Journal of Pure and Applied MicrobiologyVol. 9 No. 3

Isolation of Vi Antigen of Salmonella typhi by a Simple Method and its Immunization Evaluation in Animal Model

Ali Asgari1, Elahe Akbarifar2, Adel Hamidi3 and Majid Moghbeli2*

1Department of Infectious Diseases, AJA University of Medical Sciences, Tehran, Iran. 2Biology Department, Islamic Azad University, Damghn Branch, Damghan, Iran. 3Young Researchers and Elite Club, Karaj Branch, Islamic Azad University, Karaj, Iran.

Received on 10 April 2015 and accepted on 03 July 2015



Typhoid is a widespread disease. The most common cause of this disease is Salmonella typhi. Emergence of multidrug resistant strains has complicated the treatment of typhoid so that it is considered as a threat to future epidemics. Vaccination is accounted as the most successful approach for dealing with this disease. Polysaccharide capsule of S. typhi is used as a safe and facile tool for preventing typhoid. The aim of this study was to isolate S. typhi Vi antigen and perform animal tests in order to examine its potential for human vaccination. S. typhi Ty2 strain was cultivated in Muller-Hinton agar medium. The polysaccharide capsule was extracted by cetavlon organic solvent after collecting the cells and suspending them in physiological serum. The nucleic acid and protein content of the samples were measured by spectrophotometry at 260 nm and Bradford's test, respectively. SDS-PAGE and immunodiffusion were used to analyze Vi antigen. This antigen was injected to mice and rabbit in order to examine immunization and pyrogenesity, respectively. The smear of the test sample was completely similar to that of the standard. Occurrence of the precipitation zone confirmed the presence of Vi antigen. It produced 80% immunization in mice and its injection to rabbit demonstrated that LPS was eliminated to a great extent. The proposed method can be a facile and cheap procedure with sufficient efficiency for Vi antigen purification.

Keywords : Vi antigen, Salmonella typhi, Vaccine, Purification.