Bovine viral diarrhea is a common disease of cattle and has significant impact on animal welfare worldwide. There are fundamental approaches i.e. elimination of persistently infected animals, vaccination and biosecurity measures for effective control and eradication of BVD virus (BVDV). By this study, the presence of persistent infection with divergent BVDV subgenotype in the calves in a dairy herd having regular vaccination program was investigated. In the herd, vaccinated with a killed whole virion trivalent vaccine (composed of BVDV-1a) during the dry period of the cows, abortion cases were existed in the late autumn 2019. During herd screening by BVDV antigen-ELISA, 2 out of 300 dams were detected positive. Following, by ear notch-based BVDV antigen-ELISA, 30 calves were detected positive. Confirmation of persistent BVDV infection was performed 3 weeks later by testing with antigen-ELISA, where 8 of 9 selected newborn calves were positive for the second time. The entire antigen-ELISA positive samples were subjected to virus isolation on MDBK cell culture and identified as non-cytopathogenic pestiviruses by indirect immunoperoxidase assay. Presence of pestivirus RNA was detected in the 8 isolates by panpestivirus RT-PCR. Analysis of the 5′UTR regions revealed that BVDV-1 r circulate in the herd. Results of this study lead to questioning the efficiency of dry period vaccination strategy against BVDV. But otherwise, vaccination with BVDV-1a can be inefficient for complete protection against BVDV-1 r. Therefore, serological relationship between mentioned subgenotypes or protection by current vaccines against latest field isolates needs to be investigated before development of new BVDV vaccine candidates.

牛病毒性腹泻是牛的常见疾病，对全世界的动物福利都有重大影响。有一些基本方法，例如消除持续感染的动物，疫苗接种和生物安全措施，以有效控制和根除BVD病毒（BVDV）。通过这项研究，调查了具有常规疫苗接种计划的奶牛牛犊中小牛持续感染不同BVDV亚型的情况。在牛的干燥期间，该牛群接种了灭活的全病毒体三价疫苗（由BVDV-1a组成），在2019年秋末存在流产病例。在通过BVDV抗原ELISA进行牛群筛选的过程中，有300人中有2人大坝被检测为阳性。随后，通过基于耳朵缺口的BVDV抗原-ELISA，检测到30只小牛为阳性。3周后通过抗原ELISA测试确认了持续性BVDV感染，其中9只新生小牛中有8只第二次呈阳性。整个抗原-ELISA阳性样品在MDBK细胞培养物中进行病毒分离，并通过间接免疫过氧化物酶测定法鉴定为非致细胞病原性瘟病毒。通过全瘟病毒RT-PCR在8个分离株中检测到瘟病毒RNA的存在。对5'UTR区的分析表明，BVDV-1 r在牛群中循环。这项研究的结果导致质疑针对BVDV的旱期疫苗接种策略的有效性。但是否则，用BVDV-1a进行疫苗接种可能无法有效保护BVDV-1r。因此，