Dias R K, Cargnelutti J F, Weber M N, Canal C W, Bauermann F V, Ridpath J F, Weiblen R, Flores E F
Setor de Virologia, Universidade Federal de Santa Maria, Prédio 63A, Centro de Eventos, Universidade Federal de Santa Maria, Santa Maria, RS, 97105-900, Brazil.
Laboratório de Virologia, Faculdade de Veterinária, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil.
Vet Microbiol. 2017 May;203:221-228. doi: 10.1016/j.vetmic.2017.03.021. Epub 2017 Mar 21.
Hobi-like viruses comprise an unclassified group of bovine pestiviruses related to bovine viral diarrhea virus 1 (BVDV-1) and 2 (BVDV-2). These viruses were originally identified in fetal bovine serum from Brazilian origin and, subsequently, isolated from diseased animals in several countries. Herein we performed an antigenic characterization of eight Brazilian HoBi-like viruses isolated from persistently infected (PI) animals and from gastroenteric disease (2007-2015). Phylogenetic analysis based on the 5' unstranslated region (UTR) clustered these viruses with other HoBi-like viruses from European and Asiatic origin. Monoclonal antibody (MAb) binding indicated variability in the Hobi-like virus glycoprotein E2 and significant differences from the homologous BVDV-1 and BVDV-2 glycoprotein. Analysis of antigenic relatedness based on virus-neutralizing titers using virus-specific antisera revealed that HoBi-like viruses are antigenically very different from BVDV-1 and, to a lesser extent, from BVDV-2. Cross-neutralizing assays between pairs of HoBi-like viruses and their respective antisera indicated the existence of antigenic variability among these viruses, even for viruses isolated from the same herd in different occasions. Moreover, the identification of a HoBi-like isolate with low antigenic similarity with the other isolates indicates the potential existence of antigenic subgroups among HoBi-like virus isolates. Finally, sera of lambs immunized with commercial BVDV vaccines showed low or undetectable neutralizing activity against HoBi-like isolates. These results indicate significant antigenic differences between BVDV genotypes and Brazilian HoBi-like viruses and the existence of antigenic variability within this atypical group of pestiviruses. These findings extend the knowledge about the antigenic diversity of HoBi-like viruses and reinforce the need for their inclusion in current BVDV vaccines.
霍比样病毒是一组未分类的牛瘟病毒，与牛病毒性腹泻病毒1（BVDV - 1）和2（BVDV - 2）相关。这些病毒最初在源自巴西的胎牛血清中被鉴定出来，随后在多个国家的患病动物中被分离出来。在此，我们对从持续感染（PI）动物和胃肠疾病（2007 - 2015年）中分离出的8株巴西霍比样病毒进行了抗原特性分析。基于5'非翻译区（UTR）的系统发育分析将这些病毒与来自欧洲和亚洲的其他霍比样病毒聚类在一起。单克隆抗体（MAb）结合表明霍比样病毒糖蛋白E2存在变异性，且与同源的BVDV - 1和BVDV - 2糖蛋白有显著差异。使用病毒特异性抗血清基于病毒中和滴度分析抗原相关性，结果显示霍比样病毒在抗原性上与BVDV - 1有很大差异，与BVDV - 2的差异较小。成对的霍比样病毒及其各自抗血清之间的交叉中和试验表明，即使是在不同时间从同一牛群中分离出的病毒，这些病毒之间也存在抗原变异性。此外，鉴定出一株与其他分离株抗原相似性较低的霍比样分离株，表明霍比样病毒分离株中可能存在抗原亚群。最后，用商业BVDV疫苗免疫的羔羊血清对霍比样分离株显示出低中和活性或无法检测到的中和活性。这些结果表明BVDV基因型与巴西霍比样病毒之间存在显著的抗原差异，并且在这一非典型瘟病毒组内存在抗原变异性。这些发现扩展了关于霍比样病毒抗原多样性的知识，并强化了将其纳入当前BVDV疫苗的必要性。
