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1.
Diagn Microbiol Infect Dis ; 101(1): 115424, 2021 Sep.
Article in English | MEDLINE | ID: mdl-34111651

ABSTRACT

Cartridge-based multiplex panels covering numerous pathogens offer an advantage of minimal hands-on-time and short time to result to commercial RT-PCR assays. In this study, we evaluated the performance of the ePlex respiratory pathogen panel (RPP) compared to the Fast Track Diagnostics Respiratory pathogens 21 multiplex RT-PCR assay (FTD21) using 400 clinical respiratory samples. Discrepant results were further analysed by a reference nucleic acid amplification testing (NAT) and a composite reference approach was used for final interpretation. Discordant results were observed in 56 targets corresponding to 54 samples. Sensitivities and specificities were 85.5% and 99.9% for the ePlex RPP and 95.8% and 99.7% for the FTD21 system, respectively. Altogether, the ePlex RPP is a valuable tool for the rapid detection of a number of different respiratory viruses with the exception of the coronavirus family (low sensitivity ranging from 50-80%) and samples with a low pathogen load (Ct values >33).


Subject(s)
Molecular Diagnostic Techniques , Multiplex Polymerase Chain Reaction , Respiratory Tract Infections/diagnosis , Viruses/isolation & purification , Diagnostic Tests, Routine , Humans , Respiratory Tract Infections/virology , Sensitivity and Specificity , Time Factors , Viruses/classification , Viruses/genetics
2.
J Virol ; 94(22)2020 10 27.
Article in English | MEDLINE | ID: mdl-32907985

ABSTRACT

Mx proteins are interferon (IFN) type I (α/ß)- and type III (λ)-induced effector proteins with intrinsic antiviral activity. Mammalian Mx proteins show different subcellular localizations and distinct yet partially overlapping viral specificities. However, the precise mechanism(s) of antiviral action are still unresolved. Human MxA accumulates in the cytoplasm and inhibits a wide variety of RNA and DNA viruses, among them influenza A virus (IAV). In contrast, MxB, the second human Mx protein, localizes via its amino (N) terminus to the outer nuclear membrane at or near nuclear pores and inhibits the nuclear import of incoming human immunodeficiency viruses (HIV) and herpesviruses, but not that of IAV. Here, we evaluated whether the antiviral specificity of MxB is determined by its subcellular localization. For this purpose, we redirected MxB to the nucleus or cytoplasm by either attaching a nuclear localization signal to its N terminus or by exchanging the N terminus of MxB with that of MxA. Interestingly, ectopic expression of these MxB variants in the nucleus or in the cytoplasm rendered the host cells resistant to IAV, revealing that the capacity of MxB to block IAV replication critically depends on the site where the protein accumulates in the infected cell. Furthermore, coimmunoprecipitation (co-IP) assays demonstrated that MxB physically interacted with the nucleoprotein (NP) of IAV. Taken together, the data indicate that the subcellular localization of the MxB protein plays a pivotal role in determining its antiviral specificity.IMPORTANCE The interferon system plays a pivotal role in the defense against viral infections. The dynamin-related Mx proteins form a small family of interferon-induced effector proteins with distinct antiviral specificities and subcellular localizations. So far, it is not clear whether the different virus specificities of Mx proteins are the result of distinct mechanisms of action or are due rather to their different subcellular localization. We show here that the human MxB protein, normally localized to the outer membrane of the cell nucleus, acquires antiviral activity against IAV when redirected to the nucleus or cytoplasm, subcellular sites where other members of the Mx protein family efficiently interfere with IAV replication. Our findings thus strongly suggest that Mx proteins act primarily through a common mechanism and that their viral specificity is at least in part determined by their individual subcellular localization.


Subject(s)
Antiviral Agents/metabolism , Influenza A virus/drug effects , Myxovirus Resistance Proteins/metabolism , Active Transport, Cell Nucleus , Antiviral Agents/pharmacology , Cell Line , Cell Nucleus/metabolism , Cytoplasm/metabolism , HEK293 Cells , HeLa Cells , Humans , Influenza A virus/metabolism , Interferons/metabolism , Myxovirus Resistance Proteins/genetics , Myxovirus Resistance Proteins/pharmacology , Nucleoproteins , Virus Replication/drug effects
3.
Nat Commun ; 9(1): 1980, 2018 05 17.
Article in English | MEDLINE | ID: mdl-29773792

ABSTRACT

The type I interferon (IFN) system plays an important role in controlling herpesvirus infections, but it is unclear which IFN-mediated effectors interfere with herpesvirus replication. Here we report that human myxovirus resistance protein B (MxB, also designated Mx2) is a potent human herpesvirus restriction factor in the context of IFN. We demonstrate that ectopic MxB expression restricts a range of herpesviruses from the Alphaherpesvirinae and Gammaherpesvirinae, including herpes simplex virus 1 and 2 (HSV-1 and HSV-2), and Kaposi's sarcoma-associated herpesvirus (KSHV). MxB restriction of HSV-1 and HSV-2 requires GTPase function, in contrast to restriction of lentiviruses. MxB inhibits the delivery of incoming HSV-1 DNA to the nucleus and the appearance of empty capsids, but not the capsid delivery to the cytoplasm or tegument dissociation from the capsid. Our study identifies MxB as a potent pan-herpesvirus restriction factor which blocks the uncoating of viral DNA from the incoming viral capsid.


Subject(s)
Herpesviridae Infections/immunology , Herpesviridae/physiology , Interferon Type I/immunology , Myxovirus Resistance Proteins/immunology , Virus Replication/immunology , Capsid/immunology , Capsid Proteins/immunology , Cell Line, Tumor , Cell Nucleus/immunology , Cell Nucleus/virology , Cytoplasm , DNA, Viral/immunology , HEK293 Cells , Herpesviridae/pathogenicity , Herpesviridae Infections/virology , Humans , Myxovirus Resistance Proteins/genetics , RNA, Small Interfering/metabolism , Virus Uncoating/immunology
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