<i>Wolbachia w</i>AlbB remains stable in <i>Aedes aegypti</i> over 15 years but exhibits genetic background-dependent variation in virus blocking

Abstract

The ability of the maternally transmitted endosymbiotic bacterium <i>Wolbachia</i> to induce cytoplasmic incompatibility (CI) and virus blocking makes it a promising weapon for combatting mosquito-borne diseases through either suppression or replacement of wild-type populations. Recent field trials show that both approaches significantly reduce the incidence of dengue fever in humans. However, new questions emerge about how <i>Wolbachia</i>-mosquito associations will co-evolve over time and whether <i>Wolbachia</i>-mediated virus blocking will be affected by the genetic diversity of mosquitoes and arboviruses in the real world. Here, we have compared the <i>Wolbachia</i> density and CI expression of two <i>w</i>AlbB-infected <i>Aedes aegypti</i> lines transinfected 15 years apart. We have also assessed <i>w</i>AlbB-mediated virus blocking against dengue (DENV), Zika (ZIKV), and Chikungunya (CHIKV) viruses and examined whether host genetic backgrounds modulate viral blocking effects by comparing ZIKV infection in mosquitoes with a Mexican genetic background to those with a Singaporean background. Our results show that over 15 years, <i>w</i>AlbB maintained the capacity to form a stable association with <i>Ae. aegypti</i> in terms of both density and CI expression. There were variations in <i>w</i>AlbB-induced virus blocking against CHIKV, DENV, and ZIKV, and higher inhibitory effects on ZIKV in mosquitoes on the Singaporean genetic background than on the Mexican background. These results provide important information concerning the robustness and long-term stability of <i>Wolbachia</i> as a biocontrol agent for arbovirus disease control.