Biology subjects

Mulwa, F.

Publications and source records attributed to Mulwa, F..

3 recordsLinked to original sources

bioRxiv2024

Genomic sequence analysis of the first mpox virus detected in Kenya

Mpox is a zoonotic disease caused by the Monkeypox virus (MPXV) in the family: Poxviridae, genus: Orthopoxvirus. Historically, the disease was restricted mostly to Africa with cases being reported in Central Africa (mostly caused by clade I) and in West Africa (caused by clade II). However, there has been a recent shift in the virus range with outbreaks being reported in Europe and America, and in countries where the virus was initially not endemic. This multi-country outbreak was driven mostly by clade IIb lineage of MPXV. Since December 2023, there has been an ongoing mpox outbreak in the Democratic Republic of Congo (DRC), driven by a new clade I lineage of the virus, designated clade Ib. The DRC outbreak has persisted, with an increase in cases being reported over the past few months. Spillover of these outbreak-related cases to the neighbouring countries have also been reported in multiple countries including Uganda and Rwanda. Here, we report the rapid application of unbiased metagenomic next generation sequencing (mNGS) to reconstruct the genome sequence of the first reported case of MPXV in Kenya. Our findings show that the Kenyan case clusters together with clade Ib MPXV strains, associated with the sustained outbreak in the DRC. Clade Ib lineage has been associated with continuing geographical expansion of the virus to previously unaffected areas, high incidence of the disease as well as high case fatality (CFR 4.9-6.7%). Similar to other clade Ib strains, the Kenyan strain carries predominant APOBEC3-type mutations which is characteristic feature of human-to-human transmission, highlighting the need for surveillance to curtail any potential expansion of this MPXV strain. The lack of information on genomes associated with cases reported in different East African countries, is a gap that urgently needs to be addressed to aid in the monitoring of this MPXV strain. This case investigation, therefore, underscores the need for sequencing efforts to be enhanced across the continent to help improve our understanding of the geographical range and diversity of the MPXV strains, especially those belonging to clade I which is currently under-represented.

genomics↗

bioRxiv2024

Characterization of West Nile virus Koutango lineage from Phlebotomine Sandflies in Kenya 2021

The West Nile virus (WNV), primarily transmitted by mosquitoes, is one of the most widespread flaviviruses globally, with past outbreaks occurring in the USA and Europe. Recent studies in parts of Africa, including Kenya, have identified the West Nile virus Koutango lineage (WN-KOUTV) among phlebotomine sandfly populations, however, our understanding of this virus remains limited. Hence, this study aimed to characterize WN-KOUTV from phlebotomine sandflies. Sandflies were sampled between 12-16th March 2021 from six villages in Baringo South, Kenya, using CDC light traps. Female sandflies were taxonomically identified and pooled based on genus. Virus isolation was performed in Vero cells. Viral genome was determined using next-generation sequencing. Phylogenetic and molecular clock analyses were done to decipher the viruss evolutionary relationships. Comparative analyses of amino acid sequences were performed to determine variations. Protein modeling in Pymol was conducted to elucidate variations in key protein regions. Evolutionary pressure analysis investigated the selection pressures on the virus. In vitro experiments were done to investigate the virus growth kinetics in mammalian (Vero-E6) and mosquito (C636) cells. We report the isolation of WN-KOUTV from Salabani Baringo South, Kenya. The isolated WN-KOUTV clustered with previously identified WN-KOUTV strains. Comparative analysis revealed unique amino acid at NS5 653. Diversifying pressure was acting NS3 267 of the WN-KOUTV lineage. WN-KOUTV replicates efficiently in Vero-E6 and C636 cells comparable to West Nile virus Lineage 1a, isolated from mosquitoes. The isolation of WN-KOUTV in sandflies points to them as potential vectors, however, vector competence studies would confirm this. The efficient replication in mammalian and mosquito cell lines elucidated its adaptability to host and vector. We speculate the close genetic relationship of WN-KOUTV strains is enabled by the bird migratory route between East and West Africa. If proven, this may point to a potential future pandemic pathway for this virus.

microbiology↗

bioRxiv2023

Genetic variability and vector competence of Aedes aegypti populations from Kisumu and Busia Counties, Western Kenya, for Chikungunya and Zika viruses

Aedes aegypti is the primary vector of several arboviruses, including dengue virus (DENV), chikungunya virus (CHIKV), yellow fever virus (YFV), and Zika virus (ZIKV). This vector is widespread globally in tropical and subtropical areas, but also found in temperate areas. Kenya experienced its first chikungunya outbreaks in Lamu County in 2004 and later in Mandera: 2016, and Mombasa: 2017. While there is yet to be a report of Zika outbreaks in Kenya, sero-surveillance studies indicate low-level transmission of this virus in coastal and northern parts of the country. Despite the presence of Ae. aegypti in Kisumu and Busia counties in sufficient densities, and free movement of people between the coast and the two western Kenya counties, no outbreaks of either disease have been reported in these regions. To investigate this phenomenon, we collected Ae. aegypti mosquitoes from county headquarter towns near railway stations connecting the coast and western Kenya and reared them under controlled laboratory conditions. The mosquitoes were then assessed for genetic variability using CO1 genes as well as their efficiency to transmit viruses using Laboratory colonies (F1) of the field mosquitoes challenged with an infectious blood meal containing CHIKV and ZIKV. Genetic analysis revealed the presence of both Ae. aegypti subspecies, (Ae. aegypti aegypti [Aaa] and Ae. aegypti formosus [Aaf]) in the two western Kenya counties, with Aaf being dominant (19:8 for Kisumu samples and 25:6 for Busia samples). Additionally, pairwise comparison revealed minimal genetic differentiation (0.62%) between the study populations, with a high genetic variation (99.38%) observed within each population, indicating significant diversity within individual populations. Ae. aegypti populations from Kisumu and Busia counties exhibited competence for CHIKV, with infection, dissemination, and transmission rates of 55.2%, 85.5%, and 27.1% for Kisumu; and 57.8%, 71.8%, and 25% for Busia populations, respectively. There was no significant difference in vector competence between these two populations. Interestingly, neither population was competent for ZIKV. In conclusion, the data shows that the Ae. aegypti populations in the two cities were homogeneous. This could explain the observed similarity in vector competence for CHIKV and ZIKV. Author SummaryOur study investigated the genetic variability and vector competence of Ae. aegypti mosquito populations in Kisumu and Busia Counties to CHIKV and ZIKV; revealing the presence and even distribution of both Aaa and Aaf subspecies. We also found that the Ae. aegypti populations from the two counties were not genetically differentiated. Furthermore, our study revealed that the Ae. aegypti mosquitoes from Kisumu and Busia counties were competent for CHIKV but may be refractory to ZIKV infection. These findings highlight the importance of continued monitoring of Ae. aegypti populations and their potential for arboviral disease transmission in the region.

microbiology↗