COMPARISON AMONG OPSONIC ACTIVITY, ANTIMENINGOCOCCAL IMMUNOGLOBULIN-GRESPONSE, AND SERUM BACTERICIDAL ACTIVITY AGAINST MENINGOCOCCI IN SERA FROM VACCINEES AFTER IMMUNIZATION WITH A SEROGROUP-B OUTER-MEMBRANE VESICLE VACCINE

Opsonic activity in sera from 27 military recruits vaccinated with the Norwegian meningococcal serogroup B outer membrane vesicle vaccine wa s measured as respiratory burst with polymorphonuclear Leukocytes as t he effector cells and meningococci of the epidemic strain as the targe t. The results were compared with antimeningococcal IgG antibodies aga inst an outer membrane vesicle coat in an enzyme linked immunosorbent assay and with serum bactericidal activity. The vaccinees were immuniz ed twice, with a 6-week interval between the two, The serum samples st udied were collected at day zero, after 6 weeks, and after 12 weeks, B oth serum bactericidal activity and respiratory burst were measured by adding external serum as the complement source, The results revealed a significant increase in specific IgG response, serum bactericidal ac tivity, and respiratory burst after vaccination. We found a highly sig nificant correlation between the responses in all three assays (P < 0. 0001). The highest correlation was found between respiratory burst and antimeningococcal IgG response (r = 0.93). This result strongly indic ates that respiratory burst is mediated almost exclusively by IgG anti bodies, The correlation between antimeningococcal IgG response and ser um bactericidal activity was slightly lower (r = 0.83), The correlatio n between respiratory burst and serum bactericidal activity was furthe r reduced (r = 0.78), and some of the sera revealed a marked preferenc e for only one of the activities, This result means that respiratory b urst and serum bactericidal activity in part are induced by different mediators, and to obtain a more complete picture of the potential prot ective activity, both assays should be applied to survey a vaccine tri al.