Lutzomyia longipalpis peritrophic matrix: formation, structure, and chemical composition.

Sandflies are vectors of several pathogens, constituting serious health problems. Lutzomyia longipalpis (Lutz & Neiva, 1912) is the main vector of Leishmania chagasi, agent of visceral leishmaniasis. They synthesize a thick bag-like structure that surrounds the bloodmeal, named peritrophic matrix (PM). One of the major roles of PM in blood-fed insects includes protection against ingested pathogens by providing a defensive barrier to their development. We used traditional and modern morphological methods as well as biochemical and immunolabeling tools to define details of the PM structure of the Lu. longipalpis sandfly, including composition, synthesis, and degradation. The kinetics of PM formation and degradation was found to be related to the ingestion and time of digestion of the bloodmeal. The midgut changes its size and morphology after the blood ingestion and during the course of digestion. A striking morphological modification takes place in the midgut epithelium after the stretching caused by the bloodmeal, revealing a population of cells that was not observed in the unfed midgut. The transmission and scanning electron microscopies were used to reveal several morphological aspects of PM formation. The PM looks thicker and well formed 24 h after the bloodmeal. Presence of chitin in the PM was demonstrated by immunolabeling with an alpha-chitin monoclonal antibody. SDS-polyacrylamide gel electrophoresis showed at least five protein bands with molecular masses of 38.7-135 kDa, induced by the protein-free diet. Mouse polyclonal antiserum was produced against PMs induced by protein-free meal and used in Western blotting, which revealed at least three associated proteins.

Interaction of Trypanosoma rangeli Tejera, 1920 with different cell lines in vitro.

Intracellular multiplication of Trypanosoma rangeli was evaluated in vitro using experimental infection of Vero cells, murine macrophages, and promonocytes with T. rangeli Choachi, Macias, and SC-58 clone B1 strains. Our results revealed a low infectivity of all T. rangeli strains to these cell lines. Macrophages showed the highest infection rate; however, intracellular forms were no longer observed 48 h post infection Despite the observation of intracellular parasites up to 144 h post infection, the infection rates of Vero cells and J774G.8 promonocytes with these parasite strains were always below 5%. Pre-incubation of parasites with normal mouse serum increased the initial infectivity but not the time course of the infection. Under our experimental conditions, we did not observe any evidence of intracellular multiplication of T. rangeli within these cell lines.

Differential susceptibility of triatomines of the genus Rhodnius to Trypanosoma rangeli strains from different geographical origins.

The susceptibility of four Rhodnius species to different Trypanosoma rangeli strains was evaluated using both intracoelomic inoculation and oral infection. Rhodnius prolixus, Rhodnius domesticus, Rhodnius neglectus and Rhodnius nasutus were infected with Trypanosoma rangeli Macias (Venezuela), Choachi (Colombia) and SC-58 (Brazil) strains, revealing distinct haemolymph and salivary glands infection rates. The obtained infection rates were revealed to be dependent on the method of infection and the triatomine species. Our results suggest the existence of a high adaptation between the strain and the local vector.

Characterization of Leishmania sp. strains isolated from autochthonous cases of human cutaneous leishmaniasis in Santa Catarina State, southern Brazil.

Four Leishmania sp. samples were isolated from autochthonous human cases of American cutaneous leishmaniasis (ACL) in Santa Catarina State, southern Brazil. These strains were characterized using indirect immunofluorescence with a panel of Leishmania-specific monoclonal antibodies (MAbs), and by PCR amplification and hybridization assay of the mini-exon gene with group specific probes. The results obtained with the MAbs were in agreement with the genetic marker. Two isolates (MHOM/BR/89/JSC89-H1 and MHOM/BR/89/JSC89-H2) were identified as L. (Leishmania) amazonensis and two (MHOM/BR/96/LSC96-H3 and MHOM/BR/97/LSC97-H4) as L. (Viannia) braziliensis. The southernmost autochthonous cases of ACL in Brazil are due to two different Leishmania sp. species, confirming the spreading of ACL on the American continent.

Characterization of Trypanosoma rangeli strains isolated in Central and South America: an overview.

Trypanosoma rangeli is a hemoflagelate parasite that infects domestic and sylvatic animals, as well as man, in Central and South America. T. rangeli has an overlapping distribution with T. cruzi, the etiological agent of Chagas disease, sharing several animal reservoirs and triatomine vectors. We have isolated T. rangeli strains in the State of Santa Catarina, in southern Brazil, which dramatically increased the distribution area of this parasite. This brief review summarizes several studies comparing T. rangeli strains isolated in Santa Catarina with others isolated in Colombia, Honduras and Venezuela. The different methods used include indirect immunofluorescence and western blot assays, lectin agglutination, isoenzyme electrophoresis and random amplified polymorphic DNA analysis, triatomine susceptibility, in vitro cell infection assays, and mini-exon gene analysis.