Host immune response to A(H1N1)pdm09 vaccination and infection: a one-year prospective study on six cohorts of subjects.
BACKGROUND
The long-term immunogenicity after novel vaccine against A(H1N1)pdm09 administration or natural infection has not been well investigated.


METHODS
Six cohorts of subjects were followed up for over one year: one-dose A(H1N1)pdm09 vaccine recipient, A(H1N1)pdm09-seasonal trivalent vaccine recipients in different orders, confirmed A(H1N1)pdm09 patients without vaccination, with previous A(H1N1)pdm09 or seasonal influenza vaccination. Peripheral blood mononuclear cells and sera samples were collected at baseline and month 1, 2, 3, 7 and 14 after vaccination (infection). The immunogenicity was determined by hemagglutination-inhibition (HI) and B cell enzyme-linked immunospot (ELISPOT) assays.


RESULTS
Single dose of A(H1N1)pdm09 vaccine elicited antibody titer of greater than 1:40 in 40% adults for 1 year and mean live of this adequate antibody was determined as 8.35 months. In contrast, responses after natural infections had lower peaking level and a relatively longer antibody duration, with estimated mean lives of 11.8 months. Pre-vaccination with the seasonal flu vaccine led to a significant reduction in HI titer to A(H1N1)pdm09 one month after vaccination, while pre-vaccination with A(H1N1)pdm09 had no effect on seasonal influenza vaccination. Seasonal flu vaccination followed by A(H1N1)pdm09 infection elicited boosting effect on antibody response against A(H1N1)pdm09. A similar memory B cell response was elicited from both vaccination and infection by ELISPOT assay.


CONCLUSIONS
The long-term decay of immunity for A(H1N1)pdm09 vaccine and natural infection indicates the need of revaccination after the host lose protection acquired from either vaccination or infection. Prior infection, rather than the pre-vaccination with seasonal influenza could act on the host immunity to elicit boosting effect on the A(H1N1)pdm09.
State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, PR China. liuweixzt@yahoo.com
Wei
W
Liu
Mai-Juan
MJ
Ma
Fang
F
Tang
Cui
C
He
Xiao-Ai
XA
Zhang
Lan-Fen
LF
Jiang
Dong-Sheng
DS
Xin
Chun-Yan
CY
Hu
Caspar
C
Looman
Wu-Chun
WC
Cao
D000293:Adolescent; D000328:Adult; D000914:Antibodies, Viral / Q000097:blood; D001402:B-Lymphocytes / Q000276:immunology; D002681:China; D056738:Cross Protection; D005500:Follow-Up Studies; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D007156:Immunologic Memory; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000276:immunology*; D007251:Influenza, Human / Q000276:immunology* / Q000517:prevention & control*; D007963:Leukocytes, Mononuclear / Q000276:immunology; D011446:Prospective Studies; D055815:Young Adult
D000914:Antibodies, Viral; D007252:Influenza Vaccines