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Streptococcus zooepidemicushas recently been shown to be a severe pathogen in layer chickens, where it is able to cause serious lesions in the vascular system. To evaluate the haemostatic response, 10 layer chickens were inoculated intravenously withS. zooepidemicus. Four hypotheses were tested: that the infection-induced inflammation would increase the plasma fibrinogen (Fbg) concentration, would prolong the prothrombin time (PT) and would prompt hypercoagulability or hypocoagulability as assessed by whole-blood thromboelastography (TEG), and that a possible correlation would exist between one of the TEG values and Fbg/PT. Each parameter was measured at days 1, 3 and 6 post inoculation (p.i.), and compared with the values at day 0 from each individual bird and with values obtained from non-infected control chickens (n= 10). In the infected chickens, the mean (± standard error) of Fbg was higher at day 3 p.i. (9.4 ± 1.4 g/l) and day 6 p.i. (8.0 ± 0.7 g/l) and the PT was prolonged at day 6 p.i. (168.1 ± 21.0 sec) compared with the day 0 standards (2.6 ± 0.2 g/l and 104.6 ± 2.0 sec, respectively) (P< 0.05). The majority of infected chickens demonstrated a hypercoagulable TEG result with increased mean values of the clot formation rate (α-angle) and maximal amplitude (MA) of TEG tracing at day 3 p.i. (83.1 ± 0.7°, 83.8 ± 1.4 mm) and day 6 p.i. (84.0 ± 0.4°, 89.8 ± 1.0 mm) compared with the day 0 values (75.8 ± 2.2° and 66.9 ± 1.4 mm, respectively) (P< 0.05). In control birds, the means of Fbg (1.5 ± 0.1 g/l), PT (79.4 ± 6.4 sec), TEG-α(76.7 ± 1.5°) and TEG-MA(64.0 ± 2.3 mm) were lower at day 6 compared with values observed for the infected chickens (P< 0.05). A negative correlation coefficient (−0.71) was found between the clot formation time (TEG-K) and Fbg at day 1 in the control group (P= 0.02). In conclusion, infection withS. zooepidemicusfollowing intravenous injection in layer chickens induced haemostatic alterations including hyperfibrinogenaemia, prolonged PT, and hypercoagulability as measured by increased TEG-αand TEG-MA. [ABSTRACT FROM AUTHOR]

To evaluate Ovo-transferrin (OTF), a positive acute-phase protein in chickens, as a diagnostic biomarker of selected bacterial infections we checked the performance of a commercial Chicken-OTF-ELISA (ICL, Inc., Portland, OR, USA) by analytical and overlap performances using two groups of serum samples obtained from 26Gallibacterium anatis-infected and 20Streptococcus zooepidemicus-infected brown layer chickens. In addition, sera from 14 apparently healthy and 19 negative control chickens were analysed in theGallibacteriumgroup whereas sera from 20 healthy and 11 negative control chickens from theStreptococcusgroup were analysed. All calibration curves revealed high coefficients of determination (≥0.97) between optical density (OD450nm) and concentrations of OTF (mg/ml). OTF concentrations in high, medium and low pools (made of sera from a combination of infected and/or non-infected birds) were >6.4, >3.8 to <4.5 and <1.6 mg/ml in theGallibacteriumgroup, and >6.7, >3.5 to <3.7 and <1.1 mg/ml in theStreptococcusgroup, respectively. For each pool, low coefficients of intra-assay (7.8, 5.7 and 5.3) and inter-assay (15.8, 18.0 and 18.0) variations were obtained in theGallibacteriumstudy. In theStreptococcusstudy only the intra-assay variation was low (3.7, 3.8 and 6.2, respectively). The linearity check was acceptable demonstrating a straight line with slope and intercept, not deviating from one and zero, respectively, using theGallibacteriumsera, whereas theStreptococcussera deviated from the linear line. Detection limits were low (Gallibacterium, 0.01 mg/ml;Streptococcus, 0.32 mg/ml). OTF concentrations (mean ± standard error of the mean) in overlap performances were elevated in the sera of infected chickens (Gallibacterium, 4.4 ± 0.3 mg/ml;Streptococcus, 3.2 ± 0.4 mg/ml) compared with negative controls (1.7 ± 0.1 mg/ml) (P< 0.05). In conclusion, the Chicken-OTF-ELISA can be used to measure reproducible serum OTF concentrations in brown layer chickens as a response toG. anatisinfections, whereas an adjustment of dilution process is proposed to optimize to use inS. zooepidemicus-infected chickens. [ABSTRACT FROM AUTHOR]