Prevalence of the Puumala orthohantavirus Strains in the Pre-Kama Area of the Republic of Tatarstan, Russia

<i>Puumala orthohantavirus</i> (PUUV) causes nephropathia epidemica (NE), a mild form of hemorrhagic fever with renal syndrome (HFRS) commonly diagnosed in Europe. The majority of HFRS cases in the European part of Russia are diagnosed in the Volga Federal District, which includes the Republic of Tatarstan (RT). The current study aims to analyze the genetic variability of PUUV in Pre-Kama region of the RT bounded by the Volga, Kama, and Vyatka rivers. In 2017, bank voles were caught in seven isolated forest traps in the Pre-Kama region and for the 26 PUUV-positive samples, the partial small (S), medium (M), and large (L) genome segment sequences were obtained and analyzed. It was determined that all identified PUUV strains belong to the Russian (RUS) genetic lineage; however, the genetic distance between strains is not directly correlated with the geographical distance between bank vole populations. One of the identified strains has S and L segments produced from one parental strain, while the M segment was supplied by another, suggesting that this strain could be the reassortant. We suggest that the revealed pattern of the PUUV strains distribution could be the result of a series of successive multidirectional migratory flows of the bank voles to the Pre-Kama region in the postglacial period.