There is a growing diversity of bat-associated lyssaviruses in the Old World. In August 2017, a dead Brandt’s bat (Myotis brandtii) tested positive for rabies and based on partial sequence analysis, the novel Kotalahti bat lyssavirus (KBLV) was identified. Because the bat was in an autolyzed state, isolation of KBLV was neither successful after three consecutive cell passages on cells nor in mice. Next generation sequencing (NGS) was applied using Ion Torrent ™ S5 technology coupled with target enrichment via hybridization-based capture (myBaits^®) was used to sequence 99% of the genome, comprising of 11,878 nucleotides (nt). KBLV is most closely related to EBLV-2 (78.7% identity), followed by KHUV (79.0%) and BBLV (77.6%), supporting the assignment as phylogroup I lyssavirus. Interestingly, all of these lyssaviruses were also isolated from bat species of the genus Myotis, thus supporting that M. brandtii is likely the reservoir host. All information on antigenic and genetic divergence fulfil the species demarcation criteria by ICTV, so that we recommend KBLV as a novel species within the Lyssavirus genus. Next to sequence analyses, assignment to phylogroup I was functionally corroborated by cross-neutralization of G-deleted RABV, pseudotyped with KBLV-G by sera from RABV vaccinated humans. This suggests that conventional RABV vaccines also confer protection against the novel KBLV.

Myxomatosis, caused by myxoma virus (MYXV), is a fatal disease of the European rabbit (Oryctolagus cuniculus). It has a worldwide distribution and has become an endemic disease throughout Europe since its introduction into the rabbit population in 1950. This study describes the first outbreak caused by MYXV in Finland in summer 2020. Eighteen feral rabbits collected during the outbreak and two during the following year were confirmed positive for MYXV using real-time PCR. Coinfection with rabbit hemorrhagic disease virus (RHDV) was observed in six cases. Whole genome sequencing of MYXV was performed for five rabbit samples collected during the outbreak in 2020 and two rabbit samples collected in 2021 to assess the origin of the virus and possible evolutionary mutations. Genetic characterization revealed that the genomes of the five samples collected during the outbreak in 2020 were identical. Phylogenetic analysis demonstrated the highest nucleotide identity to the German field strain FLI-H (99.97 %). The Finnish strains contain mutations that have not previously been described and may be responsible for changes in virus properties. On the other hand, the virus genome displayed only minor changes during the one-year follow-up in Finland. These findings add to knowledge of the spread of MYXV and its evolution.