ENHANCED REDUCTION OF T4D AND T7 COLIPHAGE TITERS FROM BIOMPHALARIA GLABRATA (MOLLUSCA) HEMOLYMPH INDUCED BY PREVIOUS HOMOLOGOUS CHALLENGE

¹ Marine Biomedical Research Program and Department of Anatomy (Cell Biology), Medical University of South Carolina, Charleston, SC 29412

The hemolymph of Biomphalaria glabrata contains a soluble factor(s) that neutralizes the coliphages T4D and T7 in vitro. This neutralization is not enhanced by prior injection of the snail with the homologous or heterologous phage. In vivo titers of injected T4D and T7 decrease as a function of time postinjection (PI), with a nearly 1000-fold reduction occurring by 144 h PI. When snails are reinjected at 96 h PI with homologous phage, the in vivo titers of infective T4D and T7 decrease even more rapidly. Specifically, T7 titers at 24, 48, and 72 h post-reinjection (PR) are significantly lower than those at the same time periods PI, i.e., following a single injection. Similarly, T4D titers at 24, 48, 72, and 96 h PR are significantly lower than at 24, 48, 72, and 96 h PI. It is concluded that the reduction of phage titer in the hemolymph of injected B. glabrata is due in part to neutralization by some naturally occurring factor(s) and also to an active, probably cellular, mechanism that is enhanced by previous homologous challenge. The specificity of this enhancement is not yet known; however, prior sham or Tris diluent injections do not affect the titers of a subsequent T4D or T7 injection.