Abstract
Anopheline mosquitoes are the major vectors of human malaria. Parasite-mosquito interactions are a critical aspect of disease transmission and a potential target for malaria control. Current investigations into parasite-mosquito interactions frequently assume that genetically resistant and susceptible mosquitoes exist in nature. Therefore, comparisons between the Plasmodium susceptibility profiles of different mosquito species may contribute to a better understanding of vectorial capacity. Anopheles stephensi is an important malaria vector in central and southern Asia and is widely used as a laboratory model of parasite transmission due to its high susceptibility to Plasmodium infection. In the present study, we identified a rodent malaria-refractory strain of A. stephensi mysorensis (Ehime) by comparative study of infection susceptibility. A very low number of oocysts develop in Ehime mosquitoes infected with P. berghei and P. yoelii, as determined by evaluation of developed oocysts on the basal lamina. A stage-specific study revealed that this reduced susceptibility was due to the impaired formation of ookinetes of both Plasmodium species in the midgut lumen and incomplete crossing of the midgut epithelium. There were no apparent abnormalities in the exflagellation of male parasites in the ingested blood or the maturation of oocysts after the rounding up of the ookinetes. Overall, these results suggest that invasive-stage parasites are eliminated in both the midgut lumen and epithelium in Ehime mosquitoes by strain-specific factors that remain unknown. The refractory strain newly identified in this report would be an excellent study system for investigations into novel parasite-mosquito interactions in the mosquito midgut.
Highlights
Malaria persists today as the most widespread and devastating protozoan disease of humans
We found that the Ehime strain displayed high refractoriness to infection by the rodent malaria parasites P. berghei and P. yoelii, which are highly infectious to SDA500
Using a pair of PCR primers that anneal to the 5.8S and 28S coding regions of all species so far examined within the genus Anopheles, the intervening internal transcribed spacer 2 (ITS2) sequence was amplified from Ehime, two A. stephensi SDA500 referential lines (SDA500 and SDA500’) that were reared in different laboratories, and A. gambiae G3
Summary
Malaria persists today as the most widespread and devastating protozoan disease of humans. It is one of the major causes of mortality in children under 5 years of age in sub-Saharan Africa. After the ingestion of an infected blood meal, male and female gametocytes develop into gametes in the mosquito midgut. The newly formed zygotes transform into motile ookinetes that invade and cross the midgut epithelium between 24 and 48 h postinfection. Once they reach the basal lamina, the ookinetes undergo arrest and develop into protected capsules, called oocysts. The sporozoites are carried to the salivary glands and traverse the gland epithelium into the salivary gland lumen, where they further mature before being transferred to a new human host
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call