Exosomes are secreted by most cell types and circulate in body fluids. Recent studies have revealed that exosomes play a significant role in intercellular communication and are closely associated with the pathogenesis of disease. Therefore, exosomes are considered promising biomarkers for disease diagnosis. However, exosomes are always mixed with other components of body fluids. Consequently, separation methods for exosomes that allow high‐purity and high‐throughput separation with a high recovery rate and detection techniques for exosomes that are rapid, highly sensitive, highly specific, and have a low detection limit are indispensable for diagnostic applications. For decades, many exosome separation and detection techniques have been developed to achieve the aforementioned goals. However, in most cases, these two techniques are performed separately, which increases operation complexity, time consumption, and cost. The emergence of microfluidics offers a promising way to integrate exosome separation and detection functions into a single chip. Herein, an overview of conventional and microfluidics‐based techniques for exosome separation and detection is presented. Moreover, the advantages and drawbacks of these techniques are compared.

Previous studies have suggested that hepatitis B virus (HBV) blocks expression of the alpha interferon (IFN-a)-inducible myeloid differential primary response protein (MyD88) gene. To study the molecular mechanism(s) of the inhibition of MyD88 expression by HBV, MyD88 promoter reporter plasmids and vectors expressing different HBV viral proteins were constructed. Co-transfection experiments showed that IFN-induced MyD88 promoter activity was inhibited by HBV polymerase expression in a dose-dependent manner and that the terminal protein (TP) domain of HBV polymerase was responsible for this antagonistic activity. Analysis of site mutants showed that the region targeted by the polymerase protein contained the signal transducer and activator of transcription (Stat) binding site. Chromatin immunoprecipitation analysis showed that the IFN-induced DNA-binding activity of Stat1 was affected. Further study demonstrated that the HBV polymerase protein inhibited the Stat1 nuclear translocation induced by IFN-a, but did not induce Stat1 degradation nor interfere with its phosphorylation. In addition, HBV polymerase could inhibit the transcriptional activity of other IFN-stimulated response element-driven promoters and the expression of interferon-stimulated genes (ISGs), such as Stat1 and ISG15. In summary, these results indicate that HBV polymerase is a general inhibitor of IFN signalling and can inhibit IFN-inducible MyD88 expression by inhibiting the activity of the MyD88 promoter through blocking the nuclear translocation of Stat1.

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Myeloid differentiation primary response protein 88 (MyD88), which can be induced by alpha interferon (IFN-␣), has an antiviral activity against the hepatitis B virus (HBV). The mechanism of this antiviral activity remains poorly understood. Here, we report that MyD88 inhibited HBV replication in HepG2.2.15 cells and in a mouse model. The knockdown of MyD88 expression weakened the IFN-␣-induced inhibition of HBV replication. Furthermore, MyD88 posttranscriptionally reduced the levels of viral RNA. Remarkably, MyD88 accelerated the decay of viral pregenomic RNA in the cytoplasm. Mapping analysis showed that the RNA sequence located in the 5-proximal region of the pregenomic RNA was critical for the decay. In addition, MyD88 inhibited the nuclear export of pre-S/S RNAs via the posttranscriptional regulatory element (PRE). The retained pre-S/S RNAs were shown to degrade in the nucleus. Finally, we found that MyD88 inhibited the expression of polypyrimidine tract-binding protein (PTB), a key nuclear export factor for PRE-containing RNA. Taken together, our results define a novel antiviral mechanism against HBV mediated by MyD88.Hepatitis B virus (HBV) is a noncytopathic, enveloped virus with a circular, double-stranded DNA genome. It causes both acute and chronic infection of the human liver. Although a highly effective preventive vaccine is now available, HBV infection remains a major health problem worldwide. It is estimated that chronic HBV infection affects 350 to 400 million people globally, about a quarter of whom will eventually develop severe liver diseases, including liver cirrhosis, liver failure, and hepatocellular carcinoma (HCC) (4).Current antiviral therapies involve the use of nucleoside analogs and alpha interferon (IFN-␣) (28). IFN-␣, a type I interferon, engages the IFN-␣ receptor complex to activate the Jak/Stat pathway and trigger the transcription of a diverse set of genes, referred to as IFN-stimulated genes (ISGs) (2, 40). In total, the gene products of ISGs establish an antiviral response in target cells (2, 40). IFN-␣ inhibits HBV replication through a variety of mechanisms. It was reported previously that IFN-␣ can suppress viral gene expression, prevent the formation of viral RNA-containing core particles, and reduce the accumulation of viral replicative intermediates (11,35,37,(46)(47)(48). Importantly, the precise antiviral mechanism of IFN-␣ and the biological functions of many ISGs have not been fully elucidated.Myeloid differentiation primary response protein 88 (MyD88) is a key adaptor in the signaling cascade of the innate immune response (22). We and others have shown that MyD88 expression can be induced by IFN-␣ and that MyD88 has an antiviral activity against HBV in hepatoma cells that is mediated by nuclear factor B (NF-B) activation (12, 25, 51, 52). To counteract its inhibition, the HBV polymerase dampens the activation of the MyD88 promoter by blocking the nuclear translocation of Stat1, thereby reducing IFN-␣-inducible MyD88 expression (50), further suggesting a critical rol...