scholarly journals The N-terminal Region of Middle East Respiratory Syndrome Coronavirus Accessory Protein 8b is Essential for Enhanced Virulence of an Attenuated Murine Coronavirus

2021 ◽  
Author(s):  
Yuming Li ◽  
Yingkang Jin ◽  
Lijun Kuang ◽  
Zhenhua Luo ◽  
Fang Li ◽  
...  
Keyword(s):  
Immune Response ◽  
Middle East ◽  
Hepatitis Virus ◽  
Mouse Hepatitis Virus ◽  
Terminal Region ◽  
Middle East Respiratory Syndrome ◽  
Accessory Protein ◽  
Accessory Proteins

Middle East respiratory syndrome coronavirus (MERS-CoV) is a beta coronavirus that emerged in 2012, causing severe pneumonia and renal failure. MERS-CoV encodes five accessory proteins. Some of them have been shown to interfere with host antiviral immune response. However, the roles of protein 8b in innate immunity and viral virulence was rarely studied. Here, we introduced individual MERS-CoV accessory protein genes into the genome of an attenuated murine coronavirus (Mouse hepatitis virus, MHV), respectively and found accessory protein 8b could enhance viral replication in vivo and in vitro , and increase the lethality of infected mice. RNA-seq analysis revealed that protein 8b could significantly inhibit type I interferon production (IFN-I) and innate immune response in mice infected with MHV expressing protein 8b. We also found that MERS-CoV protein 8b could initiate from multiple internal methionine sites and at least three protein variants were identified. Residues 1-23 of protein 8b was demonstrated to be responsible for increased virulence in vivo . In addition, the inhibitory effect on IFN-I of protein 8b might not contribute to its virulence enhancement as aa1-23 deletion did not affect IFN-I production in vitro and in vivo . Next, we also found that protein 8b was localized to the endoplasmic reticulum (ER)/Golgi membrane in infected cells, which was disrupted by C-terminal region aa 88-112 deletion. This study will provide new insight into the pathogenesis of MERS-CoV infection. IMPORTANCE Multiple coronaviruses (CoV) cause severe respiratory infections and become global public health threats such as SARS-CoV, MERS-CoV, and SARS-CoV-2. Each coronavirus contains different numbers of accessory proteins which show high variability among different CoVs. Accessory proteins are demonstrated to play essential roles in pathogenesis of CoVs. MERS-CoV contains 5 accessory proteins (protein 3, 4a, 4b, 5, 8b), and deletion of all four accessory proteins (protein 3, 4a, 4b, 5), significantly affects MERS-CoV replication and pathogenesis. However, whether ORF8b also regulates MERS-CoV infection is unknown. Here, we constructed mouse hepatitis virus (MHV) recombinant virus expressing MERS-CoV protein 8b and demonstrated protein 8b could significantly enhance the virulence of MHV, which is mediated by N-terminal domain of protein 8b. This study will shed light on the understanding of pathogenesis of MERS-CoV infection.

scholarly journals Preferential Infection of Mature Dendritic Cells by Mouse Hepatitis Virus Strain JHM

2006 ◽  
Vol 80 (5) ◽  
pp. 2506-2514 ◽  
Author(s):  
Haixia Zhou ◽  
Stanley Perlman
Keyword(s):  
Immune Response ◽  
Dendritic Cells ◽  
Virus Strain ◽  
Hepatitis Virus ◽  
Ex Vivo ◽  
Mouse Hepatitis Virus ◽  
Demyelinating Diseases ◽  
Immature Cells

ABSTRACT Mouse hepatitis virus strain JHM (MHV-JHM) causes acute encephalitis and acute and chronic demyelinating diseases in mice. Dendritic cells (DCs) are key cells in the initiation of innate and adaptive immune responses, and infection of these cells could potentially contribute to a dysregulated immune response; consistent with this, recent results suggest that DCs are readily infected by another strain of mouse hepatitis virus, the A59 strain (MHV-A59). Herein, we show that the JHM strain also productively infected DCs. Moreover, mature DCs were at least 10 times more susceptible than immature DCs to infection with MHV-JHM. DC function was impaired after MHV-JHM infection, resulting in decreased stimulation of CD8 T cells in vitro. Preferential infection of mature DCs was not due to differential expression of the MHV-JHM receptor CEACAM-1a on mature or immature cells or to differences in apoptosis. Although we could not detect infected DCs in vivo, both CD8+ and CD11b+ splenic DCs were susceptible to infection with MHV-JHM directly ex vivo. This preferential infection of mature DCs may inhibit the development of an efficient immune response to the virus.

scholarly journals Localisation of the melanocortin-2-receptor and its accessory proteins in the developing and adult adrenal gland

2011 ◽  
Vol 46 (3) ◽  
pp. 227-232 ◽  
Author(s):  
Rebecca J Gorrigan ◽  
Leonardo Guasti ◽  
Peter King ◽  
Adrian J Clark ◽  
Li F Chan
Keyword(s):  
Adrenal Gland ◽  
Adrenal Cortex ◽  
Accessory Protein ◽  
Zona Fasciculata ◽  
Accessory Proteins ◽  
Similar Function ◽  
Glucocorticoid Deficiency ◽  
Inactivating Mutations

The melanocortin-2-receptor (MC2R)/MC2R accessory protein (MRAP) complex is critical to the production of glucocorticoids from the adrenal cortex. Inactivating mutations in either MC2R or MRAP result in the clinical condition familial glucocorticoid deficiency. The localisation of MC2R together with MRAP within the adrenal gland has not previously been reported. Furthermore, MRAP2, a paralogue of MRAP, has been shown in vitro to have a similar function to MRAP, facilitating MC2R trafficking and responsiveness to ACTH. Despite similar MC2R accessory functions, in vivo, patients with inactivating mutations of MRAP fail to be rescued by a functioning MRAP2 gene, suggesting differences in adrenal expression, localisation and/or function between the two MRAPs. In this study on the rat adrenal gland, we demonstrate that while MRAP and MC2R are highly expressed in the zona fasciculata, MRAP2 is expressed throughout the adrenal cortex in low quantities. In the developing adrenal gland, both MRAP and MRAP2 are equally well expressed. The MC2R/MRAP2 complex requires much higher concentrations of ACTH to activate compared with the MC2R/MRAP complex. Interestingly, expression of MC2R and MRAP in the undifferentiated zone would support the notion that ACTH may play an important role in adrenal cell differentiation and maintenance.

scholarly journals ONTOGENY OF MACROPHAGE RESISTANCE TO MOUSE HEPATITIS IN VIVO AND IN VITRO

1967 ◽  
Vol 125 (4) ◽  
pp. 537-548 ◽  
Author(s):  
Ruth Gallily ◽  
Anne Warwick ◽  
Frederik B. Bang
Keyword(s):  
Hepatitis Virus ◽  
Mouse Hepatitis Virus ◽  
Susceptible Strain ◽  
Time Of Death ◽  
Complete Resistance ◽  
Different Ages ◽  
C3h Mice ◽  
Resistant Cells

Adult or weanling C3H mice were found to be genetically resistant to a strain of mouse hepatitis virus. Infant C3H mice, however, developed infection and died from mouse hepatitis virus when minimal infectious doses of virus were given to them. There was a delay in the time of death compared to that of the genetically susceptible strain, and the virus recovered from these mice had increased pathogenicity for C3H mice. The ontogeny of resistance to hepatitis in the C3H mice thus progresses from delayed susceptibility to complete resistance as the age of the host increases. It is reflected in increased resistance of macrophages derived in vitro from liver cultures of infant mice of different ages. This increase in resistance with age was reduced by maintaining the cultures for a longer period of time before inoculation, or by increasing the number of explants in a given culture. Resistant cells were uniformly furnished by mice age 16 days, or more. It is concluded that a process of maturation of resistance of the cells takes place after the mice are born, but that this does not continue under in vitro conditions, and that it may be modified by the environment of the cells.

scholarly journals SYNCRIP, a Member of the Heterogeneous Nuclear Ribonucleoprotein Family, Is Involved in Mouse Hepatitis Virus RNA Synthesis

2004 ◽  
Vol 78 (23) ◽  
pp. 13153-13162 ◽  
Author(s):  
Keum S. Choi ◽  
Akihiro Mizutani ◽  
Michael M. C. Lai
Keyword(s):  
Mammalian Cells ◽  
Rna Synthesis ◽  
Rna Binding ◽  
Hepatitis Virus ◽  
Affinity Purification ◽  
Mouse Hepatitis Virus ◽  
Viral Rna ◽  
Negative Strand

ABSTRACT Several cellular proteins, including several heterogeneous nuclear ribonucleoproteins (hnRNPs), have been shown to function as regulatory factors for mouse hepatitis virus (MHV) RNA synthesis as a result of their binding to the 5′ and 3′ untranslated regions (UTRs) of the viral RNA. Here, we identified another cellular protein, p70, which has been shown by UV cross-linking to bind both the positive- and negative-strand UTRs of MHV RNA specifically. We purified p70 with a a one-step RNA affinity purification procedure with the biotin-labeled 5′-UTR. Matrix-assisted laser desorption ionization (MALDI)-mass spectrometry identified it as synaptotagmin-binding cytoplasmic RNA-interacting protein (SYNCRIP). SYNCRIP is a member of the hnRNP family and localizes largely in the cytoplasm. The p70 was cross-linked to the MHV positive- or negative-strand UTR in vitro and in vivo. The bacterially expressed SYNCRIP was also able to bind to the 5′-UTR of both strands. The SYNCRIP-binding site was mapped to the leader sequence of the 5′-UTR, requiring the UCUAA repeat sequence. To investigate the functional significance of SYNCRIP in MHV replication, we expressed a full-length or a C-terminally truncated form of SYNCRIP in mammalian cells expressing the MHV receptor. The overexpression of either form of SYNCRIP inhibited syncytium formation induced by MHV infection. Furthermore, downregulation of the endogenous SYNCRIP with a specific short interfering RNA delayed MHV RNA synthesis; in contrast, overexpression or downregulation of SYNCRIP did not affect MHV translation. These results suggest that SYNCRIP may be directly involved in MHV RNA replication as a positive regulator. This study identified an additional cellular hnRNP as an MHV RNA-binding protein potentially involved in viral RNA synthesis.

scholarly journals The ORF4b-encoded accessory proteins of Middle East respiratory syndrome coronavirus and two related bat coronaviruses localize to the nucleus and inhibit innate immune signalling

2014 ◽  
Vol 95 (4) ◽  
pp. 874-882 ◽  
Author(s):  
Krystal L. Matthews ◽  
Christopher M. Coleman ◽  
Yvonne van der Meer ◽  
Eric J. Snijder ◽  
Matthew B. Frieman
Keyword(s):  
Middle East ◽  
Severe Pneumonia ◽  
Cell Types ◽  
Innate Immune ◽  
Middle East Respiratory Syndrome ◽  
Signalling Pathways ◽  
Type I ◽  
Accessory Proteins ◽  
Type I Ifn

The recently emerged Middle East respiratory syndrome coronavirus (MERS-CoV), a betacoronavirus, is associated with severe pneumonia and renal failure. The environmental origin of MERS-CoV is as yet unknown; however, its genome sequence is closely related to those of two bat coronaviruses, named BtCoV-HKU4 and BtCoV-HKU5, which were derived from Chinese bat samples. A hallmark of highly pathogenic respiratory viruses is their ability to evade the innate immune response of the host. CoV accessory proteins, for example those from severe acute respiratory syndrome CoV (SARS-CoV), have been shown to block innate antiviral signalling pathways. MERS-CoV, similar to SARS-CoV, has been shown to inhibit type I IFN induction in a variety of cell types in vitro. We therefore hypothesized that MERS-CoV and the phylogenetically related BtCoV-HKU4 and BtCoV-HKU5 may encode proteins with similar capabilities. In this study, we have demonstrated that the ORF4b-encoded accessory protein (p4b) of MERS-CoV, BtCoV-HKU4 and BtCoV-HKU5 may indeed facilitate innate immune evasion by inhibiting the type I IFN and NF-κB signalling pathways. We also analysed the subcellular localization of p4b from MERS-CoV, BtCoV-HKU4 and BtCoV-HKU5 and demonstrated that all are localized to the nucleus.

scholarly journals Mouse hepatitis virus type 4 (JHM strains). induced fatal central nervous system disease. I. genetic control and murine neuron as the susceptible site of disease.

1981 ◽  
Vol 153 (4) ◽  
pp. 832-843 ◽  
Author(s):  
R L Knobler ◽  
M V Haspel ◽  
M B Oldstone
Keyword(s):  
Hepatitis Virus ◽  
Inbred Mouse ◽  
Neuronal Cells ◽  
Mouse Hepatitis Virus ◽  
Neuronal Cell ◽  
Autosomal Gene ◽  
Mouse Strains ◽  
Target Cells

Mouse hepatitis virus (JHM strain) type 4 induces acute encephalitis followed by death in many strains of laboratory mice. Immunohistochemical study in vivo and analysis of mouse neuronal cells in vitro both indicate that the target cells in this infection is the neuron. Further, examination of several inbred mouse strains and neuronal cells from them shows that disease expression is controlled by a single autosomal gene action at the level of the neuronal cell. Susceptibility is dominant but not H-2 linked. However, cultured neuronal cells and macrophages from SJL/J mice, which are resistant to this infection, fail to make significant amounts of infectious virus after an appropriate viral inoculation. Apparently the defect is not at the level of the virus-cell receptor, because these cells, in part, express viral antigens.

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