Welter M W
Oragen L.C., Des Moines, Iowa 50322, USA.
Adv Exp Med Biol. 1998;440:707-11. doi: 10.1007/978-1-4615-5331-1_91.
A virulent bovine coronavirus isolate (newborn calf diarrheal) was adapted and serially passaged in an established diploid swine testicular cell line (ST cells). The same cells have been used to produce modified live porcine rotavirus and coronavirus vaccines that are federally licensed and sold worldwide. Growth of the bovine coronavirus resulted in cytopathic effect characterized by cellular stranding and subsequent cell lysis. Virus yields were relatively high in the ST cells and active replication was confirmed by immune electron microscopy and immunofluorescence. Adaptation of bovine coronavirus to a diploid swine cell line has not been previously reported. Different cell culture passage levels of bovine coronavirus were evaluated by oral inoculation of clean-catch, colostrum-deprived calves. A passage level of bovine coronavirus was identified that multiplied in the calf without the clinical signs of disease associated with virulent passages. The modified live bovine coronavirus vaccine remained safe and efficacious even after 5-backpassages in calves. Further efficacy studies have shown that the modified live bovine coronavirus vaccine significantly protected calves from highly virulent challenges with either winter dysentery or newborn calf diarrheal coronavirus isolates.
一株强毒牛冠状病毒分离株（新生犊牛腹泻型）在已建立的二倍体猪睾丸细胞系（ST细胞）中进行适应和连续传代。同样的细胞已被用于生产经联邦许可并在全球销售的改良活猪轮状病毒和冠状病毒疫苗。牛冠状病毒的生长导致细胞病变效应，其特征为细胞条索形成及随后的细胞裂解。在ST细胞中病毒产量相对较高，免疫电镜和免疫荧光证实了病毒的活跃复制。牛冠状病毒适应二倍体猪细胞系此前未见报道。通过口服采集的清洁、未哺初乳犊牛评估了牛冠状病毒不同细胞培养传代水平。确定了一个牛冠状病毒传代水平，其在犊牛体内增殖但无与强毒传代相关的疾病临床症状。改良活牛冠状病毒疫苗即使在犊牛体内进行5次回传后仍保持安全有效。进一步的效力研究表明，改良活牛冠状病毒疫苗能显著保护犊牛免受冬季痢疾或新生犊牛腹泻型冠状病毒分离株的强毒攻击。
