Full Length Research Paper

Salmonella Enteritidis experimental infection in chickens: Effects of challenge dose on serum immunoglobulin G antibody response

Ishola, Olayinka Olabisi¹* and Holt, Peter.S.²

¹Department of Veterinary Public Health and Preventive Medicine, University of Ibadan, Ibadan, Nigeria.

²Egg Safety and Quality Research Unit, United States Department of Agriculture (USDA), Athens, USA.

*Corresponding author. E-mail: olayinkaishola@yahoo.com. Tel: 234-803-697-6193. Fax: 234-2- 8103043.

Accepted 6 October, 2008

Salmonella enterica serovar Enteritidis is a food borne pathogen of humans causing food-poisoning and sometimes deaths. In order to control egg-borne transmission of Salmonella Enteritidis to humans, prompt and accurate detection of infected poultry flocks is essential. This paper examined the effects of challenge dose of Salmonella Enteritidis on detection of specific immunoglobulin G (IgG) antibody in serum of experimentally infected chickens. An indirect ELISA technique based on lipopolysaccharide (LPS) antigen of Salmonella Enteritidis was used. Two groups of specific-pathogen-free chickens were infected orally with 10⁸ and 10⁴ colony forming units (cfu) of Salmonella Enteritidis. Serum samples were collected prior to challenge and at five subsequent weekly intervals. Levels of serum IgG antibody response observed in the chickens infected with 10⁸ cfu of Salmonella Enteritidis were significantly stronger (P<0.05) than those of the 10⁴ cfu group. Although considerable IgG response was seen with most of the chickens by 2 weeks post-infection, highest group mean optical density values of 2.177 and 0.984 were observed at 5 weeks for 10⁸ and 10⁴ cfu Salmonella Enteritidis infected groups, respectively. Chickens exposed to few Salmonella colonies during infection do not produce high IgG antibody and may continue to contaminate the flock.

Key words: Salmonella Enteritidis, immunoglobulin G, serum, chickens, antibodies.