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Human antibodies to pneumococcal surface protein A in health and disease
A Virolainen1, W Russell, M J Crain
1University of Alabama at Birmingham, USA. anni.virolainen@helsinki.fi
Insights
Antibodies to Pneumococcal surface protein A (PspA) are present in humans and may protect against pneumococcal disease. Lower PspA antibody levels were observed in children with invasive pneumococcal infections.
Area of Science:
- Immunology
- Microbiology
- Vaccinology
Background:
- Streptococcus pneumoniae infections significantly impact young children with impaired antibody responses.
- Pneumococcal surface protein A (PspA) is a promising vaccine candidate for pediatric populations.
Purpose of the Study:
- To investigate the presence and role of antibodies to PspA in human sera.
- To assess PspA antibody levels in healthy individuals and children with invasive infections.
Main Methods:
- Western blot analysis and enzyme immunoassay were used to detect and quantify PspA antibodies.
- Human sera from healthy adults and children (healthy and ill) from Finland and Alabama were analyzed.
Main Results:
- Human antibodies to PspA demonstrated cross-reactivity across various pneumococcal strains.
- Healthy adults and children had detectable IgG antibodies to PspA.
- Children with invasive pneumococcal disease exhibited significantly lower PspA antibody titers compared to those with other infections.
Conclusions:
- This study confirms the presence of PspA antibodies in human sera during health and disease.
- The findings suggest that PspA antibodies may contribute to protection against pneumococcal infections in children.
Background:
Diseases caused by Streptococcus pneumoniae have a high impact in young children whose ability to mount antibodies to capsular polysaccharides is impaired. Pneumococcal surface protein A (PspA) is a potential vaccine candidate for this age group.
Methods:
We used Western blot analysis and enzyme immunoassay to study human sera of healthy adults from Alabama (n = 20) and from Finland (n = 21), healthy children from Finland (n = 20) and ill children from Finland, those with pneumococcal invasive infection (n = 26) and those with nonpneumococcal invasive infection (n = 26).
Results:
Human antibodies to PspA exhibited strong cross-reactivity among different pneumococcal strains. The geometric mean titer of IgG antibody to PspA in sera from 21 healthy adults was 4,040, from ten 3-year-old healthy children 1,080 and from ten 2-month-old healthy children 1,650. The geometric mean titer of PspA antibody of acute phase sera of children with invasive pneumococcal disease was 140, significantly (P < 0.001) lower than the respective value, 1,020, for children with infection caused by other bacteria.
Conclusions:
We demonstrate for the first time the existence of antibodies to PspA in human sera in health and disease. The findings in ill children suggest that antibodies to PspA might play a role in protection against pneumococcal disease.