<i>Wolbachia</i>strain<i>w</i>AlbB maintains high density and dengue inhibition following introduction into a field population of<i>Aedes aegypti</i>

Abstract

<i>Aedes aegypti</i> mosquitoes carrying the <i>w</i>AlbB <i>Wolbachia</i> strain show a reduced capacity to transmit dengue virus. <i>w</i>AlbB has been introduced into wild <i>Ae. aegypti</i> populations in several field sites in Kuala Lumpur, Malaysia, where it has persisted at high frequency for more than 2 years and significantly reduced dengue incidence. Although these encouraging results indicate that <i>w</i>AlbB releases can be an effective dengue control strategy, the long-term success depends on <i>w</i>AlbB maintaining high population frequencies and virus transmission inhibition, and both could be compromised by <i>Wolbachia-</i>host coevolution in the field. Here, <i>w</i>AlbB-carrying <i>Ae. aegypti</i> collected from the field 20 months after the cessation of releases showed no reduction in <i>Wolbachia</i> density or tissue distribution changes compared to a <i>w</i>AlbB laboratory colony. The <i>w</i>AlbB strain continued to induce complete unidirectional cytoplasmic incompatibility, showed perfect maternal transmission under laboratory conditions, and retained its capacity to inhibit dengue. Additionally, a field-collected <i>w</i>AlbB line was challenged with Malaysian dengue patient blood, and showed significant blocking of virus dissemination to the salivary glands. These results indicate that <i>w</i>AlbB continues to inhibit currently circulating strains of dengue in field populations of <i>Ae. aegypti</i>, and provides additional support for the continued scale-up of <i>Wolbachia</i> wAlbB releases for dengue control. This article is part of the theme issue 'Novel control strategies for mosquito-borne diseases'.