The First Identification of Virus-1 (CSpV1) in Hanwoo () Calves in Korea.

is an obligate coccidian parasite that causes enteric diseases in bovine species. A double-stranded RNA virus associated with oocysts, virus-1 (CSpV1), has been characterized. However, the relationship between the abovementioned coccidian parasite and the virus has not been studied in the context of the known clinical outcomes. This study aimed to characterize the prevalence and molecular traits of CSpV1 in diarrheal feces of Hanwoo (Korean indigenous cattle) calves. Of the 140 fecal samples previously tested for , which were obtained from Hanwoo calves aged 60 days, 70 tested positive and 70 tested negative. These samples were included in this study. By using the polymerase chain reaction (PCR) analysis targeting the gene of CSpV1, we detected CSpV1 in 28 samples (20.0%), with infection rates of 31.4% (22/70) in -positive and 8.6% (6/70) in -negative samples. CSpV1 samples detected in the same farm were clustered together. To the best of our knowledge, this is the first study to report the prevalence and molecular characteristics of CSpV1 in Hanwoo calves in the Republic of Korea, providing important insights into the relationship between and CSpV1 in bovine hosts.