title: Peritrophic matrix formation and Brugia malayi microfilaria invasion of the midgut of a susceptible vector, Ochlerotatus togoi (Diptera: Culicidae).
abstract: The mosquito midgut is the first site that vector-borne pathogens contact during their multiplication, differentiation, or migration from blood meal to other tissues before transmission. After blood feeding, the mosquitoes synthesize a chitinous structure called peritrophic matrix (PM) that envelops the blood meal and separates the food bolus from the midgut epithelium. In this study, a systematic investigation of the PM formation and the interaction of Brugia malayi within the midgut of a susceptible vector, Ochlerotatus togoi, were performed using scanning electron microscopy (SEM). SEM analysis of the midguts dissected at different time points post feeding on a B. malayi-infected blood meal (PIBM) revealed that the PM was formed from 45 min PIBM and gradually thickened and matured during 8-18 h PIBM. The PM degraded from 24 to 72 h PIBM, when digestion was completed. The invasion process of the microfilariae was observed between 3 and 4 h PIBM. In the beginning of the process, only sheathed microfilariae interacted with the internal face of the PM by its anterior part, and then the midgut epithelium before entering the hemocoel, after that they exsheathed. Microfilarial sheaths lying within the hemocoel were observed suggesting that they may serve as a decoy to induce the immune systems of the mosquitoes to respond to the antigens on the sheaths, thereby protecting the exsheathed microfilariae. These initial findings would lead to further study on the proteins, chemicals, and factors in the midgut that are involved in the susceptibility of O. togoi as a vector of filariasis.
authors.affiliation: Department of Parasitology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand. narsuwan@mail.med.cmu.ac.th
authors.forename: Narissara
authors.initials: N
authors.lastname: Jariyapan
authors.forename: Atiporn
authors.initials: A
authors.lastname: Saeung
authors.forename: Nuchpicha
authors.initials: N
authors.lastname: Intakhan
authors.forename: Wetpisit
authors.initials: W
authors.lastname: Chanmol
authors.forename: Sriwatapron
authors.initials: S
authors.lastname: Sor-Suwan
authors.forename: Benjarat
authors.initials: B
authors.lastname: Phattanawiboon
authors.forename: Kritsana
authors.initials: K
authors.lastname: Taai
authors.forename: Wej
authors.initials: W
authors.lastname: Choochote
mesh_terms: D000818:Animals; D017178:Brugia malayi / Q000254:growth & development* / Q000648:ultrastructure; D004199:Disease Vectors; D041981:Gastrointestinal Tract / Q000469:parasitology / Q000648:ultrastructure; D008855:Microscopy, Electron, Scanning; D044969:Ochlerotatus / Q000469:parasitology* / Q000648:ultrastructure