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Maternal pneumococcal conjugate immunization protects infant chinchillas in the pneumococcal otitis media model
David M Hajek1, Moses Quartey, G Scott Giebink
1Otitis Media Research Center and the Department of Pediatrics, University of Minnesota School of Medicine, Minneapolis 55455, USA.
Insights
Maternal immunization with pneumococcal conjugate vaccines (PCVs) protects infants from early pneumococcal otitis media (POM). This strategy significantly reduced POM incidence, severity, and mortality in infant chinchillas.
Area of Science:
- Immunology
- Pediatrics
- Microbiology
Background:
- Infant immunization with pneumococcal conjugate vaccines (PCVs) is often insufficient during the first 4-6 months of life.
- This period coincides with the onset of recurrent pneumococcal otitis media (POM) in infants.
- Early-life POM and invasive pneumococcal disease pose significant health risks to infants.
Purpose of the Study:
- To investigate the efficacy of a maternal pneumococcal immunization strategy in preventing early infant POM.
- To assess the impact of maternal PCV immunization on antibody concentrations in both mothers and infants.
- To evaluate the protective effects against experimental POM and invasive pneumococcal disease in infant offspring.
Main Methods:
- Pregnant chinchillas (dams) were immunized with heptavalent PCV or saline.
- Post-partum, maternal and infant (kit) blood samples were collected for antibody concentration measurement (ELISA).
- Infant kits were challenged intranasally with a vaccine-type pneumococcal strain (19F) to assess POM and mortality.
Main Results:
- Immunized dams and their kits exhibited significantly higher anti-pneumococcal IgG antibody titers compared to controls.
- Maternal immunization significantly reduced the incidence (p=0.05) and severity (p<0.01) of experimental POM in kits.
- The strategy was 82% effective in preventing mortality from invasive pneumococcal disease; pre-challenge infant antibody levels predicted POM severity.
Conclusions:
- Maternal immunization with PCV is a viable strategy to confer protection against early-onset POM in infants.
- This approach effectively reduces the burden of POM and invasive pneumococcal disease in the vulnerable early-infancy period.
- Further research supporting maternal PCV immunization is warranted to combat infant pneumococcal infections.
Abstract:
Infant immunization with pneumococcal polysaccharide-protein conjugate vaccines (PCVs) is unlikely to elicit protective serum antibody concentrations during the first 4-6 months of life, when recurrent pneumococcal otitis media (POM) often begins. We therefore investigated a maternal pneumococcal immunization strategy to prevent early infant POM. Pregnant chinchillas (dams) received injections of heptavalent PCV or saline. Post-partum maternal and infant (kits) blood samples were obtained, and kits were subsequently challenged by intranasal inoculation of a vaccine-type pneumococcal strain (19F). Anti-pneumococcal capsular polysaccharide IgG antibody (Ab) concentration was measured using an ELISA in maternal and kit serum samples. Immunized dams and their kits had significantly higher Ab titers than control dams and their kits. Antibody titer in kits declined with a half-life of 12 days. Maternal immunization significantly reduced both the incidence (p = 0.05) and severity (p <0.01) of experimental POM in chinchilla kits, and was 82% effective at preventing mortality from invasive pneumococcal disease. Pre-challenge serum Ab concentration in kits was the single best predictor of POM severity (r = -0.66). This experiment strongly supports the hypothesis that maternal immunization with PCV will reduce the burden of early infant POM and invasive pneumococcal disease.