Immunogenicity and effectiveness of Haemophilus influenzae type b conjugate vaccine in HIV infected and uninfected African children
ABSTRACT The quantitative (anti-Hib capsular polysaccharide antibody concentrations; anti-HibPS) and qualitative (bactericidal activity and avidity) aspects in immune responses to Haemophilus influenzae type b polyribosyl ribitol phospshate-CRM(197) conjugate vaccine (HibCV; HibTiter) were evaluated in 66 HIV infected children not receiving anti-retroviral therapy and 127 HIV uninfected children. Surveillance was conducted for invasive Hib disease in a cohort of 39,865 (approximately 6.4% of whom were HIV infected) children from March 1998 to June 2004. HIV infected children had lower anti-HibPS geometric mean antibody concentrations 1 month post-immunisation than HIV uninfected children (P<0.00001) and were less likely to have anti-HibPS antibody concentrations of >or=1.0 microg/ml (RR 0.54; 95% CI 0.43-0.69). A lower proportion of HIV infected children than HIV uninfected children (RR 0.78; 95% CI 0.66-0.93) had measurable anti-Hib serum bactericidal activity (SBA) and the HibPS antibody concentration required for 50% killing of Hib bacteria was greater among HIV infected than HIV uninfected children (P=0.001). The estimated risk of HibCV failure was 35.1-fold greater (95% CI 14.6-84.6) amongst HIV infected than HIV uninfected children.
SourceAvailable from: Lucimar G Milagres[Show abstract] [Hide abstract]
ABSTRACT: To investigate the influence of CD4 T-cell activation and regulatory populations in HIV-infected children antibody response to vaccination with a conjugate C polysaccharide vaccine. CD4 T-cell activation was evaluated by expression of CD38, HLA-DR and CCR5 molecules. Regulatory CD4 T cells (TReg) were characterized as FoxP3CD127CD25 and inducer T cells (TInd) as CD4FoxP3CD25CD39. All patients (n = 36) were HIV-vertically infected, aged 2-17 years-old and were vaccinated with one vaccine injection. Blood samples were obtained before and after immunization to determine bactericidal antibody titers (SBA), CD4 T-cell activation and frequency of TReg and TInd subsets (multiparametric flow cytometry). Children not-responding (n = 18) to MenC vaccine expressed higher frequency of activated CD4 T cells (HLA-DRCD38CCR5) than responders (n = 18), both before and after vaccination (P < 0.05). A significant higher frequency of TReg was detected in responders compared with nonresponders (P = 0.0001). We also detected an inverse correlation between CD4DRCD38CCR5 (P = 0.01) or CD4DRCD38 (P = 0.02) T cells and TReg cell frequency after vaccination. CD4 T-cell activation negatively correlated (P = 0.006) with postvaccination SBA titers but a positive correlation (P = 0.0001) was detected between TReg cells and SBA. TReg and TInd subsets were inversely correlated (P = 0.04). Our findings suggest that higher CD4 T-cell activation leads to poor vaccine response in children living with HIV, which may be associated with a TReg/TInd disequilibrium.AIDS (London, England) 10/2013; 27(17). DOI:10.1097/QAD.0000000000000007 · 6.56 Impact Factor
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ABSTRACT: An international panel of experts prepared an evidenced-based guideline for vaccination of immunocompromised adults and children. These guidelines are intended for use by primary care and subspecialty providers who care for immunocompromised patients. Evidence was often limited. Areas that warrant future investigation are highlighted.Clinical Infectious Diseases 02/2014; 58(3):309-18. DOI:10.1093/cid/cit816 · 9.42 Impact Factor
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ABSTRACT: To determine whether immune function is impaired among HIV-exposed but uninfected (HEU) infants born to HIV-infected mothers and to identify potential vulnerabilities to vaccine preventable infection, we characterized mother-to-infant placental transfer of Haemophilus influenzae type b-specific IgG (Hib-IgG), and levels and avidity after vaccination in Ugandan HEU infants and in HIV-unexposed U.S. infants.Clinical and vaccine Immunology: CVI 10/2014; DOI:10.1128/CVI.00356-14 · 2.37 Impact Factor