Abstract
Inactivated Japanese encephalitis virus vaccine (Nakayama, Lot 3) was injected to persons free of serum neutralizing antibody against the virus, first in order to elucidate the development of serum antibody in the early stage after the vaccination, and secondly to study the physico-chemical properties of antibodies produced at different time after the vaccination.
The results are summarized as follows:
1) The neutralizing antibody appeared in sera from the 7th to 10th day post-vaccination. The titer reached its maximum on about the 20th day and gradually reduced thereafter.
2) The neutralizing antibody in sera collected within 3 weeks after vaccination was highly sensitive to the treatment with 2-mercaptoethanol (2-ME), while that collected on the 40-50th day was found to be somewhat insensitive to the treatment. In contrast to this, the antibody resistant to 2-ME was demonstrated in sera obtained on the 60th day post-vaccination.
3) Antibody in those sera were analyzed by means of gel filtration with Sephadex G-200. The serum collected on the 14th day post-vaccination contained only the 19S macroglobulin antibody. The serum on the 22nd day contained a small amount of the 7S antibody, in addition to the larger amount of remaining macroglobulin antibody.
Gel filtration of the 41st-day's serum showed a relative decrease in the amount of the 19S antibody, in contrast to an increase in the 7S antibody.
In serum collected one year after vaccination, persistence of minimum amount of macroglobulin antibody was demonstrated, though the majority of the neutralizing activity was contained in the 7S antibody.
A striking rise in neutralizing titer in serum following revaccination made one year after the primary injection was found to be due to an increase in the 7S antibody.
4) Evidence was obtained to indicate that the treatment with 2-ME reduced the activity of 19S antibody to one-eighth of its original titer, while that of the 7S antibody was no more affected by this reagent.
