Limits...
An impossible journey? The development of Plasmodium falciparum NF54 in Culex quinquefasciatus.

Knöckel J, Molina-Cruz A, Fischer E, Muratova O, Haile A, Barillas-Mury C, Miller LH - PLoS ONE (2013)

Bottom Line: Our results reveal that ookinetes develop in the midgut lumen of C. quinquefasciatus in slightly lower numbers than in Anopheles gambiae G3.Eight days after the mosquito's blood meal, no oocysts can be found in C. quinquefasciatus.Our results suggest that the mosquito immune system could be involved in parasite killing early in development after ookinetes have crossed the midgut epithelium and come in contact with the mosquito hemolymph.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America. julia.knoeckel@gmail.com

ABSTRACT
Although Anopheles mosquitoes are the vectors for human Plasmodium spp., there are also other mosquito species-among them culicines (Culex spp., Aedes spp.)-present in malaria-endemic areas. Culicine mosquitoes transmit arboviruses and filarial worms to humans and are vectors for avian Plasmodium spp., but have never been observed to transmit human Plasmodium spp. When ingested by a culicine mosquito, parasites could either face an environment that does not allow development due to biologic incompatibility or be actively killed by the mosquito's immune system. In the latter case, the molecular mechanism of killing must be sufficiently powerful that Plasmodium is not able to overcome it. To investigate how human malaria parasites develop in culicine mosquitoes, we infected Culex quinquefasciatus with Plasmodium falciparum NF54 and monitored development of parasites in the blood bolus and midgut epithelium at different time points. Our results reveal that ookinetes develop in the midgut lumen of C. quinquefasciatus in slightly lower numbers than in Anopheles gambiae G3. After 30 hours, parasites have invaded the midgut and can be observed on the basal side of the midgut epithelium by confocal and transmission electron microscopy. Very few of the parasites in C. quinquefasciatus are alive, most of them are lysed. Eight days after the mosquito's blood meal, no oocysts can be found in C. quinquefasciatus. Our results suggest that the mosquito immune system could be involved in parasite killing early in development after ookinetes have crossed the midgut epithelium and come in contact with the mosquito hemolymph.

Show MeSH

Related in: MedlinePlus

Comparison of blood intake of Anopheles gambiae and Culex quinquefasciatus during a blood meal.Total hemoglobin content of female mosquitoes fed on a 40% hematocrit blood solution was determined by hemoglobinometry at different time points after a blood meal. Ten mosquitoes were analyzed for each time point and the average amount of ingested blood calculated using a standard curve. Values are shown as mean ± standard deviation. The volume of blood corresponding to the determined hemoglobin amount was compared between An. gambiae (--•--) and C. quinquefasciatus ( —▪— ).
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3643899&req=5

pone-0063387-g002: Comparison of blood intake of Anopheles gambiae and Culex quinquefasciatus during a blood meal.Total hemoglobin content of female mosquitoes fed on a 40% hematocrit blood solution was determined by hemoglobinometry at different time points after a blood meal. Ten mosquitoes were analyzed for each time point and the average amount of ingested blood calculated using a standard curve. Values are shown as mean ± standard deviation. The volume of blood corresponding to the determined hemoglobin amount was compared between An. gambiae (--•--) and C. quinquefasciatus ( —▪— ).

Mentions: The amount of ingested blood determines the number of gametocytes that reach the midgut of the mosquito and subsequently can fertilize and develop into ookinetes. Additionally, the rate of digestion can influence parasite development and survival in the midgut lumen. The total hemoglobin content of blood-fed female An. gambiae and C. quinquefasciatus mosquitoes was measured at different time points after a blood meal to determine the volume of blood ingested and the rate of digestion of the blood meal. As shown in Figure 2, our hemoglobinometry analyses reveal that the amount of hemoglobin immediately after feeding is similar in both mosquito species and corresponds to a total volume of 5.7±1.53 µl blood in An. gambiae and 5.7±1.82 µl blood in C. quinquefasciatus. The number of ingested parasites should thus be the same in An. gambiae and C. quinquefasciatus.


An impossible journey? The development of Plasmodium falciparum NF54 in Culex quinquefasciatus.

Knöckel J, Molina-Cruz A, Fischer E, Muratova O, Haile A, Barillas-Mury C, Miller LH - PLoS ONE (2013)

Comparison of blood intake of Anopheles gambiae and Culex quinquefasciatus during a blood meal.Total hemoglobin content of female mosquitoes fed on a 40% hematocrit blood solution was determined by hemoglobinometry at different time points after a blood meal. Ten mosquitoes were analyzed for each time point and the average amount of ingested blood calculated using a standard curve. Values are shown as mean ± standard deviation. The volume of blood corresponding to the determined hemoglobin amount was compared between An. gambiae (--•--) and C. quinquefasciatus ( —▪— ).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3643899&req=5

pone-0063387-g002: Comparison of blood intake of Anopheles gambiae and Culex quinquefasciatus during a blood meal.Total hemoglobin content of female mosquitoes fed on a 40% hematocrit blood solution was determined by hemoglobinometry at different time points after a blood meal. Ten mosquitoes were analyzed for each time point and the average amount of ingested blood calculated using a standard curve. Values are shown as mean ± standard deviation. The volume of blood corresponding to the determined hemoglobin amount was compared between An. gambiae (--•--) and C. quinquefasciatus ( —▪— ).
Mentions: The amount of ingested blood determines the number of gametocytes that reach the midgut of the mosquito and subsequently can fertilize and develop into ookinetes. Additionally, the rate of digestion can influence parasite development and survival in the midgut lumen. The total hemoglobin content of blood-fed female An. gambiae and C. quinquefasciatus mosquitoes was measured at different time points after a blood meal to determine the volume of blood ingested and the rate of digestion of the blood meal. As shown in Figure 2, our hemoglobinometry analyses reveal that the amount of hemoglobin immediately after feeding is similar in both mosquito species and corresponds to a total volume of 5.7±1.53 µl blood in An. gambiae and 5.7±1.82 µl blood in C. quinquefasciatus. The number of ingested parasites should thus be the same in An. gambiae and C. quinquefasciatus.

Bottom Line: Our results reveal that ookinetes develop in the midgut lumen of C. quinquefasciatus in slightly lower numbers than in Anopheles gambiae G3.Eight days after the mosquito's blood meal, no oocysts can be found in C. quinquefasciatus.Our results suggest that the mosquito immune system could be involved in parasite killing early in development after ookinetes have crossed the midgut epithelium and come in contact with the mosquito hemolymph.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America. julia.knoeckel@gmail.com

ABSTRACT
Although Anopheles mosquitoes are the vectors for human Plasmodium spp., there are also other mosquito species-among them culicines (Culex spp., Aedes spp.)-present in malaria-endemic areas. Culicine mosquitoes transmit arboviruses and filarial worms to humans and are vectors for avian Plasmodium spp., but have never been observed to transmit human Plasmodium spp. When ingested by a culicine mosquito, parasites could either face an environment that does not allow development due to biologic incompatibility or be actively killed by the mosquito's immune system. In the latter case, the molecular mechanism of killing must be sufficiently powerful that Plasmodium is not able to overcome it. To investigate how human malaria parasites develop in culicine mosquitoes, we infected Culex quinquefasciatus with Plasmodium falciparum NF54 and monitored development of parasites in the blood bolus and midgut epithelium at different time points. Our results reveal that ookinetes develop in the midgut lumen of C. quinquefasciatus in slightly lower numbers than in Anopheles gambiae G3. After 30 hours, parasites have invaded the midgut and can be observed on the basal side of the midgut epithelium by confocal and transmission electron microscopy. Very few of the parasites in C. quinquefasciatus are alive, most of them are lysed. Eight days after the mosquito's blood meal, no oocysts can be found in C. quinquefasciatus. Our results suggest that the mosquito immune system could be involved in parasite killing early in development after ookinetes have crossed the midgut epithelium and come in contact with the mosquito hemolymph.

Show MeSH
Related in: MedlinePlus