Flores E F, Gil L H, Botton S A, Weiblen R, Ridpath J F, Kreutz L C, Pilati C, Driemeyer D, Moojen V, Wendelstein A C
Departamento de Medicina Veterinária Preventiva, e Departamento de Microbiologia e Parasitologia, Universidade Federal de Santa Maria, 97105-900, RS, Santa Maria, Brazil.
Vet Microbiol. 2000 Nov 15;77(1-2):175-83. doi: 10.1016/s0378-1135(00)00274-1.
Nucleotide sequencing and phylogenetic analysis of Brazilian bovine viral diarrhea virus (BVDV) field isolates identified four viruses belonging to the genotype 2. Comparison of 5' UTR sequences from these isolates to those of North American BVDV type 2 revealed genomic variations that correlated with the geographic origins of the isolates. Two of the Brazilian type 2 viruses were isolated from clinical cases of gastroenteric/respiratory disease and two were isolated from healthy bovine fetuses. The clinical cases affected young animals (8- and 18-months-old) and were characterized by diarrhea, respiratory signs, extensive oral and digestive tract erosions, conjunctival and vulvar congestion, occasional digestive bleeding and vulvar and heart petechial hemorrhage. Antigenic analysis of these isolates with a panel of 10 monoclonal antibodies revealed marked antigenic differences in the major envelope glycoprotein, gp53/E2, compared to standard laboratory and vaccine BVDV strains. In addition, virus-specific antisera raised to Brazilian BVDV type 2 viruses displayed very low serological cross-reactivity with standard BVDV type 1 strains. Differences up to 64-fold in cross-neutralization titers were observed between BVDV type 1 and Brazilian BVDV type 2 isolates. The identification of BVDV type 2 among Brazilian cattle may have important implications for epidemiological studies, diagnostic and immunization strategies. Furthermore, the low neutralizing activity of BVDV type 1 antisera against the recently identified Brazilian BVDV type 2 isolates raises the question about the degree of protection conferred by BVDV vaccines, most of them based on a single type 1 strain.
对巴西牛病毒性腹泻病毒（BVDV）野毒株进行核苷酸测序和系统发育分析，鉴定出4种属于2型的病毒。将这些毒株的5'UTR序列与北美BVDV 2型毒株的序列进行比较，发现基因组变异与毒株的地理来源相关。2株巴西2型病毒分离自胃肠/呼吸道疾病临床病例，2株分离自健康牛胎儿。临床病例影响幼龄动物（8个月和18个月大），特征为腹泻、呼吸道症状、广泛的口腔和消化道糜烂、结膜和外阴充血、偶发消化道出血以及外阴和心脏瘀点性出血。用一组10种单克隆抗体对这些毒株进行抗原分析，结果显示，与标准实验室毒株和疫苗BVDV毒株相比，主要包膜糖蛋白gp53/E2存在明显的抗原差异。此外，针对巴西BVDV 2型病毒产生的病毒特异性抗血清与标准BVDV 1型毒株的血清学交叉反应性非常低。在BVDV 1型和巴西BVDV 2型毒株之间观察到交叉中和效价相差高达64倍。在巴西牛群中鉴定出BVDV 2型可能对流行病学研究、诊断和免疫策略具有重要意义。此外，BVDV 1型抗血清对最近鉴定出的巴西BVDV 2型毒株的中和活性较低，这引发了关于BVDV疫苗（其中大多数基于单一1型毒株）所提供保护程度的问题。
