Vol 10, Issue 11, 2017 Online - 2455-3891 Print - 0974-2441 PREPARATION AND EVALUATION OF CHEMICALLY INACTIVATED SALMONELLA ENTERITIDIS VACCINE IN CHICKENS MOUNIR M EL-SAFTY 1 , HALA MAHMOUD 1 , EMAN SA ZAKI 2 , HOWAIDA I ABD-ALLA 3 * 1 Department of Evaluation of Inactivated Viral Poultry Vaccines, Central Laboratory for Evaluation of Veterinary Biologics, Abbassia 13181, Cairo, Egypt. 2 Department of Aerobic Bacterial Vaccines, Veterinary Serum and Vaccine Research Institute, Abbasia, Cairo, Egypt. 3 Department of Chemistry of Natural Compounds, Pharmaceutical Industries Division, National Research Centre, Dokki-Giza 12622, Egypt. Email: howaida_nrc@yahoo.com Received: 23 May 2017, Received and Accepted: 09 August 2017 ABSTRACT Objective: Salmonella enteritidis ghosts (SEGs) is a non-living empty bacterial cell envelopes which were generated using a different concentration of sodium hydroxide (NaOH) 6.4 mg/mL and evaluated as a vaccine candidate in specific pathogen-free (SPF) chicken. SEGs have been produced by chemical-mediated lysis and evaluated the potential efficacy of chemically induced SEG vaccine and its ability to induce protective immune responses against virulent S. enteritidis challenge in SPF chickens. Methods: SPF chickens were divided into three groups: Group A (non-vaccinated control), Group B (vaccinated with prepared vaccine), and Group C (vaccinated with commercial vaccine). Results: Vaccination of SPF chicken with SEGs induced higher immune responses before and after virulent challenge. SPF chicken vaccinated with SEGs showed increasing in serum enzyme-linked immunosorbent assay (ELISA) antibodies. During the vaccination period, Groups B and C showed higher serum antibody titer compared to Group A. The minimal inhibitory concentration (MIC) of NaOH was capable of inducing non-living SEGs, and it has successfully generated non-living SEGs by MIC of NaOH. Conclusion: It is a one-step process which means easy manufacturing and low production cost compared to protein E-mediated lysis method. Chemically induced SEG vaccine is a highly effective method for inducing protective immunity. This study strongly suggests that SEGs will be a permissive vaccine, as the method of inhibition of S. enteritidis was safe and cheaper than other methods, and it gave a good protection. Keywords: Salmonella enteritidis ghost, Specific pathogen-free, Vaccine, Enzyme-linked immunosorbent assay, Sodium dodecyl sulfate polyacrylamide gel electrophoresis. INTRODUCTION The Salmonella consists of a range of very closely related bacteria, some of which cause illness in both animals and people, and some types cause illness in animals but not in people [1]. Salmonella enteritidis, a Gram-negative bacterium, is a worldwide leading zoonotic food-borne bacterial pathogen, causing diarrhea and gastroenteritis in humans and animals [2]. S. enteritidis is transmitted to progeny through developing embryo and infects generally through contaminated eggs or undercooked specific pathogen-free (SPF) chicken products [3]. Salmonellosis is an important public health problem and causes large economic losses in the SPF chicken industry. Furthermore, in vivo and in vitro studies suggested that the bacterial virulence ability to invade and survive in epithelial cells is crucial for salmonellosis [4]. The SPF chicken model of salmonellosis has been extensively studied [5]. These studies indicate that an SPF chicken model can be used for salmonellosis. Progress in science has always been the major driving force for the development of effective agents that are given to healthy individuals to prevent infections [6,7]. Vaccination is an effective tool for the control and prevention of Salmonella infections. Previous studies have shown that the generation of live attenuated, killed, and subunit vaccines have been attempted [8], but their efficacy is not always optimal. Whole-cell killed Salmonella vaccine has the ability to stimulate beneficial antibody responses. However, it confers incomplete protection and is more reactogenic. Live attenuated vaccine is able to induce mucosal, cellular immune responses in chickens [9,10]. In addition, it protects chickens against a lethal challenge, but there is a possibility of dangerous reversion [11]. To overcome these drawbacks, there is an urgent need to find other safe and efficacious vaccine approaches to protect against salmonellosis. Bacterial ghosts (BGs) are novel and non-living empty bacterial cell envelopes raised from Gram-negative bacteria, which represent a new avenue in vaccine technology [12]. In general, the most common method for producing BGs is based on the phage-derived lysis gene E. The expression of protein E-mediated lysis leads to the formation of transmembrane pores, which consequently leads to loss of cytoplasmic contents. The resultant BGs share their functional and antigenic determinants of the envelope and represent an excellent vaccine candidate [12]. BGs from pathogenic bacteria were reported to be controlled and can protect against infectious diseases [13]. The mucosal immunizations with Escherichia coli ghosts were reported to induce protective immunity in an SPF chicken model [14]. Furthermore, the oral vaccination of Edwardsiella tarda ghosts induced higher protection against infection in mice [15]. Moreover, BGs were able to target-specific organ or tissue, indicating that they are a powerful system for drug and DNA delivery. There were several studies demonstrated BG vaccine production by genetically engineered method [16,17]. However, this genetic inactivation method still has some risk in its use as a vaccine. Therefore, in this study, it was demonstrated an alternative method to produce BGs from S. enteritidis strain using the minimal inhibitory concentration (MIC) of sodium hydroxide (NaOH). © 2017 The Authors. Published by Innovare Academic Sciences Pvt Ltd. This is an open access article under the CC BY license (http://creativecommons. org/licenses/by/4. 0/) DOI: http://dx.doi.org/10.22159/ajpcr.2017.v10i11.20144 Research Article