In the present study, Biomphalaria alexandrina and Bulinus truncatus were exposed to schistosome miracidia hatched from ova obtained from mice immunized with secretory excretory products (SEP) of Schistoma mansoni and Schistosoma haematobium eggs before infection. The snailsÂ’ infection and survival rates were calculated and their tissue homogenate was centrifuged and examined for measuring the activities of enzymes (aspartate aminotransferase [AST], alanine aminotransferase [ALT] and alkaline phosphatase [ALP]), total proteins and albumin concentrations. The miracidia hatched from ova obtained from immunized animals were weak showing a significant low infectivity to B. alexandrina and B. truncatus snails with a reduction in their infection rate by 27.6%, and 51.9%, respectively compared to the infected control. This slightly improved the survival rate of treated snails compared to those exposed to normal miracidia, being 81.4% in B. alexandrina and 82.9% in B. truncatus for the test groups and 74.3%, and 75.7% for infected control ones. A significant elevation recrded in the levels of AST, ALT and ALP enzymes in infected control with percentage of increase 58.7%, 107%, and 61.1% in case of B. alexandrina and 79.1%, 90.4%, and 32.6% in case of B. truncatus snails, respectively compared to the uninfected control. Meanwhile, the protein and albumin contents were insignificantly reduced by 4.4% and 4.9% in case of B. alexandrina and by 3.2% and 8.2% in case of B. truncatus, respectively. In snails infected with schistosome miracidia from immunized mice, the activities of the tested enzymes were approximately around the normal levels.
Key words: BIOCHEMICAL CHANGES, SCHISTOSOMIASIS VECTOR SNAILS, SCHISTOSOMA, OVA ANTIGEN PRE-INFECTION
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