Transfer of Resistance to Schistosoma mansoni in Biomphalaria glabrata by Allografts of Amoebocyte-Producing Organ

Abstract

Allografts of amoebocyte-producing organ (APO) were implanted heterotopically into the schistosome-susceptible NIH albino stock of Biomphalaria glabrata from either 13-16-R1 (a schistosome-resistant stock) or NIH albino donors. At 3, 7-8, 14-15, 21, 28-33, or 47-71 days postimplantation (PI), allograft recipients were exposed to 50 miracidia each of Schistosoma mansoni and subsequently monitored for development of sporocysts and cercariae. Relative to untampered snails and recipients of NIH albino APOs, recipients of 13-16-R1 APOs showed significantly lower infection rates from 7 days PI until the end of the experiment. The mechanism for this apparent transfer of resistance is unknown, but hypothetically it may involve chimerism, i.e., production of hemocytes with the resistant phenotype by implanted 13-16-R1 APOs, or synthesis by the implant of soluble "resistance factors" that induce cytotoxicity in recipient hemocytes, or both.