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- Title
Characterization and Spike Gene Analysis of a Candidate Attenuated Live Bovine Coronavirus Vaccine.
- Authors
Park, Gyu-Nam; Choe, SeEun; Song, Sok; Kim, Ki-Sun; Shin, Jihye; An, Byung-Hyun; Moon, Soo Hyun; Hyun, Bang-Hun; An, Dong-Jun
- Abstract
Simple Summary: Diarrheal diseases in calves cause economic losses in countries worldwide. In particular, bovine coronavirus, the main cause of diarrhea in calves, results in high economic losses for cow farmers. In South Korea, calf diarrhea, which affects newborn calves, and winter dysentery, which occurs in adult cows during the winter, are detected continuously. The vaccine strain (BC94) used in South Korea belongs to the GI type; however, a phylogenetic analysis revealed that all of the prevalent circulating strains belong to the GIIa type. Therefore, we attempted to develop a live attenuated BCoV vaccine candidate that targets recent prevalent strains. The bovine coronavirus (BCoV) KBR-1 strain, obtained from calf diarrhea samples collected in 2017, belongs to group GIIa. To attenuate this strain, it was subcultured continuously (up to 79 times) in HRT-18 cells, followed by 80–120 passages in MDBK cells. The KBR-1-p120 strain harvested from MDBK cells at passage 120 harbored 13 amino acid mutations in the spike gene. Additionally, the KBR-1-p120 strain showed a high viral titer and cytopathogenic effects in MDBK cells. Seven-day-old calves (negative for BCoV antigen and antibodies) that did not consume colostrum were orally inoculated with the attenuated candidate strain (KBR-1-p120), or with KBR-1 passaged 10 times (KBR-1-p10) in HRT-18 cells. Calves inoculated with KBR-1-p10 had a low diarrhea score, and BCoV RNA was detected at 3–7 days post-inoculation (DPI). The virus was also present in the duodenum, jejunum, and ileum at autopsy; however, calves inoculated with KBR-1-p120 had low levels of BCoV RNA in feces at 4–6 DPI, and no diarrhea. In addition, an extremely small amount of BCoV RNA was present in the jejunum and ileum at autopsy. The small intestines of calves inoculated with KBR-1-p120 were emulsified and used to infect calves two more times, but pathogenicity was not recovered. Therefore, the KBR-1-p120 strain has potential as a live vaccine candidate.
- Subjects
SOUTH Korea; COVID-19 vaccines; BOVINE viral diarrhea; CALVES; BOS; SMALL intestine; CORONAVIRUSES; JEJUNUM
- Publication
Animals (2076-2615), 2024, Vol 14, Issue 3, p389
- ISSN
2076-2615
- Publication type
Article
- DOI
10.3390/ani14030389