Vector-Borne Diseases Laboratory, Virology Center, Adolfo Lutz Institute, São Paulo, Brazil.
Enteric Diseases Laboratory, Virology Center, Adolfo Lutz Institute, São Paulo, Brazil.
Acta Trop. 2020 May;205:105401. doi: 10.1016/j.actatropica.2020.105401. Epub 2020 Feb 18.
In Brazil, flaviviruses have caused massive outbreaks. Surveillance programs designed to monitor virus activity in vectors provides a system for mapping disease distribution and for identifying specific vector species for targeted control. The present study aimed to describe the detection, whole genome characterization and phylogenetic analysis of Ilheus virus (ILHV) and Iguape virus (IGUV) strains obtained from historical mosquito's samples. Twelve isolates of pooled mosquito specimens (inoculated in neonate mouse brain) collected in the state of São Paulo, Brazil, in 1993, 1994 and 1997 were investigated. Viral RNA was extracted and analyzed by qRT-PCR using Flavivirus genus-specific primers. Positive samples were sequenced and underwent phylogenetic analyses. Flavivirus was detected in 50% of the specimens. Positive samples were successfully Sanger sequenced. Three Anopholes cruzii pools collected in 1994 were positive for IGUV. One Culex sp. pool, one Anopheles triannulatus pool, and one Coquillettidia juxtamansonia pool, collected in 1994, were positive for ILHV. Metagenomic sequencing successfully characterize one ILHV and four IGUV full genomes, and revealed a high degree of homology between the Brazilian ILHV and IGUV strains and isolates available in GenBank. Phylogenetic analysis of partial ILHV NS5 gene revealed three distinct lineages (clades), an indication of genetic heterogeneity in strains circulating in Brazil. Nucleotide insertions and a high-level of nucleotide diversity were observed in the NS1 protein and capsid region of IGUV strains, respectively. Detection of ILHV and IGUV in mosquitoes from Southeastern Brazil confirms the historical circulation of these viruses in this area. Furthermore, this first evidence of ILHV in Anopheles triannulatus suggests the potential importance of Anopheles mosquitoes in the IGUV transmission cycle. Genomic and phylogenetic analysis of these viruses provided insights into their diversity and evolution, which are important for the emergence patterns of flaviviruses and their evolutionary trends in Brazil, an endemic country for several arbovirus. in In-depth studies of ILHV and IGUV including vector competence and molecular studies are needed to shed light on their epidemiology and potential risk of future emergence.
在巴西，黄病毒已引发大规模疫情。旨在监测媒介中病毒活动的监测计划为绘制疾病分布图谱以及确定特定媒介物种以进行有针对性的控制提供了系统。本研究旨在描述从历史蚊子样本中获得的伊洛伊病毒（ILHV）和伊瓜普病毒（IGUV）株的检测、全基因组特征和系统发育分析。调查了巴西圣保罗州于 1993 年、1994 年和 1997 年收集的 12 种混合蚊子标本（接种于新生鼠脑）的 12 种分离株。使用黄病毒属特异性引物通过 qRT-PCR 提取和分析病毒 RNA。对阳性样本进行测序并进行系统发育分析。在 50%的标本中检测到黄病毒。阳性样本成功进行 Sanger 测序。1994 年采集的三带喙库蚊（Anopholes cruzii）3 个样本池为 IGUV 阳性。1994 年采集的一只库蚊（Culex sp.）、一只三带喙库蚊（Anopheles triannulatus）和一只库蚊（Coquillettidia juxtamansonia）样本池为 ILHV 阳性。宏基因组测序成功地对 1 株 ILHV 和 4 株 IGUV 全基因组进行了特征描述，并揭示了巴西的 ILHV 和 IGUV 株与 GenBank 中可用的分离株之间存在高度同源性。部分 ILHV NS5 基因的系统发育分析显示出三个不同的谱系（进化枝），表明在巴西流行的菌株中存在遗传异质性。在 IGUV 株的 NS1 蛋白和衣壳区观察到核苷酸插入和高水平的核苷酸多样性。在巴西东南部的蚊子中检测到 ILHV 和 IGUV，证实了这些病毒在该地区的历史传播。此外，在三带喙库蚊（Anopheles triannulatus）中首次发现 ILHV 表明了按蚊在 IGUV 传播周期中的潜在重要性。对这些病毒的基因组和系统发育分析提供了对其多样性和进化的深入了解，这对于黄病毒的出现模式及其在巴西的进化趋势至关重要，巴西是几种虫媒病毒的地方病流行国家。需要对 ILHV 和 IGUV 进行深入研究，包括媒介适应性和分子研究，以阐明其流行病学和未来出现的潜在风险。
