title: [Effect of the neuraminidases of Haemophilus avium and Haemophilus paragallinarum on chicken serum and other substrates].
abstract: The activity of neuraminidases of two strains of Haemophilus avium and three strains of H. paragallinarum were examined using serum of 1-day-old, 8-week-old and 2-year-old chickens as well as human serum, N-acetyl neuraminosyl-D-lactose (NL), N-acyl neuraminic acid glycoproteid (BSM) and colominic acid (Col) as substrates. Further the N-acetyl neuraminate (NAN) content in chicken and human serum was determined. No significant differences were found between the content of NAN in human serum and 1-day-old chickens serum. However, three and ten times less NAN could be determined in serum of 8-week-old and 2-year-old chickens, respectively. This suggests that NAN containing glycoproteins may be a factor of the non specific host defence mechanisms in young chickens. The neuraminidases of both Haemophilus species differ by their activity spectrum.H. avium cleaves the alpha-ketosidic linkage of NAN in its 2 --> 3, 2 --> 6 and 2 --> 8 position. Neuraminidase of H. paragallinarum was less active and cleaves mainly the 2 --> 6 linkage of NAN. Neuraminidases of H. avium and H. paragallinarum were three and ten times more active against chicken serum than human serum. This selective activity may be explained by the specific adaptation of H. avium and especially of H. paragallinarum to their natural host.
authors.affiliation: Klinik für Geflügel, Tierärztlichen Hochschule Hannover, Hannover, Bundesrepublik Deutschland.
authors.forename: K H
authors.initials: KH
authors.lastname: Hinz
authors.forename: H E
authors.initials: HE
authors.lastname: Muller