Isolation and characterization of a novel coltivirus from ticks in Northeastern China.

BACKGROUD

Coltiviruses are spherical, non-enveloped viruses with 12 double-stranded RNA segments, belonging to the family , and predominantly transmitted by ticks. This study isolated and characterized a novel coltivirus, designated Woodland tick reovirus (WLTRV), from ticks collected in Helong City, Jilin Province, in Northeastern China.

METHODS

SW-13 and Vero cells were used to isolate WLTRV through three blind passages, while seven mammalian cell lines assessed viral growth. Viral morphology was observed by electron microscopy. Next-generation sequencing, 5' and 3' rapid amplification of cDNA ends were used to determine WLTRV whole genome sequences, and phylogenetic methods were used to characterize WLTRV. A real-time quantitative polymerase chain reaction (RT-qPCR) was used to detect WLTRV RNA in ticks.

RESULTS

WLTRV grew and exerted cytopathic effects in human (SW-13 and 293T) and mouse (BHK-21 and N2A) cell lines, revealing its potential to infect mammals. Phylogenetic analysis based on RNA-dependent RNA polymerase sequences classified WLTRV within the genus , with a close evolutionary relationship to Tarumizu tick virus. The nucleotide and amino acid sequence homologies between WLTRV and Tarumizu tick virus across the 12 segments analyzed ranged from approximately 44.79% to 69.09% and 33.73% to 75.60%, respectively. WLTRV shared conserved the 5'-terminal (GACA/ /) and 3'-terminal (UGCAGUC) consensus sequences of the genus genomes. Electron microscopy revealed WLTRV as spherical (diameter ∼80 nm), non-enveloped, and morphologically consistent with coltiviruses. Among the 4,717 ticks collected from six towns in the Yanbian Korean Autonomous Prefecture, WLTRV RNA was only detected in (0.95% virus-carrying rate) but not in , and .

CONCLUSIONS

This study represents the first isolation and identification of WLTRV from in the Yanbian Korean Autonomous Prefecture, providing new insights into the genetic diversity and evolution of the genus .