Activation of the immune system of Anopheles gambiae against malaria parasite: a comparison between bacterial infection and a botanical extract
, Ahmed, A. M. . 2004
The mosquito Anopheles gambiae, the major vector of malaria in Africa, was used to test the hypothesis that the utilization of immune system against malaria parasites could be possible. Two immune elicitors, the bacteria, Micrococcus luteus and the black-seed (BS) oil, Nigella sativa, were used to stimulate the immune system of this vector against the rodent malaria parasite, Plasmodium yoelii nigeriensis. Mosquitoes were inoculated with bacteria or allowed to orally feed on glucose-oil mixture both before and after malaria infection. The resultant antimicrobial activities and the impact on the number of oocysts successfully formed were then monitored. Although infection of mosquitoes with malaria resulted in a significant antimicrobial activity, inoculation with M. luteus has induced a significantly higher antimicrobial activity. Thus, when mosquitoes injected with M. luteus immediately before malaria infection, the number of the successfully formed oocysts was significantly reduced by 46.5%. This in fact indicates that M. luteus has partially activated the immune system against the malaria parasite. On the other hand, a well-known immune activator, the BS oil has significantly reduced the number of oocysts by 90% only when fed to mosquitoes from 6 days before malaria infection and until completion of oocysts formation. This indicates that BS oil could be more effective than bacterial inoculation. This, in fact, may help in improving the recent strategies of blocking the malaria life cycle in the gut of its mosquito vector using natural products.
