Neurobiology and Pain Therapeutics Section, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, USA.
J Virol. 2012 Jun;86(11):6171-8. doi: 10.1128/JVI.00250-12. Epub 2012 Apr 4.
Genetic and biological characterization of new hepaciviruses infecting animals contributes to our understanding of the ultimate origins of hepatitis C virus (HCV) infection in humans and dramatically enhances our ability to study its pathogenesis using tractable animal models. Animal homologs of HCV include a recently discovered canine hepacivirus (CHV) and GB virus B (GBV-B), both viruses with largely undetermined natural host ranges. Here we used a versatile serology-based approach to determine the natural host of the only known nonprimate hepacivirus (NPHV), CHV, which is also the closest phylogenetic relative of HCV. Recombinant protein expressed from the helicase domain of CHV NS3 was used as antigen in the luciferase immunoprecipitation system (LIPS) assay to screen several nonprimate animal species. Thirty-six samples from 103 horses were immunoreactive, and viral genomic RNA was present in 8 of the 36 seropositive animals and none of the seronegative animals. Complete genome sequences of these 8 genetically diverse NPHVs showed 14% (range, 6.4% to 17.2%) nucleotide sequence divergence, with most changes occurring at synonymous sites. RNA secondary structure prediction of the 383-base 5' untranslated region of NPHV was refined and extended through mapping of polymorphic sites to unpaired regions or (semi)covariant pairings. Similar approaches were adopted to delineate extensive RNA secondary structures in the coding region of the genome, predicted to form 27 regularly spaced, thermodynamically stable stem-loops. Together, these findings suggest a promising new nonprimate animal model and provide a database that will aid creation of functional NPHV cDNA clones and other novel tools for hepacivirus studies.
鉴定感染动物的新型肝炎病毒的遗传和生物学特性有助于我们了解丙型肝炎病毒（HCV）在人类中的最终起源，并大大提高了我们使用可处理的动物模型研究其发病机制的能力。HCV 的动物同源物包括最近发现的犬型肝炎病毒（CHV）和 GB 病毒 B（GBV-B），这两种病毒的天然宿主范围很大程度上尚未确定。在这里，我们使用了一种基于广泛应用的血清学方法来确定唯一已知的非灵长类肝炎病毒（NPHV）CHV 的天然宿主，CHV 也是 HCV 最接近的系统发育相关病毒。用 CHV NS3 的解旋酶结构域表达的重组蛋白作为抗原，用于荧光素酶免疫沉淀系统（LIPS）检测，筛选了多种非灵长类动物物种。在 103 匹马的 36 个样本中出现了免疫反应，在 36 个血清阳性动物中有 8 个存在病毒基因组 RNA，而在血清阴性动物中则没有。这 8 种遗传多样化的 NPHV 的全基因组序列显示出 14%（范围为 6.4%至 17.2%）的核苷酸序列差异，大多数变化发生在同义位点。通过将多态性位点映射到未配对区域或（半）共变配对，对 NPHV 的 383 个碱基 5'非翻译区的 RNA 二级结构预测进行了细化和扩展。采用类似的方法来描绘基因组编码区的广泛 RNA 二级结构，预测形成 27 个规则间隔的、热力学稳定的茎环。这些发现表明了一种很有前途的新型非灵长类动物模型，并提供了一个数据库，将有助于创建功能性 NPHV cDNA 克隆和其他用于肝炎病毒研究的新型工具。
