|WHITE D J|
|JOLLEY W L|
|PURDY C W|
|STRAUS D C|
Submitted to: Infection and Immunity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/24/1995
Publication Date: N/A
Interpretive Summary: Pasteurella multocida (Pm) and Pasteurella haemolytica (Ph) are bacteria associated with bovine respiratory disease complex which costs the feeder calf industry $750,000,000 per year. The extent that Pm contributes to the acute bovine respiratory disease complex (BRDC) is not known. The virulence mechanisms of how Pasteurella bacteria induce BRDC is also poorly yunderstood. We hypothesized that neuraminidase, an enzyme secreted by these organisms, may serve as a virulence factor and may contribute to BRDC. We have isolated and purified extracellular Pm neuraminidase in this study. We determined that a Pm isolate recovered from a bovine pneumonic lung, produced extracellular neuraminidase with a molecular weight of 500,000 which is serologically unrelated to Ph neuraminidase. The Pm neuraminidase destroyed N-acetyl-neuramin lactose, alpha 1-acid glycoprotein, fetuin, and colominic acid which may serve as receptor sites for Pm in the host. Bovine mucin is also attacked by neuraminidase; host mucin is known to help trap Pm and Ph during upper respiratory infections. These results are important to the research scientist in helping to better understand that neuraminidase may serve as a possible Pm virulence factor against the bovine host.
Technical Abstract: The properties, of an extracellular neuraminidase produced by a Pasteurella multocida A:3 strain that was isolated from a case of bovine pneumonia, were examined during growth in a defined medium. This enzyme (isolated from concentrated culture supernatants of P. multocida A:3) was active against N-acetyl-neuramin lactose, human alpha 1-acid glycoprotein, fetuin, ,colominic acid, and bovine submaxillary mucin. Enzyme elaboration was correlated with the organism's growth in a defined medium with maximum quantities produced in the stationary phase. The enzyme was purified by a combination of ammonium sulfate fractionation, ion-exchange on DEAE-Sephacel, and gel filtration on Sephadex G-200. The purified neuraminidase possessed a specific activity of 9.36 mol of sialic acid released per min per mg of protein against fetuin. The enzyme possessed a pH optimum of 6.0 and a Km of 0.03 mg/ml. The P. multocida A:3 neuraminidase had a molecular weight of approximately 500,000 as estimated by gel filtration. The enzyme was stable at 40 deg C and 37 deg C for 3 h. Approximately 75% of the neuraminidase activity was lost within 30 min at 50 deg C. Greater than 90% of the enzyme activity was destroyed within 10 min at temperatures of >/= 65 deg C. The P. multocida neuraminidase does not appear to be serologically related to the Pasteurella haemolytica A1 neuraminidase as antiserum prepared against the P. haemolytica purified enzyme did not neutralize the P. multocida enzyme.