Plasmodium gallinaceum: A Refractory Mechanism of Ookinete Killing in the Mosquito, Anopheles gambiae

• Published in: Experimental parasitology Vol. 80; no. 4; pp. 583 - 595
• Main Authors: Vernick, K.D., Fujioka, H., Seeley, D.C., Tandler, B., Aikawa, M., Miller, L.H.
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 01.06.1995; Elsevier
• Subjects: ANIMAL DEVELOPMENTAL STAGES; Animals; Anopheles - genetics; Anopheles - parasitology; ANOPHELES GAMBIAE; Biological and medical sciences; Chickens; Culicidae; DEATH; DISEASE RESISTANCE; DISEASE VECTORS; Esterases - genetics; ETAPAS DEL DESARROLLO ANIMAL; Female; Fundamental and applied biological sciences. Psychology; GENE; GENES; Genes, Insect; GENETIC INHERITANCE; GENETIC REGULATION; GENETICA; GENETICS; GENETIQUE; GENOTIPOS; GENOTYPE; GENOTYPES; HEREDITE; HERENCIA GENETICA; INFECCIONES POR PROTOZOOS; INFECTIONS; Insect Vectors - genetics; Insect Vectors - parasitology; INTESTIN; INTESTINES; INTESTINOS; MALARIA; Medically important nuisances and vectors, pests of stored products and materials: population survey and control; Microscopy, Electron; MIDGUT; MORT; MUERTE; OOCYSTS; PATHOGENESE; PATHOGENESIS; PATOGENESIS; Phenotype; PLASMODIUM; PLASMODIUM GALLINACEUM; Plasmodium gallinaceum - physiology; Plasmodium gallinaceum - ultrastructure; PROTOZOAL INFECTIONS; PROTOZOOSE; RESISTANCE AUX MALADIES; RESISTENCIA A LA ENFERMEDAD; STADE DE DEVELOPPEMENT ANIMAL; SUSCEPTIBILITY; ULTRAESTRUCTURA; ULTRASTRUCTURE; VECTEUR DE MALADIE; VECTORES; VECTORS; Vectors. Intermediate hosts; Protozoa; Protozoal disease; Genetic inheritance; Ookinete; Malaria; Midgut; Insecta; Parasite; Host agent relation; Parasitosis; Plasmodium gallinaceum; Refractoriness; Immunity; Infection; Developmental arrest; Sensitivity resistance; Anopheles gambiae; Arthropoda; Pathogenic; Culicidae; Invertebrata; Sporozoa; Vector; Diptera
• ISSN: 0014-4894; 1090-2449
• DOI: 10.1006/expr.1995.1074

We have identified a mechanism for refractoriness to a bird malaria, Plasmodium gallinaceum, in the African vector of human malaria, Anopheles gambiae. Oocysts fail to develop in the refractory mosquitoes as a result of ookinete death which occurs within 27 hr of midgut invasion. Ultrastructural studies showed that parasite death occurs while the ookinete lies free in the midgut epithelial cell cytosol, usually surrounded by an organelle-free zone that consists of finely fibrillar material. The mechanism of parasite killing does not involve a previously described refractory mechanism of parasite encapsulation. We selected genetic lines which are refractory and susceptible to midgut infection. Genetic crossing of the lines suggests that the refractory trait is inherited as a single dominant genetic locus. Other loci probably influence oocyst number in susceptible mosquitoes. Intracellular ookinete killing appears to involve a previously unrecognized host defense mechanism against malaria parasites that involves direct destruction of the invading organism.