Chejanovsky, N., Department of Biological Chemistry, Institute of Life Sciences, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
Fridlender, B., International Genetic Sciences Partnership, P.O.B. 4330, 91042 Jerusalem, Israel
Loyter, A., Department of Biological Chemistry, Institute of Life Sciences, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel

F(ab′) fragments obtained from anti-Sendai virus antibodies were chemically coupled to F(ab′) fragments obtained from anti-human red blood cell antibodies (anti-hRBC-Ab). This led to the formation of hybrid antibody molecules (anti-SV-anti-hRBC(F(ab′)2) each of whose F(ab′) fragment possessed different binding specificity. The anti-SV(F(ab′)) part of the hybrid molecule interacted specifically with Sendai virus particles, while the anti-hRBC(F(ab′)) part interacted with the surface of hRBC. These hybrid antibodies were able to mediate binding and fusion of SV to hRBC, from which the virus receptors were removed by treatment with neuraminidase (desialized hRBC). Neither anti-SV-anti-SV(F(ab′)2) nor anti-hRBC-anti-hRBC(F(ab′)2) possessed the same ability. Thus, it is shown that soluble, hybrid antibody molecules can effectively mediate functional binding of Sendai virus to virus-receptor-depleted cells. © 1985.