Masoto Nosipho Z, Bester Phillip A, Snyman Louwrens P, Govender Natasha, van Jaarsveldt Danelle, Burt Felicity J
Division of Virology, University of the Free State, Bloemfontein, South Africa.
Division of Virology, National Health Laboratory Service, Universitas, Bloemfontein, South Africa.
PLoS Negl Trop Dis. 2025 Aug 12;19(8):e0013093. doi: 10.1371/journal.pntd.0013093. eCollection 2025 Aug.
Mosquito-borne viruses have the potential to spread and cause outbreaks with significant public and veterinary health consequences. Although historically a significant number of arboviruses were identified in South Africa with potential to cause sporadic outbreaks, there is limited information on the current situation in some regions of the country. Hence a study was initiated to investigate which arboviruses are currently circulating within mosquito populations in a major metropolitan area, eThekwini, KwaZulu-Natal Province. Mosquitoes were collected from seven sites throughout the metropole and a subset were screened for arboviruses from the families Togaviridae, Phenuiviridae and Peribunyaviridae. The subset of 1831 mosquitoes were collected between October 2020 and July 2021, identified morphologically, and pooled according to species, collection site and collection date. RNA was extracted from a total of 261 mosquito pools and screened using in-house nested and hemi-nested reverse transcriptase polymerase chain reaction (RT-PCR). Primers targeting conserved genes for each viral genus were used in a nested or hemi-nested two-step RT-PCR. Amplicons were sequenced to determine the virus species. Arboviral RNA was detected from 15/261 mosquito pools. The amplicons were subsequently sequenced using the Oxford Nanopore MinION. The positive samples included a Sindbis virus (SINV) isolate, three isolates of Witwatersrand virus (WITV), and 11 isolates of Bunyamwera virus (BUNV). Phylogenetic analysis of partial sequence data suggested that none were newly introduced but closely related isolates previously detected in the country. SINV is known to cause outbreaks of human disease after heavy rainfall, favoring an increase in mosquito populations. Bunyamwera virus has been associated with human febrile disease, but severe disease and regular outbreaks have not been reported previously and requires further investigation. The medical significance of WITV is currently unknown. Wyeomyia mitchellii, a New World species, is for the first time confirmed as an introduced species in South Africa and highlights the importance of vector surveillance. Identification of circulating viruses and raising the awareness of the presence of these viruses is important for early detection and determining the public health significance.
蚊媒病毒有可能传播并引发疫情，对公共卫生和兽医健康造成重大影响。尽管历史上在南非发现了大量有引发散发性疫情潜力的虫媒病毒，但该国一些地区的当前情况信息有限。因此，启动了一项研究，以调查夸祖鲁 - 纳塔尔省伊泰夸尼这个主要大都市地区的蚊虫种群中目前正在传播哪些虫媒病毒。在整个大都市的七个地点收集了蚊子，并对其中一部分进行筛选，以检测披膜病毒科、白蛉病毒科和布尼亚病毒科的虫媒病毒。在2020年10月至2021年7月期间收集了1831只蚊子的样本，进行形态学鉴定，并根据物种、采集地点和采集日期进行分组。从总共261组蚊子样本中提取RNA，并使用内部巢式和半巢式逆转录聚合酶链反应（RT-PCR）进行筛选。针对每个病毒属保守基因的引物用于巢式或半巢式两步RT-PCR。对扩增产物进行测序以确定病毒种类。从261组蚊子样本中的15组检测到了虫媒病毒RNA。随后使用牛津纳米孔MinION对扩增产物进行测序。阳性样本包括一株辛德毕斯病毒（SINV）分离株、三株威特沃特斯兰德病毒（WITV）分离株和11株布尼亚姆韦拉病毒（BUNV）分离株。对部分序列数据的系统发育分析表明，这些病毒均非新引入病毒，而是该国先前检测到的密切相关分离株。已知辛德毕斯病毒在暴雨后会引发人类疾病疫情，这有利于蚊子种群数量增加。布尼亚姆韦拉病毒与人类发热性疾病有关，但此前尚未报道过严重疾病和定期疫情，需要进一步调查。威特沃特斯兰德病毒的医学意义目前尚不清楚。米切尔怀氏蚊是一种来自新大陆的物种，首次在南非被确认为外来物种，这凸显了媒介监测的重要性。识别正在传播的病毒并提高对这些病毒存在的认识对于早期发现和确定公共卫生意义至关重要。
