Department of Microbiology and Immunology, Biosciences Institute, Univ. Estadual Paulista (UNESP), Botucatu 18618-970, São Paulo, Brazil.
Vet Microbiol. 2013 Feb 22;162(1):85-93. doi: 10.1016/j.vetmic.2012.08.025. Epub 2012 Sep 1.
Papillomaviruses (PVs) infect a wide range of animal species and show great genetic diversity. To date, excluding equine sarcoids, only three species of PVs were identified associated with lesions in horses: Equus caballus papillomavirus 1 (EcPV1-cutaneous), EcPV2 (genital) and EcPV3 (aural plaques). In this study, we identified a novel equine PV from aural plaques, which we designated EcPV4. Cutaneous samples from horses with lesions that were microscopically diagnosed as aural plaques were subjected to DNA extraction, amplification and sequencing. Rolling circle amplification and inverse PCR with specific primers confirmed the presence of an approximately 8 kb circular genome. The full-length EcPV4 L1 major capsid protein sequence has 1488 nucleotides (495 amino acids). EcPV4 had a sequence identity of only 53.3%, 60.2% and 51.7% when compared with the published sequences for EcPV1, EcPV2 and EcPV3, respectively. A Bayesian phylogenetic analysis indicated that EcPV4 clusters with EcPV2, but not with EcPV1 and EcPV3. Using the current PV classification system that is based on the nucleotide sequence of L1, we could not define the genus of the newly identified virus. Therefore, a structural analysis of the L1 protein was carried out to aid in this classification because EcPV4 cause lesion similar to the lesion caused by EcPV3. A comparison of the superficial loops demonstrated a distinct amino acid conservation pattern between EcPV4/EcPV2 and EcPV4/EcPV3. These results demonstrate the presence of a new equine PV species and that structural studies could be useful in the classification of PVs.
乳头瘤病毒（PVs）感染广泛的动物物种，并表现出极大的遗传多样性。迄今为止，除了马的肉瘤外，仅鉴定出与马的病变相关的三种 PV 物种：马乳头状瘤病毒 1（EcPV1-皮肤），EcPV2（生殖器）和 EcPV3（耳垢斑块）。在这项研究中，我们从耳垢斑块中鉴定出一种新的马乳头状瘤病毒，我们将其命名为 EcPV4。对显微镜诊断为耳垢斑块的病变马的皮肤样本进行 DNA 提取、扩增和测序。使用特定引物的滚环扩增和反向 PCR 证实存在大约 8 kb 的环状基因组。全长 EcPV4 L1 主要衣壳蛋白序列有 1488 个核苷酸（495 个氨基酸）。与已发表的 EcPV1、EcPV2 和 EcPV3 序列相比，EcPV4 的序列同一性分别为 53.3%、60.2%和 51.7%。贝叶斯系统发育分析表明，EcPV4 与 EcPV2 聚类，但与 EcPV1 和 EcPV3 不聚类。使用基于 L1 核苷酸序列的当前 PV 分类系统，我们无法定义新鉴定病毒的属。因此，进行了 L1 蛋白的结构分析以帮助进行这种分类，因为 EcPV4 引起的病变与 EcPV3 引起的病变相似。浅层环的比较显示 EcPV4/EcPV2 和 EcPV4/EcPV3 之间存在明显的氨基酸保守模式。这些结果表明存在一种新的马乳头状瘤病毒物种，并且结构研究可能有助于 PV 的分类。
