tetano
Editor, Senior Moderator
Virology. 2016 Mar 4;492:187-196. doi: 10.1016/j.virol.2016.02.021. [Epub ahead of print]
[h=1]Intravirion cohesion of matrix protein M1 with ribonucleocapsid is a prerequisite of influenza virus infectivity.[/h] Zhirnov OP[SUP]1[/SUP], Manykin AA[SUP]2[/SUP], Rossman JS[SUP]3[/SUP], Klenk HD[SUP]4[/SUP].
[h=3]Author information[/h]
[h=3]Abstract[/h] Influenza virus has two major structural modules, an external lipid envelope and an internal ribonucleocapsid containing the genomic RNA in the form of the ribonucleoprotein (RNP) complex, both of which are interlinked by the matrix protein M1. Here we studied M1-RNP cohesion within virus exposed to acidic pH in vitro. The effect of acidification was dependent on the cleavage of the surface glycoprotein HA. Acidic pH caused a loss of intravirion RNP-M1 cohesion and activated RNP polymerase activity in virus with cleaved HA (HA1/2) but not in the uncleaved (HA0) virus. The in vitro acidified HA1/2 virus rapidly lost infectivity whereas the HA0 one retained infectivity, following activation by trypsin, suggesting that premature activation and release of the RNP is detrimental to viral infectivity. Rimantadine, an inhibitor of the M2 ion channel, was found to protect the HA1/2 virus interior against acidic disintegration, confirming that M2-dependent proton translocation is essential for the intravirion RNP release and suggesting that the M2 ion channel is only active in virions with cleaved HA. Acidic treatment of both HA0 and HA1/2 influenza viruses induces formation of spikeless bleb-like protrusion of ~25nm in diameter on the surface of the virion, though only the HA1/2 virus was permeable to protons and permitted RNP release. It is likely that this bleb corresponds to the M2-enriched and M1-depleted focus arising from pinching off of the virus during the completion of budding. Cooperatively, the data suggest that the influenza virus has an asymmetric structure where the M1-mediated organization of the RNP inside the virion is a prerequisite for infectious entry into target cell.
Copyright ? 2016 Elsevier Inc. All rights reserved.
[h=4]KEYWORDS:[/h] Asymmetric structure; Cleavage HA; Influenza virus; Ion channel M2; Protein M1; Virus entry
PMID: 26954078 [PubMed - as supplied by publisher]
[h=1]Intravirion cohesion of matrix protein M1 with ribonucleocapsid is a prerequisite of influenza virus infectivity.[/h] Zhirnov OP[SUP]1[/SUP], Manykin AA[SUP]2[/SUP], Rossman JS[SUP]3[/SUP], Klenk HD[SUP]4[/SUP].
[h=3]Author information[/h]
- [SUP]1[/SUP]D.I. Ivanovsky Institute of Virology, Moscow 123098, Russia. Electronic address: zhirnov@inbox.ru.
- [SUP]2[/SUP]D.I. Ivanovsky Institute of Virology, Moscow 123098, Russia.
- [SUP]3[/SUP]School of Biosciences, University of Kent, Canterbury CT27NJ, UK.
- [SUP]4[/SUP]Institute of Virology, Philipps University, Marburg 35037, Germany.
[h=3]Abstract[/h] Influenza virus has two major structural modules, an external lipid envelope and an internal ribonucleocapsid containing the genomic RNA in the form of the ribonucleoprotein (RNP) complex, both of which are interlinked by the matrix protein M1. Here we studied M1-RNP cohesion within virus exposed to acidic pH in vitro. The effect of acidification was dependent on the cleavage of the surface glycoprotein HA. Acidic pH caused a loss of intravirion RNP-M1 cohesion and activated RNP polymerase activity in virus with cleaved HA (HA1/2) but not in the uncleaved (HA0) virus. The in vitro acidified HA1/2 virus rapidly lost infectivity whereas the HA0 one retained infectivity, following activation by trypsin, suggesting that premature activation and release of the RNP is detrimental to viral infectivity. Rimantadine, an inhibitor of the M2 ion channel, was found to protect the HA1/2 virus interior against acidic disintegration, confirming that M2-dependent proton translocation is essential for the intravirion RNP release and suggesting that the M2 ion channel is only active in virions with cleaved HA. Acidic treatment of both HA0 and HA1/2 influenza viruses induces formation of spikeless bleb-like protrusion of ~25nm in diameter on the surface of the virion, though only the HA1/2 virus was permeable to protons and permitted RNP release. It is likely that this bleb corresponds to the M2-enriched and M1-depleted focus arising from pinching off of the virus during the completion of budding. Cooperatively, the data suggest that the influenza virus has an asymmetric structure where the M1-mediated organization of the RNP inside the virion is a prerequisite for infectious entry into target cell.
Copyright ? 2016 Elsevier Inc. All rights reserved.
[h=4]KEYWORDS:[/h] Asymmetric structure; Cleavage HA; Influenza virus; Ion channel M2; Protein M1; Virus entry
PMID: 26954078 [PubMed - as supplied by publisher]