Exsheathment and midgut invasion of nocturnally subperiodic Brugia malayi microfilariae in a refractory vector, Aedes aegypti (Thailand strain).

Exsheathment and midgut invasion of nocturnally subperiodic Brugia malayi microfilariae were analyzed using light and scanning electron microscopy in a refractory vector, Aedes aegypti (Thailand strain). Results showed that exsheathed microfilariae represented only approximately 1% of the total microfilaria midguts dissected at 5-min post-infected blood meal (PIBM). The percentage of exsheathed microfilariae found in midguts progressively increased to about 20, 60, 80, 90, and 100% at 1-, 2-5-, 6-12-, 18-36-, and 48-h PIBM, respectively. Importantly, all the microfilariae penetrating the mosquito midguts were exsheathed. Midgut invasion by the exsheathed microfilariae was observed between 2- and 48-h PIBM. SEM analysis revealed sheathed microfilariae surrounded by small particles and maceration of the microfilarial sheath in the midguts, suggesting that the midguts of the refractory mosquitoes might have protein(s) and/or enzyme(s) and/or factor(s) that induce and/or accelerate exsheathment. The microfilariae penetrated the internal face of the peritrophic matrix (PM) by their anterior part and then the midgut epithelium, before entering the hemocoel suggesting that PM was not a barrier against the microfilariae migrating towards the midgut. Melanized microfilariae were discovered in the hemocoel examined at 96-h PIBM suggesting that the refractory mosquitoes used melanization reactions against this parasite. This study provided evidence that A. aegypti (Thailand strain) has refractory mechanisms against B. malayi in both midgut and hemocoel.

Morphological and protein analyses of adult female salivary glands of Anopheles barbirostris species A1 (Diptera: Culicidae).

Morphology and protein profiles of female salivary glands of Anopheles barbirostris species A1 were analyzed. Female glands consisted of a distinctive tri-lobed structure connected to a main salivary canal, a single medial and two lateral lobes with proximal and distal portions. Cellular architecture was similar among the lobes, with secretory material appearing as large masses. Cells of the proximal-lateral lobes contained secretory masses with a finely filamentous aspect. In the distal-lateral lobes, cells had a dense secretory product with mottled pattern. Cells of the medial lobe had secretory masses which were uniformly stained and highly electron dense. Following emergence, the glands accumulated secretory material rapidly and developed completely within three days. Degenerative changes including loss of stored secretion and increase of cytoplasmic vacuolation and concentric lamellar structures were observed from day 16 post emergence that correlated with total amount of the salivary gland proteins determined during development. SDS-PAGE, nanoLC-MS, and glycoprotein analysis revealed at least eleven major protein bands, of which each morphological region contained different major proteins. Two glycoproteins, apyrase/5'-nucleotidase and D7, were identified. These results form a basis for further studies on details of cytopathological changes of malarial infected glands and roles of the proteins in disease transmission.