title: Isolation and characterization of conglutinin as an influenza A virus inhibitor.
abstract: Normal horse and guinea pig sera contain alpha 2-macroglobulin which inhibits the infectivity and hemagglutinating activity of influenza A viruses of the H2 and H3 subtypes. On the other hand, normal bovine serum contains a component termed beta inhibitor that inhibits the infectivity and hemagglutinating activity of influenza A viruses of the H1 and H3 subtypes. To investigate the nature of the beta inhibitor of influenza A virus, we purified the conglutinin and examined its characteristics. First, we found a high correlation between the hemagglutination inhibition(HI) titer and conglutinin titer in several bovine sera (r = 0.906, p less than 0.005). The HI of bovine serum was mainly dependent on conglutinin because the HI activity was abrogated by N-acetylglucosamine but not by D-mannose. The conglutinin, purified from bovine serum, had neutralizing-activity as well as HI activity on influenza A viruses of the H1 and H3 subtypes. The HI activity of conglutinin was heat stable (56 degrees C, 30 min), Ca(++)-dependent, and resistant to both neuraminidase and periodate treatments. The HI activity of purified conglutinin was blocked by N-acetylglucosamine but not by D-mannose. The conglutinin was bound to hemagglutinin which had high mannose and complex sugar chains and its binding was inhibited by N-acetylglucosamine and dependent on divalent cations. These data indicate that the beta-like inhibitor activity of bovine serum is mainly dependent on conglutinin which inhibits hemagglutination and neutralizes the virus infectivity by its binding to a carbohydrate site at the HA.
authors.affiliation: Department of Pathology, Osaka University, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Wakamiya
authors.forename: Y
authors.initials: Y
authors.lastname: Okuno
authors.forename: F
authors.initials: F
authors.lastname: Sasao
authors.forename: S
authors.initials: S
authors.lastname: Ueda
authors.forename: K
authors.initials: K
authors.lastname: Yoshimatsu
authors.forename: M
authors.initials: M
authors.lastname: Naiki
authors.forename: T
authors.initials: T
authors.lastname: Kurimura
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000302:isolation & purification*; D002417:Cattle; D037222:Collectins; D006385:Hemagglutination Inhibition Tests; D006389:Hemagglutinins, Viral / Q000378:metabolism; D009980:Influenza A virus / Q000187:drug effects* / Q000378:metabolism; D009500:Neutralization Tests; D011233:Precipitin Tests; D012712:Serum Globulins / Q000494:pharmacology*
chemical_list: D000998:Antiviral Agents; D037222:Collectins; D006389:Hemagglutinins, Viral; D012712:Serum Globulins; C024014:conglutinin