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Published on: June 15, 2018
Group-specific antibody levels surrounding invasive pneumococcal illness in children infected with human
J C King1, W Borkowsky, N Mahidhara
1Department of Pediatrics, University of Maryland School of Medicine, Baltimore, MD 21201, USA. jking@som.umaryland.edu.
Insights
Children with human immunodeficiency virus (HIV) show poor antibody responses to pneumococcal infections. Most HIV-infected children had low pneumococcal antibody levels, with limited protective immune memory after systemic pneumococcal illness (SPI).
Area of Science:
- Immunology
- Pediatrics
- Infectious Diseases
Background:
- Children with human immunodeficiency virus (HIV) are at increased risk for invasive pneumococcal disease.
- Assessing immune responses in HIV-infected children is crucial for understanding their susceptibility to infections.
Purpose of the Study:
- To measure pneumococcal antibody levels in children with HIV surrounding episodes of systemic pneumococcal illness (SPI).
- To evaluate the antibody response to pneumococcal polysaccharides (PnPs) in HIV-infected children after SPI.
Main Methods:
- Archived serum samples from 28 HIV-infected children with 34 SPI cases were analyzed.
- Enzyme-linked immunosorbent assay (ELISA) was used to measure antipneumococcal polysaccharide (PnPs) IgG antibody levels to 6 serotypes.
- Serum samples were collected before and after SPI episodes.
Main Results:
- Pre-SPI antibody levels to infecting serotypes varied widely (0.16-30.80 microg/mL), with a geometric mean of 0.83 microg/mL.
- 76% of antibody values were below 2.0 microg/mL, indicating low pre-existing immunity.
- Homologous seroresponses (≥4-fold rise) were observed in only 27% of paired samples, with frequent heterologous responses.
Conclusions:
- HIV-infected children exhibit inadequate antipneumococcal antibody levels and poor seroresponse following SPI.
- Low pre-existing antibody levels and limited homologous immune memory suggest continued vulnerability to pneumococcal infections in this population.
Abstract:
Pneumococcal antibody levels surrounding systemic pneumococcal illness (SPI) were measured in children infected with human immunodeficiency virus (HIV). Archived serum samples were collected from 28 HIV-infected children who had 34 cases of SPI, caused by pneumococcal groups 4, 6, 9, 14, 19, and 23. Serum samples collected within 23 weeks before and 13 weeks after the SPI were assayed by ELISA for antipneumococcal polysaccharide (PnPs) IgG antibody to 6 representative pneumococcal serotypes. There was a wide range (0. 16-30.80 microg/mL) of pre-SPI anti-PnPs antibody levels to the presumed infecting serotypes, with a geometric mean level of 0.83 microg/mL (n=34). Seventy-six percent of the antibody values were <2.0 microg/mL, and 95% were <5.0 microg/mL. Homologous seroresponses (>/=4-fold rise in anti-PnPs antibody) were detected in only 4 (27%) of 15 paired serum samples. Heterologous, noninfecting group seroresponses were detected frequently (72%) in the paired serum samples from these 4 homologous group seroresponders.
