Prevalence and Genetic Characterization of Mammalian Orthoreoviruses in Diarrheic Cattle from Guangxi, China

Mammalian orthoreoviruses (MRVs) infect a wide range of animal hosts, yet epidemiological data from southern China remain limited. Here, we performed regional screening of diarrheic cattle in Guangxi, China, from 2023 to 2025. Using L1-targeted RT-PCR, MRV was detected in 8.4% (15/178) of fecal specimens collected across eight prefectures, with a higher detection rate during the cool (autumn-winter) season (October-March). We obtained two complete S1 segments, assigning one Guangxi strain to MRV1 and the other to MRV3. Phylogenetic analysis of L1 sequences indicated a single local lineage nested within a broader multi-host cluster, which was consistent with segment reassortment. σ1 protein alignment revealed a conserved central/C-terminal scaffold and a variable distal head; notably, the MRV3 σ1 sequence contained an extended ~360-390 aa region compared with MRV1. Overall, these findings provide an epidemiological baseline for Guangxi cattle, integrating detection rate, serotype context, and seasonality to support targeted, seasonally informed surveillance and MRV risk assessment.