Infections with E. coli are a common cause of diarrhoea in weaning rabbits. The present study was conducted to evaluate the changes in the blood concentrations of haptoglobin (Hp), ceruloplasmin (Cp) and fibrinogen (Fb) during experimentally induced E. coli infection in weaning rabbits. A total of 18 rabbits, 40-45 days old and weaned at 4 weeks were used: 12 were inoculated with the E. coli strain type 015:H- suspension (6. 107 cfu) and the 6 remained rabbits served as controls. Blood samples for acute phase proteins (APPs) analysis were collected before (0 h) and at 24 th and 72th hours and on days 7, 11, 18 and 30 after inoculation. The presence of coliforms was investigated in rectal samples on days 1, 6, 11, 16, 25 and 31. The excretion of the 015:H- type began 2 days after experimental challenge in 3 rabbits and was intensified on day 3 whereas mild to severe diarrhoea episodes were observed between the 5 th day to the 21st day in all rabbits except 2. In parallel, bacterial excretion gradually declined. Moreover, Hp concentrations dramatically increased after E. coli inoculation since 24th hours, reached maximal values on day 7 (multiplied by a factor 9) and remained significantly elevated compared to basal values until the 30th day. By contrast, significant changes in Fb and Cp concentrations compared to initial values appeared later (on days 3 and 7 respectively), less intense (maximal concentrations observed on day 11 were only roughly doubled) and were more transient (normal values were obtained on days 30 and 18 respectively). Increases of all APP concentrations were associated with the intensity of the diarrhoea. Moderate positive correlations were evidenced between Hp and Cp or Fb concentrations while Cp and Fb concentrations were strongly correlated. The time course and the magnitude of changes of these APPs induce to consider Cp and Fb as slow reacting positive APPs while Hp has to be classified as a rapid major positive APP useful for early detection of bacterial infections in weaning rabbits, before the clinical appearance of diarrhoea and faecal excretion of E. coli.

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Keywords Acute phase response, Ceruloplasmin, E.coli infection, Fibrinogen, Haptoglobin, Rabbit
Journal Revue de Medecine Veterinaire
Georgieva, T.M. (T. Mircheva), Georgiev, I.P. (I. Penchev), Tanev, S, Vachkov, A. (A.), Petrov, V. (V.), Eckersall, P.D. (P. D.), … Nikolov, J. (J.). (2009). Variations of acute phase protein (haptoglobin, fibrinogen and ceruloplasmin) concentrations in weaning rabbits after experimental infection with E.coli. Revue de Medecine Veterinaire, 160(3), 133–139.