Development of flow cytometric opsonophagocytosis and antibody-mediated complement deposition assays for non-typeable Haemophilus influenzae.

BACKGROUND: Haemophilus influenzae is found in the nasopharynx of 80% of the human population. While colonisation with non-typeable Haemophilus influenzae (NTHi) is usually asymptomatic, it is capable of causing acute and chronic otitis media (OM) in infants, invasive disease in susceptible groups and is the leading cause of exacerbations of patients with chronic obstructive pulmonary disease (COPD). Current methods for assessing functional antibody immunity to NTHi are limited and labour intensive. Flow cytometric assays could provide an attractive alternative to evaluate immune responses to candidate vaccines in clinical trials. RESULTS: We have developed a duplexed flow-cytometric uptake and oxidative burst opsonophagocytosis assay (fOPA). We have also developed a duplexed antibody-mediated complement C3b/iC3b and C5b-9 deposition assay (CDA). Antibody-mediated C3b/iC3b deposition correlated with opsonophagocytic uptake (r = 0.65) and with opsonophagocytic oxidative burst (r = 0.69). Both fOPA and CDA were reproducible, with the majority of samples giving a coefficient of variation (CV) of < 20% and overall assay CVs of 14% and 16% respectively. CONCLUSIONS: The high-throughput flow cytometric assays developed here were successfully optimised for use with NTHi. Assays proved to be sensitive and highly reproducible for the measurement of bacterial uptake and oxidative burst opsonophagocytosis and antibody-mediated deposition of C3b/iC3b and C5b-9. These assays are useful tools for use in large scale epidemiological studies and to assist in the assessment of functional antibody induced by NTHi candidate vaccines.

Immunogenicity and safety of the adjuvanted recombinant zoster vaccine co-administered with the 23-valent pneumococcal polysaccharide vaccine in adults ≥50 years of age: A randomized trial.

BACKGROUND: This study evaluated immunogenicity and safety of the adjuvanted recombinant zoster vaccine (RZV) when the first dose was co-administered with the 23-valent pneumococcal polysaccharide vaccine (PPSV23) in adults aged ≥50 years. METHODS: In this open label, multi-center study (NCT02045836), participants were randomized 1:1 to receive either the first dose of RZV and PPSV23, co-administered at Day 0 and the second dose of RZV at Month 2 (Co-Ad group), or PPSV23 at Day 0, the first dose of RZV at Month 2 and second dose of RZV at Month 4 (Control group). Co-primary objectives were the RZV vaccine response rate (VRR) in the Co-Ad group and the non-inferiority of the antibody responses to RZV and PPSV23 in the Co-Ad group compared to the Control group. Reactogenicity and safety were also assessed. RESULTS: 865 participants were vaccinated (Co-Ad: 432, Control: 433). VRRs to RZV were >98% in both groups. Humoral immune responses to co-administration of RZV and PPSV23 were non-inferior to sequential administration. All three co-primary immunogenicity objectives were met. Solicited local symptoms after the first RZV dose were reported by similar percentages of participants in both groups. Solicited general symptoms were more frequently reported when the first dose of RZV and PPSV23 were co-administered. No differences were apparent between groups after the second RZV dose. CONCLUSIONS: No immunologic interference was observed between RZV and PPSV23 when co-administered in adults ≥50 years. No safety concerns were raised.

Pneumococcal serotype 3 otitis media, limited effect of polysaccharide conjugate immunisation and strain characteristics.

BACKGROUND: In contrast to the other vaccine serotypes, no protection could be demonstrated in the POET study against serotype 3 acute otitis media (AOM) following primary and booster vaccination with a multi-valent pneumococcal conjugate vaccine. METHODS: AOM efficacy and immunogenicity data were reviewed. Pheno- and genotypic characteristics of different serotype 3 strains including efficacy study AOM isolates were evaluated. RESULTS: Evaluation of vaccine efficacy before and after booster vaccination indicated that lack of efficacy against serotype 3 pneumococci might have been due to declined protection following the booster dose. However, although atypical immunogenicity was observed for serotype 3 in the second year of life, the capacity to respond to serotype 3 plain polysaccharide was not impaired. All but one of the serotype 3 strains examined had abundant polysaccharide capsules. Comparison of serotype 3 capsular polysaccharide biosynthesis gene sequences found no relevant differences between any of the serotype 3 strains, but mRNA transcript levels were lower for the less densely encapsulated strain. CONCLUSION: Lack of clinical efficacy against serotype 3 AOM following pneumococcal conjugate vaccination may be due to an impaired induction of immune memory. A possible alternative explanation may lie with the atypically abundant expression of capsular polysaccharide which could make serotype 3 strains less susceptible to anti-polysaccharide antibody defence mechanisms in the middle ear. The occurrence of acapsular forms during biofilm growth may also play a role. Clinical impact against otitis media, of vaccines containing pneumococcal serotype 3 components, remains unclear until further investigations have demonstrated the value.

Pneumococcal Haemophilus influenzae protein D conjugate vaccine induces antibodies that inhibit glycerophosphodiester phosphodiesterase activity of protein D.

Haemophilus influenzae outer membrane protein D (PD) is a glycerophosphodiester phosphodiesterase (GlpQ) activity-possessing virulence factor and a promising vaccine antigen, providing 35.3% efficacy against acute otitis media caused by nontypeable H. influenzae (NTHI) when it was used as a carrier protein in a novel pneumococcal PD conjugate (Pnc-PD) vaccine. To study if PD-induced protection against NTHI could be due to antibodies that inhibit or neutralize its enzymatic activity, a GlpQ enzyme inhibition assay was developed, and serum samples collected from Finnish infants before and after Pnc-PD vaccination were analyzed for enzyme inhibition and anti-PD immunoglobulin G (IgG) antibody concentration. Before vaccination at age 2 months, the majority (84%) of infants (n = 69) had no detectable anti-PD IgG antibodies, and all were enzyme inhibition assay negative (inhibition index, <20). At age 13 to 16 months, all infants receiving three or four doses of Pnc-PD had detectable anti-PD IgG antibodies and 36% (8/22 infants) of the infants receiving three doses and 26% (6/23 infants) of the infants receiving four doses of Pnc-PD were inhibition assay positive (inhibition index, >/=20). No significant rise in anti-PD IgG antibodies or enzyme inhibition among control vaccinees (n = 24) receiving three doses of hepatitis B vaccine was detected. A modest correlation (r(s), approximately 0.66) between anti-PD IgG concentration and enzyme inhibition was detected; however, their kinetics were clearly different. These data suggest that measurement of antibody responses that inhibit PD's enzymatic activity could be a useful tool for assessing Pnc-PD vaccine-induced protective immunity against NTHI.

Multilaboratory evaluation of a viability assay for measurement of opsonophagocytic antibodies specific to the capsular polysaccharides of Streptococcus pneumoniae.

Opsonophagocytosis is a correlate of protection that measures the functional activity of vaccine-induced antibodies. A standardized opsonophagocytosis assay (OPA) should be used as part of the evaluation of current and future pneumococcal (Pnc) polysaccharide (Ps)-based vaccines. We enrolled five laboratories to evaluate a previously standardized viability OPA. Each laboratory was provided with a detailed OPA protocol, seven target Pnc strains (serotypes 4, 6B, 9V, 14, 18C, 19F, and 23F), two quality control sera and 12 paired sera (blinded) from adult donors who received one dose of the 23-valent Pnc Ps vaccine. Laboratories sent their results to the Centers for Disease Control and Prevention for analysis. Sera were tested in duplicate (single run), and the results were averaged to yield a single OPA titer (> or = 50% killing) for each serum sample. The percentage of sera within one or two dilutions of the calculated median OPA titer was determined for each laboratory and for each serotype. In general, laboratories were capable of detecting OPA titers within one or two dilutions of the median for at least 75 and 88%, respectively, of the sera tested. The level of agreement with the median OPA titers varied depending on the participating laboratory (overall agreement = 0.8 [99% confidence interval = 0.75 to 0.85]). All OPA median titers reported for quality control sera were within one dilution of the expected titer. We conclude that this OPA can be done in multiple laboratories with a high degree of interlaboratory reproducibility.