Microbiology, Faculty of veterinary medicine, University of Kufa, Najaf, Iraq.
Pathology and poultry diseases, Faculty of veterinary medicine, University of Kufa, Najaf, Iraq.
F1000Res. 2021 Apr 16;10:293. doi: 10.12688/f1000research.28421.2. eCollection 2021.
Infectious Bursal Disease (IBD) is a highly infectious disease which causes huge economic losses to the poultry industry due to the direct impact of the illness and indirect consequences such as decreasing the general immunity of the flock, leaving it naive to other diseases. In Iraq, IBD is highly prevalent despite vaccination programs, yet studies on sequence diversity of the causative virus are still rare. A sample from Bursa of Fabricius from an IBD outbreak in a flock in the city of Najaf in Iraq was smeared on an FTA card. Amplicons of targeted regions in VP1 and VP2 genes were generated and sequenced. Sequences were then compared with other local and global sequences downloaded from GenBank repositories. Sequence alignment and DNA sequence analyses were achieved using MUSCLE, UGENE and MEGAx software. The molecular clock and sequence evolutionary analyses were applied using MEGAx tools. The strain sequenced in this study belongs to a very virulent Infectious Bursal Disease Virus (vvIBDV) as the DNA and phylogenetic analysis of VP1 and VP2 gene sequences showed a mutual clustering with similar sequences belonging to vvIBDV genogroup 3. Analyses of the hyper variable region of VP2 gene (hvVP2) of IBDV isolates from Iraq indicates a presence of sequence diversity. Interestingly, the two vaccine strains Ventri IBDV Plus and ABIC MB71 that showed the highest sequence similarity to the local isolates in the hvVP2 region are not used in vaccination routine against IBDV in Iraq. Sequences of vvIBDV in Iraq are diverse. Remarkably, some of the available vaccine strains show high sequence similarity with local strains in Iraq; however, they are not included in the routine vaccination programs. Analysis of more samples involving more geographical regions is needed to draw a detailed map of antigenic diversity of IBDV in Iraq.
传染性法氏囊病（IBD）是一种高度传染性疾病，由于疾病的直接影响和间接后果，如降低禽类群体的总体免疫力，使它们对其他疾病变得幼稚，给家禽养殖业造成了巨大的经济损失。在伊拉克，尽管有疫苗接种计划，但 IBD 仍然高度流行，然而，关于致病病毒序列多样性的研究仍然很少。从伊拉克纳杰夫市一群爆发 IBD 的法氏囊中采集的样本涂在 FTA 卡上。针对 VP1 和 VP2 基因的靶向区域的扩增子被生成并测序。然后将序列与从 GenBank 存储库下载的其他本地和全球序列进行比较。使用 MUSCLE、UGENE 和 MEGAx 软件进行序列比对和 DNA 序列分析。应用 MEGAx 工具进行分子钟和序列进化分析。本研究中测序的毒株属于非常毒力的传染性法氏囊病病毒（vvIBDV），因为 VP1 和 VP2 基因序列的 DNA 和系统发育分析表明，与属于 vvIBDV 基因 3 组的相似序列密切聚类。对来自伊拉克的 IBDV 分离株 VP2 基因（hvVP2）的高变区进行分析表明，存在序列多样性。有趣的是，在 hvVP2 区域与当地分离株具有最高序列相似性的两种疫苗株 Ventri IBDV Plus 和 ABIC MB71 并没有在伊拉克常规接种 IBDV 疫苗。伊拉克的 vvIBDV 序列多样化。值得注意的是，一些可用的疫苗株与伊拉克当地株在 hvVP2 区域具有高度相似性；然而，它们未被纳入常规疫苗接种计划。需要分析更多的样本，涉及更多的地理区域，以绘制伊拉克 IBDV 抗原多样性的详细图谱。
