Distribution of Mukawa virus (Phlebovirus mukawaense) in Russia

Phleboviruses, a diverse group within the Phenuiviridae family, include mosquito-, tick-, and sandfly-borne viruses, several of which are pathogenic to humans and animals. Among them, Phlebovirus mukawaense (formerly Mukawa virus, MKWV), a tick-associated member of the Phlebovirus genus, exhibits features, indicative of an emerging arbovirus with potential pathogenicity for humans and animals. This study investigated the distribution, genetic diversity, and host/vector interactions of MKWV across Russia. It identified two genotypes: the previously described Mukawa genotype and the newly characterized Gomselga genotype. This study presents complete genomic sequences of ten MKWV isolates from Russia and analyzes their phylogenetic relationship with other known isolates. The isolates share 88-89% nucleotide identity, and 97-98% RdRp amino acid identity, with the MKWV reference strain (MKW73). This places them within the same species under current ICTV classification criteria. Genetic distance correlated with geographic origin for the L and M segments. The S segment, particularly the NSs gene fragment, showed less regional variability. The findings suggest that previously described Gomselga viruses in Russia are part of the MKWV species and highlight the virus's broader geographic distribution and genetic diversity across East Asia and Europe. Segment reassortments were observed both within the Gomselga genotype and within the Mukawa genotype. While the Mukawa genotype replicates in mammalian cells, the Gomselga genotype does not. This indicates possible differences in host tropism or pathogenic potential. Despite these differences, both genotypes have evolutionary features consistent with arboviruses, including reassortment and geographical clustering of genomic variants. Although vertical transmission in ticks remains unproven, the detection of MKWV in multiple tick species and vertebrate hosts supports the likelihood of vector-borne transmission. These findings suggest that MKWV is a probable arboviral pathogen with an extensive geographic range and potential public health relevance. This warrants further surveillance and virological characterization to assess its epidemic potential.