SCHISTOSOMA-JAPONICUM - IN-VITRO CULTIVATION OF MIRACIDIUM TO DAUGHTER SPOROCYST USING A BIOMPHALARIA-GLABRATA EMBRYONIC-CELL LINE

In vitro cultivation of Schistosoma japonicum miracidia to the mother sporocyst (MS) and then to the daughter sporocyst (DS) stage was achie ved using the Biomphalaria glabrata embryonic (Bge) cell line as a coc ulture system. When comparing the effect of Bge cell and MS density on MS development, it was apparent that Bge cell density had a highly si gnificant effect on both MS viability and growth. Viability and growth rate of MS cultured under high cell density conditions (350 cells/mm( 2)) were almost 2 times greater than those of MS cultured under condit ions of low cell density (60 cells/mm(2)). Growth under high cell dens ity conditions corresponded to a 20 to 30 times increase in MS estimat ed volume within the first 9 weeks of cultivation. Emergence of fully formed motile DS was first observed after 11 weeks of cocultivation. A few DS lived for 14 weeks after emergence and attained a size of 770 +/- 100 mu m in length and 48 +/- 13 mu m in width. In contrast to wha t was observed in Bge cell/Schistosoma mansoni cocultures, Bge cells d id not encapsulate S. japonicum MS. Our results show that, although th e cellular interactions between Bge cells and schistosomes MS display some level of specificity, Bge cells apparently secrete soluble factor s that permit excellent survival and can trigger advanced in vitro dev elopment of S. japonicum. (C) 1997 Academic Press.