Centre International de Recherches Médicales de Franceville (CIRMF), Franceville, Gabon.
Institut Pasteur de Bangui, Bangui, Central African Republic.
Intervirology. 2018;61(4):174-184. doi: 10.1159/000495136. Epub 2019 Jan 9.
Non-malarial febrile illness outbreaks were documented in 2007 and 2010 in Gabon. After investigation, these outbreaks were attributed to the chikungunya and dengue viruses (CHIKV and DENV). However, for more than half of the samples analyzed, the causative agent was not identified. Given the geographical and ecological position of Gabon, where there is a great animal and microbial diversity, the circulation of other emerging viruses was suspected in these samples lacking aetiology. A total of 436 undiagnosed samples, collected between 2007 and 2013, and originating from 14 urban, suburban, and rural Gabonese locations were selected. These samples were used for viral isolation on newborn mice and VERO cells. In samples with signs of viral replication, cell supernatants and brain suspensions were used to extract nucleic acids and perform real-time RT-PCR targeting specific arboviruses, i.e., CHIKV, DENV, yellow fever, Rift Valley fever, and West Nile and Zika viruses. Virus isolation was conclusive for 43 samples either on newborn mice or by cell culture. Virus identification by RT-PCR led to the identification of CHIKV in 37 isolates. A total of 18 complete genomes and 19 partial sequences containing the E2 and E1 genes of CHIKV were sequenced using next-generation sequencing technology or the Sanger method. Phylogenetic analysis of the complete genomes showed that all the sequences belong to the East Central South Africa lineage. Furthermore, we identified 2 distinct clusters. The first cluster was made up of sequences from the western part of Gabon, whereas the second cluster was made up of sequences from the southern regions, reflecting the way CHIKV spread across the country following its initial introduction in 2007. Similar results were obtained when analyzing the CHIKV genes of the E2 and E1 structural proteins. Moreover, study of the mutations found in the E2 and E1 structural proteins revealed the presence of several mutations that facilitate the adaptation to the Aedes albopictus mosquito, such as E2 I211T and E1 A226V, in all the Gabonese CHIKV strains. Finally, sequencing of 6 additional viral isolates failed to lead to any conclusive identification.
2007 年和 2010 年，在加蓬记录了非疟疾发热性疾病暴发。经过调查，这些暴发归因于基孔肯雅热病毒和登革热病毒（CHIKV 和 DENV）。然而，对于分析的超过一半的样本，病原体未被识别。鉴于加蓬的地理位置和生态位置，那里有很大的动物和微生物多样性，怀疑在这些缺乏病因的样本中循环着其他新兴病毒。总共选择了 436 个未诊断的样本，这些样本采集于 2007 年至 2013 年之间，来自加蓬的 14 个城市、郊区和农村地点。这些样本用于在新生小鼠和 VERO 细胞上进行病毒分离。在有病毒复制迹象的样本中，使用细胞上清液和脑悬液提取核酸，并进行针对特定虫媒病毒的实时 RT-PCR，即基孔肯雅热病毒、登革热病毒、黄热病病毒、裂谷热病毒、西尼罗河病毒和寨卡病毒。在新生小鼠或细胞培养上对 43 个样本进行病毒分离，结果均为阳性。通过 RT-PCR 进行病毒鉴定，在 37 个分离株中鉴定出基孔肯雅热病毒。使用下一代测序技术或 Sanger 法对 18 个完整基因组和包含基孔肯雅热病毒 E2 和 E1 基因的 19 个部分序列进行测序。完整基因组的系统发育分析表明，所有序列均属于东中非南非谱系。此外，我们鉴定了 2 个不同的聚类。第一个聚类由来自加蓬西部的序列组成，而第二个聚类由来自南部地区的序列组成，这反映了 2007 年基孔肯雅热病毒首次传入该国后的传播方式。在分析 E2 和 E1 结构蛋白的基孔肯雅热病毒基因时得到了类似的结果。此外，对 E2 和 E1 结构蛋白中发现的突变进行研究，揭示了所有加蓬基孔肯雅热病毒株中存在的几个促进适应白纹伊蚊的突变，如 E2 I211T 和 E1 A226V。最后，对 6 个额外病毒分离株的测序未能得出任何明确的鉴定结果。
