RESUMO
Cystoisospora belli is an opportunistic protozoan that causes human cystoisosporiasis, an infection characterized by diarrhea, steatorrhea, abdominal pain, fever, and weight loss. The lack of animal models susceptible to C. belli, and the difficulty in obtaining clinical samples with fair amounts of oocysts have limited the research pertaining to the basic biology of this parasite. This study aimed to describe the ultrastructure of endogenous stages of C. belli in Monkey Rhesus Kidney Cells (MK2) and Human Ileocecal Adenocarcinoma cells (HCT-8). Zoites of C. belli exhibited typical morphological features of coccidia, which included a trilaminar pellicle, an apical complex formed by a conoid, polar rings, rhoptries, and micronemes, in addition to dense granules and the endoplasmic reticulum. No crystalloid body was observed but various lipid and amylopectin granules were usually present in the cytoplasm of zoites. We observed a tendency of the endoplasmic reticulum of the host cell to be located near the parasitophorous vacuole membrane. Merozoites were formed by endodyogeny and during replication, the apical complex of the mother cell remained intact. The formation of gametes or oocysts was not observed. The ultrastructural findings of C. belli are further evidence of its proximity to Sarcocystidae family members and corroborate their reclassification as Cystoisospora spp.
Assuntos
Isospora/ultraestrutura , Animais , Linhagem Celular/parasitologia , Linhagem Celular/ultraestrutura , Linhagem Celular Tumoral/parasitologia , Linhagem Celular Tumoral/ultraestrutura , Humanos , Rim/citologia , Rim/parasitologia , Macaca mulatta , Merozoítos/ultraestrutura , Microscopia Eletrônica de TransmissãoRESUMO
INTRODUCTION: Cell culture is an important method for isolating Toxoplasma gondii to make clinical diagnosis or for biotechnological purposes. OBJECTIVE: The percentage of invasion and production levels of T. gondii was determined for THP1 and Vero cell lines. MATERIALS AND METHODS: The growth conditions for T. gondii in Vero and THP1 cell lines were determined by counting in hemocytometer chamber. The percentage of invasion of T. gondii in THP1 and Vero cells was determined by flow cytometry in different cell/tachyzoite ratios: 1/5, 1/20, 1/50. The growth performance index of the T. gondii RH strain and the CIBM1 isolate was calculated for THP1 cells. RESULTS: Vero cells multiplied faster than the THP1 cells, showing an exponential and a sigmoidal growth curve respectively, within a period of 7 days. The CIBM1 isolate infected the THP1 cells in three different parasite concentrations: 1/5, 1/20 and 1/50, with invasion percentages in THP1 cells of 57.1%, 15.5% and 12.2% and for the Vero cells 25.3%, 17.8% and 8.8% respectively. The RH strain of T. gondii had the lowest invasion percentage with 32.6%, 14.8% and 8.1% in THP1 cells and 22.3%, 14.1% and 3.4% in Vero cells. CONCLUSIONS: The CIBM1 isolate had a higher yield than the RH strain of T. gondii in THP1 cells. THP1 cells were indicated to be a good model for the study of invasion and for the assays of new pharmacological candidates against T. gondii.