Recent research advances in the development of Dabie Banda virus vaccines.

Severe fever with thrombocytopenia syndrome (SFTS) is a newly identified tick-borne viral hemorrhagic fever caused by Dabie Banda virus (DBV). The virus was first discovered in eastern China in 2009 and is now considered an infectious disease with a mortality rate ranging from 6.3% to 30%. The best strategy for controlling SFTS is to develop effective vaccines. However, no approved vaccines are currently available to prevent this disease, despite the number of extensive and in-depth studies conducted on DBV in the past few years. This review focuses on the structure of DBV and the induced host immune responses which are the fundamental factors in vaccine development, and thoroughly summarizes the current research progress on DBV vaccines. The developing DBV vaccines include protein subunit vaccines, live attenuated vaccines, recombinant virus vector vaccines, and DNA vaccines. At present, almost all candidate vaccines for DBV are in the laboratory development or preclinical stages. There remain challenges in successfully developing clinically approved DBV vaccines.

Multi-omic and comparative analyses revealed monocyte-derived alpha-defensin-1 correlated with COVID-19 severity and inhibited SARS-CoV-2 infection.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the etiological pathogen of coronavirus disease 2019 (COVID-19), a highly contagious disease, spreading quickly and threatening global public health. The symptoms of COVID-19 vary from mild reactions to severe respiratory distress or even fatal outcomes probably due to the different status of host immunity against the virus. Here in the study, we unveiled plasma proteomic signatures and transcriptional patterns of peripheral blood mononuclear cells (PBMCs) using blood samples of 10 COVID-19 patients with different severity. Through systemic analysis, α-defensin-1 (DEFA1) was identified to be elevated in both plasma and PBMCs, and correlated with disease severity and stages. In vitro study demonstrated that DEFA1 was secreted from immunocytes and suppressed SARS-CoV-2 infection of both original and mutated strains with dose dependency. By using sequencing data, we discovered that DEFA1 was activated in monocytes through NF-κB signaling pathway after infection, and secreted into circulation to perturb SARS-CoV-2 infection by interfering protein kinase C expression. It worked mainly during virus replication instead of entry in host cells. Together, the anti-SARS-CoV-2 mechanism of DEFA1 has unveiled a corner of how innate immunity is against SARS-CoV-2 and explored its clinical potential in disease prognosis and therapeutic intervention.

Recent Advancements in Mosquito-Borne Flavivirus Vaccine Development.

Lately, the global incidence of flavivirus infection has been increasing dramatically and presents formidable challenges for public health systems around the world. Most clinically significant flaviviruses are mosquito-borne, such as the four serotypes of dengue virus, Zika virus, West Nile virus, Japanese encephalitis virus and yellow fever virus. Until now, no effective antiflaviviral drugs are available to fight flaviviral infection; thus, a highly immunogenic vaccine would be the most effective weapon to control the diseases. In recent years, flavivirus vaccine research has made major breakthroughs with several vaccine candidates showing encouraging results in preclinical and clinical trials. This review summarizes the current advancement, safety, efficacy, advantages and disadvantages of vaccines against mosquito-borne flaviviruses posing significant threats to human health.

Hepatitis C Virus Infection Cycle-Specific MicroRNA Profiling Reveals Stage-Specific miR-4423-3p Targets RIG-I to Facilitate Infection.

Hepatitis C virus (HCV) infection is one of the main causes of chronic liver diseases, the disorders of which involve multiple pathological processes and elements including host factors such as non-coding small RNAs. Although several genes have been reported to be correlated with HCV infection, the potential regulatory network has not been deciphered clearly. By small RNA sequencing, we clarified the expression profile of microRNAs (miRNAs) in HCV-infected Huh7 and Huh7.5.1 cells and identified 6 dysregulated miRNAs with the same expression trend and 32 dysregulated miRNAs with different expression trends during different stages of HCV life cycle. By looking into each infection stage, we found that 6 miRNAs were entry stage specific, 4 miRNAs were replication stage specific, and 1 miRNA was related to the transmission stage. Moreover, due to the fact that Huh7.5.1 cells have a retinoic acid-inducible gene 1 (RIG-I) mutation which causes reduced production of interferons (IFNs), we here focused on the miRNAs of different trends to decipher the RIG-I/IFN specific miRNAs. Among them, miR-4423-3p showed a significant promotive effect on HCV infection by suppressing RIG-I/IFN pathway through direct binding to RIG-I mRNA. Together, the results displayed novel insights into the miRNA regulatory networks in HCV infection and progression, thus providing a prosperous perspective into the establishment of novel therapeutic and diagnostic targets of the disease.

Rifapentine is an entry and replication inhibitor against yellow fever virus both in vitro and in vivo.

Yellow fever virus (YFV) infection is a major public concern that threatens a large population in South America and Africa. No specific anti-YFV drugs are available till now. Here, we report that rifapentine is a potent YFV inhibitor in various cell lines by high-throughput drugs screening, acting at both cell entry and replication steps. Kinetic test and binding assay suggest that rifapentine interferes the viral attachment to the target cells. The application of YFV replicon and surface plasmon resonance assay indicates that rifapentine suppresses viral replication by binding to the RNA-dependent RNA polymerase (RdRp) domain of viral nonstructural protein NS5. Further molecular docking suggests that it might interact with the active centre of RdRp. Rifapentine significantly improves the survival rate, alleviates clinical signs, and reduces virus load and injury in targeted organs both in YFV-infected type I interferon receptor knockout A129-/- and wild-type C57 mice. The antiviral effect in vivo is robust during both prophylactic intervention and therapeutic treatment, and the activity is superior to sofosbuvir, a previously reported YFV inhibitor in mice. Our data show that rifapentine may serve as an effective anti-YFV agent, providing promising prospects in the development of YFV pharmacotherapy.

SNORD126 Promotes Hepatitis C Virus Infection by Upregulating Claudin-1 via Activation of PI3K-AKT Signaling Pathway.

Hepatitis C virus (HCV) infection involves a variety of viral and host factors, some of which promote the infection process. A small nucleolar RNA, C/D box 126 (SNORD126), was previously shown to be associated with hepatocellular carcinoma (HCC). However, the role of SNORD126 in HCV infection, which is one of the primary reasons for HCC development, has not been elucidated. In the present study, using small nucleolar RNA profiling, we observed that SNORD126 was significantly downregulated during HCV infection in both Huh7 and Huh7.5.1 cells. In addition, overexpression of SNORD126 enhanced HCV entry into host cells, whereas SNORD126 knockdown showed the opposite effect, suggesting that SNORD126 promotes HCV infection, especially through viral entry. Further functional analysis revealed that SNORD126 could enhance the expression level of claudin-1 (CLDN1), a key HCV entry factor, by increasing the levels of phosphorylated AKT. Additionally, the function of SNORD126 in HCV infection was associated with ribonucleoprotein (RNP) complexes. In summary, our findings demonstrate that oncogenic SNORD126 levels are decreased during HCV infection probably due to the host defense reaction, and SNORD126 may be important to promote viral entry by increasing CLDN1 expression through activation of the PI3K-AKT pathway, the mechanism of which is partly associated with SNORD126-mediated snoRNA RNP (snoRNP) function. Our work here provides initial evidence that endogenous snoRNA takes part in HCV infection and shows potential as a diagnostic or antiviral agent.