Journal of Vaccines & Vaccination

Immunogenicity and protective efficacy of live trans-conjugant Shigella hybrid (LTSH) strain in animal model

8^th Indo Global summit and Expo on Vaccines, Therapeutics & Healthcare

November 02-04, 2015 HICC, Hyderabad, India

Ushasi Bhaumik, Hemanta Koley and Dhrubajyoti Nag

National Institute of Cholera and Enteric Diseases, India

Posters-Accepted Abstracts: J Vaccines Vaccin

Abstract:

An avirulent, live trans-conjugant Shigella hybrid (LTSHÎ?stx) strain was constructed in our earlier study by introducing a plasmid vector, pPR1347 carrying both the RFB gene cluster and the RFC gene of Salmonella typhimurium, into a Shiga-toxin gene deleted Shigella dysenteriae. Trans-conjugants were Sereny negative and were unable to invade the HeLa cells. Trans-conjugants exhibited strong cross reactivity with S. dysenteriae 1 antisera but they showed weak reaction with Salmonella typhimurium antisera. Serum IgG and IgA titers showed exponential increase during oral immunization and peaking on the 28th day and remained at that level till the 120th day in both the rabbit and the mouse models. Antigen specific sIgA was also determined from intestinal lavage of immunized mice and fecal sample of immunized rabbits. Protection studies showed 100% homologous and up to 70% heterologous protection against the challenge with wild type shigella in rabbits and mice model. Three successive oral administrations of LTSHÎ?stx to female adult mice produced comprehensive passive homologous and heterologous protection in their offspring against challenge with wild type circulating shigellae. The stomach extracts of neonates from immunized mice, mainly containing motherâ??s milk, contained significant levels of anti-LTSHÎ?stx immunoglobulin. These studies suggest that the LTSHÎ?stx can be a new live oral vaccine candidate against shigellosis in the near future.

Biography :

Ushasi Bhaumik completed her MSc in Biotechnology in 2014. She has joined the lab in National Institute of Cholera and Enteric Disease for her PhD under Dr. Hemanta Koley. She is a DST-INSPIRE fellow. She is currently focused on “Outer membrane vesicle of Shigella and its immunomodulatory role on immune system”.

Email: bhaumikushasi7@gmail.com