الفهرس | Only 14 pages are availabe for public view |
Abstract Schistosomiasis remains a truly neglected tropical disease and an important public health problem in many countries. It was suggested that an alarming 201.5 million cases of schistosomiasis may occur in Africa alone and that over 90% of all schistosomiasis cases are found in underdeveloped areas of Africa. The control of schistosomiasis in human depends mainly on treatment with the drug praziquantel (PZQ). Although PZQ is the cornerstone of current schistosomiasis control programs, there is some evidence of developing resistance. This highlights the need to find other alternatives including vaccination. However, none of the vaccines tested before proved to be effective. Thus, there is a persistent need to find ways to increase the efficacy of vaccination. In the present study, we tested cercarial transformation fluid antigen (CTF) singly and in combination with crude cercarial antigen (CCA) as immunizing agent against experimental schistosomiasis mansoni. The study was performed on 96 male Swiss strain Albino mice. The mice were divided into two main groups: control and experimental and each was subdivided into three subgroups. Control group included non-infected control mice (subgroup Ia), infected control mice (subgroup Ib) and adjuvant infected control mice (subgroup Ic). While experimental group included; mice receiving CTF (subgroup IIa), mice receiving CCA (subgroup IIb) and mice receiving combined antigens (subgroup IIc). Mice of the experimental group and subgroup Ic followed the same schedule of immunization and infection. They received two separate doses of the vaccines one week apart. Then they were infected two weeks after the second dose of the vaccination by tail immersion technique with 100 freshly shed cercariae. At the end of the experimental study, 45 days post-infection, mice of each subgroup were sacrificed. The following studies were done: parasitological, biochemical and immunological. The parasitological studies included estimation of adult worms load, counting of Schistosoma mansoni ova in liver and intestine, estimation of the size of the hepatic granulomata and ultrastructural study by scanning electron microscopic examination. Biochemical study included measurement of liver enzymes (AST, ALT). In addition, immunological study included measurement of CD4+ T-lymphocytes by flow cytometry. The results were tabulated and statistical analysis was performed. Results of all studied parameters were in favour of combined antigens given to subgroup IIc. The mean adult worm load reduction was the highest in mice receiving combined antigens (subgroup IIc) as it showed 62.12% reduction. It was 26.47% and 43.75% in mice receiving CTF (subgroup IIa) and mice receiving CCA (subgroup IIb) respectively when compared to infected control subgroup (subgroup Ib). The percentage of reduction of liver tissue egg count was 26.47% in subgroup IIa, 60.28% in subgroup IIb and 77.93% in subgroup IIc. While percentage of reduction of intestinal tissue egg count was 28.69%, 76.50% and 87.26% in subgroups IIa, IIb and IIc respectively. Regarding the granuloma size, the highest reduction was recorded in subgroup IIc followed by subgroups |