Monoclonal antibodies to Shigella LPS useful for vaccine production

ABSTRACT

There is a significant need for an effective multivalent Shigella vaccine targeting the most prevalent serotypes. Most Shigella vaccines under development utilize serotype-specific LPS as a major component based on protection and epidemiological data. As vaccine formulations advance from monovalent to multivalent, assays and reagents need to be developed to accurately and reproducibly quantitate the amount of LPS from multiple serotypes in the final product. To facilitate the effort, we produced 36 hybridomas secreting monoclonal antibodies against the O-antigen on the LPS from S. flexneri 2a, S. flexneri 3a and S. sonnei. We used six of these monoclonal antibodies for inhibition ELISA, measuring LPS with high sensitivity and specificity. It was also demonstrated that the Shigella-serotype specific Mabs were useful for bacterial surface staining detected by flow cytometry. These Mabs are also useful for standardizing the serum bactericidal assays for Shigella. Functional assays, such as the in vitro bactericidal assay, are necessary for vaccine evaluation and may serve as an immunological correlate of immunity. A S. flexneri 2a-specific monoclonal antibody killed S. flexneri 2b suggesting that S. flexneri 2a LPS may induce cross-protection against S. flexneri 2b. Overall, the Shigella LPS-specific Mabs described have potential utility to the vaccine development community for assessing multivalent vaccine composition and as a reliable control for multiple immunoassays used to assess vaccine potency.