Evidence for natural hybridization and novel Wolbachia strain superinfections in the Anopheles gambiae complex from Guinea

Abstract

Wolbachia , a widespread bacterium which can influence mosquito-borne pathogen transmission, has recently been detected within Anopheles ( An .) species that are malaria vectors in Sub-Saharan Africa. Although studies have reported Wolbachia strains in the An. gambiae complex, apparent low density and prevalence rates require confirmation. In this study, wild Anopheles mosquitoes collected from two regions of Guinea were investigated. In contrast with previous studies, RNA was extracted from adult females ( n = 516) to increase the chances for the detection of actively expressed Wolbachia genes, determine Wolbachia prevalence rates and estimate relative strain densities. Molecular confirmation of mosquito species and Wolbachia multilocus sequence typing (MLST) were carried out to analyse phylogenetic relationships of mosquito hosts and newly discovered Wolbachia strains. Strains were detected in An. melas (prevalence rate of 11.6%–16/138) and hybrids between An. melas and An. gambiae sensu stricto (prevalence rate of 40.0%–6/15) from Senguelen in the Maferinyah region. Furthermore, a novel high-density strain, termed w AnsX, was found in an unclassified Anopheles species. The discovery of novel Wolbachia strains (particularly in members, and hybrids, of the An. gambiae complex) provides further candidate strains that could be used for future Wolbachia -based malaria biocontrol strategies.

Transmission-Blocking Strategies Against Malaria Parasites During Their Mosquito Stages

“…This is mainly owing to the benefits of Wolbachia infections, which induce mosquitoes to produce two desirable properties for disease vector control, cytoplasmic incompatibility (CI) and pathogen inhibition ( Walker et al, 2021 ). Meanwhile, there is increasing evidence that Wolbachia infections in mosquitoes are common ( Baldini et al, 2014 ; Niang et al, 2018 ; Jeffries et al, 2021 ); 25 species of African Anopheles mosquitoes have been found to carry 16 varieties of Wolbachia infections ( Ayala et al, 2019 ). The desirable induction properties and diverse flora have prompted researchers to further increase their interest in using Wolbachia for developing biological control strategies against malaria transmission ( Figure 2 ).…”

Wolbachia 16S rRNA haplotypes detected in wild Anopheles stephensi in eastern Ethiopia

“…stephensi . Chen et al [ 20 ] showed that An. stephensi can be stably infected by wAlbB and that there was no change in the microbiome of the mosquitoes upon Wolbachia infection.…”

“…These genes include the 16S -encoding gene, the surface protein-encoding gene (Wolbachia surface protein [ wsp ]), and the five multilocus strain typing (MLST) genes ( ftsZ , fbpA , hcpA , coxA , and gatB ) [ 10 ]. Previous studies have depended solely on Wolbachia 16S for confirming infection [ 18 , 19 ]; however, more recent research has indicated that multiple genes must be detected in order to confirm infection [ 20 ]. Very few Anopheles species have been screened for Wolbachia , with proven infection occurring only in two highly diverged species in sub-Saharan Africa [ 21 ].…”

“…There has also been significant difficulty in many studies with amplifying the genes in MLST. Gomes et al were only able to amplify three out of five genes, and Jeffries et al were unable to amplify any MLST genes in multiple sample groups [ 18 , 20 ]. This may indicate that environmental contamination is present or that divergence among these genes has emerged, precluding the use of the standard MLST primer set [ 18 , 22 , 23 ].…”

Life Sciences New Talent collection

“…Kok-Lung Chan, a Sir Henry Dale Fellow at the University of Sussex, reviews the causes and consequences of incomplete genomic DNA replication and the role of replication stress on genomic instability [ 12 ]. Thomas Walker, a Sir Henry Dale Fellow at the London School of Hygiene and Tropical Medicine, presents research from his group on novel Wolbachia bacterial strains in populations of the mosquito Anopheles gambiae in Guinea—findings that identify further candidate strains that might be used in the future for malaria biocontrol strategies [ 13 ]. Christos Gkogkas, a Sir Henry Dale Fellow at the University of Edinburgh, contributes a timely review of recent developments in translational controls in brain development in neurons and endothelial cells, and implications for the treatment of neurodevelopmental disorders [ 14 ].…”