Ridpath J F, Neill J D, Frey M, Landgraf J G
Metabolic Disease and Immunology Unit, NADC/ARS/USDA, 2300 Dayton Avenue, Ames, IA, USA.
Vet Microbiol. 2000 Nov 15;77(1-2):145-55. doi: 10.1016/s0378-1135(00)00271-6.
Bovine viral diarrhea virus (BVDV) infection continues to have a significant impact upon US cattle producers despite the availability of more than 140 federally licensed vaccines. Detection and control is hampered by viral heterogeneity that results in differences in neutralizing epitopes, cytopathology and virulence. Recently it was found that there are two different genotypes, BVDV1 and BVDV2, among BVDV. BVDV2 isolates make up a significant proportion of the BVDV isolated in North America. Serologically BVDV2 viruses can be distinguished from BVDV1 and border disease viruses. Mab binding also distinguishes between BVDV1, BVDV2 and BDV. Like the BVDV1 viruses, BVDV2 viruses may exist as one of two biotypes, cytopathic or noncytopathic, based on their activity in cultured cells. Cytopathogenic effects on cultured cells does not correlate with virulence in vivo, as BVDV2 associated with hemorrhagic syndrome (HS) are noncytopathic. Variation among BVDV1 and BVDV2 in the 5' UTR is similar. Phylogenetic analysis and differences in virulence suggest that BVDV2 are heterogeneous. Symptoms resulting from BVDV2 infections may range from clinically inapparent to clinically severe. Recently, disease outbreaks associated with acute uncomplicated BVDV infection have been reported in the US and Canada. These outbreaks of clinically severe disease, termed HS, were all associated with viruses from the BVDV2 genotype. Not all BVDV2 isolates cause clinically severe disease. Avirulent BVDV2 isolates do exist and may predominate over virulent BVDV2 in nature. When virulent BVDV2 viruses are inoculated into calves they induce a disease characterized by fever, diarrhea, leukopenia, lymphopenia, neutropenia, thrombocytopenia, and death. Infection with avirulent BVDV2 results in a reduction of luekocytes that may be accompanied by a low-grade fever. These viruses do not cause clinical disease or a clinical leukopenia.
尽管有140多种获得联邦许可的疫苗，但牛病毒性腹泻病毒（BVDV）感染仍继续对美国养牛户产生重大影响。病毒的异质性导致中和表位、细胞病理学和毒力存在差异，从而妨碍了对该病毒的检测和控制。最近发现，在BVDV中存在两种不同的基因型，即BVDV1和BVDV2。BVDV2分离株在北美分离出的BVDV中占很大比例。在血清学上，BVDV2病毒可与BVDV1和边界病病毒区分开来。单克隆抗体结合也能区分BVDV1、BVDV2和BDV。与BVDV1病毒一样，BVDV2病毒根据其在培养细胞中的活性可能以两种生物型之一存在，即细胞病变型或非细胞病变型。对培养细胞的细胞病变效应与体内毒力无关，因为与出血综合征（HS）相关的BVDV2是非细胞病变型的。BVDV1和BVDV2在5'非翻译区的变异相似。系统发育分析和毒力差异表明BVDV2是异质的。BVDV2感染引起的症状范围从临床上不明显到临床上严重。最近，在美国和加拿大都报告了与急性单纯性BVDV感染相关的疾病暴发。这些临床上严重疾病的暴发，称为HS，均与BVDV2基因型的病毒有关。并非所有BVDV2分离株都会引起临床上严重的疾病。无毒力的BVDV2分离株确实存在，并且在自然界中可能比有毒力的BVDV2占优势。当将有毒力的BVDV2病毒接种到犊牛中时，它们会引发一种以发热、腹泻、白细胞减少、淋巴细胞减少、中性粒细胞减少、血小板减少和死亡为特征的疾病。感染无毒力的BVDV2会导致白细胞减少，可能伴有低热。这些病毒不会引起临床疾病或临床白细胞减少。
