Characterization of the Antibody Response to Acetone-Killed Typhoid Vaccine

1AJBORATORY EVALUATION of the J efficacy of typhoid vaccine has generally produced results which show little correlation with those obtained in field-trial evaluation.Hence, extensive field trials have been deemed necessary to evaluate the various typhoid vac- cines {1-S).Recent advances in immuno- logical methodology have demonstrated distinct classes of immunoglobulins with differing bio¬ logical activities (4).The application of these techniques has resulted in the detection of patients with im- munoglobulin deficiencies who can produce normal levels of gamma M antibody but who cannot synthesize gamma G antibody (5).These patients are extremely susceptible to various bacterial infections, a sensitivity sug- gesting that while gamma M antibody is able to agglutinate with antigen in the laboratory, it is unable to protect against infection.