| Abstract |
The goal of this undertaking was to conduct a research on the topic of a possible vector for a paratransgenic approach in the mosquito, so as to combat malaria. Based on results from other laboratories, where it has been proven that the bacterium Asaia sp. has the ability to colonize the micro-flora of the midgut lumen of Anopheles stephensi and Aedes aegypti (Favia et al., 2007), we moved on to investigating the ability of Asaia to colonize Anopheles gambiae, which is the major vector of malaria in sub-Saharan Africa.
Due to the speciation event that is happening in the Anopheles complex, it was decided that a specific strain of Anopheles gambiae was going to be used, namely the Ngousso strain, which is M form only. The advantage of this is that the results will be as genetically “clean” as possible.
Larvae were infected with a transformed strain of the bacterium, with a plasmid containing a GFP cassette for easy detection under fluorescent light. The infection was successful and colonies in the gut of the larvae were clearly visible. The same observation was made for the midgut of the adult mosquito.
Another, unexpected, observation was a difference in the developmental rate between infected and non-infected larvae. Infected larvae showed a faster advance in development, ranging from 1 to 2 days, traversing the four developmental stages of larvae and arriving at the pupal stage faster than their non-infected counterparts. No difference in development was observed for adult mosquitoes.
Finally, RNA was extracted and collected from all the different larval stages, both for infected and non-infected, so as to conduct an expression profiling analysis through microarrays for possible correlation of genes which are already known to be affected by the Plasmodium parasite.
Asaia sp. seems to remain stable in both larval stages and in the adult stage of the mosquito. Questions regarding any potential fitness costs regarding the presence of the transformed bacteria in the mosquito need to be answered, but if any of those early indications prove to be facts, Asaia could fill the role of a paratransgenic vehicle in the fight against malaria.
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Investigating the ability of Asaia sp. to act as a paratransgenic vehicle in the fight against malaria
