Sequential study of IgG antibody response in immunized rabbit and development of immunization protocol for raising monospecific antibody.

The present study was planned to develop an immunization protocol to decide the bleeding modalities for harvesting anti IgG antibody from the immunized rabbit. A fourteen dose immunization protocol (four primary and ten boosters) of the purified human IgG spread over the one calendar year was executed. The antibody titre estimated by Reverse Single Radial Immunodiffusion displayed a six-phased pattern. The titre following the initial immunization ranged between nil to 1.02, characteristic of the primary response while the titres after 7th and 8th boosters (phase V) ranged between 0.5 to 3.87 consistent with secondary response. Phase II, III, IV had moderately elevated titres. The antibody titre amongst the six phases reached to its peak generally by the 12th day after the last dose of protocol and it took about 60 days to reach to its basal level. Administration of antigen with the higher levels of residual antibody did not produce high titre antibody and is probably ascribed to elimination of antigen through an immunecomplex mechanism. Based on the data we recommend that 15 batches. (3 per phase, phase I to phase V) with a total yield of 100 to 120 ml of serum can be procured from one immunised animal over the span of one calendar year and that should make the programme cost effective.