The genus Orbivirus includes a variety of pathogenic viruses that are transmitted by biting midges, mosquitoes and ticks. Some of the economically most relevant orbiviruses are endemic to Namibia, like the livestock-pathogenic Bluetongue and African horse sickness viruses. Here, we assessed the diversity of orbiviruses circulating in the Zambezi region of north-eastern Namibia. A total of 10 250 biting midges and 10 206 mosquitoes were collected and screened for orbivirus infections. We identified Palyam virus (PALV) in a pool of biting midges (Culicoides sp.) sampled in the Wuparo Conservancy and three strains of Corriparta virus (CORV) in Culex sp. mosquitoes sampled in Mudumu National Park and the Mashi Conservancy. This is, to our knowledge, the first detection of PALV and CORV in Namibia. Both viruses infect vertebrates but only PALV has been reported to cause disease. PALV can cause foetal malformations and abortions in ruminants. Furthermore, a novel orbivirus, related to Kammavanpettai virus from India and Umatilla virus from North America, was discovered in biting midges (Culicoides sp.) originating from Mudumu National Park and tentatively named Mudumu virus (MUMUV). Complete genomes of PALV, CORV and MUMUV were sequenced and genetically characterized. The Namibian CORV strain showed 24.3 % nucleotide divergence in its subcore shell gene to CORV strains from Australia, indicating that African CORV variants vary widely from their Australian relatives. CORV was isolated in cell culture and replicated to high titres in mosquito and duck cells. No growth was found in rodent and primate cells. The data presented here show that diverse orbiviruses are endemic to the Zambezi region. Further studies are needed to assess their effects on wildlife and livestock.

中文翻译：

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来自纳米比亚赞比西河地区的叮咬蠓和蚊子中的环状病毒

环状病毒属包括多种通过叮咬蠓、蚊子和蜱传播的病原病毒。一些经济上最相关的环状病毒是纳米比亚的地方性病毒，如家畜致病性蓝舌病病毒和非洲马病病毒。在这里，我们评估了在纳米比亚东北部赞比西河地区传播的环状病毒的多样性。共收集了 10 250 只叮咬蠓和 10 206 只蚊子，并筛查了是否感染了环状病毒。我们蠓池标识Palyam病毒（PALV）（库蠓属）在Wuparo水利采样，并Corriparta病毒（CORV）的三种毒株库蚊sp. 在 Mudumu 国家公园和 Mashi 保护区采样的蚊子。据我们所知，这是纳米比亚首次检测到 PALV 和 CORV。两种病毒都会感染脊椎动物，但据报道只有 PALV 会引起疾病。PALV 可导致反刍动物的胎儿畸形和流产。此外，在叮咬蠓（Culicoidessp.) 起源于穆杜姆国家公园，暂定名为穆杜姆病毒 (MUMUV)。对 PALV、CORV 和 MUMUV 的完整基因组进行了测序和遗传表征。纳米比亚 CORV 菌株在其亚核壳基因中与来自澳大利亚的 CORV 菌株显示出 24.3% 的核苷酸差异，表明非洲 CORV 变体与其澳大利亚亲属的差异很大。CORV 在细胞培养物中分离，并在蚊子和鸭细胞中复制到高滴度。在啮齿动物和灵长类动物细胞中未发现生长。此处提供的数据表明，赞比西河地区特有多种环状病毒。需要进一步研究以评估它们对野生动物和牲畜的影响。