Vaccination of Seropositive Subjects with CHIRON CMV gB Subunit Vaccine Combined with MF59 Adjuvant for Production of CMV Immune Globulin

The safety and immunogenicity of four different regimens of CHIRON cytomegalovirus (CMV) gB subunit vaccine combined with MF59 adjuvant and administered to seropositive plasma donors were evaluated to ascertain whether vaccination of seropositive subjects would significantly increase antibody titer to gB glycoprotein. This was done to select the best vaccination regimen for generating high-titered plasma for manufacture of CMV immune globulin. No serious adverse events were attributed to this vaccine, and the vaccine was well tolerated. Only the first dose of vaccine in each regimen stimulated a four-fold or greater antibody response to gB glycoprotein and each regimen induced similar antibody titers. However, initial vaccination followed by a 1 week rest from plasmapheresis and two booster vaccinations at 8 and 24 weeks, each followed with another 1 week rest from plasmapheresis, maintained the highest geometric mean gB ELISA titer of the four regimens over the 34-week post-vaccination period. CMVIG manufactured from a pool of high titered plasma units from two of four subject groups had gB ELISA and neutralizing antibody titers nine and six times higher, respectively, compared to Cytogam, indicating that vaccination of seropositive subjects with CHIRON gB vaccine combined with MF59 adjuvant prior to harvesting plasma can enhance functional antibody in a CMVIG product.