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ABSTRACTHelicobacter pyloriinfection is widespread in some breeding groups of a rhesus monkey colony (71% H. pyloripositive by 1 year), and the rate of seroconversion is also high. As a result, these groups can be used to test the safety and efficacy of an anti-H. pylorivaccine. Nine-month-old female animals were randomized to receive either 8 mg of recombinant urease (rUre) plus 25 μg of Escherichia coliheat-labile enterotoxin (LT) (n= 26) or placebo plus LT (n= 29), given four times at 1-week intervals followed by a booster 1 month later. Ten months after the start of the immunization, the animals were subjected to endoscopy and biopsy samples were obtained. H. pylorinegativity was defined as no H. pylorigrowth by culture and no H. pyloriobserved at histology. By this criterion, 2 (7%) of 29 animals receiving placebo and 8 (31%) of 26 immunized animals were H. pylorinegative (P< 0.035). In addition, antral gastritis score was significantly less in H. pylori-negative immunized monkeys than in H. pylori-positive animals, whether they were given rUre plus LT or placebo plus LT (P< 0.02 orP< 0.01, respectively). Interestingly, antral gastritis was also significantly less in H. pylori-positive animals given rUre plus LT than in H. pylori-positive animals given placebo plus LT (P< 0.02). However, quantitative cultures did not demonstrate significant differences between the two latter groups. It is concluded that oral administration of rUre vaccine plus LT significantly protects nonhuman primates against H. pyloriinfection while not causing undesirable side effects.

IN REPLY Dr Reus criticizes as "overstated" and "critically dependent on one subject" our reporting of a significant relationship between CSF 5-HIAA concentrations and aggression. We note that even when the single subject in question is dropped from the analysis, the results remain statistically significant (r=.46, P&lt;.05). While our study is the first, to our knowledge, to correlate interindividual differences in CSF 5-HIAA with aggression in nonhuman primates, our primary hypothesis of a negative correlation between aggression and CSF 5-HIAA was based on other cited studies of nonhuman primates, showing that increasing or decreasing serotonin activity pharmacologically produces the decrease or increase in aggression, respectively.In a follow-up study of these subjects, we extended this initial finding. We reported at the meeting of the American Society of Primatology1 that when direct behavioral observations of these animals are collected, they are more impulsive and engage in aggressive acts with a high likelihood of