Experimental bovine pneumonic pasteurellosis

2000

ABSTRACT. Lipoprotein lipid and apoprotein concentrations are known to be altered during the acute-phase response. We have previously shown that the serum activity of lecithin:cholesterol acyltransferase (LCAT) and concentration of cholesteryl esters, both constituents of the high-density lipoprotein (HDL) fraction, are reduced in calves inoculated with Pasteurella haemolytica and bovine herpes virus-1, the two major pathogens for calf pneumonia. The concentration of apolipoprotein C-III (apoC-III), a low molecular mass protein component distributed mainly in the HDL fraction, was therefore examined in bacteria-and virus-inoculated calves. An enzyme-linked immunosorbent assay demonstrated that it was decreased by inoculations of Pasteurella haemolytica and bovine herpes virus-1. The decrease was detected as early as 1 day after inoculation in both groups. A decreased serum apoC-III concentration was also observed by immunoblot analysis. It was detected in the HDL fractions from the bacteria-and virus-inoculated calves, and HDL apoC-III concentrations in the inoculated calves were decreased compared with controls. These results, coupled with the previous findings on LCAT activity and the cholesteryl ester concentration, indicate that a decreased HDL concentration is one of the early events occurring during the acute-phase response evoked by infections with Pasteurella haemolytica and bovine herpes virus-1. inoculated with Pasteurella haemolytica and bovine herpes virus-1 (BHV-1), the two major pathogens for calf pneumonia [3,12,14,16,20], we have shown that LCAT activity and the cholesteryl ester concentration are decreased [10]. Because apoC-III also is distributed in the HDL fraction, it is conceivable that the apoC-III concentration is decreased in experimental pneumonia. The purpose of the study reported here was to evaluate the apoC-III concentration in calves inoculated with Pasteurella haemolytica and BHV-1, in order to elucidate the involvement of apoC-III in the pathogenesis of calf pneumonia, one of the most economically important disorders in calves. MATERIALS AND METHODS Induction of pneumonia:Pneumonia was experimentally induced by inoculations of Pasteurella haemolytica and BHV-1 into calf lung lobes, as described previously [7,8,10,17]. Briefly, a suspension of Pasteurella haemolytica (serotype 1, I29 strain; 1 × 10 9 colony forming units) was administered to right lung lobes of 10 Holstein male calves (2 to 3 months old) using a fiberoptic bronchoscope. Ten other calves receiving the vehicle (phosphate-buffered saline [PBS]) alone were used as controls. Under xylazine-and procaine-induced anesthesia, calves were exsanguinated at day 1 (3 control and 3 inoculated calves), day 2 (3 control and 3 inoculated), day 4 (2 control and 2 inoculated) and day 7 (2 control and 2 inoculated). Blood was collected at 0 (1 hr before administration) and 0.25 (6 hr after) and at 1, Apolipoprotein C-III (apoC-III) is the low molecular mass protein component of lipoproteins and is distributed in human plasma in chylo...

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Decreased Apolipoprotein C-III Concentration in the High-Density Lipoprotein Fraction from Calves Inoculated with Pasteurella haemolytica and Bovine Herpes Virus-1

Yamamoto

2000

“…Two other calves were similarly treated, received the vehicle alone, and used as controls. Clinical and pathologic changes induced by the bacterial inoculation were essentially as described in earlier reports [5,23].…”

Section: Purification Of Aposaamentioning

confidence: 99%

The Presence of Two Low Molecular Mass Proteins Immunologically Related to 14 Kilodalton Serum Amyloid A in the Lipoprotein Fraction and Their Decreased Serum Concentrations in Calves with Experimentally Induced Pneumonia

Yamamoto

Adachi

1998

ABSTRACT. A 14 kilodalton (kDa) serum amyloid A (apoSAA) protein was purified from cow serum. Rabbit antiserum to the 14 kDa apoSAA recognized, in addition to the 14 kDa protein, a 7.5-9.0 kDa protein and a protein having a molecular mass of less than 6.5 kDa (<6.5 kDa protein). The possibility that the two proteins were contaminants was excluded by results showing that the two proteins detected in early stages of purification procedures were not found in the purified 14 kDa apoSAA fraction, as revealed by immunoblot analysis. As in the 14 kDa apoSAA, the 7.5-9.0 kDa protein was localized in the high-density lipoprotein fraction, while the <6.5 kDa protein was in the low-density lipoprotein fraction. In calves with pneumonia induced by inoculation to the lungs of Pasteurella haemolitica, the serum concentration of the 14 kDa apoSAA was increased, whereas those of the 7.5-9.0 kDa and the <6.5 kDa proteins were conversely decreased. The time-course study indicated that the increase in concentration of the 14 kDa apoSAA and decrease in that of the <6.5 kDa protein occurred almost simultaneously. These results suggest that the 14 kDa apoSAA and the immunologically related 7.5-9.0 kDa and <6.5 kDa proteins act as positive and negative acute phase reactants, respectively, and also that concentrations of the three proteins are regulated in concert in acute phase plasma. fraction and, moreover, the serum concentration of the 14 kDa apoSAA was increased whereas those of the two low molecular mass proteins were conversely decreased in sera from calves with pneumonia induced by inoculation of Pasteurella haemolitica. MATERIALS AND METHODS Purification of apoSAA:ApoSAA was purified from cow serum during the course of purification of apoC-III [26]. Briefly, the total lipoprotein fraction [d<1.21, containing chylomicrons (CM) to HDL] prepared from sera of Holstein cows during midlactation was treated with an equal volume of acetone to extract low molecular mass apolipoproteins such as apoC-III and apoSAA. The supernatant obtained by centrifugation at 140 × g for 10 min was lyophilized and thereafter delipidated by mixing with 20 volumes of 2-propanol. Apolipoproteins pelleted by centrifugation at 1,300 × g for 10 min, were dissolved in 6 M urea and 50 mM Tris-HCl (pH 8.6), and applied to a column (2.5 × 90 cm) of Sephadex G-75 (Pharmacia Biotech, Uppsala, Sweden). Fractions rich in low molecular mass apolipoproteins were next applied to a DEAE-Sephacel (Pharmacia Biotech, Uppsala, Sweden) column (2 × 25 cm), and bound proteins were eluted by use of a linear gradient of NaCl (0-0.125 M, total 1 liter). Fractions containing apoSAA were dialyzed against 10 mM ammonium hydrogen carbonate, using cellulose dialyzer tubing with a 3,500 molecular weight cutoff, after which the dialysate was

“…The purpose of the present study was to examine whether LCAT activity and the LCAT-related lipid concentrations are affected in experimental calf pneumonia. Pneumonia was induced by inoculation of calf lungs with Pasteurella haemolytica and bovine herpes virus-1 (BHV-1), the two major pathogens for calf pneumonia [5,7,19]. We report here that LCAT activity and the CE concentration are reduced in calves with pneumonia induced by both pathogens.…”

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confidence: 96%

Reduced Serum Lecithin:Cholesterol Acyltransferase Activity and Cholesteryl Ester Concentration in Calves Experimentally Inoculated with Pasteurella haemolytica and Bovine Herpes Virus-1

Nakagawa¹,

1999

ABSTRACT. Lecithin:cholesterol acyltransferase (LCAT), the enzyme responsible for esterification of cholesterol in plasma, is reported to be implicated in the regulation of inflammation in laboratory animals. The purpose of the present study was to elucidate the possible relevance of LCAT in the pathogenesis of calf pneumonia induced by inoculations of Pasteurella haemolytica and bovine herpes virus-1 into the calf lung. Serum LCAT activity was significantly (P<0.01) reduced in calves inoculated with Pasteurella haemolytica. The concentration of cholesteryl esters (CE), the product of the LCAT reaction, was also decreased in the inoculated group. Decreases in LCAT activity and the CE concentration were similarly observed in calves in which bovine herpes virus-1 was inoculated. In both bacteria-and virus-inoculated calves, CE concentrations in the high-density lipoprotein fractions were distinctly decreased, whereas those in the low-density lipoprotein fractions were practically unaltered. The acute-phase proteins haptoglobin and serum amyloid A were detected in sera from the bacteria-and virus-inoculated calves; however, the two acute-phase proteins were also found in sera from the control calves. These results suggest that decreases in LCAT activity and the CE concentration are involved in the pathogenesis of pneumonia induced by inoculation of calves with Pasteurella haemolytica and bovine herpes virus-1, and also that the change in the LCAT system is more intimately related to the occurrence of calf pneumonia than the induction of acute-phase proteins such as haptoglobin.-KEY WORDS: bovine, cholesteryl ester, high-density lipoprotein, lecithin:cholesterol acyltransferase, pneumonia.J. Vet. Med. Sci. 61(10): [1101][1102][1103][1104][1105][1106] 1999 enzyme is also reported to be responsible for hydrolyzing platelet-activating factor, the phospholipid (PL) having a broad range of biologic effects, including neutrophil activation and smooth muscle contraction [10]. An association of hypocholesterolemia with calf penumonia is observed in field cases (Nakagawa, unpublished results).The decreased cholesterol concentration in calves with pneumonia implies that LCAT activity is also reduced in those calves, because CE (in cattle serum, more than 80% of cholesterol is CE) is the product of the LCAT reaction. The purpose of the present study was to examine whether LCAT activity and the LCAT-related lipid concentrations are affected in experimental calf pneumonia. Pneumonia was induced by inoculation of calf lungs with Pasteurella haemolytica and bovine herpes virus-1 (BHV-1), the two major pathogens for calf pneumonia [5,7,19]. We report here that LCAT activity and the CE concentration are reduced in calves with pneumonia induced by both pathogens. MATERIALS AND METHODS Bacterial and viral inoculations:Twenty 2-to 3-monthold male Holstein calves weighing 72 to 108 kg were used to induce experimental pneumonic pasteurellosis [9,20]. Calves were housed individually in pens, and were acclimated for 2 weeks. Room temper...