Bolin Steven R, Lim Ailam, Grotelueschen Dale M, McBeth William W, Cortese Victor S
Diagnostic Center for Population and Animal Health, College of Veterinary Medicine, Michigan State University, Lansing, MI 48910, USA.
Am J Vet Res. 2009 Jan;70(1):86-91. doi: 10.2460/ajvr.70.1.86.
To collect and partially characterize strains of bovine viral diarrhea viruses(BVDVs) isolated from persistently infected (PI) calves born to vaccinated dams, determine genetic diversity of the isolated viruses, and identify regional distribution of genetically similar virus subpopulations.
17 noncytopathic (NCP) BVDVs from PI calves from 11 herds of beef or dairy cattle.
Viral RNA was extracted from infected cell cultures, and BVDV-specific PCR primers were used to amplify > 1,000 bases of the viral genome. Derived sequences were used for molecular phylogenetic analyses to determine the viral genotype and viral genogroup and to assess genetic similarity among BVDVs.
Analysis of the 17 NCP strains of BVDV failed to detect a viral genotype or viral genogroup not already reported to exist in the United States. One virus was classified as genotype 1, genogroup 1b, and 16 viruses were classified as genotype 2, genogroup 2a. Genotype 2 strains were genetically diverse, and genetic similarities were not obvious among viruses from geographic regions larger than a small locale.
Viruses isolated from herds where a genotype 1, genogroup 1a BVDV vaccine was administered prior to breeding were primarily genetically diverse genotype 2, genogroup 2a BVDVs. Vaccination with multiple BVDV genotypes may be needed to improve protection. Methods used in this study to obtain and analyze field strains are applicable to assessing efficacy of current BVDV vaccines. Candidates for future vaccines are viruses that appear able to elude the immune response of cattle vaccinated against BVDV with existing vaccines.
收集并部分鉴定从接种疫苗的母牛所生的持续性感染（PI）犊牛中分离出的牛病毒性腹泻病毒（BVDV）毒株，确定分离病毒的遗传多样性，并识别基因相似病毒亚群的区域分布。
来自11个肉牛或奶牛群的PI犊牛的17株非细胞病变（NCP）BVDV。
从感染的细胞培养物中提取病毒RNA，并使用BVDV特异性PCR引物扩增病毒基因组的1000多个碱基。所得序列用于分子系统发育分析，以确定病毒基因型和病毒基因组，并评估BVDV之间的遗传相似性。
对17株BVDV的NCP毒株进行分析，未检测到美国尚未报道存在的病毒基因型或病毒基因组。1株病毒被分类为基因型1，基因组1b，16株病毒被分类为基因型2，基因组2a。基因型2毒株具有遗传多样性，来自大于小区域的地理区域的病毒之间的遗传相似性不明显。
从配种前接种基因型1、基因组1a BVDV疫苗的牛群中分离出的病毒主要是遗传多样的基因型2、基因组2a BVDV。可能需要接种多种BVDV基因型疫苗以提高保护效果。本研究中用于获取和分析田间毒株的方法适用于评估当前BVDV疫苗的效力。未来疫苗的候选毒株是那些似乎能够逃避用现有疫苗接种BVDV的牛的免疫反应的病毒。
