Epidemiology and Genomic characteristics of Wenzhou viruses in rodents from the southeast coast of China

Abstract Background: Wenzhou virus (WENV), a member of the Mammarenavirus genus in the Arenaviridae family, has been detected in wild rodents from eight provinces in China and Southeast Asia. The IgG-antibodies to WENV have been detected in healthy people and patients with unknown fever andrespiratory symptoms. However, since WENV was discovered, its potential harmfulness has been underestimated due to its mild symptoms after human infection, similar to respiratory diseases. Thus, it is imperative to further understand the pathogenicity of WENV and its mechanisms, to improve WENV surveillance in wild rodents, particularly Rattus norvegicus, and to detect the prevalence of WENV as needed. Results: During 2017-2021, a total of 390 wild rodents were collected from six provinces in eastern and southern coastal areas, containing nine species of rats, of which 36.4% were Rattus norvegicus. Samples of each tissue were collected and PCR amplification was performed. Four WENV-positive samples were detected, all from Rattus norvegicus. No genomic sequence of WENV was detected in Rattus flavipectus, Rattus losea, Suncus murinus, Apodemus agrarius, Mus musculus, Microtus fortis, Micromys minutus, and Niviventer niviventer from Jiangsu, Zhejiang, Fujian, Hainan, Guangdong and Guangxi Provinces. The full-length strain of WENV (HNHKW40/2020) was amplified from Rattus norvegicus in Hainan, which was most closely related to Wufeng/ WFS. The nucleotide sequence homology was 84.5-89.4% and the amino acid sequence homology was 91.6-98.9%. The sequences obtained in Xiamen, Fujian Provinces had more than 90% homology with WENV, which may be a strain of WENV. 83% of the positive sequences detected in Wuxi, Jiangsu Province were homologous to Lassa virus (LASV), which may be a member of LASV. Phylogenetic analysis indicated that all WENVs clustered together to form the Old World group with LASV and Loei River virus (LORV). Conclusions: In this study, we systematically examined the prevalence of WENV amongrodents inthe southeast coast of China and characterized the genome of a newly discovered WENV strain, confirming that rodents of Rattus norvegicus played a main role in WENV transmission. The need to enhance WENV surveys in wild rodents and humans was emphasized.