Journal of Vaccines & Vaccination

Preparation and evaluation of immunogenic conjugates of Salmonella enterica serovars typhi and paratyphi O-specific polysaccharides with diphtheria toxoid

7^th Middle East - Global Summit and Expo on Vaccines & Vaccination

September 28-29, 2015 Dubai, UAE

Abdul Haque1, Aamir Ali2 and Rodney Carbis3

1The University of Faisalabad, Pakistan
2National Institute for Biotechnology and Genetic Engineering, Pakistan
3International Vaccine Institute, South Korea

Posters-Accepted Abstracts: J Vaccines Vaccin

Abstract:

Enteric fever caused by Salmonella enterica serovars typhi (S. typhi) and paratyphi (S. paratyphi) is a major health problem particularly in developing countries. The available vaccines are effective for a short time and do not induce an immune response in children below 2 years of age. Conjugate vaccines due to their protein component induce a T-cell dependent immune response characterized by enhanced immunogenicity in all ages. In this study, O-specific polysaccharides (OSP) of S. typhi and S. paratyphi were conjugated to diphtheria toxoid (DT) with and without adipic acid dihydrazide (ADH) as a linker. These conjugates (OSP-AH-DT) were then evaluated for their immunogenicity using mice as a model and showed significantly higher levels of IgG ELISA titers than lipopolysaccharides alone. Different immunization schedules were compared and it was found that schedule-B (three injections with 4-weeks interval) induced higher immune responses than schedule-A (three injections with 2-weeks interval). We showed that diphtheria toxoid can be successfully employed as a carrier protein for conjugation with OSPs of S. typhi and S. paratyphi and play an important role in facilitating adequate immune response.

Biography :

Email: ahaq_nibge@yahoo.com