Comparative studies on the antigenic structures of five subspecies of Oncomelania snails by immunoelectrophoresis.

To approach the biochemical relationships of five subspecies of Oncomelania snails, antigenic structures among the subspecies were compared using immunoelectrophoresis. The results obtained are summarized as follows: 1) For five subspecies of Oncomelania hupensis snails (Oncomelania hupensis hupensis, O.h.nosophora, O.h. formosana, O.h. chiui and O.h. quadrasi), 23-24 precipitin bands were observed between the antigens and their homologous antisera, while 18-22 bands were observed in the heterologous reactions. 2) For each subspecies, residual bands observed after absorption procedure demonstrated the presence of antigens unique to each subspecies except O.h. chiui. Based on the immunological antigenic structures among the Oncomelania subspecies, it is suggested that O.h. nosophora and O.h. hupensis forms are closely related group, while O.h. formosana, O.h. chiui and O.h. quadrasi forms are another group.

Experimental infection of five subspecies of Oncomelania snails with Angiostrongylus cantonensis.

Five subspecies of Oncomelania snails, Oncomelania hupensis nosophora, O.h. hupensis, O.h.chiui, O.h.formosana and O.h.quadrasi, were experimentally exposed to the first stage larvae of Angiostrongylus cantonesis. The presence of third stage larvae was observed in all of the five subspecies of Oncomelania snails 20 days after infection. Infection rates of the third stage larvae of the parasite in Oncomelania snails were 38.0-40.0%. There were no differences in preferences among Oncomelania snails. The third stage larvae in Oncomelania snails almost distributed in kidney and intestine region, and most of the larvae were active and free in tissues. The distribution pattern of the larvae in Oncomelania snails was quite different from that in Achatina fulica and Ampullarium sp. These third stage larvae were ingested by rats, and developed to adults. These data suggest that Oncomelania snails may play important role when A. cantonensis will spread, and indicate the possibility of human infection with A. cantonensis.

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.

Studies on common antigenicities between the Belo Horizonte strain, Brazil of Schistosoma mansoni eggs and Biomphalaria snails by immunoelectrophoresis.

Immunoelectrophoretic studies of common antigenicities were carried out by using rabbit sera immunized against the Belo Horizonte strain of Schistosoma mansoni eggs and crude antigens of Biomphalaria snails and vice versa. With regard to common antigenicities between S. mansoni eggs and Biomphalaria snails, S. mansoni eggs produced 4 to 5 bands with Biomphalaria glabrata pigmentado, 3 to 4 bands with B. glabrata albino and only 1 band with B. straminea. In our laboratory, the infection rate of S. mansoni miracidia to B. glabrata pigmentado was 64.3% and 55.0% for B. glabrata albino, but B. straminea was not found to be susceptible to S. mansoni miracidia. It was observe that more bands were seen between S. mansoni egg and suitable hosts. Biomphalaria snail crude antigens were fractionated by Sephadex G-100 column, and each fraction antigen was tested with anti-S. mansoni egg sera by immunoelectrophoresis. As results, three fractions were collected form each snail strains. The common antigenicities between fractionated antigens from Biomphalaria snails crude antigens and anti-S. mansoni egg sera mostly existed in the first fraction and they were estimated to have molecular weights over 45,000.