic trees, based on host cytochrome b and cytochrome c oxidase subunit I genes of mitochondrial DNA, and on host recombination activating gene 1 of nuclear DNA, suggested that the Asian house shrew and Asian highland shrew (Suncus montanus) comprised a species complex. Overall, the geographic-specific clustering of TPMV strains in Asian countries suggested local host-specific adaptation. Additional in-depth studies are warranted to ascertain if TPMV originated in Asian house shrews on the Indian subcontinent.