Biology subjects

Wanjiru, T.

Publications and source records attributed to Wanjiru, T..

3 recordsLinked to original sources

bioRxiv2026

Metagenomic Characterization of Aedes aegypti Virome in Kwale County, Kenya

BackgroundAedes aegypti is a primary vector of arboviruses, including dengue, chikungunya, yellow fever, and Zika, and is widespread along the Kenyan coast, a region with recurrent outbreaks. In addition to human-pathogenic arboviruses, Ae. aegypti harbors insect-specific viruses (ISVs) that replicate exclusively in arthropods and may influence mosquito physiology, immunity, and vector competence. However, data on ISVs in Kenyan Ae. aegypti populations are limited. MethodsTwenty-nine mosquito pools containing 20 individual mosquitoes from Kwale County were homogenized, combined into a superpool, and subjected to total RNA extraction. Libraries were sequenced on an Illumina MiSeq platform. Initial analysis was done on CZ-ID platform. Reads were quality-filtered using PrinseqLite and assembled de novo with MEGAHIT. Phylogenetic analyses was performed with IQ-TREE using the Maximum Likelihood method. ResultsMetagenomic analysis revealed diverse ISVs in Ae. aegypti. Complete genomes of Fako virus and Tesano Aedes virus, and partial genomes of Aedes partiti-like virus, Cell fusing agent virus, and Formosus virus, were recovered. Genome lengths ranged from 1,149 to 10,146 nucleotides, with 91-99.5% identity to reference strains. Phylogenetic analysis placed the viruses within established ISV lineages, showing close evolutionary relationships with strains previously reported from Africa and other regions. ConclusionsThis study provides comprehensive characterization of ISVs in Ae. aegypti from Kwale County. The recovery of complete and near-complete genomes demonstrates the diversity and active circulation of ISVs, establishing a baseline for future studies on mosquito viromes, virus-mosquito interactions, and potential impacts on vector competence. ImportanceInsect-specific viruses (ISVs) are widespread in mosquitoes and replicate exclusively in arthropods, influencing mosquito physiology, immunity, and potentially vector competence for human-pathogenic arboviruses. Despite recurrent arboviral outbreaks along the Kenyan coast, the diversity and ecological roles of ISVs in Aedes aegypti remain poorly understood. This study provides a comprehensive metagenomic characterization of ISVs in Ae. aegypti from Kwale County, revealing complete genomes of Fako virus and Tesano Aedes virus, along with near-complete genomes of Aedes partiti-like virus, Cell fusing agent virus, and Formosus virus. These findings establish a baseline for mosquito virome composition in this region and underscore the active circulation of diverse ISVs in natural populations. Understanding these virus-mosquito interactions is critical for interpreting arbovirus ecology, assessing the potential impacts of ISVs on vector competence, and informing future vector surveillance and biological control strategies.

genomics↗

bioRxiv2025

Detection and Characterization of West Nile Virus with evidence of Transovarial Transmission in the Coastal region, Kenya

BackgroundWest Nile virus (WNV) is a mosquito-borne flavivirus of global public health significance, maintained in an enzootic cycle between birds and mosquitoes, with humans and other mammals as incidental hosts. Understanding WNV circulation in diverse mosquito populations is critical for predicting and mitigating outbreaks. This study investigated mosquito populations from coastal Kenya, where WNV was detected, genetically characterized, and evidence of transovarial transmission in Aedes aegypti was observed. MethodsMosquitoes were collected from Kwale, Kilifi, Mombasa, and Isiolo counties (n=14,105) and pooled by species and location (1,596 pools). Pools were inoculated on Vero E6 cells, followed by RNA extraction, Illumina MiSeq sequencing, and preliminary analysis on CZ-ID. Reads were quality-controlled (PrinseqLite v0.20.4), assembled de novo (MEGAHIT v1.2.9), and analyzed via BLAST. Phylogenetic reconstruction used Maximum Likelihood, and codon-level selection pressure was evaluated using FEL, MEME, and FUBAR on Datamonkey. ResultsWNV was detected in ten pools: eight Lineage 1a and two Lineage 2. Virus isolates came from Culex pipiens, Culex univittatus, Anopheles funestus, Aedes aegypti, and Eretmapodites chrysogaster. Notably, one Lineage 1a isolate from a male Aedes aegypti confirmed transovarial transmission. Six codons were under diversifying selection, NS2B gene was found to carry the V103A mutation. ConclusionWNV in coastal Kenyan mosquitoes revealed transovarial transmission in Aedes aegypti. Lineage-specific evolution, codons under positive selection, and the NS2B:V103A mutation demonstrate ongoing viral adaptation. These findings highlight the need for continued genomic surveillance and targeted vector studies to guide WNV control strategies in Kenya and the wider region. ImportanceWest Nile virus (WNV) remains a globally important arbovirus, yet genomic and experimental data from under-sampled regions such as coastal East Africa are limited. This study provides the first integrated molecular and genotypic characterization of WNV circulating along the Kenyan coast, revealing the co-detection of Lineage 1a and the first identification of Lineage 2 in this region. By combining field surveillance, whole-genome sequencing, evolutionary analyses, and lineage-specific replication assays across multiple vertebrate and mosquito cell lines, we demonstrate clear genetic and biological differences with implications for transmission and adaptation. Importantly, the detection of WNV in a male Aedes aegypti mosquito and recovery of full genomes offers compelling evidence of transovarial transmission, a mechanism that may support viral maintenance independent of vertebrate hosts. These findings expand current knowledge of WNV ecology in Africa and underscore the need for continued genomic surveillance to detect emerging variants and inform public health strategies.

genomics↗

bioRxiv2021

Endocervical regulatory T cells are associated with decreased genital inflammation and lower HIV target cell abundance

Regulatory T cells (Tregs) play important roles in tissue homeostasis, but few studies have investigated tissue Tregs in the context of genital inflammation, HIV target cell density, and vaginal microbiota in humans. In women from Nairobi (n=64), the proportion of CD4+ CD25+ CD127low Tregs in the endocervix correlated with those in blood (r=0.31, p=0.01), with a higher Treg frequency observed in the endocervix (median 3.8 vs 2.0%, p<0.0001). Most Tregs expressed FoxP3 in both compartments, and CTLA-4 expression was higher on endocervical Tregs compared to blood (median 50.8 vs 6.0%, p<0.0001). More than half (34/62, 55%) of participants displayed a non-Lactobacillus dominant vaginal microbiota, which was not associated with endocervical Tregs or CD4+ T cell abundance. In a multivariable linear regression, endocervical Treg proportions were inversely associated with the number of elevated pro-inflammatory cytokines (p=0.03). Inverse Treg associations were also observed for specific cytokines including IL-1{beta}, G-CSF, Eotaxin, IL-1RA, IL-8, and MIP-1 {beta}. Higher endocervical Treg proportions were associated with lower abundance of endocervical CD4+ T cells (0.30 log10 CD4+ T cells per log10 Treg, p=0.00028), with a similar trend for Th17 cells (p=0.09). Selectively increasing endocervical Tregs may represent a pathway to reduce genital tract inflammation in women.

immunology↗