Adjuvant effect of oral microorganisms on the primary immune response to sheep erythrocytes was investigated in CF1 mice by the direct antibody plaque technique at 2, 4 and 6 days after immunization. An adjuvant effect was detected on day 2 with Veillonella alcalescens ATCC 17745, Fusobacterium fusiforme HT-40 and Bacteroides melaninogenicus 32-2 and a weaker effect was found with the same organisms on day 4. Actinomyces viscosus ATCC 15987 showed an adjuvant effect on day 2 only, whilst Streptococcus mutans Ingbritt had no effect at any time. None of the organisms had any effect on the antibody response on day 6. But adjuvant effect of Veillonella to 7S antibody production on the primary immune response at 6 days after immunization was detected. Moreover, Veillonella showed an adjuvant effect to 19S and 7S antibody production on the secondary immune response at 4 days after booster injection. Adjuvant effect on the cellular hypersensitivity to bovine serum albumin was assayed in guinea pigs by skin, corneal and macrophage migration inhibition tests at 3 or 4 weeks after immunization. An enhanced cellular hypersinsitivity was not found with Veillonella, Fusobacterium or Streptococcus. With Bacteroides and Actinomyces an adjuvant effect was detected by skin and corneal tests but not by the migration inhibition test. But with Actinomyces an adjuvant effect on the cellular hypersensitivity was detected by skin, corneal and macrophage migration inhibition tests at 2 weeks after immunization.
