tetano
Editor, Senior Moderator
J Virol. 2015 Jan 21. pii: JVI.00012-15. [Epub ahead of print]
[h=1]Influenza viruses with receptor-binding N1 neuraminidases occur sporadically in several lineages and show no attenuation in cell culture or mice.[/h] Hooper KA[SUP]1[/SUP], Crowe JE Jr[SUP]2[/SUP], Bloom JD[SUP]3[/SUP].
[h=3]Author information[/h]
[h=3]Abstract[/h] In nearly all characterized influenza viruses, hemagglutinin (HA) is the receptor-binding protein while neuraminidase (NA) is a receptor-cleaving protein that aids in viral release. However in recent years, several groups have described point mutations that confer receptor-binding activity on NA, albeit in laboratory rather than natural settings. One of these mutations, D151G, appears to arise in the NA of recent human H3N2 viruses upon passage in tissue culture. We inadvertently isolated the second of these mutations, G147R, in the NA of the lab-adapted A/WSN/33 (H1N1) strain, while we were passaging a heavily engineered virus in the lab. G147R also occurs at low frequency in the reported sequences of viruses from three different lineages: human 2009 pandemic H1N1 (pdmH1N1), human seasonal H1N1, and chicken H5N1. Here we reconstruct a representative G147R NA from each of these lineages, and find that all the proteins have acquired the ability to bind an unknown cellular receptor while retaining substantial sialidase activity. We then reconstruct a virus with the HA and NA of a reported G147R pdmH1N1 variant, and find no attenuation of viral replication in cell culture or change in pathogenesis in mice. Furthermore, the G147R virus has modestly enhanced resistance to neutralization by the Fab of an antibody against the receptor-binding pocket of HA, although it remains completely sensitive to the full-length IgG. Overall, our results suggest that circulating N1 viruses occasionally may acquire the G147R NA receptor-binding mutation without impairment of replicative capacity.
[h=4]IMPORTANCE:[/h] Influenza viruses have two main proteins on their surface: one (hemagglutinin) binds incoming viruses to cells, while the other (neuraminidase) helps release newly formed viruses from these same cells. Here we characterize unusual mutant neuraminidases that have acquired the ability to bind to cells. We show that the mutation that allows neuraminidase to bind cells has no apparent adverse effect on viral replication, but does make the virus modestly more resistant to a fragment of an antibody that blocks the normal hemagglutinin-mediated mode of viral attachment. Our results suggest that viruses with receptor-binding neuraminidases may occur at low levels in circulating influenza lineages.
Copyright ? 2015, American Society for Microbiology. All Rights Reserved.
PMID: 25609803 [PubMed - as supplied by publisher]
http://www.ncbi.nlm.nih.gov/pubmed/25609803
[h=1]Influenza viruses with receptor-binding N1 neuraminidases occur sporadically in several lineages and show no attenuation in cell culture or mice.[/h] Hooper KA[SUP]1[/SUP], Crowe JE Jr[SUP]2[/SUP], Bloom JD[SUP]3[/SUP].
[h=3]Author information[/h]
[h=3]Abstract[/h] In nearly all characterized influenza viruses, hemagglutinin (HA) is the receptor-binding protein while neuraminidase (NA) is a receptor-cleaving protein that aids in viral release. However in recent years, several groups have described point mutations that confer receptor-binding activity on NA, albeit in laboratory rather than natural settings. One of these mutations, D151G, appears to arise in the NA of recent human H3N2 viruses upon passage in tissue culture. We inadvertently isolated the second of these mutations, G147R, in the NA of the lab-adapted A/WSN/33 (H1N1) strain, while we were passaging a heavily engineered virus in the lab. G147R also occurs at low frequency in the reported sequences of viruses from three different lineages: human 2009 pandemic H1N1 (pdmH1N1), human seasonal H1N1, and chicken H5N1. Here we reconstruct a representative G147R NA from each of these lineages, and find that all the proteins have acquired the ability to bind an unknown cellular receptor while retaining substantial sialidase activity. We then reconstruct a virus with the HA and NA of a reported G147R pdmH1N1 variant, and find no attenuation of viral replication in cell culture or change in pathogenesis in mice. Furthermore, the G147R virus has modestly enhanced resistance to neutralization by the Fab of an antibody against the receptor-binding pocket of HA, although it remains completely sensitive to the full-length IgG. Overall, our results suggest that circulating N1 viruses occasionally may acquire the G147R NA receptor-binding mutation without impairment of replicative capacity.
[h=4]IMPORTANCE:[/h] Influenza viruses have two main proteins on their surface: one (hemagglutinin) binds incoming viruses to cells, while the other (neuraminidase) helps release newly formed viruses from these same cells. Here we characterize unusual mutant neuraminidases that have acquired the ability to bind to cells. We show that the mutation that allows neuraminidase to bind cells has no apparent adverse effect on viral replication, but does make the virus modestly more resistant to a fragment of an antibody that blocks the normal hemagglutinin-mediated mode of viral attachment. Our results suggest that viruses with receptor-binding neuraminidases may occur at low levels in circulating influenza lineages.
Copyright ? 2015, American Society for Microbiology. All Rights Reserved.
PMID: 25609803 [PubMed - as supplied by publisher]
http://www.ncbi.nlm.nih.gov/pubmed/25609803