tetano
Editor, Senior Moderator
Front Microbiol. 2018 Aug 21;9:1939. doi: 10.3389/fmicb.2018.01939. eCollection 2018.
[h=1]Acquisition of Innate Inhibitor Resistance and Mammalian Pathogenicity During Egg Adaptation by the H9N2 Avian Influenza Virus.[/h] Lee CY[SUP]1[/SUP], An SH[SUP]1[/SUP], Choi JG[SUP]2[/SUP], Lee YJ[SUP]2[/SUP], Kim JH[SUP]1,[/SUP][SUP]3[/SUP], Kwon HJ[SUP]3,[/SUP][SUP]4,[/SUP][SUP]5[/SUP].
[h=3]Author information[/h]
[h=3]Abstract[/h] An H9N2 avian influenza A virus (AIV), A/chicken/Korea/01310/2001 (01310-CE20), was established after 20 passages of influenza A/chicken/Korea/01310/2001 (01310-CE2) virus through embryonated chicken eggs (ECEs). As a result of this process, the virus developed highly replicative and pathogenic traits within the ECEs through adaptive mutations in hemagglutinin (HA: T133N, V216G, and E439D) and neuraminidase (NA: 18-amino acid deletion and E54D). Here, we also established that 01310-CE20 acquired resistance to innate inhibitors present in the egg white during these passages. To investigate the role of egg-adapted mutations in resistance to innate inhibitors, we generated four PR8-derived recombinant viruses using various gene combinations of HA and NA from 01310-CE2 and 01310-CE20 (rH[SUB]2[/SUB]N[SUB]2[/SUB], rH[SUB]2[/SUB]N[SUB]20[/SUB], rH[SUB]20[/SUB]N[SUB]2[/SUB], and rH[SUB]20[/SUB]N[SUB]20[/SUB]). As expected, rH[SUB]20[/SUB]N[SUB]20[/SUB] showed significantly higher replication efficiency in MDCK cells and mouse lungs, and demonstrated greater pathogenicity in mice. In addition, rH[SUB]20[/SUB]N[SUB]20[/SUB] showed higher resistance to innate inhibitors than the other viruses. By using a loss-of-function mutant and receptor-binding assay, we demonstrated that a T133N site directed mutation created an additional N-glycosite at position 133 in rH[SUB]20[/SUB]N[SUB]20[/SUB]. Further, this mutation played a crucial role in viral replication and resistance to innate inhibitors by modulating the binding affinities to avian-like and mammalian-like receptors on the host cells and inhibitors. Thus, egg-adapted HA and NA may exacerbate the mammalian pathogenicity of AIVs by defying host innate inhibitors as well as by increasing replication efficiency in mammalian cells.
[h=4]KEYWORDS:[/h] H9N2; avian influenza virus; egg adaptation; hemagglutinin; innate inhibitor; mammalian pathogenicity; neuraminidase
PMID: 30186261 PMCID: PMC6110911 DOI: 10.3389/fmicb.2018.01939
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[h=1]Acquisition of Innate Inhibitor Resistance and Mammalian Pathogenicity During Egg Adaptation by the H9N2 Avian Influenza Virus.[/h] Lee CY[SUP]1[/SUP], An SH[SUP]1[/SUP], Choi JG[SUP]2[/SUP], Lee YJ[SUP]2[/SUP], Kim JH[SUP]1,[/SUP][SUP]3[/SUP], Kwon HJ[SUP]3,[/SUP][SUP]4,[/SUP][SUP]5[/SUP].
[h=3]Author information[/h]
[h=3]Abstract[/h] An H9N2 avian influenza A virus (AIV), A/chicken/Korea/01310/2001 (01310-CE20), was established after 20 passages of influenza A/chicken/Korea/01310/2001 (01310-CE2) virus through embryonated chicken eggs (ECEs). As a result of this process, the virus developed highly replicative and pathogenic traits within the ECEs through adaptive mutations in hemagglutinin (HA: T133N, V216G, and E439D) and neuraminidase (NA: 18-amino acid deletion and E54D). Here, we also established that 01310-CE20 acquired resistance to innate inhibitors present in the egg white during these passages. To investigate the role of egg-adapted mutations in resistance to innate inhibitors, we generated four PR8-derived recombinant viruses using various gene combinations of HA and NA from 01310-CE2 and 01310-CE20 (rH[SUB]2[/SUB]N[SUB]2[/SUB], rH[SUB]2[/SUB]N[SUB]20[/SUB], rH[SUB]20[/SUB]N[SUB]2[/SUB], and rH[SUB]20[/SUB]N[SUB]20[/SUB]). As expected, rH[SUB]20[/SUB]N[SUB]20[/SUB] showed significantly higher replication efficiency in MDCK cells and mouse lungs, and demonstrated greater pathogenicity in mice. In addition, rH[SUB]20[/SUB]N[SUB]20[/SUB] showed higher resistance to innate inhibitors than the other viruses. By using a loss-of-function mutant and receptor-binding assay, we demonstrated that a T133N site directed mutation created an additional N-glycosite at position 133 in rH[SUB]20[/SUB]N[SUB]20[/SUB]. Further, this mutation played a crucial role in viral replication and resistance to innate inhibitors by modulating the binding affinities to avian-like and mammalian-like receptors on the host cells and inhibitors. Thus, egg-adapted HA and NA may exacerbate the mammalian pathogenicity of AIVs by defying host innate inhibitors as well as by increasing replication efficiency in mammalian cells.
[h=4]KEYWORDS:[/h] H9N2; avian influenza virus; egg adaptation; hemagglutinin; innate inhibitor; mammalian pathogenicity; neuraminidase
PMID: 30186261 PMCID: PMC6110911 DOI: 10.3389/fmicb.2018.01939
Free full text