Assessment of Mouse Ileal loop Protection against Clinically Isolated Vibrio cholerae Outer Membrane Vesicles as a Vaccine Candidate

Document Type: Original Articles

Authors

1 Department of Microbiology, Pasteur Institute of Tehran, Iran

2 Department of Mycobacteriology and Pulmonary Research, Pasteur Institute of Tehran, Iran

3 Department of Biotechnology Research, Pasteur Institute of Tehran, Iran

4 Department of Nano-Biotechnology, Pasteur Institute of Teran,Iran

Abstract

ABSTRACT
Cholera, a life-threatening disease caused by the Gram-negative bacterium Vibrio cholera, remains as a concern in developing countries. Present study reports the immunogenicity and protective immunity of outer membrane vesicles (OMVs) and combination of OMV and killed whole-cell (WC) of a local strain isolated in the last outbreak in Iran as well as reference strain of V. cholerae El Tor O1 in comparison with Dukoral vaccine in mice model. The protein content, morphology, and size of extracted OMVs were evaluated by electrophoresis and microscopic analyses, respectively. The serum titer of total IgG, IgG1, IgG2a, as well as secretory IgA and total IgG in different treatment of mice groups, were determined by ELISA assay.
In addition, fluid accumulation assay in the context of resistance to live strain of V. cholerae in ligated ileal loops was carried out to determine of cholera infection by OMV or combination of OMV and WC in comparison with Dukoral vaccine.
SDS-PAGE analysis of purified OMVs indicated proteins profile ranging from 34 to 52 kDa and transmission electron microscopy (TEM) revealed the spherical shaped vesicles of 50-200 nm diameter. ELISA assay indicated significant titers of systemic and mucosal immune anti-OMV IgGs in immunized BALB/c mice with different vaccine regimens; additionally, the fluid accumulation evolution demonstrated a notable increase in FA ratio. The results indicated that the combination of WC-OMV of local strain is able to induce a high level of antibody responses exhibiting more protection than OMV or WC, separately. Additionally, it can be considered as an effective immunogen against V. cholerae.

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