Ain-Najwa Mohd Yuseri, Yasmin Abd Rahaman, Omar Abdul Rahman, Arshad Siti Suri, Abu Jalila, Mohammed Hussni O, Kumar Kiven, Loong Shih Keng, Rovie-Ryan Jeffrine J, Mohd-Kharip-Shah Ahmad-Khusaini
Department of Veterinary Laboratory Diagnostics, Faculty of Veterinary Medicine, Universiti Putra Malaysia, Malaysia.
Laboratory of Vaccines and Immunotherapeutics, Institute of Bioscience, Universiti Putra Malaysia, Malaysia.
One Health. 2020 Apr 19;10:100134. doi: 10.1016/j.onehlt.2020.100134. eCollection 2020 Dec.
West Nile virus (WNV) is a zoonotic mosquito-borne flavivirus that is harbored and amplified by wild birds via the enzootic transmission cycle. Wide range of hosts are found to be susceptible to WNV infection including mammals, amphibians and reptiles across the world. Several studies have demonstrated that WNV was present in the Malaysian and captive birds. However, no data are available on the WNV prevalence in wild birds found in Malaysia. Therefore this study was conducted to determine the serological and molecular prevalence of WNV in wild birds in selected areas in the West Coast of Peninsular Malaysia. Two types of wild birds were screened, namely migratory and resident birds in order to explore any possibility of WNV transmission from the migratory birds to the resident birds. Thus, a cross-sectional study was conducted at the migratory birds sanctuary located in Kuala Gula, Perak and Kapar, Selangor by catching 163 migratory birds, and 97 resident birds from Kuala Gula and Parit Buntar, Perak at different time between 2016 and 2017 (Total, = 260). Blood and oropharyngeal swabs were collected for serological and molecular analysis, respectively. Serum were screened for WNV antibodies using a commercial competitive ELISA (c-ELISA) (ID Screen® West Nile Competition Multi-species ELISA, ID VET, Montpellier, France) and cross-reactivity towards Japanese Encephalitis virus (JEV) was also carried out using the JEV-double antigen sandwich (DAS) ELISA. Oropharyngeal swabs were subjected to one-step RT-PCR to detect WNV RNA, in which positive reactions were subsequently sequenced. WNV seropositive rate of 18.71% (29/155) at 95% CI (0.131 to 0.260) and molecular prevalence of 15.2% (16/105) at 95% CI (0.092 to 0.239) were demonstrated in migratory and resident wild birds found in West Coast Malaysia. Phylogenetic analyses of the 16 WNV isolates found in this study revealed that the local strains have 99% similarity to the strains from South Africa and were clustered under lineage 2. Evidence of WNV infection in resident and migratory birds were demonstrated in this study. As a summary, intervention between migratory birds, resident birds and mosquitoes might cause the introduction and maintenance of WNV in Malaysia, however the assumption could be further proven by studying the infection dynamics in the mosquitoes present in the studied areas.
西尼罗河病毒（WNV）是一种人畜共患的蚊媒黄病毒，通过动物间传播循环在野生鸟类中栖息和增殖。现已发现世界各地的多种宿主对WNV感染易感，包括哺乳动物、两栖动物和爬行动物。多项研究表明，马来西亚的野生鸟类和圈养鸟类中存在WNV。然而，关于马来西亚野生鸟类中WNV流行情况的数据尚无可用信息。因此，本研究旨在确定马来西亚半岛西海岸选定地区野生鸟类中WNV的血清学和分子流行情况。对两种野生鸟类进行了筛查，即候鸟和留鸟，以探索WNV从候鸟传播至留鸟的任何可能性。因此，在霹雳州瓜拉古拉和雪兰莪州瓜拉雪兰莪的候鸟保护区进行了一项横断面研究，于2016年至2017年期间的不同时间捕获了163只候鸟以及霹雳州瓜拉古拉和峇株文打97只留鸟（总计n = 260）。分别采集血液和口咽拭子用于血清学和分子分析。使用商业竞争ELISA（c-ELISA）（ID Screen® West Nile Competition Multi-species ELISA，ID VET，法国蒙彼利埃）筛查血清中的WNV抗体，并使用日本脑炎病毒（JEV）双抗原夹心（DAS）ELISA检测其对JEV的交叉反应性。对口咽拭子进行一步RT-PCR以检测WNV RNA，随后对阳性反应进行测序。在马来西亚西海岸发现的候鸟和留鸟中，WNV血清阳性率为18.71%（29/155），95%置信区间为（0.131至0.260），分子流行率为15.2%（16/105），95%置信区间为（0.092至0.239）。对本研究中发现的16株WNV分离株进行系统发育分析表明，本地毒株与来自南非的毒株有99%的相似性，属于2型分支。本研究证实了留鸟和候鸟中存在WNV感染。总之，候鸟、留鸟和蚊子之间的相互作用可能导致WNV在马来西亚的传入和维持，然而这一假设可通过研究研究区域内蚊子的感染动态进一步得到证实。
