Colonization of Aedes aegypti midgut by the endosymbiont-bearing trypanosomatid Blastocrithidia culicis.
Monoxenous trypanosomatids inhabit invertebrate hosts throughout their life cycle. However, there have been cases of HIV-positive patients who have presented opportunistic infections caused by these protozoa, offering new perspectives to the study of interactions between monoxenics and hematophagous insect vectors. Some monoxenous trypanosomatids present a symbiotic bacterium in the cytoplasm, which seems to promote biochemical and morphological changes in the host trypanosomatids, such as alterations in plasma membrane carbohydrates and the reduction of the paraxial rod. In this work, we investigated the colonization of Aedes aegypti with Blastocrithidia culicis, an endosymbiont-bearing trypanosomatid. B. culicis remained in the insect digestive tract for 38 days after feeding. Optical microscopy analysis revealed an infection process characterized by a homogenous distribution of the trypanosomatid along the midgut epithelium; no preferential interaction of protozoa with any cell type was observed. Ultrastructural analysis showed that during the colonization process, trypanosomatids interacted mainly with midgut cells through their flagellum, which penetrates the microvilli preferentially near the tight junctions. Prolonged infections promoted insect midgut degradation, culminating with the arrival of protozoa in the hemocel. By demonstrating B. culicis colonization in a bloodsucking insect, we suggest that vector transmission of monoxenous trypanosomatids to vertebrate host may occur in nature.
Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, CCS, Blogo G, subsolo, Ilha do Fundão, 21.941-900, Rio de Janeiro, RJ, Brazil.
Miguel S
MS
Corrêa-da-Silva
Patrícia
P
Fampa
Luiz P
LP
Lessa
Edalton dos Reis
Edos R
Silva
Jacenir Reis
JR
dos Santos Mallet
Elvira M B
EM
Saraiva
Maria Cristina M
MC
Motta
D000330:Aedes / Q000469:parasitology* / Q000648:ultrastructure; D000818:Animals; D005260:Female; D006790:Host-Parasite Interactions; D007303:Insect Vectors / Q000469:parasitology* / Q000648:ultrastructure; D007422:Intestines / Q000469:parasitology* / Q000648:ultrastructure; D008018:Life Cycle Stages / Q000502:physiology*; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D013559:Symbiosis; D014351:Trypanosomatina / Q000502:physiology* / Q000648:ultrastructure