Blastocystis hominis is a ubiquitous enteric protozoan whose pathogenic potential is still controversial. This study was carried out to clarify the pathogenecity of B. hominis infection and to study the proper number of parasites for mice infection. A total of 15 albino mice were orally inoculated with B. hominis and divided according to the inoculums, 10(2), 10(5), and 4 x 10(7) B. hominis forms/100 microl saline, into three groups consisting of five mice each, GI, GII GIII, respectively. In addition with group IV (uninfected control) consisting of five mice. All mice were sacrificed 2 weeks post-infection. The results revealed that all mice of GIII and two mice of GII got the infection while all mice of GI showed a completely negative result. Histopathological examination of large intestine on highly infected group (GIII) showed that B. hominis infiltrated the lamina propria, the submucosa, and the muscle layers in the form of collection of vacuolar forms. This was accompanied by active colitis with infiltration of mixed inflammatory cells. In conclusion, this study revealed that large number of B. hominis is essential for oral infection of mice and that vacuolar forms of B. hominis can invade the lamina propria, the submucosa, and even the muscle layers.

The diagnosis of patients with cystic echinococcosis (CE) by means of serology has a limited support in clinical practice due to cross-reactivity with other helminthes leading to overestimation of the parasite's true prevalence. A wealth of reports on the diagnostic performance of antigen B (AgB) has been produced. This study was designed to comparatively assess the diagnostic efficacy of crude sheep hydatid cyst fluid (HCF), AgB and its subunit (12 KDa) to detect IgG or IgG4 antibodies in CE patients' sera using enzyme-linked immunosorbent assay (ELISA).The best diagnostic performance was obtained with anti-HCF IgG ELISA which gave 92.4% sensitivity and 92.6% specificity. Despite the low sensitivity of anti AgB IgG ELISA (84%), it gave the best specificity (94.4%) with less cross-reaction with sera of subjects infected with other parasites. In conclusion, it is recommended to use anti-HCF IgG ELISA for initial screening in large seroprevalence studies. Further analysis of positive serum samples with anti AgB IgG ELISA would allow the confirmation of true positives. Specific IgG4 ELISA may represent a complementary assay, useful as secondary confirmatory tests for patients with suspected CE and negative for total IgG ELISA.

The present study was performed to characterize the protein profiles of Blastocystis hominis isolates from symptomatic and asymptomatic individuals by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting using sera from symptomatic and asymptomatic patients. The presence of immunogenic bands associated with pathogenicity or of diagnostic potentials was also evaluated. The study comprised 80 individuals classified into four groups, 20 each: symptomatic blastocystosis (G1), asymptomatic blastocystosis (G2), other parasitic infections (G3), and healthy control subjects (G4). SDS-PAGE analysis of individual antigens form symptomatic and asymptomatic B. hominis isolates revealed similar and distinctive antigenic bands with significant differences in two high (123.5 and 112.3 kDa) and few low molecular weight bands (48.5, 38, 42.3, and 35.5 kDa). Immunoblotting was performed using symptomatic and asymptomatic antigen pools with sera of the four studied groups. It was found that anti-B. hominis IgG reacted with nine protein bands ranging from 100 to 18 kDa of the symptomatic antigen pool. There was a significant difference between G1 and G2 in the recognition of 64, 56, 38, and 29 kDa antigen bands. Also, anti-B. hominis IgG reacted with five protein bands ranging from 56 to 12 kDa of asymptomatic antigen pool. There was a significant difference between G1 and G2 in the recognition of 29 kDa antigen band. These findings suggest the potential use of the 29-kDa antigen as marker of pathogenicity and implicate its use in the diagnosis and differentiation between symptomatic and asymptomatic blastocystosis.

Genetic polymorphisms of encoding antigen B2 gene (AgB2) in Echinococcus granulosus were studied using PCR-RFLP and DNA sequencing among 20 Egyptian isolates. Five isolates from different host origins (humans, camels, pigs, and sheep) were collected and used. All examined isolates of each host group gave very similar patterns of PCR-RFLP after restriction enzyme digestion with AluI, with the gene size of approximately 140 bp and 240 bp for sheep and human isolates, and approximately 150 bp and 250 bp for pig and camel isolates. No digestion pattern was obtained after incubation of all studied isolates with EcoRI. These results reveal high intra-group homogeneity. DNA sequence analysis highlighted that human infecting strain showed 100% identity with respect to sheep infecting isolate, 96% and 99% with pig and camel infecting isolates, respectively.

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