Studies on host-parasite relationship between the Puerto Rican strain of Schistosoma mansoni and Biomphalaria snails.

Immunoelectrophoretic studies on common antigenicities were carried out by using rabbits sera immunized with the Puerto Rican strain of Schistosoma mansoni adult worms or eggs and antigens of several adult Biomphalaria snails and vice versa. As the result, S. mansoni adult worm extracts produced 8 bands both with extracts of Biomphalaria glabrata pigmentation and B. glabrata pigmentado, 3 to 4 bands with those of B. glabrata albino and 1 to 2 bands with those of B. straminea. On the other hand, S. mansoni egg extracts produced 5 bands with extracts of B. glabrata pigmentation, 4 bands with those of B. glabrata pigmentado, 2 bands with those of B. glabrata albino and 1 band with those of B. straminea. In the experimental infection of adult Biomphalaria snails with five S. mansoni miracidia, the infection rate in B. glabrata pigmentation was 78.8%, and 71.2% in B. glabrata pigmentado, whereas the infection rate in B. glabrata albino was 10.3%, and B. straminea was not susceptible to S. mansoni. The infectivity of each snail corresponded with the number of bands representing common antigenicities between host and parasite. Crude antigens of Biomphalaria snails were fractionated by Sephadex G-100 column, and each antigen fraction was tested with anti-S. mansoni adult worm and egg sera by immunoelectrophoresis. The common antigenicities between fractionated antigens of Biomphalaria snails and of ani-S. mansoni adult worm or egg sera mostly existed in the first fraction 1 with Mr > 45 kDa.