The Journal of Experimental Medicine, Vol 134, 1431-1441,
Copyright © 1971 by The Rockefeller University Press
SIGNIFICANCE OF BIVALENCE OF ANTIBODY IN VIRAL NEUTRALIZATION
Robert W. Rosenstein Ph.D.1,
Alfred Nisonoff Ph.D.1, and
Jonathan W. Uhr M.D.1
1 From the Department of Biological Chemistry, University of Illinois College of Medicine, Chicago, Illinois 60680, and the Irvington House Institute and Department of Medicine, New York University School of Medicine, New York 10016
The role of bivalence of antibody in its capacity to neutralize virus was studied with rabbit antibodies to the bacteriophage, 
X174. Univalent Fab or Fab' fragments of IgG isolated from antiviral antisera obtained early in the immunization schedule had virtually no activity compared to that of the intact IgG. When the antibodies were isolated from antisera of the same rabbits several months later, the univalent fragments and IgG were essentially equal in activity. The results are interpreted on the basis that an IgG molecule, because of its bivalence, has a higher effective combining affinity (avidity) than a univalent fragment. After prolonged immunization, however, the affinity of univalent antibody becomes sufficiently high that it exceeds a threshold value, above which further increase in affinity, through bivalence, is no longer significant. The results could explain the variability in relative effectiveness of univalent antibodies observed in previous studies. These data, and the fact that F(ab')2 fragments from either "early" or "late" antisera were as effective as IgG, indicate that fragment Fc is not a significant factor in neutralization.
No differences in dissociation from the virus of univalent antibody from early and late antisera could be demonstrated by dilution at temperatures up to 47°C. The attachment at sites of neutralization on the virus appears to be functionally almost irreversible in this system.
Submitted on July 26, 1971
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
