A novel genetic lineage of Tula orthohantavirus in Altai voles (Microtus obscurus) from Turkey

Abstract

Orthohantaviruses (family Hantaviridae order Bunyavirales) are emerging pathogens with a significant impact on human health. They are transmitted via aerosolized excreta of rodents which also act as reservoir hosts, constituting a unique route for dispersion. Dobrava-Belgrade and Puumala orthohantaviruses have been previously reported from Anatolia, in rodents, case reports and occasional outbreaks. We have collected rodents at several locations during a surveillance study in eastern Anatolia. The specimens were morphologically-identified and various tissues were screened via a generic orthohantavirus reverse transcription polymerase chain reaction assay. DNA barcoding via mitochondrial cytochrome b sequencing was performed in rodents with detectable orthohantavirus sequences. High throughput sequencing was performed for viral genome characterization. Fifty rodents were collected and identified morphologically as Microtus spp. (96%) and Apodemus spp. (4%). Orthohantavirus sequences were detected in lung and spleen or liver tissues of 4 voles (8%), barcoded as Microtus obscurus. The virus sequences were identified as Tula orthohantavirus (TULV) and near-complete genomic segments of the prototype viral genome, tentatively named as the Tula orthohantavirus-Turkey (TULV-T), could be characterized. Putative open reading frames for viral nucleocapsid and a nonstructural protein on the S segment, glycoproteins G1 and G2 on the M segment and viral replicase on the L segment were identified on the TULV-T. Several minor sequence variants were further characterized. No evidence of recombination could be detected and pairwise comparisons displayed over 95% amino acid sequence identities to various Eurasian TULV strains. Phylogenetic analyses revealed distinct clustering of all genome segments from previously-characterized TULV strains via various approaches and models. Here, TULV-T constituted a novel lineage, forming an intermediate among Asian and European TULV lineages. This report describes the initial documentation of TULV circulation and its potential reservoir in Anatolia. The extent of virus dispersion, alternate hosts or outcomes of human exposure require elucidation.