TITLE:
Polyfunctional T Cell and Neutralizing Antibody Responses to ACAM2000TM Smallpox Vaccine Immunization in Primary-Vaccinated Individuals
AUTHORS:
Suchada Sukhumvittaya, Silawun Ampol, Kovit Pattanapanyasat, Wannee Kantakamalakul
KEYWORDS:
Smallpox Vaccine, Primary Immunization, T Cell, Neutralizing Antibody
JOURNAL NAME:
Advances in Microbiology,
Vol.6 No.3,
March
15,
2016
ABSTRACT: Smallpox eradication
was successful via prophylactic administration of live attenuated vaccinia
virus. As a result of the discontinuation of the smallpox immunization program,
many individuals are now susceptible to smallpox virus infection should it be
used as a biological weapon. Presently, only individuals at high risk for
exposure are required to receive smallpox vaccine, such as laboratory personnel
that handle variola/vaccinia virus. This study endeavored to investigate a one-year
period of vaccinia virus-specific T cell responses using polychromatic flow
cytometry and neutralizing (Nt) antibody responses using plaque reduction
neutralization test (PRNT) in individuals receiving primary immunization (n = 5)
with ACAM2000TM smallpox vaccine. Functional and phenotypic profiles of vaccinia
virus-specific T cell responses were characterized. Each single functional
measurement {CD107a/b expression, production of interferon g (IFN-g), macrophage inflammatory protein 1b (MIP-1b), interleukin 2 (IL-2), and tumor necrosis
factor a (TNF-a)} demonstrated that vaccinia virus-specific
CD8+ T cells were functional at least one time point after
vaccination (p ≤ 0.05). However, vaccinia virus-specific CD4+ T cells were functional only for MIP-1b production (p ≤ 0.05). Vaccinia
virus-specific CD8+ T cells induced in these individuals showed
increased polyfunctionality in at least 2 phenotypes relative to
pre-vaccination (p ≤ 0.05). Although only three of five individuals
(60%) showed positive Nt antibody (titer ≥ 20) at first month after
vaccination, all five individuals (100%) demonstrated Nt antibody at 2 months,
post-immunization. Interestingly, all vaccinees could retain the Nt antibody
for 6 months after primary vaccination. In conclusion, ACAM2000TM smallpox
vaccine induced both polyfunctional T cell-and Nt antibody-responses in primary
immunized individuals.