Discovery of prevalent naturalWolbachiainAedes aegyptiin Metropolitan Manila, Philippines using locally designed primers: bacterial density is influenced by strain and host sex

Abstract

AbstractWolbachiaare maternally transmitted bacteria that are utilized for arboviral disease prevention. Cytoplasmic incompatibility (CI) and viral blocking, two characteristics that makeWolbachiasuitable for vector control, both depend on bacterial infection prevalence and density. Although numerous mosquito species naturally harborWolbachia, the prevalence ofWolbachiainAedes aegyptivaries from minimal to absent. The absence of naturalWolbachiainAe. aegyptiis considered advantageous for novelWolbachiatransinfection because interference caused by incompatibleWolbachiastrains will not occur. In this study, we screened forWolbachiadensity in 429 individualAe. aegypticollected from Metropolitan Manila, Philippines using locally designed primers to determine whether primer compatibility improvesWolbachiadetection in naturally infectedAe. aegypti. We also investigated the effects of host sex andWolbachiastrain onWolbachiadensity. We found a highWolbachiaprevalence for16S rRNA(40%) andwsp(62%) markers. RelativeWolbachiadensities ranged from −3.840 to 2.710 for16S rRNAand from −4.020 to 1.810for wsp, and these relative densities were higher among male mosquitoes than female mosquitoes. Phylogenetic analysis revealed that most of theAe. aegyptiwere clustered into supergroup B, with 63% (142/226) of these sequences representing a unique strain referred to here as “wAegML,” which exhibited a significantly lower density inAe. aegyptithan the other twoWolbachiastrains detected (wAegB/wAlbB andwAlbA) as well as a higher density in maleAe. aegyptithan in females. Overall, locally designed primers improvedWolbachiadetection in naturally infectedAe. aegypti. The unique strainwAegML occurs at a low density and is related to the use ofwAlbB in mass-release programs; therefore, it is unlikely to interfere with such programs. Further studies on naturalWolbachiainfection inAe. aegypticombining methodological and biological factors are warranted to help resolve current conflicts in the field.