Nyunja, A. | bioRxiv Science

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↗

bioRxiv2018

Recent outbreaks of chikungunya virus (CHIKV) in Africa and Asia are driven by a variant carrying mutations associated with increased fitness for Aedes aegypti

BackgroundIn 2016, a chikungunya virus (CHIKV) outbreak was reported in Mandera, Kenya. This was the first major CHIKV outbreak in the country since the global re-emergence of this virus, which arose as an initial outbreak in Kenya in 2004. Therefore, we collected samples and sequenced viral genomes from the 2016 Mandera outbreak.\n\nMethodology/Principal FindingsAll Kenyan genomes contained two mutations, E1:K211E and E2:V264A, recently reported to have an association with increased infectivity, dissemination and transmission in the Aedes aegypti (Ae. aegypti) vector. Phylogeographic inference of temporal and spatial virus relationships using Bayesian approaches showed that this Ae. aegypti adapted strain emerged within the East, Central, and South African (ECSA) lineage of CHIKV between 2005 and 2008, most probably in India. It was also in India where the first large outbreak caused by this strain appeared, in New Delhi, 2010. More importantly, our results also showed that this strain is no longer contained to India, and that it has more recently caused several major outbreaks of CHIKV, including the 2016 outbreaks in India, Pakistan and Kenya, and the 2017 outbreak in Bangladesh. In addition to its capability to cause large outbreaks in different regions of the world, this CHIKV strain has the capacity to replace less adapted wild type strains in Ae. aegypti-rich regions. Indeed, all the latest full CHIKV genomes of the ECSA Indian Ocean Lineage (IOL), from the regions of high Ae. aegypti prevalence, carry these two mutations, including samples collected in Japan, Australia, and China.\n\nConclusions/SignificanceOur results point to the importance of continued genomic-based surveillance of this strains global spread, and they prompt urgent vector competence studies in Asian and African countries, in order to assess the level of vector receptiveness, virus transmission, and the impact this might have on this strains ability to cause major outbreaks.\n\nAuthor summaryChikungunya virus (CHIKV) causes a debilitating infection with high fever, intense muscle and bone pain, rash, nausea, vomiting and headaches, and persistent and/or recurrent joint pains for months or years after contracting the virus. CHIKV is spread by two mosquito vectors, Aedes albopictus and Aedes aegypti, with increased presence around the globe. In this study, we report global spread of a CHIKV strain that carries two mutations that have been suggested to increase this virus ability to infect the Aedes aegypti mosquito, as well as to increase CHIKVs ability to be transmitted by this vector. We show that this strain appeared sometime between 2005 and 2008, most probably in India, and has now spread to Africa, Asia, and Australia. We show that this strain is capable of driving large outbreaks of CHIKV in the human population, causing recent major outbreaks in Kenya, Pakistan, India and Bangladesh. Thus, our results stress the importance of monitoring this strains global spread, as well as the need of improved vector control strategies in the areas of Aedes aegypti prevalence.

evolutionary biology↗