Sodium Dodecyl Sulfate-cured Nalidixic Acid Resistant 85-kb Plasmid Salmonella gallinarum Immunoglobulin G Response in Brown Layer Hens
Ogochukwu P. Offor
Department of Pharmaceutical Microbiology and Biotechnology, Faculty of Pharmaceutical Sciences, University of Nigeria, Nsukka, Nigeria.
Ngozi Offor
Department of Pharmaceutics, Faculty of Pharmaceutical Sciences, University of Nigeria, Nsukka, Nigeria.
Damian C. Odimegwu
Department of Pharmaceutical Microbiology and Biotechnology, Faculty of Pharmaceutical Sciences, University of Nigeria, Nsukka, Nigeria.
Wilfred I. Ugwuoke
Department of Veterinary Anatomy, Faculty of Veterinary Medicine, University of Nigeria, Nsukka, Enugu State, Nigeria.
Ebele B. Onuigbo *
Department of Pharmaceutical Microbiology and Biotechnology, Faculty of Pharmaceutical Sciences, University of Nigeria, Nsukka, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Aim: Fowl typhoid vaccination is a necessary complement to farm hygiene in reducing antimicrobial resistance caused by extensive prophylaxis of antibiotics in poultry. This study was undertaken to develop a vaccine candidate from a virulent strain by plasmid-curing.
Place and Duration of Study: The research was carried out in the Department of Pharmaceutical Microbiology and Biotechnology, University of Nigeria Nsukka, for six months.
Methodology: Thirty day-old pullets were divided into three groups of ten birds each. This comprised a negative control group (unvaccinated) (NEG), a live SG9R vaccine positive group (SG9R), and a nalidixic acid resistant plasmid-cured 85-kb plasmid Salmonella gallinarum (NAR). Plasmid curing of the virulent strain was done by incubating in sodium dodecyl sulfate (SDS) and loss of the 85-kb plasmid was identified and determined on agarose gel electrophoresis. Vaccination was done subcutaneously at 4 and 7 weeks of age, followed by challenge with the virulent S. gallinarum. IgG was measured using Enzyme-linked Immunosorbent Assay (ELISA). The scalability of the SDS-cured nalidixic acid resistant 85kb plasmid Salmonella gallinarum immunity was demonstrated by vaccinating layer birds and comparing the humoral immunity with that of a commercial fowl typhoid vaccine (SG9R).
Results: There were higher IgG levels in the NAR group than the SG9R group. Protection was above 70 % in the vaccinated groups.
Conclusion: The outcome of this present study shows that vaccination with viable cells of sodium dodecyl sulfate- cured nalidixic acid resistant 85-kb plasmid Salmonella gallinarum (NAR) provided layer birds with protective humoral immunity against subsequent challenge with the parent virulent strain containing the 85-kb plasmid.
Keywords: Salmonella gallinarum, plasmid, curing, immunoglobulin G, layer hens