African Swine Fever Virus Protein pE199L Mediates Virus Entry by Enabling Membrane Fusion and Core Penetration

ABSTRACT African swine fever virus (ASFV) is a complex nucleocytoplasmic large DNA virus (NCLDV) causing a lethal hemorrhagic disease that currently threatens the global pig industry. Despite its relevance in the infectious cycle, very little is known about the internalization of ASFV in the host ce...

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Autores principales:	Tania Matamoros, Alí Alejo, Javier María Rodríguez, Bruno Hernáez, Milagros Guerra, Alberto Fraile-Ramos, Germán Andrés
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2020
Materias:	African swine fever virus ASFV giant DNA virus nucleocytoplasmic large DNA virus NCLDV viral fusion Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/521cf6d19ec84aa7ac92b89c05f49247
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spelling	oai:doaj.org-article:521cf6d19ec84aa7ac92b89c05f492472021-11-15T15:56:43ZAfrican Swine Fever Virus Protein pE199L Mediates Virus Entry by Enabling Membrane Fusion and Core Penetration10.1128/mBio.00789-202150-7511https://doaj.org/article/521cf6d19ec84aa7ac92b89c05f492472020-08-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.00789-20https://doaj.org/toc/2150-7511ABSTRACT African swine fever virus (ASFV) is a complex nucleocytoplasmic large DNA virus (NCLDV) causing a lethal hemorrhagic disease that currently threatens the global pig industry. Despite its relevance in the infectious cycle, very little is known about the internalization of ASFV in the host cell. Here, we report the characterization of ASFV protein pE199L, a cysteine-rich structural polypeptide with similarity to proteins A16, G9, and J5 of the entry fusion complex (EFC) of poxviruses. Using biochemical and immunomicroscopic approaches, we found that, like the corresponding poxviral proteins, pE199L localizes to the inner viral envelope and behaves as an integral transmembrane polypeptide with cytosolic intramolecular disulfide bonds. Using an ASFV recombinant that inducibly expresses the E199L gene, we found that protein pE199L is not required for virus assembly and egress or for virus-cell binding and endocytosis but is required for membrane fusion and core penetration. Interestingly, similar results have been previously reported for ASFV protein pE248R, an inner membrane virion component related to the poxviral L1 and F9 EFC proteins. Taken together, these findings indicate that ASFV entry relies on a form of fusion machinery comprising proteins pE248R and pE199L that displays some similarities to the unconventional fusion apparatus of poxviruses. Also, these results provide novel targets for the development of strategies that block the first stages of ASFV replication. IMPORTANCE African swine fever virus (ASFV) causes a highly lethal swine disease that is currently present in many countries of Eastern Europe, the Russian Federation, and Southeast Asia, severely affecting the pig industry. Despite extensive research, effective vaccines or antiviral strategies are still lacking and relevant gaps in knowledge of the fundamental biology of the viral infection cycle exist. In this study, we identified pE199L, a protein of the inner viral membrane that is required for virus entry. More specifically, pE199L is necessary for the fusion event that leads to the penetration of the genome-containing core in the host cell. Our results significantly increase our knowledge of the process of internalization of African swine fever virus, which may instruct future research on antiviral strategies.Tania MatamorosAlí AlejoJavier María RodríguezBruno HernáezMilagros GuerraAlberto Fraile-RamosGermán AndrésAmerican Society for MicrobiologyarticleAfrican swine fever virusASFVgiant DNA virusnucleocytoplasmic large DNA virusNCLDVviral fusionMicrobiologyQR1-502ENmBio, Vol 11, Iss 4 (2020)
institution	DOAJ
collection	DOAJ
language	EN
topic	African swine fever virus ASFV giant DNA virus nucleocytoplasmic large DNA virus NCLDV viral fusion Microbiology QR1-502
spellingShingle	African swine fever virus ASFV giant DNA virus nucleocytoplasmic large DNA virus NCLDV viral fusion Microbiology QR1-502 Tania Matamoros Alí Alejo Javier María Rodríguez Bruno Hernáez Milagros Guerra Alberto Fraile-Ramos Germán Andrés African Swine Fever Virus Protein pE199L Mediates Virus Entry by Enabling Membrane Fusion and Core Penetration
description	ABSTRACT African swine fever virus (ASFV) is a complex nucleocytoplasmic large DNA virus (NCLDV) causing a lethal hemorrhagic disease that currently threatens the global pig industry. Despite its relevance in the infectious cycle, very little is known about the internalization of ASFV in the host cell. Here, we report the characterization of ASFV protein pE199L, a cysteine-rich structural polypeptide with similarity to proteins A16, G9, and J5 of the entry fusion complex (EFC) of poxviruses. Using biochemical and immunomicroscopic approaches, we found that, like the corresponding poxviral proteins, pE199L localizes to the inner viral envelope and behaves as an integral transmembrane polypeptide with cytosolic intramolecular disulfide bonds. Using an ASFV recombinant that inducibly expresses the E199L gene, we found that protein pE199L is not required for virus assembly and egress or for virus-cell binding and endocytosis but is required for membrane fusion and core penetration. Interestingly, similar results have been previously reported for ASFV protein pE248R, an inner membrane virion component related to the poxviral L1 and F9 EFC proteins. Taken together, these findings indicate that ASFV entry relies on a form of fusion machinery comprising proteins pE248R and pE199L that displays some similarities to the unconventional fusion apparatus of poxviruses. Also, these results provide novel targets for the development of strategies that block the first stages of ASFV replication. IMPORTANCE African swine fever virus (ASFV) causes a highly lethal swine disease that is currently present in many countries of Eastern Europe, the Russian Federation, and Southeast Asia, severely affecting the pig industry. Despite extensive research, effective vaccines or antiviral strategies are still lacking and relevant gaps in knowledge of the fundamental biology of the viral infection cycle exist. In this study, we identified pE199L, a protein of the inner viral membrane that is required for virus entry. More specifically, pE199L is necessary for the fusion event that leads to the penetration of the genome-containing core in the host cell. Our results significantly increase our knowledge of the process of internalization of African swine fever virus, which may instruct future research on antiviral strategies.
format	article
author	Tania Matamoros Alí Alejo Javier María Rodríguez Bruno Hernáez Milagros Guerra Alberto Fraile-Ramos Germán Andrés
author_facet	Tania Matamoros Alí Alejo Javier María Rodríguez Bruno Hernáez Milagros Guerra Alberto Fraile-Ramos Germán Andrés
author_sort	Tania Matamoros
title	African Swine Fever Virus Protein pE199L Mediates Virus Entry by Enabling Membrane Fusion and Core Penetration
title_short	African Swine Fever Virus Protein pE199L Mediates Virus Entry by Enabling Membrane Fusion and Core Penetration
title_full	African Swine Fever Virus Protein pE199L Mediates Virus Entry by Enabling Membrane Fusion and Core Penetration
title_fullStr	African Swine Fever Virus Protein pE199L Mediates Virus Entry by Enabling Membrane Fusion and Core Penetration
title_full_unstemmed	African Swine Fever Virus Protein pE199L Mediates Virus Entry by Enabling Membrane Fusion and Core Penetration
title_sort	african swine fever virus protein pe199l mediates virus entry by enabling membrane fusion and core penetration
publisher	American Society for Microbiology
publishDate	2020
url	https://doaj.org/article/521cf6d19ec84aa7ac92b89c05f49247
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African Swine Fever Virus Protein pE199L Mediates Virus Entry by Enabling Membrane Fusion and Core Penetration

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