Abrahão J S, de Souza Trindade G, Pereira-Oliveira G, de Oliveira Figueiredo P, Costa G, Moreira Franco-Luiz A P, Lopes Assis F, Bretas de Oliveira D, Mattos Paim L R, de Araújo Oliveira C E, Lemos Maia Neto A, Geessien Kroon E
Laboratório de Vírus, Universidade Federal de Minas Gerais, Minas Gerais, Brazil.
ADAB - Agência Estadual de Defesa Agropecuária da Bahia, Salvador, Brazil.
Equine Vet J. 2017 Mar;49(2):221-224. doi: 10.1111/evj.12571. Epub 2016 Mar 23.
In August 2014, an outbreak of oral exanthematous disease in equids was reported in Brazil, affecting 11 donkeys and 3 mules.
To investigate if Vaccinia virus (VACV) was the aetiological agent in this outbreak.
Investigation of clinical cases using serological, molecular and phylogenetic approaches.
To analyse the presence of neutralising antibodies against VACV, samples were submitted in triplicate to a plaque-reduction neutralisation test (PRNT ). On the basis of previous studies which detected VACV DNA in sera, we submitted extracted DNA samples to different polymerase chain reaction (PCR) platforms targeting Orthopoxvirus (OPV) genes (C11R, A56R and A26L). The PCR products were directly sequenced in both orientations using specific primers and capillary electrophoresis. The alignment and phylogenetic analysis of the A26L and A56R nucleotide sequences (maximum likelihood) were prepared with the obtained nucleotide fragments.
Serological and molecular data suggested VACV as the aetiological agent. The neutralising antibodies against OPV were detected in 5 (55.5%) of the equids, with titres ≥40 neutralising u/ml. Based on the results obtained from all PCR platforms, all samples were positive for OPV: 9 (100%) for A56R, 4 (44.4%) for C11R and 3 (33.3%) for A26L. The alignment of the nucleotide sequences of the A26L and A56R fragments revealed that the samples were highly similar to the homologous genes from other Brazilian VACV Group 1 isolates (98.8% identity on average). Furthermore, both the A26L and A56R sequences showed signature deletions also present in the sequences of Group 1 VACV isolates from Brazil.
Our data raises questions about the role of equids in the chain of VACV epidemiology. The surveillance of equids in VACV-affected areas worldwide is relevant.
2014年8月，巴西报告了一起马属动物口腔疹性疾病暴发，涉及11头驴和3头骡。
调查痘苗病毒（VACV）是否为此疫情的病原体。
采用血清学、分子学和系统发育学方法对临床病例进行调查。
为分析针对VACV的中和抗体的存在情况，将样本一式三份送去进行蚀斑减少中和试验（PRNT）。基于先前在血清中检测到VACV DNA的研究，我们将提取的DNA样本送去不同的针对正痘病毒（OPV）基因（C11R、A56R和A26L）的聚合酶链反应（PCR）平台。使用特异性引物和毛细管电泳对PCR产物进行双向直接测序。用获得的核苷酸片段对A26L和A56R核苷酸序列进行比对和系统发育分析（最大似然法）。
血清学和分子学数据表明VACV是病原体。在5头（55.5%）马属动物中检测到针对OPV的中和抗体，滴度≥40中和单位/毫升。根据所有PCR平台获得的结果，所有样本的OPV均呈阳性：A56R为9份（100%），C11R为4份（44.4%），A26L为3份（33.3%）。A26L和A56R片段的核苷酸序列比对显示，这些样本与巴西其他VACV第1组分离株的同源基因高度相似（平均同一性为98.8%）。此外，A26L和A56R序列均显示出巴西第1组VACV分离株序列中也存在的特征性缺失。
我们的数据对马属动物在VACV流行病学传播链中的作用提出了疑问。对全球受VACV影响地区的马属动物进行监测具有重要意义。
