ABROGATION OF ANTIGENIC-COMPETITION BETWEEN CAMPYLOBACTER-JEJUNI AND PLESIOMONAS-SHIGELLOIDES BY COLLOIDAL CARBON - ITS ROLE IN POLYVALENT VACCINES

Immune response to Campylobacter jejuni was suppressed asa result of a response to a second unrelated antigen, Plesiomonas shigelloides, a p henomenon called antigen competition. However, this phenomenon was abr ogated by the injection of colloidal carbon few hours after administra tion of C. jejuni before injection of P. shigelloides. Six to ten week s old rats that received a commercial diet and tap water regularly wer e used. Bacterial cells were washed thrice in PBS pH 7.2 and suspended to the desired concentration of 1 x 10(5) cells/ml prior to injection of C jejuni and later P. shigelloides. Control rats received only C. jejuni. Antibody levels were determined using haemogglutination test i n wells of microlitre plates. Resistance of lgG to 2 mercaptoethanol ( 2.M.E) was used to determine IgG levels. Antigenic competition (AC) wa s established and was abrogated by injection of colloidal carbon 48 ho urs before the injection of the other antigen. Results showed that tot al antibody levels (ABL) of control was reduced from a mean peak of 25 60 to 640 in rats undergoing AC. On days 8, 12 and 16, ABL for control s were 640, 1280 and 1280 respectively but the values dropped to 160,1 60 and 320 correspondingly. When colloidal carbon was injected, ABL of 160,320, 160 and 80 on days 12,16,24 and 26 increased to 1280,2560 an d 1280 respectively. Results have revealed that multiple vaccines agai nst diarrhoeagenic agents may not be very effective but these could be circumvented by abrogating competition between the antigens.