Current development of therapeutic vaccines for the treatment of chronic infectious diseases.

Chronic infectious diseases refer to diseases that require a long period of time from onset to cure or death, the use of therapeutic vaccines has recently emerged to eradicate diseases. Currently, clinical research is underway to develop therapeutic vaccines for chronic infectious diseases based on various vaccine formulations, and the recent success of the messenger RNA vaccine platform and efforts to apply it to therapeutic vaccines are having a positive impact on conquering chronic infectious diseases. However, since research on the development of therapeutic vaccines is still relatively lacking compared to prophylactic vaccines, there is a need to focus more on the development of therapeutic vaccines to overcome threats to human health caused by chronic infectious diseases. In order to accelerate the development of therapeutic vaccines for chronic infectious diseases in the future, it is necessary to establish a clear concept of therapeutic vaccines suitable for the characteristics of each chronic infectious disease, as well as standardize vaccine effectiveness evaluation methods, secure standards/reference materials, and simplify the vaccine approval procedure.

Production of Plant-Derived Japanese Encephalitis Virus Multi-Epitope Peptide in Nicotiana benthamiana and Immunological Response in Mice.

The current production of the Japanese encephalitis virus (JEV) vaccine is based on animal cells, where various risk factors for human health should be resolved. This study used a transient expression system to express the chimeric protein composed of antigenic epitopes from the JEV envelope (E) protein in Nicotiana benthamiana. JEV multi-epitope peptide (MEP) sequences fused with FLAG-tag or 6× His-tag at the C- or N-terminus for the purification were introduced into plant expression vectors and used for transient expression. Among the constructs, vector pSK480, which expresses MEP fused with a FLAG-tag at the C-terminus, showed the highest level of expression and yield in purification. Optimization of transient expression procedures further improved the target protein yield. The purified MEP protein was applied to an ICR mouse and successfully induced an antibody against JEV, which demonstrates the potential of the plant-produced JEV MEP as an alternative vaccine candidate.

Label-free detection and discrimination of respiratory pathogens based on electrochemical synthesis of biomaterials-mediated plasmonic composites and machine learning analysis.

Seasonal outbreaks of respiratory viral infections remain a global concern, with increasing morbidity and mortality rates recorded annually. Timely and false responses contribute to the widespread of respiratory pathogenic diseases owing to similar symptoms at an early stage and subclinical infection. The prevention of emerging novel viruses and variants is also a big challenge. Reliable point-of-care diagnostic assays for early infection diagnosis play a critical role in the response to threats of epidemics or pandemics. We developed a facile method for specifically identifying different viruses based on surface-enhanced Raman spectroscopy (SERS) with pathogen-mediated composite materials on Au nanodimple electrodes and machine learning (ML) analyses. Virus particles were trapped in three-dimensional plasmonic concave spaces of the electrode via electrokinetic preconcentration, and Au films were simultaneously electrodeposited, leading to the acquisition of intense and in-situ SERS signals from the Au-virus composites for ultrasensitive SERS detection. The method was useful for rapid detection analysis (<15 min), and the ML analysis for specific identification of eight virus species, including human influenza A viruses (i.e., H1N1 and H3N2 strains), human rhinovirus, and human coronavirus, was conducted. The highly accurate classification was achieved using the principal component analysis-support vector machine (98.9%) and convolutional neural network (93.5%) models. This ML-associated SERS technique demonstrated high feasibility for direct multiplex detection of different virus species for on-site applications.

The efficacy of a 2,4-diaminoquinazoline compound as an intranasal vaccine adjuvant to protect against influenza A virus infection in vivo.

Adjuvants are substances added to vaccines to enhance antigen-specific immune responses or to protect antigens from rapid elimination. As pattern recognition receptors, Toll-like receptors 7 (TLR7) and 8 (TLR8) activate the innate immune system by sensing endosomal single-stranded RNA of RNA viruses. Here, we investigated if a 2,4-diaminoquinazoline-based TLR7/8 agonist, (S)-3-((2-amino-8-fluoroquinazolin-4-yl)amino)hexan-1-ol (named compound 31), could be used as an adjuvant to enhance the serological and mucosal immunity of an inactivated influenza A virus vaccine. The compound induced the production of proinflammatory cytokines in macrophages. In a dose-response analysis, intranasal administration of 1 µg compound 31 together with an inactivated vaccine (0.5 µg) to mice not only enhanced virus-specific IgG and IgA production but also neutralized influenza A virus with statistical significance. Notably, in a virus-challenge model, the combination of the vaccine and compound 31 alleviated viral infection-mediated loss of body weight and increased survival rates by 40% compared with vaccine only-treated mice. We suggest that compound 31 is a promising lead compound for developing mucosal vaccine adjuvants to protect against respiratory RNA viruses such as influenza viruses and potentially coronaviruses.

Comparison of Antiviral Activity of Gemcitabine with 2'-Fluoro-2'-Deoxycytidine and Combination Therapy with Remdesivir against SARS-CoV-2.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the coronavirus disease 2019 (COVID-19) pandemic. The virus still spreads globally through human-to-human transmission. Nevertheless, there are no specific treatments clinically approved. This study aimed to compare antiviral activity of gemcitabine and its analogue 2'-fluoro-2'-deoxycytidine (2FdC) against SARS-CoV-2 as well as cytotoxicity in vitro. Fluorescent image-based antiviral assays revealed that gemcitabine was highly potent, with a 50% effective concentration (EC50) of 1.2 µM, more active than the well-known nucleoside monophosphate remdesivir (EC50 = 35.4 µM). In contrast, 2FdC was marginally active (EC50 = 175.2 µM). For all three compounds, the 50% cytotoxic concentration (CC50) values were over 300 µM toward Vero CCL-81 cells. Western blot and quantitative reverse-transcription polymerase chain reaction analyses verified that gemcitabine blocked viral protein expression in virus-infected cells, not only Vero CCL-81 cells but also Calu-3 human lung epithelial cells in a dose-dependent manner. It was found that gemcitabine has a synergistic effect when combined with remdesivir. This report suggests that the difluoro group of gemcitabine is critical for the antiviral activity and that its combination with other evaluated antiviral drugs, such as remdesivir, could be a desirable option to treat SARS-CoV-2 infection.

Understanding occult hepatitis C infection.

BACKGROUND: Occult hepatitis C infection (OCI) is a type of hepatitis C virus (HCV) infection, defined as the presence of HCV RNA in hepatocytes or peripheral blood mononuclear cells (PBMCs) and the absence of HCV RNA in serum. STUDY DESIGN AND METHODS: A literature review was conducted to identify articles that characterized OCI as a disease, including its epidemiology, mode of transmission, pattern of infection, progression, and treatment. RESULTS: OCI patients experience a milder degree of inflammatory and cirrhotic changes than patients with chronic hepatitis C. OCI is transmissible parenterally both in vivo and in vitro, however the duration and outcome of OCI remains unclear. OCI is most consistently found in patients with previous hepatitis C disease and hemodialysis patients. Beyond the at-risk populations, OCI has also been demonstrated among healthy individuals and blood donors. CONCLUSIONS: This review summarises our current understanding of OCI and suggests areas for further research to improve our understanding of this phenomenon, including a better understanding of its epidemiology and full clinical course. The current understanding of OCI and its clinical implications remain limited. Further standardized detection methods, ongoing surveillance, and investigation of its potential transmissions are required.