Target SOCS3 in HSCs, which, in turn, activates the STAT3-mediated TGF- signaling pathway and enhances fibrosis marker genes . Certainly, non-canonical STAT3 activation induces a higher TGF-1 and collagen I expression. Furthermore, other variables such as Ago2, miR-122 and HSP90, happen to be discovered to intensify HCV replication . miR-122 is one of the most abundant miRNAs within the liver tissue, representing about 70 with the total miRNA pool . The key function of microRNAs would be to regulate the translation of cellular mRNAs by way of their integration into a protein complicated named RISC (RNA-induced silencing complex) with crucial proteins called Argonautes (Ago), of which human cells have four varieties: Ago1, -2, -3 and -4 . Argonaute two (Ago2), the effector of RNA interference (RNAi), demands and associates with heat shock protein 90 (Hsp90). The latter is one of the heat shock proteins (Hsps), molecular chaperones that control the folding and function of proteins. Nevertheless, it’s necessary to underline that these components potentiate viral replication, however they are not vital, considering the fact that their inhibition will not prevent it. In conclusion, these data demonstrate how the EVs released throughout HCV infection provide various molecules that favor effective viral replication in recipient cells [112,122]. four.3. The Case of SARS Viruses Coronaviruses (CoVs) belong to a large family of enveloped RNA viruses involved in a variety of respiratory syndromes. The name coronavirus derives from their characteristic electron microscopy appearance. They have a common round “fringe” that recalls the solar corona, which surrounds a spherical enveloped particle containing the good single-stranded RNA genome. The latter is complexed with the N viral protein, therefore forming a helical symmetrical nucleocapsid complicated . These viruses possess the largest recognized viral RNA genome (about 30 kb). All CoVs are characterized by a typical set of structural proteins: the nucleocapsid (N), the spike (S), the membrane (M) along with the envelope (E) proteins [124,125]. This type of viruses was identified to cause mild to moderate illnesses in humans, often characterized by cold-like symptoms and more rarely by the improvement of severe respiratory syndromes. Even so, some previously unknown species have brought on epidemics with serious clinical situations within the new millennium. That is the case of the serious acute respiratory syndrome virus (SARS-CoV), which emerged in southern China in the finish of 2002; the Middle East respiratory syndrome virus (MERS-CoV), which emerged in Saudi Arabia in 2012; and now the extreme acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which originated in the city of Wuhan in China in December 2019 . The interaction with the CoV S glycoprotein with its surface receptor is crucial to decide the cellular host tropism. MERS-CoV S protein binds the human receptor dipeptidyl peptidase-Viruses 2020, 12,10 of(DPP4) or adenosine deaminase complexing protein two, which is expressed Leukocyte Ig-Like Receptor B4 Proteins Species around the surface in the cells from the airway method. A function carried out throughout the first SARS-CoV epidemic identified the human host factor angiotensin-converting enzyme 2 (ACE2) because the receptor for SARS-CoV . ACE2 is really a metalloprotease expressed in the epithelial and alveolar cells on the human lung, in the intestine, liver, heart, vascular endothelium and kidneys . SARS-CoV-2 spike (S) protein has been TLK2 Proteins Species experimentally shown to bind ACE2 in host cells with considerably higher affi.