The Bank Vole (Clethrionomys glareolus)—Small Animal Model for Hepacivirus Infection

Many people worldwide suffer from hepatitis C virus (HCV) infection, which is frequently persistent. The lack of efficient vaccines against HCV and the unavailability of or limited compliance with existing antiviral therapies is problematic for health care systems worldwide. Improved small animal models would support further hepacivirus research, including development of vaccines and novel antivirals. The recent discovery of several mammalian hepaciviruses may facilitate such research. In this study, we demonstrated that bank voles (Clethrionomys glareolus) were susceptible to bank vole-associated Hepacivirus F and Hepacivirus J strains, based on the detection of hepaciviral RNA in 52 of 55 experimentally inoculated voles. In contrast, interferon α/β receptor deficient C57/Bl6 mice were resistant to infection with both bank vole hepaciviruses (BvHVs). The highest viral genome loads in infected voles were detected in the liver, and viral RNA was visualized by in situ hybridization in hepatocytes, confirming a marked hepatotropism. Furthermore, liver lesions in infected voles resembled those of HCV infection in humans. In conclusion, infection with both BvHVs in their natural hosts shares striking similarities to HCV infection in humans and may represent promising small animal models for this important human disease.

Helminths in Myomorph Rodents (Rodentia, Myomorpha) from the National Park “Smolny” and Its Surroundings (European Russia)

The National Park “Smolny” is a large forest area, located in the center of European Russia. The helminth fauna of myomorph rodents was studied for the first time within the National Park in 2018–2020. Rodents were examined by the method of complete helminthological dissection. A total of 30 species of parasites were recorded in 11 rodent species: 6 trematodes, 11 cestodes and 13 nematodes. The trematode Plagiorchis maculosus (Rudolphi, 1802) was found in Clethrionomys glareolus (Schreber, 1780) from the Russian fauna for the first time. Clethrionomys glareolus and Microtus arvalis (Pallas, 1779) are new hosts for P. maculosus and metacestode Versteria mustelae (Gmelin, 1790), respectively. The most widespread and eurybiont rodent species have the most diverse and rich helminth fauna, such as C/glareolus (14 species), Apodemus agrarius (Pallas, 1771) (12) and Sylvaemus uralensis (Pallas, 1811) (10). The helminth fauna is less diverse in Sylvaemus flavicollis (Melchior, 1834), M. arvalis (7 species each), Microtus agrestis (Linnaeus, 1761) (5), Microtus subterraneus (de Selys-Longchamps, 1836) (3), Sicista betulina (Pallas, 1779) (2) and Arvicola amphibius (Linnaeus, 1758) (1). Сomparative analysis the helminth fauna of small rodents from the National Park “Smolny” with micromammals from other regions of European Russia revealed that the high similarity with other areas reaches the helminth fauna of M. subterraneus, S. flavicollis, S. uralensis, S. betulina, A. amphibius and M. agrestis.

Commensals of underground mammals: European mole (Talpa europaea, Eulipotyphla, Talpidae) and the greater mole-rat (Spalax microphthalmus, Rodentia, Spalacidae)

Stepanova I, Andreychev A, Kulakhmetov R, Lobachev E. 2021. Commensals of underground mammals: European mole (Talpa europaea, Eulipotyphla, Talpidae) and the greater mole-rat (Spalax microphthalmus, Rodentia, Spalacidae). Biodiversitas 22: 4665-4670. The study of lodgers of burrows of underground mammals was carried out using the method of hunting cylinders (cans). In the study, 29 different representatives from the following classes were identified in the courses of the greater mole-rat and European mole: Diplopoda, Chilopoda, Gastropoda, Insecta, Amphibia, and Mammalia. Among the vertebrates captured are Eurasian common shrew (Sorex araneus), Eurasian pygmy shrew (Sorex minutus), bank vole (Clethrionomys glareolus), common spadefoot toad (Pelobates fuscus), moor frog (Rana arvalis), and common toad (Bufo bufo). Twenty-six different species have been identified among invertebrates. Many animals seek shelter in the burrows of underground mammals from enemies and adverse climatic factors for food or conditions for reproduction. In the central part of Russia, more species of commensals were found in European mole burrows (29) than in greater mole-rat burrows (21).

Influence of Season, Population and Individual Characteristics on the Prevalence of Leptospira spp. in Bank Voles in North-West Germany

Leptospirosis is a worldwide zoonotic disease with more than 1 million human cases annually. Infections are associated with direct contact to infected animals or indirect contact to contaminated water or soil. As not much is known about the prevalence and host specificity of Leptospira spp. in bank voles (Clethrionomys glareolus), our study aimed to evaluate Leptospira spp. prevalence and genomospecies distribution as well as the influence of season, host abundance and individual characteristics on the Leptospira prevalence. Bank voles, which are abundant and widely distributed in forest habitats, were collected in the years 2018 to 2020 in North-West Germany, covering parts of North Rhine-Westphalia and Lower Saxony. The DNA of 1817 kidney samples was analyzed by real-time PCR targeting the lipl32 gene. Positive samples were further analyzed by targeting the secY gene to determine Leptospira genomospecies and multilocus sequence typing (MLST) to determine the sequence type (ST). The overall prevalence was 7.5% (95% confidence interval: 6.4–8.9). Leptospira interrogans (83.3%), L. kirschneri (11.5%) and L. borgpetersenii (5.2%) were detected in bank voles. Increasing body weight as a proxy for age increased the individual infection probability. Only in years with high bank vole abundance was this probability significantly higher in males than in females. Even if case numbers of human leptospirosis in Germany are low, our study shows that pathogenic Leptospira spp. are present and thus a persisting potential source for human infection.

Rodent species in urban cemeteries of Chisinau city, Republic of Moldova

The research has been conducted in 3 biggest cemeteries of Chisinau city: Central (“Armenian”), “Saint Lazarus” (“Doina”) and Jewish. We found 9 species of small mammals (7 species of rodents and 2 shrews). Species of rodents were Clethrionomys glareolus, Microtus rossiaemeridionalis, Apodemus flavicollis, A. sylvaticus, A. uralensis, Rattus norvegicus and Mus musculus and 2 shrew species – Sorex araneus and Crocidura suaveolens. A.sylvaticus was dominant species, followed by M. rossiaemeridionalis and A. flavicollis.

Inhibition of interferon I induction by non-structural protein NSs of Puumala virus and other vole-associated orthohantaviruses: phenotypic plasticity of the protein and potential functional domains

The orthohantavirus Puumala virus (PUUV), which is transmitted by bank voles (Clethrionomys glareolus), and other vole-borne hantaviruses contain in their small (S) genome segment two overlapping open reading frames, coding for the nucleocapsid protein and the non-structural protein NSs, a putative type I interferon (IFN-I) antagonist. To investigate the role of NSs of PUUV and other orthohantaviruses, the expression pattern of recombinant NSs constructs and their ability to inhibit human IFN-I promoter activity were investigated. The NSs proteins of PUUV and related cricetid-borne orthohantaviruses showed strong inhibition of IFN-I promoter induction. We identified protein products originating from three and two methionine initiation codons in the NSs ORF of PUUV during transfection and infection, respectively. The three putative start codons are conserved in all PUUV strains analysed. Translation initiation at these start codons influenced the inhibitory activity of the NSs products, with the wild-type (wt) construct expressing two proteins starting at the first and second methionine and showing strong inhibition activity. Analysis of in vitro-generated variants and naturally occurring PUUV NSs proteins indicated that amino acid variation in the NSs protein is well tolerated, suggesting its phenotypic plasticity. The N-terminal 20-amino-acid region of the NSs protein was found to be associated with strong inhibition and to be highly vulnerable to amino acid exchanges and tag fusions. Infection studies using human, bank vole, and Vero E6 cells did not show obvious differences in the replication capacity of PUUV Sotkamo wt and a strain with a truncated NSs protein (NSs21Stop), showing that the lack of a full-length NSs might be compensated by its N-terminal peptide, as seen in transfection experiments. These results contribute to our understanding of virus-host interactions and highlight the importance of future innate immunity studies in reservoir hosts.

Geographical Distribution and Genetic Diversity of Bank Vole Hepaciviruses in Europe

The development of new diagnostic methods resulted in the discovery of novel hepaciviruses in wild populations of the bank vole (Myodes glareolus, syn. Clethrionomys glareolus). The naturally infected voles demonstrate signs of hepatitis similar to those induced by hepatitis C virus (HCV) in humans. The aim of the present research was to investigate the geographical distribution of bank vole-associated hepaciviruses (BvHVs) and their genetic diversity in Europe. Real-time reverse transcription polymerase chain reaction (RT-qPCR) screening revealed BvHV RNA in 442 out of 1838 (24.0%) bank voles from nine European countries and in one of seven northern red-backed voles (Myodes rutilus, syn. Clethrionomys rutilus). BvHV RNA was not found in any other small mammal species (n = 23) tested here. Phylogenetic and isolation-by-distance analyses confirmed the occurrence of both BvHV species (Hepacivirus F and Hepacivirus J) and their sympatric occurrence at several trapping sites in two countries. The broad geographical distribution of BvHVs across Europe was associated with their presence in bank voles of different evolutionary lineages. The extensive geographical distribution and high levels of genetic diversity of BvHVs, as well as the high population fluctuations of bank voles and occasional commensalism in some parts of Europe warrant future studies on the zoonotic potential of BvHVs.

Babesia microti in Rodents from Different Habitats of Lithuania

Babesia microti (Aconoidasida: Piroplasmida) (Franca, 1910) is an emerging tick-borne parasite with rodents serving as the considered reservoir host. However, the distribution of B. microti in Europe is insufficiently characterized. Based on the sample of 1180 rodents from 19 study sites in Lithuania, the objectives of this study were: (1) to investigate the presence of Babesia parasites in eight species of rodents, (2) to determine the prevalence of Babesia parasites in rodents from different habitats, and (3) to characterize the detected Babesia strains using partial sequencing of the 18S rRNR gene. Babesia DNA was detected in 2.8% rodents. The highest prevalence of Babesia was found in Microtus oeconomus (14.5%) and Microtus agrestis (7.1%) followed by Clethrionomys glareolus (2.3%), Apodemus flavicollis (2.2%) and Micromys minutus (1.3%). In M. minutus, Babesia was identified for the first time. The prevalence of Babesia-infected rodents was higher in the meadow (5.67%) than in the ecotone (1.69%) and forest (0.31%) habitats. The sequence analysis of the partial 18S rRNA gene reveals that Babesia isolates derived from rodents were 99–100% identical to human pathogenic B. microti ‘Jena/Germany’ strain.