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Otitis-Prone Children Produce Functional Antibodies to Pneumolysin and Pneumococcal Polysaccharides.

ABSTRACT: The pneumococcus is a major otitis media (OM) pathogen, but data are conflicting regarding whether otitis-prone children have impaired humoral immunity to pneumococcal antigens. We and others have shown that otitis-prone and healthy children have similar antibody titers to pneumococcal proteins and polysaccharides (vaccine and nonvaccine types); however, the quality of antibodies from otitis-prone children has not been investigated. Antibody function, rather than titer, is considered to be a better correlate of protection from pneumococcal disease. Therefore, we compared the capacities of antibodies from otitis-prone (cases) and healthy (controls) children to neutralize pneumolysin, the pneumococcal toxin currently in development as a vaccine antigen, and to opsonize pneumococcal vaccine and nonvaccine serotypes. A pneumolysin neutralization assay was conducted on cholesterol-depleted complement-inactivated sera from 165 cases and 61 controls. A multiplex opsonophagocytosis assay (MOPA) was conducted on sera from 20 cases and 20 controls. Neutralizing and opsonizing titers were calculated with antigen-specific IgG titers to determine antibody potency for pneumolysin, pneumococcal conjugate vaccine (PCV) polysaccharides, and non-PCV polysaccharides. There was no significant difference in antibody potencies between cases and controls for the antigens tested. Antipneumolysin neutralizing titers increased with the number of episodes of acute OM, but antibody potency did not. Pneumolysin antibody potency was lower in children colonized with pneumococci than in noncarriers, and this was significant for the otitis-prone group (P < 0.05). The production of functional antipneumococcal antibodies in otitis-prone children demonstrates that they respond to the current PCV and are likely to respond to pneumolysin-based vaccines as effectively as healthy children.

SUBMITTER: Kirkham LS

PROVIDER: S-EPMC5339643 | biostudies-literature | 2017 Mar

REPOSITORIES: biostudies-literature

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Otitis-Prone Children Produce Functional Antibodies to Pneumolysin and Pneumococcal Polysaccharides.

Kirkham Lea-Ann S LS Wiertsema Selma P SP Corscadden Karli J KJ Mateus Tulia T Mullaney Gemma L GL Zhang Guicheng G Richmond Peter C PC Thornton Ruth B RB

Clinical and vaccine immunology : CVI 20170306 3

The pneumococcus is a major otitis media (OM) pathogen, but data are conflicting regarding whether otitis-prone children have impaired humoral immunity to pneumococcal antigens. We and others have shown that otitis-prone and healthy children have similar antibody titers to pneumococcal proteins and polysaccharides (vaccine and nonvaccine types); however, the quality of antibodies from otitis-prone children has not been investigated. Antibody function, rather than titer, is considered to be a bet ...[more]

PMID: 28031178

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Project description:BackgroundNontypeable Haemophilus influenzae (NTHi) is the most common bacterial otopathogen associated with otitis media (OM). NTHi persists in biofilms within the middle ears of children with chronic and recurrent OM. Australian Aboriginal children suffer exceptionally high rates of chronic and recurrent OM compared to non-Aboriginal children. NTHi protein vaccines comprised of antigens associated with both adhesion and persistence in a biofilm are under development and could be beneficial for children with chronic and recurrent OM. Understanding the ontogeny of natural antibody development to these antigens provides insight into the value of vaccinating with particular antigens.MethodsAn in-house multiplex fluorescent bead immunoassay was used to measure serum IgG titres and avidity for three putative vaccine antigens: recombinant soluble PilA (rsPilA), ChimV4, and outer membrane protein 26 (OMP26) in sera from Australian Aboriginal otitis-prone children (n=77), non-Aboriginal otitis-prone children (n=70) and non-otitis-prone children (n=36). Serum IgG titres were adjusted for age, and geometric mean concentrations (GMCs) were compared between groups using a univariate analysis model. Antibody avidity was calculated as a relative avidity index and compared between groups using ANOVA.ResultsAustralian Aboriginal otitis-prone children had lower serum IgG titres to rsPilA and ChimV4 than non-Aboriginal otitis-prone children (p<0.001), and non-otitis-prone children (p<0.020). No differences were observed between serum IgG titres from non-Aboriginal otitis-prone children and non-otitis-prone children. There were also no differences in the proportion of high avidity IgG specific for these antigens between these groups. Serum IgG titres to OMP26 were similar between all groups (p>0.670) although otitis-prone children had a higher proportion of high avidity antibodies to this antigen.ConclusionsAustralian Aboriginal otitis-prone children had lower serum IgG titres to 2/3 major NTHi vaccine candidate antigens, suggesting these children are unable to develop persistent IgG responses due to repeated NTHi exposure. These reduced IgG titres may relate to earlier and more frequent exposure to diverse NTHi strains in Aboriginal children through carriage or infection. These data suggest that Aboriginal children may benefit from immunisation with vaccines containing these antigens to increase titres of protective antibodies.

Project description:Influenza A virus (IAV) predisposes individuals to secondary infections with the bacterium Streptococcus pneumoniae (the pneumococcus). Infections may manifest as pneumonia, sepsis, meningitis or otitis media (OM). It remains controversial as to whether secondary pneumococcal disease is due to the induction of an aberrant immune response or IAV induced immunosuppression. Moreover, as the majority of studies have been performed in the context of pneumococcal pneumonia, it remains unclear how far these findings can be extrapolated to other pneumococcal disease phenotypes. Here, we demonstrate that the viral hemagglutinin (HA) mediates bacterial OM by inducing a pro-inflammatory response in the middle ear cavity in a replication-dependent manner. Importantly, our findings show that it is the inflammatory response that mediates pneumococcal replication; not viral suppression of the immune system or epithelial damage. This study provide the first evidence that HA induced inflammation drives pneumococcal replication in the middle ear cavity, which has important consequences to the treatment of pneumococcal OM. Five-day old C57BL/6 mice were colonised intranasally (i.n.) with 2M-CM-^W103 colony forming units (CFU) of S. pneumoniae EF3030Lux in 3 M-BM-5Ls of PBS. Alternatively, mice were mock-infected with an equivalent volume of phosphate buffered saline (PBS). At 14-days of age, infant mice were infected i.n. with 20 plaque forming units (PFU) (PR8/34, Cambridge/34 and WSN/33) or 102.5 PFU (all other virus strains) of egg-grown IAV in 3 M-BM-5Ls of PBS. Viral doses were selected to ensure a reproducible infection with minimum morbidity and no mortality. Six days post-IAV infection, mice were euthanised and organs were collected for analysis. Six independent biological replicates (where both ears from one mouse were pooled to create one sample) were used for each condition and analyzed using the NimbleGen platform (12M-CM-^W135K Mouse Gene Expression Arrays, Roche Nimblegen, USA). Indirect labeling, hybridization and washing was performed according to the manufacturerM-bM-^@M-^Ys instructions. Array images were acquired with a NimbleGen MS200 scanner, and images were processed with NimbleScan software using the RMA algorithm. Data was processed using Arraystar (DNASTAR, USA) with default settings as described in the manual. Differential expression tests were performed with a moderated T-test implemented in Arraystar, followed by FDR correction of the P values (Q-values) according to the method of Storey and Tibshirani

Dataset Information

Otitis-Prone Children Produce Functional Antibodies to Pneumolysin and Pneumococcal Polysaccharides.

Publications

Otitis-Prone Children Produce Functional Antibodies to Pneumolysin and Pneumococcal Polysaccharides.

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