Broad geographical distribution and high genetic diversity of shrew-borne Seewis hantavirus in Central Europe

Abstract

For a long time hantaviruses were believed to be exclusively rodent-borne pathogens. Recent findings of numerous shrew- and mole-borne hantaviruses raise important questions on their phylogenetic origin. The objective of our study was to prove the presence and distribution of shrew-associated Seewis virus (SWSV) in different Sorex species in Central Europe. Therefore, a total of 353 Sorex araneus, 59 S. minutus, 27 S. coronatus, and one S. alpinus were collected in Germany, the Czech Republic, and Slovakia. Screening by hantavirus-specific L-segment RT-PCR revealed specific amplification products in tissues of 49 out of 353 S. araneus and four out of 59 S. minutus. S-segment sequences were obtained for 45 of the L-segment positive S. araneus and all four L-segment positive S. minutus. Phylogenetic investigation of these sequences from Germany, the Czech Republic, and Slovakia demonstrated their similarity to SWSV sequences from Hungary, Finland, Austria, and other sites in Germany. The low intra-cluster sequence variability and the high inter-cluster divergence suggest a long-term SWSV evolution in isolated Sorex populations. In 28 of the 49 SWSV S-segment sequences, an additional putative open reading frame (ORF) on the opposite strand to the nucleocapsid protein-encoding ORF was identified. This is the first comprehensive sequence analysis of SWSV strains from Germany, the Czech Republic, and Slovakia, indicating its broad geographical distribution and high genetic divergence. Future studies have to prove whether both S. araneus and S. minutus represent SWSV reservoir hosts or spillover infections are responsible for the parallel molecular detection of SWSV in both species.

The broad spectrum of hantaviruses and their hosts in Central Europe

“…Later on, SWSV was detected in S. araneus shrews captured in Finland and Hungary (Kang et al, 2009a) as well as and in Austria and Germany (EU418604-16;Nowotny et al, unpublished data). Extensive phylogenetic study of Schlegel et al (2012b) focusing on Germany, the Czech Republic and Slovakia confirmed a wide geographic distribution of SWSV across Europe and indicated high genetic divergence and strong geographical clustering of the virus in local shrew populations. European common shrew is regarded as the main reservoir of SWSV, however other species such as Pygmy shrew (S. minutus) and Mediterranean or Miller΄s water shrew (Neomys anomalus) have been shown to carry SWSV, too, probably only in the form of random and transient, so called "spill-over" infections (Schlegel et al, 2012b).…”

“…Prominent examples of hantaviruses that cause human disease are Hantaan virus, Seoul virus, Dobrava-Belgrade virus (DOBV), and Puumala virus (PUUV) causing HFRS in Eurasia while Sin Nombre virus and Andes virus cause hantavirus cardiopulmonary syndrome in the Americas . Recently, hantaviruses have also been found in Africa (Klempa et al, 2006Kang et al, 2011;Weiss et al, 2012;Sumibcay et al, 2012;Meheretu et al, 2012) where they may also represent a significant public health threat (Klempa et al, 2010(Klempa et al, , 2012b.…”

Serological survey of Seewis virus antibodies in patients suspected for hantavirus infection in Finland; a cross-reaction between Puumala virus antiserum with Seewis virus N protein?

“…S. araneus has been established as a host of SWSV; the hantavirus antigen was found in its tissues using ELISA as early as 1982 (Gavrilovskaya et al, 1983). In Finland, bank voles and common shrews, which are commonly found together in the same habitats, have been screened for hantavirus antibodies using IFA (Voutilainen et al, 2012), but no obvious positive reactions were found from S. araneus samples, most probably due to the fact that the anti-mouse secondary antibodies cross-reacted with the shrew IgG at a low level (Schlegel et al, 2012b). It is quite likely that more soricomorph-borne hantaviruses will be discovered in the near future.…”

“…To our knowledge cell culture isolates of SWSV do not exist, which to some extent compromises the use of the term virus; however, for the sake of clarity we will use SWSV when referring to Seewis virus. Soon after its discovery, SWSV was also detected in Austria, the Czech Republic, Finland, Germany, Hungary, Poland, Russia, Slovakia and Slovenia (Kang et al, 2009;Ling et al, 2014;Resman et al, 2013;Schlegel et al, 2012b;Song et al, 2007b;Yashina et al, 2010). SWSV is divided into three genotypes; the Finnish subtype is distant from both the Russian and Central European SWSV subtypes.…”

“…SWSV shares its most recent common ancestor with the Muridae-associated hantaviruses HTNV and SEOV, which is considered to be due to a horizontal transmission event between the rodents and soricomorphs (Plyusnin & Sironen, 2014). The prevalence of SWSV is fairly high and about 12 to 14 % of common shrews are positive for SWSV RNA (Ling et al, 2014;Schlegel et al, 2012b). SWSV is geographically widespread but the evidence for SWSV existence is limited to nucleic acid detection and serological evidence is lacking.…”