Estudo morfobiológico, ultraestrutural e histopatológico de amostras silvestres isoladas de Triatoma vitticeps (Stal, 1859) no Estado do Rio de Janeiro

Abstract

Triatoma vitticeps is a wild species with restricted geographic distribution to the States of Rio de Janeiro, Espírito Santo, Minas Gerais and Bahia. In Minas Gerais and Espírito Santo it is invading the domicile, being found sometimes domiciliated, frequently with high rates of infection by Trypanosoma cruzi. The aim of this study is to evaluate the parasite diversity in the three sites (two in the municipality of Santa Maria Madalena and one in Conceição de Macabu) throught morphobiology, biometric, ultrastructural and histopatological parameters. Seven isolates identifield as T. cruzi were maintained in NNN+LIT+20% bovine fetal serum. Morphometric studies and cellular differentiation were based on epimastigotes and trypomastigotes forms obtained in the growth curves in the 4, 7, 10, 13, 17 and 20º days for SMM32, SMM53, SMM81, SMM98, SMM100 proceeding from the area A, SMM36 proceeding from area B, SMM 81 and SMM1 proceeding from area F and extended to 23, 27, 30, 33, 37 and 40º days to the SMM 36 and SMM 98 samples. The maximum growth was observed in the 4 th day for SMM100 isolate (45.000 parasites/μl); the 7 day for SMM53 (52.750 parasites/μl) the 10 th day for SMM1 (21.000 parasites/μl) and SMM32 (33.125 parasites/μl); the 13 th day for SMM81 (46.000 parasites/μl) and 20 th day for SMM36 (54.375 parasites/μl) and SMM98 (44.000 parasites/μl). The SMM32 and SMM100 isolates return to grow after a slight decline. The rate of metacyclogenese was lesser than 30% in SMM32, SMM53, SMM100 and SMM1 isolates and higher than 80% in SMM81 and SMM98 isolates. These results demonstrate diversity in the behavior of these isolates. Morphometrical analysis based on epimastigotes and trypomastigotes forms found in the10 th, 17 th and 20 th days of the growth curve, suggests heterogeneity. Althrough the majority ultrastructural data of T. cruzi has been obtained from epimastigote forms maintained in culture was media, this study carried out with isolated forms from triatomines showing the same tipical structures present as the kinetoplast, the sub-pellicular microtubules, the flagellar pocket and the axoneme.The SMM36 strain was the most lethal a high mortality. Histopathological results with 10 and 60 days after inoculation have shown an intense tropism for cardiac muscle and intense mononuclear infiltrate. These results give evidences of the diversity of parasites that infection specimens of T. vitticeps, emphasizing the wild habit of this species and the epidemiological complexity of studied region.