Abstract
Background and study aim: Current schistosomiasis control strategies are mainly based on chemotherapy, but many researchers believed that the best long term strategy to control schistosomiasis is through immunization with anti-schistosomiasis vaccines. This study aims at assessment of the efficacy of different potential anti-schistosomal vaccines (as crude soluble egg antigens (SEA), soluble worm antigen preparation (SWAP) and combined SEA & SWAP) by parasitological and molecular studies in experimental murine models. Materials and Methods: Sixty male laboratory bred Swiss Albino mice were used and divided into six groups; control normal (G1), control infected by ± 80 cercariae by S.C. route (G2), Freund’s adjuvant (adj.) received then infected (G3), SEA+adj. received then infected (G4), SWAP+ adj. received then infected (G5) and combined (SEA+SWAP) + adj. received then infected (G6). A schedule of sensitization, immunization and schistosomiasis challenge were followed and performed on different mice groups. Mice were euthanized 10 weeks post-infection. Potential vaccine efficacy was investigated by parasitological and molecular studies including egg count/gram stool using modified Kato thick smear,liver egg load, oogram pattern in the liver and stool PCR to detect S. mansoni egg DNA in stools of studied mice. Results: The combined (SEA+SWAP) vaccine caused the highest significant reduction in the fecal egg count followed by SWAP then SEA antigens. On the other hand, the highest percentage reduction in eggs/gram liver tissue was attributed to the combined (SEA+SWAP) followed by SEA then SWAP antigens. Regarding oogram results, the combined (SEA+ SWAP) antigens were more efficient in increasing the number of dead ova with highly significant reduction in the number of mature & immature ova, followed by SEA then SWAP antigens. The lowest percentage of S. mansoni egg DNA detected by PCR in stool samples was encountered with the combined (SEA+ SWAP), followed by SEA then SWAP antigens. Conclusion:The parasitological and PCR-based assessment studies denoted that the combined (SEA+SWAP) vaccine candidate was the most effective in protection against schistosomiasis challenge. The results of parasitological and molecular studies were nearly similar but the molecular study was more sensitive, definite and accurate.
Highlights
Schistosomiasis is a parasitic disease caused by blood flukes of the genus Schistosoma
The current study aims at assessment of the efficacy of different potential antischistosomal vaccines as crude soluble egg antigen (SEA), SWAP and combined SEA & SWAP by parasitological and molecular (PCR) studies experimentally, in murine models
Schistosomiasis is a parasitic disease caused by the digenetic trematodes of the genus Schistosoma members which are commonly known as blood flukes [23]
Summary
Schistosomiasis is a parasitic disease caused by blood flukes of the genus Schistosoma. Afro-Egypt J Infect Endem Dis 2016; 6(3):142151 http://mis.zu.edu.eg/ajied/home.aspx associated with schistosomiasis via protective immune responses leading to reduced worm burdens and decreased egg production [3]. Schistosoma parasites secrete & excrete a number of different antigens into circulation of the host; these antigens are classified according to the stage of development of the parasite into cercarial; adult worm and egg antigens [4]. In order to develop an accurate immunization procedure, many different antigens have been prepared and tested as adult worm and egg antigens [5] and irradiated cercarial antigen [6]. This study aims at assessment of the efficacy of different potential anti-schistosomal vaccines (as crude soluble egg antigens (SEA), soluble worm antigen preparation (SWAP) and combined SEA & SWAP) by parasitological and molecular studies in experimental murine models
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