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Biomedical subjects

K A Ryan-Poirier

Publications and source records attributed to K A Ryan-Poirier.

4 recordsLinked to original sources
PubMed1993

Alpha 2-macroglobulin is the major neutralizing inhibitor of influenza A virus in pig serum.

Horse, pig, and rabbit sera contain distinct glycoprotein inhibitors of influenza A viruses that inhibit hemagglutinating activity and neutralize viral infectivity. Although alpha 2-macroglobulin has been identified as the inhibitor in horse serum, the inhibitors in pig and rabbit sera have not been identified. As an initial step in elucidating the structural differences among inhibitor molecules, we sought to isolate the inhibitor in pig serum. The purified inhibitor decreased the hemagglutinating activity of influenza A virus, A/Los Angeles/2/87 (H3N2), and represented the majority of the virus-neutralizing activity in pig serum. The inhibitor corresponded in size to alpha 2-macroglobulin and cross-reacted antigenically with human alpha 2-macroglobulin. Characterization of the inhibitor's oligosaccharide moiety using linkage-specific lectins revealed the presence of N-acetylneuraminic acid-alpha 2,6-galactose but not N-acetylneuraminic acid-alpha 2,3-galactose. These data indicate that alpha 2-macroglobulin is the major neutralizing inhibitor of influenza A virus in pig serum.

Animals↗
PubMed1992

Application of Directigen FLU-A for the detection of influenza A virus in human and nonhuman specimens.

Directigen FLU-A, a new enzyme immunoassay membrane test, rapidly detects influenza A virus antigen in specimens from patients. Nasopharyngeal washes and pharyngeal gargles were used to determine the effectiveness of the assay as applied to different types of routinely collected clinical samples. All specimens had been previously shown to contain influenza A virus by virus isolation in tissue culture. Directigen FLU-A was 90% sensitive (95% confidence interval, 56 to 99.7%) with nasopharyngeal washes but only 39% sensitive (95% confidence interval, 17 to 64%) with pharyngeal gargles (P = 0.018) when used with samples containing similar amounts of infectious virus (50% tissue culture infective dose, 1.0 to 4.5). The intensity of the positive reaction with Directigen FLU-A did not correlate with the amount of virus in the specimens. Directigen FLU-A was found to detect cell-associated antigen more readily than free virus; only 20 infected cells were required to identify cell-associated influenza A virus antigen, whereas the limit of detection for free virus was 1.63 x 10(3) infectious virus particles. These findings suggest that Directigen FLU-A detects the cell-associated antigen present in clinical specimens rather than free virus. In addition, Directigen FLU-A detected avian and swine influenza A viruses in both cloacal swabs (75% sensitivity) and swine lung homogenates (86% sensitivity), indicating its potential usefulness in the surveillance of nonhuman influenza A viruses.

Animals↗
PubMed1991

Distinct glycoprotein inhibitors of influenza A virus in different animal sera.

Normal horse and guinea pig sera contain the glycoprotein inhibitor alpha 2-macroglobulin, which inhibits the infectivity and hemagglutinating activity of influenza A viruses of the H2 and H3 subtypes. In the current study, the presence of inhibitors of influenza A virus in pig and rabbit sera was investigated. Variants of influenza virus type A/Los Angeles/2/87(H3N2) that were resistant to horse, pig, or rabbit serum were isolated. Analysis of the variant viruses with anti-hemagglutinin (HA) monoclonal antibodies revealed that antigenic changes occurred with the development of serum inhibitor resistance. Characterization of the inhibitors in pig and rabbit sera by using periodate and receptor-destroying enzyme demonstrated that carbohydrate is an important constituent of the active portion of both inhibitor molecules and that sialic acid is involved in the interaction of the inhibitors with influenza virus HA. Nucleotide sequence analysis of the HA molecule revealed that the serum-resistant variants each acquired a different set of amino acid alterations. The multiply resistant variants maintained the original amino acid changes and acquired additional changes. Sequence modifications in the HA involved the conserved amino acids within the receptor binding site (RBS) at position 137 and the second-shell RBS residues at positions 155 and 186. Amino acid changes also occurred within antigenic site A (position 145) and directly behind the receptor binding pocket (position 220). Amino acid alterations resulted in the acquisition of a potential glycosylation site at position 128 and the loss of potential glycosylation sites at positions 246 and 248. The localization of the amino acid changes in HA1 to the region of the RBS supports the concept of serum inhibitors as receptor analogs. The unique set of mutations acquired by the serum inhibitor-resistant variants strongly suggests that horse, pig, and rabbit sera each contain distinct glycoprotein inhibitors of influenza A virus.

Amino Acid Sequence↗