Impact of infection or vaccination on pre-existing serological memory

Once established, serum antibody responses against a specific pathogen may last a lifetime. We describe a cohort of four subjects who received smallpox vaccination, and a single subject who received multiple vaccinations, with antibody levels to unrelated antigens monitored for 1–3 years. These immunizations provided the opportunity to determine if infection/vaccination and the resulting toll-like receptor stimulation would alter antigen-specific serological memory to other antigens, including bacterial toxins (tetanus, diphtheria, and pertussis) and viruses (yellow fever virus, measles, mumps, rubella, Epstein-Barr virus, and varicella-zoster virus). Our results indicate that serum IgG levels are remarkably stable and infection or vaccination are unlikely to increase or decrease pre-existing antigen-specific antibody responses.