title: Analysis of the antibody response in humans with a new inactivated hepatitis A vaccine.
abstract: Sera from subjects vaccinated with the Pasteur Merieux (PM) inactivated hepatitis A vaccine (AVAXIM) have been analysed in order: (1) to assess comparability of the results provided by a modified radio-immunoassay (mRIA) in the different laboratories involved in testings of sera during clinical trials and by enzyme-linked immunoabsorbent assay (ELISA) used during development of other inactivated hepatitis A vaccines; (2) to describe the IgM responses elicited by this vaccine compared with one control vaccine [HAVRIX, 720 ELISA antigens units; Smithkline Beecham (SB), Rixensart, Belgium]; (3) to provide comparative data between the PM vaccine and the SB vaccine on neutralizing activities of vaccine-induced antibodies. Vaccine-induced antibody titres evaluated by a mRIA in different laboratories correlated well and validated the comparability of the results obtained in various vaccine trials conducted by PM. Geometric mean titres (GMTs) expressed as milli-international units (mlU/ml) were higher with ELISA especially after the first dose, but seroconversion rates were similar and a good correlation was found between the two assays. IgM vaccine-induced antibodies were detectable in nearly all vaccinated subjects from week 2 after vaccination, with a peak titre between weeks 2 and 4 after the first dose. Comparison of GMTs by the Student Fisher t-test was statistically significant (P < 0.05) only at week 2 with higher titres in PM vaccinees. Neutralizing antibodies were detected after vaccination with the PM inactivated hepatitis A vaccine. The titres gradually increased between the second week after the first dose and the booster dose (week 24). A strong booster effect of the second dose on neutralizing titres was observed. Seroneutralizing titres induced at week 2 in subjects vaccinated with the PM inactivated hepatitis A vaccine were statistically significantly higher (P < 0.05) from those induced by the SB vaccine.
authors.affiliation: Pasteur Merieux Serums et Vaccins, Marcy l'Etoile, France.
authors.forename: E
authors.initials: E
authors.lastname: Vidor
authors.forename: C
authors.initials: C
authors.lastname: Xueref
authors.forename: C
authors.initials: C
authors.lastname: Blondeau
authors.forename: A
authors.initials: A
authors.lastname: Bajard
authors.forename: A
authors.initials: A
authors.lastname: Francon
authors.forename: A
authors.initials: A
authors.lastname: Goudeau
authors.forename: F
authors.initials: F
authors.lastname: Peyron
authors.forename: P
authors.initials: P
authors.lastname: Brasseur
authors.forename: A
authors.initials: A
authors.lastname: Zuckerman
mesh_terms: D000293:Adolescent; D000328:Adult; D006506:Hepatitis A / Q000517:prevention & control*; D035922:Hepatitis A Antibodies; D022362:Hepatitis A Vaccines; D006508:Hepatitis Antibodies / Q000097:blood*; D006507:Hepatovirus / Q000276:immunology*; D006801:Humans; D007075:Immunoglobulin M / Q000097:blood; D008297:Male; D008875:Middle Aged; D009500:Neutralization Tests; D011863:Radioimmunoassay; D015164:Vaccines, Inactivated / Q000276:immunology*; D014761:Viral Hepatitis Vaccines / Q000276:immunology*
chemical_list: D035922:Hepatitis A Antibodies; D022362:Hepatitis A Vaccines; D006508:Hepatitis Antibodies; D007075:Immunoglobulin M; D015164:Vaccines, Inactivated; D014761:Viral Hepatitis Vaccines