Transgenic expression of Wolbachia cytoplasmic incompatibility factors in Aedes aegypti mosquitoes

McNamara, Cameron James (2023) Transgenic expression of Wolbachia cytoplasmic incompatibility factors in Aedes aegypti mosquitoes. PhD thesis, University of Glasgow.

Abstract

Many strains of the maternally transmitted intracellular bacteria Wolbachia can invade arthropod populations and remain at high frequency through modifications of host reproduction. Most commonly this manipulation occurs via a mechanism known as cytoplasmic incompatibility (CI), whereby Wolbachia-mediated modification of the paternal chromatin renders infected males incompatible with uninfected females. If the females carry a compatible Wolbachia strain this incompatibility is rescued which provides Wolbachia-carrying females with a relative fitness advantage. The basis for incompatibility stems from two Wolbachia encoded CI factors (Cifs), CifA and CifB, which interact in a cognate-specific manner. If Wolbachia strains possess divergent copies of the cif genes, then incompatibility cannot be rescued. The modifications associated with CI induction and rescue are largely attributed to CifB and CifA respectively. However, prior research in transgenic insect species has revealed that CifA might play a role in the induction phenotype which has led to diverging hypotheses on the mechanism of CI. Although the conditional sterility associated with Wolbachia-mediated CI has been exploited to control populations of the primary arbovirus vector Ae. aegypti, an understanding of how the Cifs manipulate reproduction in this species remained unknown. In this study, the phenotypes of CI induction and rescue were recapitulated through the transgenic expression of cif genes in Ae. aegypti mosquitoes and revealed that the Cifs likely interact in a toxin-antidote mechanism. Interchanging Cif homologues from alternate strains revealed different levels of CifB toxicity in the male reproductive tissues, which might explain the discrepancies concerning the need for paternal cifA-antidote expression in sterility induction between alternate studies of cif variants. As Wolbachia-mediated Ae. aegypti control strategies have proven effective at reducing disease transmission, the transgenic mediation of CI in this species provides an opportunity to utilise this reproductive manipulation for vector control in the absence of the bacterium. It is believed that the findings of this study could be used to generate different transgenic systems that either replace or suppress Ae. aegypti populations and thus reduce the burden of arboviral diseases.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Subjects: Q Science > QR Microbiology > QR355 Virology
• Colleges/Schools: College of Medical Veterinary and Life Sciences > School of Infection & Immunity
• Supervisor's Name: Sinkins, Professor Steven P.
• Date of Award: 2023
• Depositing User: Theses Team
• Unique ID: glathesis:2023-83561
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 28 Apr 2023 11:29
• Last Modified: 13 Jun 2025 08:59
• Thesis DOI: 10.5525/gla.thesis.83561
• URI: https://theses.gla.ac.uk/id/eprint/83561