Serum levels of anti-PspA and anti-PspC IgG decrease with age and do not correlate with susceptibility to experimental human pneumococcal colonization.

Araujo, Adriano P, Colichio, Gabriela B C, Oliveira, Maria Leonor S, German, Esther, Nikolaou, Elissave, Chen, Tao ORCID: https://orcid.org/0000-0002-5489-6450, Adler, Hugh ORCID: https://orcid.org/0000-0003-4437-2298, Ferreira, Daniela ORCID: https://orcid.org/0000-0002-0594-0902 and Miyaji, Eliane N (2021) 'Serum levels of anti-PspA and anti-PspC IgG decrease with age and do not correlate with susceptibility to experimental human pneumococcal colonization.'. PLoS ONE, Vol 16, Issue 2, e0247056.

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Abstract

Older adults are at increased risk of pneumococcal disease. This work aims to evaluate whether there is any decrease in serum IgG against variants of the antigens Pneumococcal surface protein A (PspA) and Pneumococcal surface protein C (PspC) in healthy adults with increasing age. Levels of IgG against PspA and PspC variants were determined by ELISA in serum samples comparing volunteers 18-30 years of age with volunteers who were 50-70+ before and after an experimental pneumococcal colonization challenge. The serotype 6B strain used in the challenge belongs to a minor group of pneumococcal isolates expressing two PspC variants. There was a decrease in levels of IgG with increasing age for the most common PspA variants and for all PspC variants analyzed. No correlation was found between basal levels of IgG against these antigens and protection against colonization. There was an increase in levels of IgG against PspA variants that are more cross-reactive with the variant expressed by the challenge strain post challenge in younger individuals who became colonized. Since the challenge strain used in our study expresses two different PspC variants, an increase in serum IgG against all PspC variants tested was observed in younger individuals who became colonized. For some of the antigen variants tested, a decrease in serum IgG was observed in young volunteers who were challenged but did not become colonized. Serum IgG antibodies against PspA and PspC variants thus decrease with age in healthy adults, but there is no correlation between levels of IgG against these antigens and protection against human experimental colonization. Though no correlation between naturally induced serum IgG antibodies against PspA and PspC and protection against colonization was observed, these results do not rule out the protective potential of these antigens as vaccines against pneumococcal infections.

Item Type:	Article
Subjects:	QW Microbiology and Immunology > Bacteria > QW 142 Gram-positive bacteria (General) QW Microbiology and Immunology > Reference Works. General Immunology > QW 520 Research (General) QW Microbiology and Immunology > Antigens and Antibodies. Toxins and Antitoxins > QW 570 Serology. WC Communicable Diseases > Infection. Bacterial Infections > Bacterial Infections > WC 217 Pneumococcal infections
Faculty: Department:	Clinical Sciences & International Health > Clinical Sciences Department
Digital Object Identifer (DOI):	https://doi.org/10.1371/journal.pone.0247056
Depositing User:	Julie Franco
Date Deposited:	03 Mar 2021 12:14
Last Modified:	03 Mar 2021 12:14
URI:	https://archive.lstmed.ac.uk/id/eprint/17153

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