Virulent Newcastle disease virus in Nigeria: identification of a new clade of sub-lineage 5f from livebird markets
Virulent Newcastle disease virus in Nigeria: identification of a new clade of sub-lineage 5f from livebird markets
复制标题
尼日利亚的强毒新城疫病毒：从活禽市场鉴定出亚谱系 5f 的新分支
作者：
P. Solomon;C. Abolnik;T. Joannis;S. Bisschop
纽卡斯尔病（Newcastle disease，ND）是由1型禽副粘病毒（Paramyxovirus Type 1）引起的一种传染性极强的病毒性传染病，在世界范围内广泛流行，对家禽的生产和消费造成巨大的经济损失。尽管据报道ND在尼日利亚是地方性的，但关于该国纽卡斯尔病病毒（NDV）的分子流行病学和谱系分布的信息很少，特别是在活禽市场（LBM）。最近的研究报告发现了三个独特的亚系。即：西非的5f、5g和5h，特别是尼日利亚的非商业农场中的亚系5f和5g。在这项研究中，33个NDV分离株，其中包括从尼日利亚的LBM回收NDV，在2007年至2008年的主动监测和病毒回收的后院和商业鸡场在同一时期内爆发进行了分析。根据F0酶切位点氨基酸序列测定和系统发育分析，将分离株归类为强毒株，16株为5g亚系，17株为5f亚系。有趣的是，来自5f组的13个菌株形成了一个独特的簇，在类似的研究中没有被其他组识别出来。发现的密切遗传相似性首次提供了证据，证明在LBM中传播的病毒与2007年至2008年尼日利亚后院和商业养鸡场爆发的病毒之间存在流行病学联系。新亚系的出现和鉴定让我们深入了解了尼日利亚NDV毒株中发生的高遗传漂变率，并引发了人们对该国当前ND控制措施有效性的许多担忧。
Newcastle disease (ND), caused by Avian Paramyxovirus Type 1, is a highly contagious and devastating viral disease of poultry of worldwide distribution with an enormous economic impact. Although ND is reported to be endemic in Nigeria, little information exists on the molecular epidemiology and the lineage distribution of the Newcastle disease viruses (NDVs) in the country, especially in the live bird markets (LBMs). Recent studies reported the identification of three unique sub-lineages. namely; 5f, 5g and 5h in West Africa, and sub-lineages 5f and 5g in particular in non-commercial farms in Nigeria. In this study, 33 NDV isolates, which included NDVs recovered from LBMs in Nigeria, during active surveillance from 2007 to 2008 and viruses recovered from outbreaks in backyard and commercial chicken farms within the same period were analysed. Based on determination of the F0 cleavage site amino acid sequence and phylogenetic analysis, the isolates were classified as virulent; 16 strains were identified as sub-lineage 5g and 17 as sub-lineage 5f. Interestingly, 13 strains from the 5f group formed a distinct cluster that was not identified by other groups in similar studies. The close genetic similarities identified, provided evidence for the first time of the epidemiological link between the viruses circulating in the LBMs and those recovered from outbreaks in backyard and commercial chicken farms in Nigeria between 2007 and 2008. The emergence and identification of new sub-lineages provide an insight into the high rate of genetic drift occurring in NDV strains in Nigeria, and raises a lot of concerns about the efficacy of current ND control measures in the country.