title: Humoral immune response to influenza A(H1N1)pdm2009 in patients with natural infection and in vaccine recipients in the 2009 pandemic.
abstract: The 2009 pandemic H1N1 mainly affected adolescents and children, and most of the elderly in Japan escaped clinical illness. To clarify the role of humoral immunity in the infection, the time kinetics of hemagglutination inhibition (HI), neutralization (NT), and IgG subclass antibody response directed against influenza A(H1N1)pdm2009 were analyzed in three consecutive specimens obtained from 51 young adults and children (group 1) who contracted pandemic influenza and from 74 pediatric clinic employees (group 2) inoculated with pandemic monovalent vaccine. In group 1 patients, 6 and 30 patients had lower HI and NT antibody in the acute phase respectively. Thereafter, HI and NT antibody titers increased fourfold or more in 50 patients with peak response in the third specimens obtained four weeks after the onset. IgG1 in 45 patients, IgG3 in 18 patients, and IgG4 in 29 patients showed elevated responses. Forty (54%) and 70 (95%) subjects in group 2 had positive HI and NT antibodies in the prevaccination samples, with increased antibody responses in the follow-up peaking in the second specimens. Forty of those vaccinated had increased IgG1 responses peaking in the third specimens, whereas elevated IgG3 was observed in 22 recipients with the highest level in the second samples. IgG4 did not show any increase in subjects in group 2. A few participants showed an IgG2 response in both groups. An immunologically naive population contracted influenza with apparent clinical symptoms. However, already primed subjects through subclinical infection elicited the unique pattern of IgG subclass responses by vaccination, which differed from those of naive populations.
authors.affiliation: 1 Pediatric Allergy and Infectious Diseases Society of Sapporo, Kumagai Pediatric Clinic , Sapporo, Japan .
authors.forename: Takuji
authors.initials: T
authors.lastname: Kumagai
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Nakayama
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Okuno
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Kase
authors.forename: Naoko
authors.initials: N
authors.lastname: Nishimura
authors.forename: Takao
authors.initials: T
authors.lastname: Ozaki
authors.forename: Akiko
authors.initials: A
authors.lastname: Miyata
authors.forename: Eitaro
authors.initials: E
authors.lastname: Suzuki
authors.forename: Teruo
authors.initials: T
authors.lastname: Okafuji
authors.forename: Takao
authors.initials: T
authors.lastname: Okafuji
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Ochiai
authors.forename: Nobuo
authors.initials: N
authors.lastname: Nagata
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tsutsumi
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Okamatsu
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Sakoda
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kida
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Ihara
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D057134:Antibodies, Neutralizing / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D056724:Immunity, Humoral; D007074:Immunoglobulin G / Q000097:blood; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000276:immunology*; D007251:Influenza, Human / Q000276:immunology* / Q000821:virology*; D007564:Japan; D008297:Male; D008875:Middle Aged; D009500:Neutralization Tests; D013997:Time Factors; D055815:Young Adult
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D007074:Immunoglobulin G; D007252:Influenza Vaccines