NEUTRALIZING ANTIBODY-RESPONSES TO JAPANESE ENCEPHALITIS VACCINE IN CHILDREN

  • 1 January 1983
    • journal article
    • research article
    • Vol. 26  (1) , 25-34
Abstract
Two shots of the current Japanese encephalitis (JE) vaccine were given to children and their immune responses to the Nakayama strain (the vaccine strain) and 2 wild strains (JaGAr-01 and E-50) of JE virus were examined by neutralizing (N) antibody titrations. Seventy vaccinees had no N antibody to JE virus before the 1st vaccination and were bled 1 mo. after the 2nd vaccination. The N antibody responses to the JaGAr-01 and E-50 strains were found to be similar and to be less than that to the Nakayama strain after the 2nd vaccination: the geometric mean titers (GMT) of N antibodies to the JaGAr-01 and E-50 strains (as logarithms) were 1.87 and 1.75, respectively, while the GMT to the Nakayama strain was 2.89. The seroconversion rates to the Nakayama, JaGAr-01 and E-50 strains were 70/70 (100%), 69/70 (99%) and 68/70 (97%), respectively, after the 2nd vaccination. Of the 70 vaccinees, 27 were also bled before the 2nd vaccination. Most showed a considerably high N antibody response against the Nakayama strain and only 1 vaccine failed to show seroconversion after the 1st vaccination. The antibody response to the E-50 strain appeared to be rather low and 9 of 25 vaccinees did not show any seroconversion. Similarly, 3 of 25 failed to show any seroconversion against the JaGAr-01 strain. Evidently, at the initial immunization, 2 shots, at least, of the current JE vaccine are necessary to stimulate effective immune responses to wild strains of JE virus.