Limited cross strain CMV protection by a bivalent (gB/pp65) vaccine is based on an impaired gB antibody response and evasion of pp65 cell mediated immunity

A bivalent AdgB+AdGP83 vaccine in guinea pigs shows only partial cross-strain protection against clinical GPCMV TAMYC (SQ) challenge, without preventing viremia or organ dissemination.

• Why it matters: Cross-strain efficacy is a key benchmark for congenital CMV vaccines, yet prior GPCMV work largely used prototype 22122 and did not test protection against clinically relevant strains.
• What they did: Guinea pigs were immunized with AdgB+AdGP83 and assessed for pp65-specific IFN{gamma} ELISPOT responses and anti-gB titers, including neutralization, then challenged with clinical TAMYC (SQ) in a pathogenicity study.
• The result: The combined vaccine generated pp65 T cell responses and similar anti-gB/prefusion gB titers to historical AdgB sera, but impaired gB(AD-1) oligomerization domain antibody reduced neutralizing titers, yielding limited cross-strain protection and failure to block dissemination.

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