Tracking dengue virus intra-host genetic diversity during human-to-mosquito transmission
Autor(es): Sim, Shuzhen; Aw, Pauline P. K.; Wilm, Andreas; Teoh, Garrett; Hue, Kien Duong Thi; Nguyen, Nguyet Minh; Nagarajan, Niranjan; Simmons, Cameron P.; Hibberd, Martin L.
Resumo: Dengue virus (DENV) infection of an individual human or mosquito host produces a dynamic population of closely-related sequences. This intra-host genetic diversity is thought to offer an advantage for arboviruses to adapt as they cycle between two very different host species, but it remains poorly characterized. To track changes in viral intra-host genetic diversity during horizontal transmission, we infected Aedes aegypti mosquitoes by allowing them to feed on DENV2-infected patients. We then performed whole-genome deep-sequencing of human- and matched mosquito-derived DENV samples on the Illumina platform and used a sensitive variant-caller to detect single nucleotide variants (SNVs) within each sample. >90% of SNVs were lost upon transition from human to mosquito, as well as from mosquito abdomen to salivary glands. Levels of viral diversity were maintained, however, by the regeneration of new SNVs at each stage of transmission. We further show that SNVs maintained across transmission stages were transmitted as a unit of two at maximum, suggesting the presence of numerous variant genomes carrying only one or two SNVs each. We also present evidence for differences in selection pressures between human and mosquito hosts, particularly on the structural and NS1 genes. This analysis provides insights into how population drops during transmission shape RNA virus genetic diversity, has direct implications for virus evolution, and illustrates the value of high-coverage, whole-genome next-generation sequencing for understanding viral intra-host genetic diversity. Dengue virus (DENV) is transmitted between humans through the bite of infected female Aedes aegypti mosquitoes. Virus populations experience significant drops in size and are subject to differing selection pressures as they cycle between human and mosquito hosts. Subsequent changes in viral intra-host genetic diversity may have consequences for the adaptability and fitness of the virus population as a whole but are poorly understood. To study the impact of human-to-mosquito transmission on DENV populations, we allowed mosquitoes to feed directly on patients with acute dengue infections, then deep-sequenced DENV populations from patient plasma samples and from the abdomens and salivary glands of corresponding mosquitoes. These matched samples allowed us to estimate the size of the population drop that occurs during establishment of infection in the mosquito, track changes in viral intra-host variant repertoires at different stages in transmission, and investigate the possibility of host-specific immune selection pressures acting on the virus population. These novel insights improve our understanding of DENV population dynamics during horizontal transmission.
Palavras-Chave: Population genetics; Human diseases; Viral diseases; Environmental impact; Genetic diversity; Hosts; Aquatic insects; Disease transmission; Public health; Genomes; RNA viruses; Infection; Salivary gland; Population dynamics; Nucleotides; Adaptability; Dengue; Evolution
Imprenta: Plos Neglected Tropical Diseases, v. 9, n. 9, 2015.
Descritores: Aedes aegypti - RNA ; Aedes aegypti - Infectious diseases ; Aedes aegypti - Viral infections ; Aedes aegypti - Virus ; Aedes aegypti - Transmission ; Aedes aegypti - Dengue
Data de publicação: 2015
