| Functional Immunity to Cross-Reactive Serotype 6A Induced by Serotype 6B in Pneumococcal Polysaccharide Vaccine |
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Kyung Hyo Kim |
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Department of Pediatrics, College of Medicine, Ewha Woman's University, Seoul, Korea |
| 폐구균 다당질 백신 내 혈청형 6B에 의해 유도되는 교차 반응 혈청형 6A에 대한 기능적 면역 |
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김경효 |
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이화여자대학교 의과대학 소아과학교실 |
Correspondence:
Kyung Hyo Kim, Email: kaykim@ewha.ac.kr
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| Abstract |
Purpose
: Streptococcus pneumoniae serotype 6B and 6A are important pathogens in pneumococcal infections. It is commonly assumed that the 6B vaccines elicit antibodies cross-reacting with the 6A serotype and the cross-reactive antibodies protect against infections of 6A. To examine this assumption, we measured the opsonophagocytic capacity to serotype 6A and 6B in adults.
Methods
: Twenty-four adults were immunized with pneumococcal PS vaccine that contains 6B PS. Their preimmune and postimmune sera were studied for the capacity to opsonize 6B and 6A serotypes with opsonophagocytic killing assay.
Results
: Opsonization titers to 6B were significantly higher than those to 6A in preimmune and postimmune sera. Because significant increasesof opsonization titers were observed in adults with polysaccharide vaccines for 6A(cross-reactive) serotype as well as for 6B(vaccine) serotype, 6B PS in vaccine elicited cross-protective antibodies to 6A, but not in all cases. One adult did not have detectable levels of opsonization titers to 6A after immunization.
Conclusion
: Although 6B PS in pneumococcal PS vaccine elicits antibodies cross-reacting with 6A serotype in some adults, it may not occur always. This study should be extended to other age groups such as children and elderly people. The presence of the cross-protection should be directly determined in clinical trials of the pneumococcal vaccines as well as during the postlicensure monitoring surveys by serotyping the clinical isolates of pneumococci. |
| Key Words:
Streptococcus pneumoniae , Pneumococcal polysaccharide type 6 , Antibodies , Cross- reaction , Opsonins |
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