Kobrak A, Weber E L
Instituto de Virología, Centro de Investigaciones en Ciencias Veterinarias, INTA, Castelar, Argentina.
Rev Argent Microbiol. 1997 Jan-Mar;29(1):47-61.
Bovine Viral Diarrhea Virus (BVDV) is a pathogen of cattle, member of the family Flaviviridae, genus pestivirus, which also includes Classical Swine Fever Virus (CSFV, or hog cholera virus), and Border Disease Virus of sheep (BDV). It causes important economical losses associated mainly with reproductive failure. Pestiviruses are small enveloped viruses, with a diameter of about 40 nm. The nucleocapsid is probably icosahedral . The genome consists of a single stranded positive RNA, encoding approximately 430 kD of proteic product. Genetic expression consists of the synthesis of a polyprotein which is co- and post-translationally processed. According to its behavior "in vitro" two biotypes can be distinguished: non cytopathic (ncp) and cytopathic (cp), most probably derived from the ncp through mutations and/or recombination. BVDV is able to cross the placenta and infect the fetus, causing a variety of problems, from fetal death to the birth of a persistently infected (P) calf, according to the fetal age at the time of infection. PI animals are immunotolerant to the virus and shed it in all secretions. Only the ncp biotype has been isolated from PI animals. The superinfection of a PI animal with a cp strain causes mucosal disease, always fatal. Outbreaks of a severe, sometimes hemorrhagic disease, caused by ncp BVDV, have occurred in Canada and USA since 1993. Genomic and serological differences between the "traditional" strains and the viruses isolated from these outbreaks led to the division of BVDV in subtypes I and II, both including cp and ncp strains. Analyses of the non coding 5'-UTR zone of the genome of pestiviruses from different species (bovine, ovine, porcine) suggest that there are at least 3 genotypes within the genus. A new classification of these viruses, based on genomic sequence instead of species of origin, has been proposed. Genomic heterogeneity exists in the BVDV genome, which presents 3 hypervariable zones, 2 of them in the major neutralizing protein. In Argentina prevalence of BVDV antibodies in cattle population is 70%, and the prevalence of persistent infections is around 1%.
牛病毒性腹泻病毒（BVDV）是牛的一种病原体，属于黄病毒科瘟病毒属，该属还包括猪瘟病毒（CSFV，即猪霍乱病毒）和绵羊边界病病毒（BDV）。它会导致主要与繁殖失败相关的重大经济损失。瘟病毒是小型包膜病毒，直径约40纳米。核衣壳可能是二十面体。基因组由单链正RNA组成，编码约430千道尔顿的蛋白质产物。基因表达包括合成一种聚蛋白，该聚蛋白在翻译过程中和翻译后进行加工。根据其“体外”行为可区分出两种生物型：非细胞病变型（ncp）和细胞病变型（cp），很可能是ncp型通过突变和/或重组衍生而来。BVDV能够穿过胎盘并感染胎儿，根据感染时的胎龄，会导致从胎儿死亡到出生一头持续感染（P）小牛等各种问题。持续感染动物对该病毒具有免疫耐受性，并在所有分泌物中排出病毒。仅从持续感染动物中分离出了ncp生物型。持续感染动物被cp毒株再次感染会引发黏膜病，通常是致命的。自1993年以来，加拿大和美国发生了由ncp BVDV引起的严重、有时是出血性疾病的疫情。“传统”毒株与从这些疫情中分离出的病毒之间的基因组和血清学差异导致BVDV分为I型和II型亚型，两者都包括cp和ncp毒株。对来自不同物种（牛、羊、猪）的瘟病毒基因组非编码5'-UTR区的分析表明，该属内至少有3个基因型。有人提出了基于基因组序列而非起源物种的这些病毒的新分类法。BVDV基因组存在基因异质性，有3个高变区，其中2个位于主要中和蛋白中。在阿根廷，牛群中BVDV抗体的流行率为70%，持续感染的流行率约为1%。
