NEUTRALIZATION OF BACTERIAL VIRUSES BY ANTIBODIES OF YOUNG ANIMALS .I. DEPENDENCE OF NEUTRALIZING ACTIVITY OF 19-S AND 7-S ANTIBODIES ON COMPLEMENT IN COURSE OF PRIMARY AND SECONDARY RESPONSE OF YOUNG RABBITS IMMUNIZED WITH T2 PHAGE

The development of neutralizing antibodies against bacteriophage T 2 in newborn rabbits was investigated. On the seventh day after antigen injection only antibodies of 19 S type were detected following the fractionation of serum on a saccharose density gradient. The neutralizing activity of these antibodies was heavily complement-dependent: the neutralizing capacity was completely destroyed by inactivation at 56° C for 30 min; however, it was possible to renew it by the addition of fresh complement. Antibodies of the 7 S type detected on the fifteenth day after immunization by ultracentrifugation, were also dependent on complement in their neutralizing capacity. Antibodies of the 7 S type produced on the 28th day after immunization were still partially dependent on complement; however, antibodies produced in the secondary response no longer required complement for their neutralizing activity. The obtained results indicate that in the course of the primary and secondary response to bacteriophage T 2, antibodies of 19 S and 7 S are gradually formed in the newborn with higher ability to neutralize the phage particle alone without the potentiating action of complement. © 1969 Academia, nakladatelství Československé akademie věd.