Submitted to: Poultry Science Meeting
Publication Type: Abstract Only
Publication Acceptance Date: August 11, 1999
Publication Date: N/A
Technical Abstract: The cell wall components of both Gram (-) and Gram (+) bacteria cause immunological stress which is responsible for the virulence of these organisms. To understand whether there is a common physiological response to bacterial components that can be used as diagnostic markers of infection in poultry, we injected birds with lipopolysaccharide (LPS, 4mg/kg BW), or dried whole cells of S. aureus (12 mg/kg BW). Serum chemistry and interleukin-6 (IL-6) levels were measured in six birds in each group at 3, 6, 12, and 24 h following injection using a clinical chemistry analyzer and a B9 hybridoma bioassay, respectively. Serum IL-6 levels were elevated in both S. aureus and LPS-injected birds at 3 h post-treatment, reached a maximum at 6 h, and then decreased at 12 h. At 24 h serum IL-6 level decreased significantly, whereas in control birds, serum IL-6 level was insignificant or below the limits of detection at all time points. The only consistent changes in both LPS and S. aureus-treated birds at all time points were a decrease in concentrations of serum cholesterol and high density lipoprotein (HDL). There were other transient changes in some blood parameters, such as a decrease in the levels of triglycerides at 3 and 12 h time points following both LPS and S. aureus injections, and a decrease in serum P and Fe levels at 3 h in LPS-treated birds. It appears that blood IL-6 and cholesterol may be acute phase indicators of bacterial infection in chickens. This is consistent with the literature in other species. The decrease in blood cholesterol due to LPS and S. aureus injection may relate to the changes in hepatic metabolisms during the acute phase reaction following bacterial infections.