RESUMEN
OBJECTIVES: The molecular mechanisms underlying the pathogenesis of human coronavirus OC43 (HCoV-OC43) infection are poorly understood. In this study, we investigated the ability of HCoV-OC43 to antagonize the transcriptional activation of antiviral response elements. METHODS: HCoV-OC43 structural (membrane M and nucleocapsid N) and accessory proteins (ns2a and ns5a) were expressed individually in human embryonic kidney 293 (HEK-293) cells. The transcriptional activation of antiviral response elements was assessed by measuring the levels of firefly luciferase expressed under the control of interferon (IFN)-stimulated response element (ISRE), IFN-ß promoter, or nuclear factor kappa B response element (NF-κB-RE). The antiviral gene expression profile in HEK-293 cells was determined by PCR array. RESULTS: The transcriptional activity of ISRE, IFN-ß promoter, and NF-κB-RE was significantly reduced in the presence of HCoV-OC43 ns2a, ns5a, M, or N protein, following the challenge of cells with Sendai virus, IFN-α or tumor necrosis factor-α. The expression of antiviral genes involved in the type I IFN and NF-κB signaling pathways was also downregulated in the presence of HCoV-OC43 structural or accessory proteins. CONCLUSION: Both structural and accessory HCoV-OC43 proteins are able to inhibit antiviral response elements in HEK-293 cells, and to block the activation of different antiviral signaling pathways.
Asunto(s)
Infecciones por Coronavirus/virología , Coronavirus Humano OC43/patogenicidad , Proteínas de la Nucleocápside/metabolismo , Elementos de Respuesta/genética , Proteínas de la Matriz Viral/metabolismo , Proteínas Reguladoras y Accesorias Virales/metabolismo , Proteínas M de Coronavirus , Proteínas de la Nucleocápside de Coronavirus , Coronavirus Humano OC43/genética , Regulación hacia Abajo , Genes Reporteros , Células HEK293 , Humanos , Interferones/genética , FN-kappa B/genética , FN-kappa B/metabolismo , Proteínas de la Nucleocápside/genética , Regiones Promotoras Genéticas/genética , Transducción de Señal , Activación Transcripcional , Proteínas de la Matriz Viral/genética , Proteínas Reguladoras y Accesorias Virales/genéticaRESUMEN
Human coronavirus OC43 (HCoV-OC43) is a respiratory virus that usually causes a common cold. However, it has the potential to cause severe infection in young children and immunocompromised adults. Both SARS-CoV and MERS-CoV were shown to express proteins with the potential to evade early innate immune responses. However, the ability of HCoV-OC43 to antagonise the intracellular antiviral defences has not yet been investigated. The potential role of the HCoV-OC43 structural (M and N) and accessory proteins (ns2a and ns5a) in the alteration of antiviral gene expression was investigated in this study. HCoV-OC43M, N, ns2a and ns5a proteins were expressed in human embryonic kidney 293 (HEK-293) cells before challenge with Sendai virus. The Human Antiviral Response PCR array was used to profile the antiviral gene expression in HEK-293 cells. Over 30 genes were downregulated in the presence of one of the HCoV-OC43 proteins, e.g. genes representing mitogen-activated protein kinases, toll-like receptors, interferons, interleukins, and signaling transduction proteins. Our findings suggest that similarly to SARS-CoV and MERS-CoV, HCoV-OC43 has the ability to downregulate the transcription of genes critical for the activation of different antiviral signaling pathways. Further studies are needed to confirm the role of HCoV-OC43 structural and accessory proteins in antagonising antiviral gene expression.