Paratransgenesis: a promising new strategy for mosquito vector control

Abstract

The three main mosquito genera, Anopheles, Aedes and Culex, transmit respectively malaria, dengue and lymphatic filariasis. Current mosquito control strategies have proved unsuccessful, and there still is a substantial number of morbidity and mortality from these diseases. Genetic control methods have now arisen as promising alternative strategies, based on two approaches: the replacement of a vector population by disease-refractory mosquitoes and the release of mosquitoes carrying a lethal gene to suppress target populations. However, substantial hurdles and limitations need to be overcome if these methods are to be used successfully, the most significant being that a transgenic mosquito strain is required for every target species, making genetically modified mosquito strategies inviable when there are multiple vector mosquitoes in the same area. Genetically modified bacteria capable of colonizing a wide range of mosquito species may be a solution to this problem and another option for the control of these diseases. In the paratransgenic approach, symbiotic bacteria are genetically modified and reintroduced in mosquitoes, where they express effector molecules. For this approach to be used in practice, however, requires a better understanding of mosquito microbiota and that symbiotic bacteria and effector molecules be identified. Paratransgenesis could prove very useful in mosquito species that are inherently difficult to transform or in sibling species complexes. In this approach, a genetic modified bacteria can act by: (a) causing pathogenic effects in the host; (b) interfering with the host’s reproduction; (c) reducing the vector’s competence; and (d) interfering with oogenesis and embryogenesis. It is a much more flexible and adaptable approach than the use of genetically modified mosquitoes because effector molecules and symbiotic bacteria can be replaced if they do not achieve the desired result. Paratransgenesis may therefore become an important integrated pest management tool for mosquito control.

Ascension Island: a survey to assess the presence of Zika virus vectors

“…Paratransgenesis has also been suggested as a promising strategy for mosquito vector control against C. quinquefasciatus. 29 …”

Learning from the Enemy: Innate RNA Interference Renders Mosquitos Asymptomatic to Arboviral Infection and Provides Researchers with New Approaches to Subdue its Effects

“…Paratransgenesis, a term which refers to the debilitation of a host parasite by first preventing the spread of its symbiont (mosquitoes), has been invoked by an up and coming method that has proved successful. Genetically modified bacteria (or in rare cases, fungi) have the advantage of spreading between multiple species of mosquitoes more easily; they produce molecules which could not only debilitate and sterilize the mosquitoes, but also could interfere with the arbovirus that it carries [22].…”

Protective microbe enhances colonisation of a novel host species by modifying immune gene expression

“…Although new protective symbioses form naturally(8–11), their creation is being rapidly pursued for the biocontrol of infectious disease, either by introducing existing symbionts into new hosts(12), or by generating new symbionts, e.g. via paratransgenesis(13–15). For example, Aedes and Anopheles mosquitoes have been artificially infected with strains of the inherited symbiont Wolbachia that inhibit the replication of dengue and Zika viruses, as well as malaria(5, 16–18).…”