Abstract | BACKGROUND: Postexposure vaccination strategies rely on a rapid induction of poxvirus-specific immune responses. Postvaccination cell-mediated immune (CMI) responses have not been compared by use of controlled trials in previously vaccinated ( vaccinia-nonnaive) and nonvaccinated ( vaccinia-naive) individuals. METHODS: To assess the time course of vaccinia-specific CMI responses, 20 previously vaccinated and 10 vaccinia-naive individuals were vaccinated with Dryvax, and serial blood samples were drawn. RESULTS: Both groups developed peak levels of vaccinia-specific interferon (IFN)- gamma -producing T cells by day 14 after vaccination. In vaccinia-nonnaive individuals, vaccinia-specific CMI responses were detected by day 7 after vaccination and preceded the increase in antibody titers. IFN- gamma enzyme-linked immunospot responses were significantly different between the 2 groups on days 7 (greater in vaccinia-nonnaive than in vaccinia-naive individuals) and 14 (greater in vaccinia-naive than in vaccinia-nonnaive individuals). Lymphoproliferation responses in vaccinia-nonnaive individuals were significantly higher on days 3 and 7, but cytotoxic T cell lysis activity was not statistically different at any time point. Antibody responses conformed to expected primary and secondary patterns of induction. CONCLUSIONS: This study demonstrates that the kinetics of CMI responses are different after primary vaccination versus after revaccination and indicates that memory can exist in individuals vaccinated >/=30 years ago. These data support the epidemiological observation in smallpox outbreaks that successful revaccination within 4 days of exposure is partially protective. In vaccinia-nonnaive individuals, protection against smallpox during the postexposure revaccination period may require T cell memory as an essential component for the rapid induction of protective cellular and humoral responses.
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Authors | Jeffrey S Kennedy, Sharon E Frey, Lihan Yan, Alan L Rothman, John Cruz, Frances K Newman, Laura Orphin, Robert B Belshe, Francis A Ennis |
Journal | The Journal of infectious diseases
(J Infect Dis)
Vol. 190
Issue 7
Pg. 1286-94
(Oct 01 2004)
ISSN: 0022-1899 [Print] United States |
PMID | 15346340
(Publication Type: Clinical Trial, Journal Article, Randomized Controlled Trial)
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Chemical References |
- Antibodies, Viral
- Smallpox Vaccine
- Interferon-gamma
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Topics |
- Adult
- Antibodies, Viral
(blood)
- Humans
- Immunization, Secondary
- Immunologic Memory
- Interferon-gamma
(biosynthesis)
- Lymphocyte Activation
- Middle Aged
- Smallpox Vaccine
(immunology)
- T-Lymphocytes, Cytotoxic
(immunology)
- Vaccination
- Vaccinia virus
(immunology)
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