ABSTRACT
The safety and immunogenicity of a group B meningococcal vaccine, consisting of N-propionylated (NPr) B capsular polysaccharide conjugated to tetanus toxoid, was tested for the first time, in 17 healthy male volunteers aged between 18 and 40 years. Four escalating dosages of vaccine were tested and each was given as three intramuscular injections at 4-week intervals. The vaccine was well tolerated and induced only mild and transient, dose-dependent, injection-site reactions. One month after the last injection, there was no evidence of the production of autoantibodies or antibodies binding to PSA-NCAM. The vaccine induced an increase in the pre-existing titres of IgM specific to B polysaccharide and NPr B polysaccharide. Moreover, it induced IgG antibodies specific to NPr B polysaccharide, which were undetectable before vaccination. However, no functional activity of vaccine-induced antibodies was demonstrated in bactericidal assays, opsonophagocytic tests or passive protection tests.
Subject(s)
Meningococcal Vaccines/immunology , Neisseria meningitidis, Serogroup B/immunology , Polysaccharides/immunology , Adult , Animals , Antibodies, Bacterial/analysis , Antibodies, Bacterial/biosynthesis , Antibody Specificity , Autoantibodies/analysis , Autoantibodies/biosynthesis , Colony Count, Microbial , Cross Reactions , Enzyme-Linked Immunosorbent Assay , Humans , Immunization , Immunoglobulin G/analysis , Immunoglobulin G/biosynthesis , Immunoglobulin M/analysis , Immunoglobulin M/biosynthesis , Male , Meningococcal Infections/prevention & control , Meningococcal Vaccines/adverse effects , Mice , Neural Cell Adhesion Molecules/immunology , Precipitin Tests , Rats , Vaccines, Conjugate/adverse effects , Vaccines, Conjugate/immunologyABSTRACT
Respiratory syncytial virus (RSV) is responsible for severe low respiratory tract infections in young infants and the elderly. To investigate whether BBG2Na, a recombinant subunit vaccine comprising aa 130-230 of the RSV G protein, induced protective Abs in subjects over 60 years during phase II clinical trial, pre- and postimmunization sera of individuals immunized with BBG2Na or placebo were transferred into SCID mice before RSV challenge. These sera dose-dependently reduced lung RSV titers. However at some points of serial dilutions, postimmunization sera of BBG2Na-immunized subjects only were significantly more efficient than the corresponding preimmunization sera, in agreement with the induction of an increased Ab response against multiple epitopes on RSV-A G protein. Thus, BBG2Na is immunogenic in the elderly and confers passive protection in mice after serum transfer. To our knowledge, this is the first description of protective Abs induced by a subunit vaccine in human.
