21st European Congress of Clinical Microbiology and Infectious Diseases

Specific antibody functional activity in recipients of one-dose vaccine contained Leningrad3 mumps virus strain: a 3year follow-up

Abstract number: R2752

Atrasheuskaya A., Karpov I.A., Ignatyev G.M.

Mumps virus-neutralizing antibodies are believed to be the most predictable surrogate marker of protective immunity. The remote history of vaccination also suggests that waning immunity could have contributed to the vaccinees' susceptibility. Mumps outbreaks in vaccinated populations are usually caused by the phylogenetically distinct from the vaccine strains mumps viruses (MuV).

To examine these issues, the kinetics of titer, avidity and neutralizing activity level and spectrum of the specific IgG were studied in 3-year follow-up serum samples from the healthy volunteers (n = 60) with no vaccination and mumps in the past, after the one vaccine dose contained "Leningrad-3" (L-3) MuV strain.

Full seroconversion, confirmed by ELISA and PRN against the vaccine MuV strain, was registered in all volunteers 3 months after vaccination. Antibodies induced by the vaccine strain effectively neutralized five heterologous MuV strains (genotype A, B, D, and those earlier isolated during the local mumps outbreaks, C and H) starting from month 6 after vaccination at all time points tested thereafter, albeit at levels lower than those seen against the vaccine strain (>2-fold difference). The specific IgG titers measured in ELISA demonstrated an "early" decrease after 9 months post vaccination. At the same time, the specific IgG functional activity characterized by their avidity, level and spectrum of neutralizing activity reached its maximum within month 18 after vaccination. Antibodies capable of neutralizing the heterologous MuV genotypes in the absence of antigenic boosting demonstrated a decrease to the critical levels (1:8) in a part of vaccinees after the third year post vaccination, while the specific IgG neutralizing activity against the vaccine strain still demonstrated a titer previously associated with protection against MuV infection (1:8).

The current study possessing several limitations demonstrated for the first time a broad-spectrum neutralizing activity of the specific IgG in recipients of one dose vaccine containing the L-3 MuV strain within 3 years after vaccination.