Title Gamma-irradiation of Streptococcus pneumoniae for the use as an immunogenic whole cell vaccine
Author Min Yong Jwa1, Soyoung Jeong1, Eun Byeol Ko1, A Reum Kim1, Hyun Young Kim1, Sun Kyung Kim1, Ho Seong Seo2, Cheol-Heui Yun3, and Seung Hyun Han1*
Address 1Department of Oral Microbiology and Immunology, DRI, and BK21 Plus Program, School of Dentistry, Seoul National University, Seoul 08826, Republic of Korea, 2Research Division for Biotechnology, Korea Atomic Energy Research Institute, Jeongeup 56212, Republic of Korea, 3Department of Agricultural Biotechnology and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 08826, Republic of Korea
Bibliography Journal of Microbiology, 56(8),579–585, 2018,
DOI 10.1007/s12275-018-8347-1
Key Words vaccine, Streptococcus pneumoniae, gamma-irradiation, killed whole cell vaccine
Abstract Streptococcus pneumoniae is a major respiratory pathogen that causes millions of deaths worldwide. Although subunit vaccines formulated with the capsular polysaccharides or their protein conjugates are currently-available, low-cost vaccines with wide serotype coverage still remain to be developed, especially for developing countries. Recently, gamma- irradiation has been considered as an effective inactivation method to prepare S. pneumoniae vaccine candidate. In this study, we investigated the immunogenicity and protective immunity of gamma-irradiated S. pneumoniae (r-SP), by comparing with heat-inactivated S. pneumoniae (h-SP) and formalin-inactivated S. pneumoniae (f-SP), both of which were made by traditional inactivation methods. Intranasal immunization of C57BL/6 mice with r-SP in combination with cholera toxin as an adjuvant enhanced S. pneumoniaespecific antibodies on the airway mucosal surface and in sera more potently than that with h-SP or f-SP under the same conditions. In addition, sera from mice immunized with r- SP potently induced opsonophagocytic killing activity more effectively than those of h-SP or f-SP, implying that r-SP could induce protective antibodies. Above all, immunization with r-SP effectively protected mice against S. pneumoniae infection. Collectively, these results suggest that gamma- irradiation is an effective method for the development of a killed whole cell pneumococcal vaccine that elicits robust mucosal and systemic immune responses.