Vaccination with two different vaccinia recombinant viruses: long-term inhibition of secondary vaccination.

The effects of immunity to vaccinia virus on the efficiency of vaccination with a vaccinia recombinant virus were studied. In mice the efficiency and duration of the B-cell response to the recombinant gene product of a second vaccinia recombinant virus were suppressed for more than 9 months, i.e. practically lifelong. Antibody titres against the recombinant gene product were not only lower but also lasted for a shorter time. Thus, immunity to vaccinia virus may influence both the titre and duration of the antibody response induced by a second distinct vaccinia recombinant vaccine.