Assessment of Infected Biomphalaria alexandrina Snails by Detecting Schistosoma mansoni Antigen and Specific Gene

Abs tract: To control s pread of Schi s t o s oma mansoni infection, rapid and accurate inves tigation of infected Biomphalaria alexandrina s nails that s urveyed from any s us pected area is required. Routine ass ays for ass ess ment of infected s nails are time cons umin g and may not be able to detect prepatent s chis tos omal infections . In the present study two methods were evaluate d for assessment of infected s n a ils . The firs t was detection of S. mansoni s oluble egg antigens (SEA ) in s nail hemolymp h u s in g two murine monoclonal antibodies (M A bs ) in sandwich ELIS A ass ay. The S. mansoni antigens measured in the h e molymph of infected s nails at intervals 1, 2, 3 weeks pos t expos ure to miracidia, at early shedding snails (4,5) weeks a n d after the infected snails stopped shedding. Although the pos itivity, s ens itivit y a n d s pecificity were 100% in the infected control group of s nails , the detection of antigen (s ) was only pos s ible after the second we a k o f miracidial infection. In the second method, genomic DNA of infected snails in addition to non infected (as negative control) w e re s u b je c t e d to nested polymerase chain reaction PCR u s in g primers s pecific to S. mansoni fructos e -1,6-bis phos phate aldolas e (SM A LD O ) g e n e . PCR was able to detect infection (100% s ens itivity) at the 3rd day pos t infection. In spite of the superiority and the higher specificity of the immunodetection for larg s cale detection of prepatency of B. alexandrina s nails infected with S mansoni, the nes ted PCR as s ay revealed much higher s ensitivity which enables 100% detection o f S . ma n soni infection down to 3 days pos t infection. So this as s ay provided higher efficiency for determin a t io n of infection prevalence in snails and schis tos omias is trans mis s ion