Fengwei Bai

Chikungunya virus (CHIKV) infection is increasingly linked to cardiovascular complications, but the mechanisms underlying CHIKV-induced cardiovascular disease (CVD) remain unclear, and targeted therapies are lacking. Although elevated interleukin-17A (IL-17A) levels have been reported in CHIKV patients and associated with cardiovascular pathology, its role in CHIKV-induced cardiac disease is poorly defined. To address this question, we employed our newly developed heterozygous interferon α/β/γ receptor-deficient ( Ifnag ^+/− ) mice and primary human cardiac fibroblasts to investigate the contribution of IL-17A signaling to CHIKV-associated cardiac pathology. We found that CHIKV infection induced IL-17A production in the heart, and that mice deficient in Il17a ( Il17a ^−/− ) and in its receptor gene, Il-17ra ( Il17ra ^−/− ), exhibited marked resistance to CHIKV infection in both cardiac tissue and primary cardiac fibroblasts. Genetic deletion of IL-17A signaling significantly enhanced type I interferon responses and decreased viral burden in mouse hearts. Interestingly, blockade of IL-17RA with an FDA-approved monoclonal antibody for plaque psoriasis, Brodalumab, drastically increased type I interferon production and reduced viral replication in both human cardiac fibroblasts and human embryonic kidney 293 (HEK 293) cells. In addition, inhibition of IL-17A signaling suppressed the expression of pro-inflammatory mediators, including Il-1β , Tnf-α , and Cxcl2 , reduced immune cell infiltration into cardiac tissue, and mitigated cardiac injury. Importantly, therapeutic blockade of IL-17A signaling after CHIKV infection reduced viral replication in both the heart and circulation. Collectively, these findings identify IL-17A signaling as a critical regulator of CHIKV replication and cardiac inflammation and highlight the IL-17A/IL-17RA axis as a promising therapeutic target for CHIKV-associated cardiovascular disease. Importance: Chikungunya virus (CHIKV) infection has been frequently associated with cardiovascular complications, yet the host pathways that promote viral infection and cardiac injury remain poorly understood. Here, we identify IL-17A signaling as a previously unrecognized regulator of CHIKV pathogenesis in the heart. Using a novel heterozygous interferon receptor-deficient mouse model and primary human cardiac fibroblasts, we demonstrate that IL-17A signaling facilitates CHIKV replication via suppressing antiviral type I interferon responses. Genetic deletion or pharmacological blockade with an FDA-approved monoclonal antibody of IL-17A signaling reduced viral burden, attenuated inflammatory cytokine production, limited immune cell infiltration, and protected against cardiac injury. Importantly, therapeutic inhibition of IL-17A signaling after infection remained effective in reducing viral replication in both cardiac tissue and circulation and mitigating cardiac damage. These findings reveal a critical role for the IL-17A/IL-17RA axis in linking antiviral immunity to CHIKV-induced cardiovascular disease and identify a potential translatable therapeutic target for CHIKV-caused cardiac complications.

West Nile Virus (WNV), a mosquito-borne neurotropic flavivirus, is a major cause of viral encephalitis in the United States, posing a continuous threat to public health. Unfortunately, no vaccine or specific therapeutic intervention is available against WNV infection. Previous studies, including ours, demonstrated that interleukin-17A (IL-17A) signaling promotes the cytotoxicity of CD8⁺ T cells to facilitate WNV and parasite clearance; however, the molecular mechanism is not understood. IL-17 receptor C (IL-17RC) is an obligatory co-receptor with IL-17 receptor A (IL-17RA) for signaling induced by IL-17A, IL-17A/F, and IL-17F. In this study, we found that IL-17RC deficient (Il17rc^-/-) mice were more susceptible to WNV infection with a higher viral load in the brain than wild-type (WT) control mice. The number of infiltrating WNV-specific CD8⁺ T cells and the expression levels of cytotoxicity mediators, such as perforin, in the T cells in the brain of Il17rc^-/- mice were reduced. In addition, WNV-specific CD8⁺ T cells from IL-17RA deficient (Il17ra^-/-) mice and CD8⁺ cell-specific Il17ra conditional knockout (cre-KO) mice expressed lower levels of perforin than their counterpart controls. Moreover, supplementing mouse recombinant IL-17A ex vivo increased the perforin production in WNV-specific CD8⁺ T cells from the WT mice but not Il17rc^-/- or cre-KO mice. Interestingly, we found that IL-17A signaling activated the phosphatidylinositol-3-kinase/mammalian target of rapamycin (PI3K-mTOR) signaling pathway in CD8⁺ T cells, leading to increased metabolism of CD8⁺ T cells to cope with the higher energy demand for WNV clearance in the brain. In summary, our findings reveal a novel IL-17A-PI3K-mTOR signaling axis in promoting the effector functions of CD8⁺ T cells, suggesting potential broader implications in stimulating immune responses to combat WNV and other intracellular infections.

Although chikungunya virus (CHIKV)-caused cardiovascular diseases are frequently reported in clinics, the underlying mechanisms are poorly understood, which is primarily due to a lack of animal models. In this study, we report that CHIKV infection in homozygous interferon α/β receptor-deficient (ifnar1^-/-) and interferon α/β/γ receptor-deficient (ifnag^-/-) mice resulted in high viral loads in the hearts as early as day (D) 1 post-infection (p.i.) but with 100% mortality within three days p.i. In contrast, the heterozygous ifnar1^+/-and ifnag^+/- mice survived CHIKV infection and bore higher viral burdens in the heart tissues than the wild-type (WT) controls. Immunohistochemistry and flow cytometry revealed that more leukocytes, particularly neutrophils, infiltrated the heart of ifnag^+/- and ifnar1^+/- mice than WT mice. In addition, the Hematoxylin and Eosin staining analysis showed that CHIKV infection caused vasculitis in the left ventricles on D5 p.i. in both heterozygous groups and the vacuole formation and pyknosis in ifnar1^+/- mice. Moreover, CHIKV infection may also lead to cardiac fibrosis, as indicated by the upregulation of the expression of the Connective Tissue Growth Factor gene in the hearts of ifnar1^+/- mice. In summary, our data suggest that the heterozygous ifnar1^+/- and ifnag^+/- mice are invaluable for studying pathogenesis and testing therapeutic interventions for CHIKV-caused cardiac diseases.

Biomolecular condensates (BCs) are phase-separated viscoelastic hubs within demixed solutions enriched in proteins and nucleic acids. Such condensates, also called membraneless organelles, are increasingly observed in cells and serve as transient hubs for spatial organization and compartmentalization of biomolecules. Along with the transiency of formation and dissolution, their ability to sequester molecules has inspired us to develop BCs as potential vehicles to transport and deliver molecular cargo. We recently reported the design of disulfide bond cross-linked phase-separating peptide (PSP) condensates that spontaneously dissolve in reducing conditions ( JACS, 2024, 146 , 255299 ). Based on the premise that the highly reducing cytoplasm could dissolve PSP condensates and release partitioned cargo, here, we demonstrate the ability of PSP condensates to deliver molecular cargo to the cytoplasm of HeLa cells efficiently. We show that PSP condensates deliver a variety of cargos that differ in their sizes and chemistries, including small molecules, peptides, GFP protein (31 kDa), DNA (1.7 kbp), and mRNA. The transfection efficiencies of PSP condensates for delivering DNA and mRNA were also significantly greater than those of a commercial transfection agent. With room to tailor the condensate properties based on cargo and cell types, these results showcase the potential of disulfide-cross-linked PSPs as effective and customizable cellular delivery vehicles, filling a critical demand gap for such delivery systems.

Oropouche virus (OROV) is a neglected and emerging arbovirus that infects humans and animals in South and Central America. OROV is primarily transmitted to humans through the bites of infected midges and possibly some mosquitoes. It is the causative agent of Oropouche fever, which has high morbidity but low mortality rates in humans. The disease manifests in humans as high fever, headache, myalgia, arthralgia, photophobia, and, in some cases, meningitis and encephalitis. Additionally, a recent report suggests that OROV may cause fetal death, miscarriage, and microcephaly in newborns when women are infected during pregnancy, similar to the issues caused by the Zika virus (ZIKV), another mosquito-borne disease in the same regions. OROV was first reported in the mid-20th century in the Amazon basin. Since then, over 30 epidemics and more than 500,000 infection cases have been reported. The actual case numbers may be much higher due to frequent misdiagnosis, as OROV infection presents similar clinical symptoms to other co-circulating viruses, such as dengue virus (DENV), chikungunya virus (CHIKV), ZIKV, and West Nile virus (WNV). Due to climate change, increased travel, and urbanization, OROV infections have occurred at an increasing pace and have spread to new regions, with the potential to reach North America. According to the World Health Organization (WHO), over 10,000 cases were reported in 2024, including in areas where it was not previously detected. There is an urgent need to develop vaccines, antivirals, and specific diagnostic tools for OROV diseases. However, little is known about this surging virus, and no specific treatments or vaccines are available. In this article, we review the most recent progress in understanding virology, transmission, pathogenesis, diagnosis, host–vector dynamics, and antiviral vaccine development for OROV, and provide implications for future research directions.

Flaviviruses such as Dengue, West Nile, and Zika viruses are mosquito-borne RNA viruses that can cause serious diseases in humans. To develop effective drugs for treating these viruses’ infections, we create a new approach for developing common or shared drugs that may work for several different viral species of flaviviruses. It is based on the conserved RNA-dependent RNA polymerase (RdRp), which is the key enzyme for viral replication. We built up a common structure of RdRps (POLcon) from their consensus sequence. A conserved Triple-D structural motif was identified at the active site of POLcon that has been used for virtual compound screening. We have identified three inhibitors that have potent activities against Dengue, West Nile, and Zika viruses. All these three inhibitors are Benzothiophene derivatives. This is the first report of Benzothiophene-derived compounds as inhibitors for flaviviruses. Furthermore, our approach has provided a proof-of-concept that it is feasible to identify shared drugs for several different viral species of flaviviruses.

Bats are reservoirs for numerous viruses that cause serious diseases in other animals and humans. Several mechanisms are proposed to contribute to the tolerance of bats to these pathogens. This study investigates the response of bat cells to double-stranded RNA generated by SARS-CoV-2 replication. Here, we found the involvement of Dicer in the processing of viral genomic RNAs during SARS-CoV-2 infection. Examining RNA sequencing of infected cells, small-interfering RNA (siRNA)-like fragments were found derived from viral RNAs. Depletion of Dicer showed a reduction in these RNAs and an increase in viral loads suggesting unlike other mammals, bats may use Dicer to limit viral replication. This prompted the exploration of key dsRNA sensors in bat cells. Our analysis showed significant upregulation of OAS1 and MX1 in response to dsRNA, while PKR levels remained low, suggesting alternative dsRNA-response mechanisms are present that eschew the common PKR-based system. These results further show how bats employ distinct strategies for antiviral defense that may contribute to tolerating viral infections. They suggest the involvement of Dicer in antiviral mechanisms in bats, a function not observed in other mammals. This highlights a mechanism for bat originating viruses to evolve features that in other animals could cause extreme antiviral responses such as is seen with SARS-CoV-2. GRAPHICAL SUMMARY:

Flaviviruses such as Dengue, West Nile, and Zika viruses are mosquito-borne RNA viruses that can cause serious diseases in humans. To develop effective drugs for treating these viruses’ infections, we create a new approach for developing common or shared drugs that may work for several different viral species of flaviviruses. It is based on the conserved RNA-dependent RNA polymerase (RdRp), which is the key enzyme for viral replication. We built up a common structure of RdRps (POLcon) from their consensus sequence. A conserved Triple-D structural motif was identified at the active site of POLcon that has been used for virtual compound screening. We have identified three inhibitors that have potent activities against Dengue, West Nile, and Zika viruses. All these three inhibitors are Benzothiophene derivatives. This is the first report of Benzothiophene-derived compounds as broad-spectrum inhibitors for flaviviruses. Furthermore, our approach has provided a proof-of-concept that it is feasible to identify shared drugs for several different viral species of flaviviruses.

Lectins are a class of carbohydrate-binding proteins that may have antiviral activity by binding to the glycans on the virion surface to interfere with viral entry. We have identified a novel lectin (named Shictin) from Shiitake mushroom (Lentinula edodes)-derived vesicle-like nanoparticles (VLNs, or exosomes) that exhibits strong activity against the SARS-CoV-2 Omicron variant with an IC₅₀ value of 87 nM. Shictin contains 298 amino acids and consists of two unique domains (N-terminal and C-terminal domain). The N-terminal domain is the carbohydrate-binding domain (CBD) that is homologous with CBDs of other lectins, suggesting that Shictin inhibits SARS-CoV-2 infection by binding to the glycans on the virion surface to prevent viral entry. This finding demonstrates that exosomes of vegetables are a valuable source for the identification of antiviral lectins. Therefore, it is believed that lectins from vegetable VLNs have potential as antiviral therapeutic agents.

To develop an inhalable drug delivery system, we synthesized poly (lactic-co-glycolic acid) nanoparticles with Remdesivir (RDV NPs) as an antiviral agent against SARS-CoV-2 replication and formulated Remdesivir-loaded nanocomposites (RDV NCs) via coating of RDV NPs with novel supramolecular cell-penetrating peptide nanofibers (NFs) to enhance cellular uptake and intracellular drug delivery. RDV NPs and RDV NCs were characterized using variou techniques, including Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS), and fluorescent microscopy. The cytotoxicity of RDV NCs was assessed in Vero E6 cells and primary human lung epithelial cells, with no significant cytotoxicity observed up to 1000 μg mL⁻¹ and 48 h. RDV NCs were spherically shaped with a size range of 200–300 nm and a zeta potential of ∼+31 mV as well as indicating the presence of coated nanofibers. Reverse Transcription-quantitative Polymerase Chain Reaction (RT-qPCR), immunofluorescence and plaque assays of SARS-CoV-2 infected Vero E6 treated with RDV NCs showed significantly higher antiviral activities compared to those of free drug and uncoated RDV NPs. RDV NCs exhibited high antiviral activity against SARS-CoV-2, and the nanocomposite platform has the potential to be developed into an inhalable drug delivery system for other viral infections in the lungs.