Blood serum concentrations of total proteins and main protein fractions in weaning rabbits experimentally infected with E. coli

Abstract

The objective of the present study was to evaluate the changes in the concentrations of major blood proteins associated with experimental E. coli infection in weaning rabbits. For that, in the assay group. 12 weaning White New Zealand rabbits (45 days old) were orally infected with a bacterial suspension of enteropathogenic E. coli strain type O15:H- (6.107 cfu) whereas the 6 control rabbits received only 0.9% NaCI solution. Serum total protein, albumin, globulin and lysozyme concentrations as well as plasma fibrinogen concentrations were measured before (0h) and I, 3, 7, 11, 18 and 30 days after oral treatment. In parallel, presence of coliforms was investigated in rectal samples on days 0, 1.6. 11, 16, 25 and 30. Infected rabbits began to excrete E. coli strains on day 2 after administration, whereas the first signs of diarrhoea were observed on day 5. Between days 11 and 18 severe diarrhoea was found in all rabbits and then clinical signs gradually disappeared although 3 rabbits continue to excrete the bacteria on day 30. In inoculated rabbits, hypoproteinemia and hypo-albuminemia compared to control values were evidenced since the 7th day whereas the blood concentrations of lysozyme and fibrinogen at a lesser extend were dramatically increased on days 11-18 and on days 3-18 respectively, leading to a significantly lowered albumin/globulin ratio since the 11th day. These results confirm that albumin is a negative acute phase protein (APP) while fibrinogen and lysozyme were 2 positive APP in response to an experimental bacterial infection in rabbits