title: Immunogenicity of three Haemophilus influenzae type b protein conjugate vaccines in HIV seropositive adults and analysis of predictors of vaccine response.
abstract: HIV-seropositive adults may be at increased risk of infection due to Haemophilus influenzae type b (Hib) as compared with HIV-seronegative adults. Protein conjugate vaccines have been demonstrated to induce protective levels of antibodies against Hib in immunocompetent infants and also in HIV-seropositive infants. In this study we determined the immunogenicity of three protein conjugate Hib vaccines (PRP-D, HbOC, HbNOMP) in 135 HIV-seropositive adults who received one dose of Hib vaccine. Anti-polyribosylribitol phosphate (PRP) antibodies were measured at 0, 1, 3 and 12 months postimmunization by the Farr method. We demonstrate that all three vaccines are highly immunogenic and result in protective (> 1.0 microg/ml) levels of antibody. Overall the anti-PRP antibody level was > 1.0 microg/ml in 26% of patients preimmunization, 91% at both 1 and 3 months, and 79% at 12 months postvaccination. Comparison of responses to the three vaccines over time demonstrated differences in the mean geometric anti-PRP antibody level at 1 month (p=0.03) and the 12 month time points (p=0.03) with lower geometric mean levels in the HbNOMP group, though baseline differences in groups limit the interpretation of these findings. In a univariate analysis of baseline characteristics which predicted poor vaccine response, low total IgG2 levels preimmunization predicted a poor antibody response at 1 month (p < 0.01) and at 12 months (p=0.05), while low CD4 T-cell count predicted poor response at 12 months (p < 0.01). We conclude that all three US licensed protein conjugate Hib vaccines are immunogenic in HIV-seropositive adults, and that baseline CD4 T-cell count and IgG2 levels predict the likelihood of antibody response to vaccine.
authors.affiliation: Infectious Disease Research and Mayo Vaccine Research Group, Mayo Clinic, Rochester, MN 55905, USA.
authors.forename: D H
authors.initials: DH
authors.lastname: Dockrell
authors.forename: G A
authors.initials: GA
authors.lastname: Poland
authors.forename: J M
authors.initials: JM
authors.lastname: Steckelberg
authors.forename: P C
authors.initials: PC
authors.lastname: Wollan
authors.forename: S R
authors.initials: SR
authors.lastname: Strickland
authors.forename: C
authors.initials: C
authors.lastname: Pomeroy
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000907:Antibodies, Bacterial / Q000097:blood; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology* / Q000627:therapeutic use; D005544:Forecasting; D006679:HIV Seropositivity / Q000276:immunology* / Q000382:microbiology; D006192:Haemophilus Infections / Q000517:prevention & control*; D018073:Haemophilus Vaccines / Q000276:immunology* / Q000627:therapeutic use; D006193:Haemophilus influenzae / Q000276:immunology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012737:Sex Factors; D018074:Vaccines, Conjugate / Q000276:immunology / Q000627:therapeutic use
chemical_list: D000907:Antibodies, Bacterial; D001425:Bacterial Outer Membrane Proteins; D018073:Haemophilus Vaccines; D018074:Vaccines, Conjugate; C067559:outer membrane protein P1, Haemophilus influenzae type b