Group-specific antibody levels surrounding invasive pneumococcal illness in children infected with human immunodeficiency virus

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 antibo dy to 6 representative pneumococcal serotypes, There was a wide range (0.16 -30.80 mu g/mL) of pre-SPI anti-PnPs antibody levels to the presumed infect ing serotypes, with a geometric mean level of 0.83 mu g/mL (n = 34), Sevent y-six percent of the antibody values were <2.0 mu g/mL and 95% were <5.0 mu g/mL. Homologous seroresponses (greater than or equal to 4-fold rise in an ti-PnPs antibody) were detected in only 4 (27%) of 15 paired serum samples. Heterologous, noninfecting group seroresponses were detected frequently (7 2%) in the paired serum samples from these 4 homologous group seroresponder s.