Protection from lethal coronavirus infection by affinity-purified spike glycoprotein of murine hepatitis virus, strain A59

ABSTRACT Infection by the coronavirus mouse hepatitis virus strain A59 (MHV-A59) requires the release of the viral genome by fusion with the respective target membrane of the host cell. Fusion is mediated by the viral S protein. Here, the entry pathway of MHV-A59 into murine fibroblast cells was studied by independent approaches. Infection of cells assessed by plaque reduction assay was strongly inhibited by lysosomotropic compounds and substances that interfere with clathrin-dependent endocytosis, suggesting that MHV-A59 is taken up via endocytosis and delivered to acidic endosomal compartments. Infection was only slightly reduced in the presence of substances inhibiting proteases of endosomal compartments, precluding that the endocytic uptake is required to activate the fusion potential of the S protein by its cleavage. Fluorescence confocal microscopy of labeled MHV-A59 confirmed that virus is taken up via endocytosis. Bright labeling of intracellular compartments suggests their fusion with the viral envelope. No fusion with the plasma membrane was observed at neutral pH conditions. However, when virus was bound to cells and the pH was lowered to 5.0, we observed a strong labeling of the plasma membrane. Electron microscopy revealed low pH triggered conformational alterations of the S ectodomain. Very likely, these alterations are irreversible because low-pH treatment of viruses in the absence of target membranes caused an irreversible loss of the fusion activity. The results imply that endocytosis plays a major role in MHV-A59 infection and the acidic pH of the endosomal compartment triggers a conformational change of the S protein mediating fusion.

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Expression of Hemagglutinin Esterase Protein from Recombinant Mouse Hepatitis Virus Enhances Neurovirulence

Journal of Virology ◽

10.1128/jvi.79.24.15064-15073.2005 ◽

2005 ◽

Vol 79 (24) ◽

pp. 15064-15073 ◽

Cited By ~ 36

Author(s):

Lubna Kazi ◽

Arjen Lissenberg ◽

Richard Watson ◽

Raoul J. de Groot ◽

Susan R. Weiss

Keyword(s):

Receptor Binding ◽

Demyelinating Disease ◽

Hepatitis Virus ◽

Critical Role ◽

Spike Glycoprotein ◽

Murine Hepatitis Virus ◽

Recombinant Viruses ◽

Viral Spread ◽

The Central Nervous System

ABSTRACT Murine hepatitis virus (MHV) infection provides a model system for the study of hepatitis, acute encephalitis, and chronic demyelinating disease. The spike glycoprotein, S, which mediates receptor binding and membrane fusion, plays a critical role in MHV pathogenesis. However, viral proteins other than S also contribute to pathogenicity. The JHM strain of MHV is highly neurovirulent and expresses a second spike glycoprotein, the hemagglutinin esterase (HE), which is not produced by MHV-A59, a hepatotropic but only mildly neurovirulent strain. To investigate a possible role for HE in MHV-induced neurovirulence, isogenic recombinant MHV-A59 viruses were generated that produced either (i) the wild-type protein, (ii) an enzymatically inactive HE protein, or (iii) no HE at all (A. Lissenberg, M. M. Vrolijk, A. L. W. van Vliet, M. A. Langereis, J. D. F. de Groot-Mijnes, P. J. M. Rottier, and R. J. de Groot, J. Virol. 79:15054-15063, 2005 [accompanying paper]). A second, mirror set of recombinant viruses was constructed in which, in addition, the MHV-A59 S gene had been replaced with that from MHV-JHM. The expression of HE in combination with A59 S did not affect the tropism, pathogenicity, or spread of the virus in vivo. However, in combination with JHM S, the expression of HE, regardless of whether it retained esterase activity or not, resulted in increased viral spread within the central nervous system and in increased neurovirulence. Our findings suggest that the properties of S receptor utilization and/or fusogenicity mainly determine organ and host cell tropism but that HE enhances the efficiency of infection and promotes viral dissemination, at least in some tissues, presumably by serving as a second receptor-binding protein.

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Fulminant Hepatic Failure in Murine Hepatitis Virus Strain 3 Infection: Tissue-Specific Expression of a Novel fgl2 Prothrombinase

Journal of Virology ◽

10.1128/jvi.72.4.3504a-3504a.1998 ◽

1998 ◽

Vol 72 (4) ◽

pp. 3504-3504

Author(s):

J. W. Ding ◽

Q. Ning ◽

M. F. Liu ◽

A. Lai ◽

J. Leibowitz ◽

...

Keyword(s):

Virus Strain ◽

Fulminant Hepatic Failure ◽

Hepatic Failure ◽

Hepatitis Virus ◽

Murine Hepatitis Virus ◽

Specific Expression ◽

Tissue Specific ◽

Tissue Specific Expression

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Loss of resistance to murine hepatitis virus strain 3 infection after treatment with corticosteroids is associated with induction of macrophage procoagulant activity.

Journal of Virology ◽

10.1128/jvi.70.7.4275-4282.1996 ◽

1996 ◽

Vol 70 (7) ◽

pp. 4275-4282 ◽

Cited By ~ 14

Author(s):

R J Fingerote ◽

M Abecassis ◽

M J Phillips ◽

Y S Rao ◽

E H Cole ◽

...

Keyword(s):

Virus Strain ◽

Hepatitis Virus ◽

Procoagulant Activity ◽

Murine Hepatitis Virus ◽

Loss Of Resistance

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Inhibiting ACSL1 related ferroptosis restrains MHV-A59 infection

10.1101/2021.10.14.464337 ◽

2021 ◽

Author(s):

Huawei Xia ◽

Zeming Zhang ◽

Fuping You

Keyword(s):

Hepatitis Virus ◽

Murine Hepatitis Virus ◽

Viral Propagation ◽

Triacsin C ◽

Representative Model ◽

Infected Cells ◽

Coronavirus Infection ◽

Syncytia Formation ◽

In Vivo Administration

Murine hepatitis virus strain A59 (MHV-A59) belongs to the β-coronavirus and is considered as a representative model for studying coronavirus infection. MHV-A59 was shown to induce pyroptosis, apoptosis and necroptosis of infected cells, especially the murine macrophages. However, whether ferroptosis, a recently identified form of lytic cell death, was involved in the pathogenicity of MHV-A59, is unknown. Here, we demonstrate inhibiting ferroptosis suppresses MHV-A59 infection. MHV-A59 infection upregulates the expression of Acsl1, a novel ferroptosis inducer. MHV-A59 upregulates Acsl1 expression depending on the NF-kB activation, which is TLR4-independent. Ferroptosis inhibitor inhibits viral propagation, inflammatory cytokines release and MHV-A59 infection induced cell syncytia formation. ACSL1 inhibitor Triacsin C suppresses MHV-A59 infection induced syncytia formation and viral propagation. In vivo administration of liproxstatin-1 ameliorates lung inflammation and tissue injuries caused by MHV-A59 infection. Collectively, these results indicate that ferroptosis inhibition protects hosts from MHV-A59 infection. Targeting ferroptosis may serves as a potential treatment approach for dealing with hyper-inflammation induced by coronavirus infection.

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