A bivalent conjugate vaccine containing PspA families 1 and 2 has the potential to protect against a wide range of Streptococcus pneumoniae strains and Salmonella Typhi

作者：Kothari Neha; Kothari Sudeep; Choi Young Joo; Dey Ayan; Briles David E; Rhee Dong Kwon; Carbis Rodney^*

来源：Vaccine, 2015, 33(6): 783-788.

DOI：10.1016/j.vaccine.2014.12.032

• Vaccine development
• Vi-PspA conjugate vaccine
• Streptococcus pneumoniae
• Salmonella Typhi

Previously we showed that conjugation of pneumococcal surface protein A (PspA) to Vi capsular polysaccharide from Salmonella Typhi enhanced the anti-PspA response without the need to add adjuvant. In the current study conjugates consisting of the a helical regions of PspA families 1 or 2 bound to Vi were used to vaccinate mice to test their ability to protect against a lethal intravenous challenge of a range of various strains of Streptococcus pneumoniae. Conjugate vaccine containing PspA family 1 provided good protection from PspA family 1 challenge strains but offered very little protection against PspA family 2 challenge strains. Similarly, PspA family 2 conjugates provided good protection from PspA family 2 challenge strains and poor protection against PspA family 1 challenge strains. This observation was supported by the low levels of cross-reactivity of PspA antibodies seen in ELISA plates coated with the heterologous PspA family. Cytokine profiles showed a mixed Th1/Th2 response to Vi and the Vi-PspA conjugates. IgG subclass analysis of the anti-Vi response showed a shift from predominantly IgG2a/3 to IgG1 after conjugation to PspA was consistent with other polysaccharide conjugate vaccines. The results demonstrate that conjugation of the a helical region of PspA to Vi enhances its capacity to induce a protective immune response and that a vaccine based on the a helical region of PspA should contain PspA from both families I and 2 to achieve broad cross-protection.

• 出版日期2015-2-4