Development and application of an indirect ELISA for the detection of antibodies against encephalomyocarditis virus

Development of efficient, sensitive, and specific detection method for Encephalomyocarditis virus based on CRISPR/Cas13a

The Encephalomyocarditis virus (EMCV) is one of the major zoonosis pathogens, and it can cause acute myocarditis in young pigs or reproductive failure in sows. EMCV has been recognized as a pathogen infecting many species and causes substantial economic losses worldwide. Therefore, the development of a rapid, sensitive, and accurate detection of this virus is essential for the diagnosis and control of the EMCV-induced disease. The RNA-guiding, RNA-targeting CRISPR effector CRISPR/Cas13a (Cas13a, previously known as C2c2) exhibits a "collateral effect" of promiscuous RNase activity upon the target recognition. When the crRNA of LwCas13a binds to the target RNA, the collateral cleavage activity of LwCas13a is activated to degrade the non-targeted RNA. In this study, we developed an efficient, sensitive, and specific EMCV detection method based on the collateral cleavage activity of LwCas13a by combining recombinase-aided amplification (RAA) and a lateral flow strip. This method was an isothermal detection at 37 °C, which allowed visual observation by the naked eyes. We also optimized the reaction conditions of this method, and the detection result could be obtained within 60 min. The sensitivity of our method reached up to 10¹ copies/µL. Furthermore, no cross-reactions with other 8 major swine viruses were observed, indicating the excellent specificity of this method. At the same time, the assay had a 100 % coincidence rate with qPCR detection of the EMCV in 37 clinical samples. In addition, our developed method requires only 2-step operations and basic equipment, and thus it is simple and inexpensive. Overall, CRISPR/Cas13a-based detection has a great application potential for the EMCV detection.

Host protein, HSP90β, antagonizes IFN-β signaling pathway and facilitates the proliferation of encephalomyocarditis virus in vitro

Encephalomyocarditis virus (EMCV) is a small, non-enveloped, single stranded RNA virus which infects a wide variety of mammalian species, and has zoonotic importance. Many host proteins are known to regulate EMCV proliferation by interacting with its structural or nonstructural proteins, but the regulatory role and mechanism of heat shock protein 90β (HSP90β), in EMCV infection has not been reported yet. Here, we report that overexpression of HSP90β significantly promotes the growth and proliferation of EMCV in vitro. On the contrary, down-regulation of HSP90β by RNAi or geldanamycin inhibits EMCV replication. HSP90β suppresses IFN-β responses in the RLRs pathway by targeting the expression of the key adaptor molecules MAVS, TBK1, and IRF3, but not MDA5. This study demonstrates the firsthand information that HSP90β plays a positive role in viral proliferation by inhibiting EMCV induced IFN-β production. Collectively, the results reveal new insights into HSP90β-assisted progression of EMCV infection.

Transmembrane Protein 39A Promotes the Replication of Encephalomyocarditis Virus via Autophagy Pathway

Encephalomyocarditis virus (EMCV) causes encephalitis, myocarditis, neuropathy, reproductive disorders, and diabetes in animals. EMCV is known to induce cell autophagy; however, the molecular mechanisms underlying this remain unclear. Here, we show that the type III-transmembrane protein, transmembrane protein 39A (TMEM39A), plays a critical role in EMCV replication. We showed that EMCV GS01 strain infection upregulated TMEM39A expression. Importantly, EMCV induced autophagy in a range of host cells. The autophagy chemical inhibitor, 3-MA, inhibited EMCV replication and reduced TMEM39A expression. This is the first study demonstrating TMEM39A promoting the replication of EMCV via autophagy. Overall, we show that TMEM39A plays a positive regulatory role in EMCV proliferation and that TMEM39A expression is dependent on the autophagy pathway.