Loss of the N-linked Glycan at Residue 173 on Human Parainfluenza Virus Type 1 Hemagglutinin-Neurami
June 28th, 2008 | by admin |Loss of the N-linked Glycan at Residue 173 on Human Parainfluenza Virus Type 1 Hemagglutinin-Neuraminidase Exposes a Second Receptor-Binding Site.
BCX 2798 effectively inhibited the activities of the hemagglutinin-neuraminidase (HN) of human parainfluenza viruses (hPIV) in vitro, and protected mice from lethal infection with a recombinant Sendai virus whose HN was replaced with that of hPIV-1 (rSeV[hPIV-1HN]) (Alymova, I. V., G. Taylor, T. Takimoto, T. H. Lin., P. Chand, Y. S. Babu, C. Li, X. Xiong, and A. Portner. 2004. Antimicrob. Agents Chemother. 48:1495-1502). The ability of BCX 2798 to select drug-resistant variants in vivo was examined. A variant with mutation Asn to Ser at residue 173 (N173S) in HN was recovered from mice after a second passage of rSeV(hPIV-1HN) in the presence of BCX 2798 (10 mg/kg daily). The N173S mutant remained sensitive to BCX 2798 in neuraminidase-inhibition assays, but was more than 10,000-fold less sensitive to the compound in hemagglutination-inhibition tests, as compared to that of rSev(hPIV-1HN). Its susceptibility to BCX 2798 in plaque-reduction assays was reduced 5-fold and did not differ from that of rSeV(hPIV-1HN) in mice. The N173S mutant failed to efficiently elute from erythrocytes and release from cells.It demonstrated reduced growth in cell culture and superior growth in mice. Gel electrophoresis analysis was consistent with the loss of the N-linked glycan at residue 173 in the mutant. Sequence and structural comparisons revealed that residue 173 on hPIV-1 HN is closely located to the region of the second receptor-binding site identified in Newcastle disease virus HN. Our study suggests that the N-linked glycan at residue 173 masks a second receptor-binding site on hPIV-1 HN.
Alymova IV, Taylor G, Mishin VP, Watanabe M, Murti KG, Boyd K, Chand P, Babu YS, Portner A.
Departments of Infectious Diseases, Molecular Biotechnology, and Animal Resources Center, St. Jude Children\’s Research Hospital, 332 N. Lauderdale, Memphis, TN 38105-2794, USA; Center for Biomolecular Science, University of St. Andrews, North Haugh, St. Andrews, Fife KY16 9ST, Scotland; BioCryst Pharmaceuticals, Inc., 2190 Parkway Lake Drive, Birmingham, AL 35244, USA.