Hao Luyao, Zhao Fengmiao, Guo Ting, Gao Yuan, Hao Yongqing
College of Veterinary Medicine, Inner Mongolia Agricultural University, Hohhot, China.
Key Laboratory of Clinical Diagnosis and Treatment of Animal Diseases, Ministry of Agriculture, National Animal Medicine Experimental Teaching Center, Hohhot, China.
Front Vet Sci. 2025 Feb 27;12:1554986. doi: 10.3389/fvets.2025.1554986. eCollection 2025.
In recent years, bovine viral diarrhea virus (BVDV) has been associated with increased respiratory and gastrointestinal diseases in cattle. Comprehensive monitoring and investigations into the virus's pathological features are crucial for developing effective prevention strategies. This study investigated BVDV prevalence and pathogenicity in farms undergoing elimination protocols, with a focus on characterizing a novel Cytopathic Bovine Viral Diarrhea Virus (CP-type BVDV) strain (HH839) isolated from a symptomatic calf in Hohhot, Inner Mongolia. During 2021 and 2022, 103 bovine samples were screened for BVDV via nucleic acid detection. Positive cases underwent viral isolation using MDBK cells. The HH839 strain was analyzed for cytopathic effects, ultrastructure (electron microscopy), antigenicity (serum neutralization), and genetic lineage (whole genome sequencing). Pathogenicity of Cytopathic Bovine Viral Diarrhea Virus (CP-type BVDV) infected group, Noncytopathic Bovine Viral Diarrhea Virus (NCP-type BVDV) infected group, and the mixed-infection group of CP-type and NCP-type BVDV was evaluated in New Zealand White rabbits, with viral distribution and histopathological damage assessed in multiple organs. We identified 33 positive BVDV nucleic acid cases, resulting in a positivity rate of 32.04%. Five strains of NCP-type BVDV were isolated, yielding a 15.15% separation rate, alongside one strain of CP-type BVDV with a separation rate of 3.03%. The CP strain HH839 was isolated from a severely symptomatic calf in Hohhot, Inner Mongolia. The HH839 strain demonstrated significant cytopathic effects in MDBK cells, including cellular crumpling and syncytia formation, with a concentration of 5.23 logTCID/0.1 mL. Electron microscopy revealed a spherical morphology with a diameter of 40-60 nm. Genetic analysis indicated a close relationship with the BVDV FBS-D8 strain from the BVDV-1d subtype. Pathogenicity trials showed slight fever and minor body weight loss in infected subjects, with BVDV detected in the trachea, lungs, spleen, and small intestines, predominantly in the spleen. The isolation of HH839, a pathogenic CP-type BVDV-1d strain, underscores the coexistence of multiple BVDV biotypes in regional cattle populations. Enhanced pathogenicity observed in mixed infections highlights complex viral interactions. These findings emphasize the necessity for sustained surveillance and biotype-specific control strategies to mitigate BVDV-associated economic losses in livestock industries.
近年来，牛病毒性腹泻病毒（BVDV）与牛呼吸道和胃肠道疾病增多有关。对该病毒病理特征进行全面监测和调查对于制定有效的预防策略至关重要。本研究调查了正在执行清除方案的养殖场中BVDV的流行情况和致病性，重点是对从内蒙古呼和浩特一头有症状的小牛分离出的一株新型细胞病变型牛病毒性腹泻病毒（CP型BVDV）毒株（HH839）进行特征描述。在2021年至2022年期间，通过核酸检测对103份牛样本进行了BVDV筛查。阳性病例使用MDBK细胞进行病毒分离。对HH839毒株进行了细胞病变效应、超微结构（电子显微镜）、抗原性（血清中和）和遗传谱系（全基因组测序）分析。在新西兰白兔中评估了细胞病变型牛病毒性腹泻病毒（CP型BVDV）感染组、非细胞病变型牛病毒性腹泻病毒（NCP型BVDV）感染组以及CP型和NCP型BVDV混合感染组的致病性，并对多个器官的病毒分布和组织病理学损伤进行了评估。我们鉴定出33例BVDV核酸阳性病例，阳性率为32.04%。分离出5株NCP型BVDV毒株，分离率为15.15%，同时分离出1株CP型BVDV毒株，分离率为3.03%。CP毒株HH839是从内蒙古呼和浩特一头症状严重的小牛中分离出来的。HH839毒株在MDBK细胞中表现出显著的细胞病变效应，包括细胞皱缩和多核巨细胞形成，浓度为5.23 logTCID/0.1 mL。电子显微镜显示其形态为球形，直径为40 - 60 nm。遗传分析表明它与BVDV - 1d亚型的BVDV FBS - D8毒株关系密切。致病性试验显示感染动物有轻微发热和体重略有减轻，在气管、肺、脾和小肠中检测到BVDV，主要在脾脏中。致病性CP型BVDV - 1d毒株HH839的分离突出了区域牛群中多种BVDV生物型的共存。混合感染中观察到的增强致病性凸显了复杂的病毒相互作用。这些发现强调了持续监测和针对生物型的控制策略对于减轻畜牧业中与BVDV相关的经济损失的必要性。
