Serum lecithin:cholesterol acyltransferase activity evaluated as a possible indicator in dairy heifers with suspected bovine respiratorysyncytial virus infection

摘要

In both experimental and natural calf pneumonia serum lecithin:cholesterol acyltransferase (LCAT) activity is reported to decrease, which may be due to the involvement of cytokines in the respiratory infection. This study aimed to evaluate whether LCAT activity was definitely reduced in dairy heifers with suspected bovine respiratory syncytial virus (BRSV) infection and, in addition, to assess the relevance of LCAT to other metabolites, including tumor necrosis factor a (TNF- a). An outbreak of BRSVinfection happened in12 dairy heifers on a farm and sera were obtained at days 0， 3, 7 (acute phase), 22 (convalescent phase) and 50 (postconvalescent phase). The serum concentrations of haptoglobin (Hp) andひ1-acid glycoprotein (AGP) were remarkably increased in the acute phase, which reflected the severity of the inflammatory process due to pneumonia. After therapy, the concentrations of Hp and AGP returned to normal from day 22. Serum LCAT activities were reduced in the acute phase. Briefly, the activities reached a significant nadir at day 3 compared with the postconvalescent phase and thereafter returned to normal. The serum TNF-a concentrations increased from day 3 and reached the maximum at day 7. Elevation of the serum apolipoprotein A-I (ApoA-I) concentration in the acute phase may be associated with affinity for Hp. In conclusion, reduced serum LCAT activity may be a useful indicator for monitoring viral respiratory infections like BRSV, but the reduced activity in this field study could not be simply explained by the actions of TNF-a and/or ApoA-L.