A novel nanocomposite drug delivery system for SARS-CoV-2 infections

Processing of genomic RNAs by Dicer in bat cells limits SARS-CoV-2 replication

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.

Intranasal liposomal remdesivir induces SARS-CoV-2 clearance in K18-hACE2 mice and ensures survival

A huge challenge after the emergence of COVID-19 has been the discovery of effective antiviral drugs. Although remdesivir (RDV) emerged as one of the most promising drugs, its pharmaceutical formulation Veklury® is limited by moderate efficacy, high toxicity and need for parenteral administration. The aim of the present work was to develop a liposomal formulation of RDV for pulmonary administration and evaluate its efficacy in models of COVID-19. Liposomal RDV nanoformulation (LRDV) was selected based on high drug encapsulation efficiency, sustained drug release property and high in vitro selectivity index. A pharmacokinetic study of intranasal LRDV in mice demonstrated effective delivery of the drug to the lungs. LRDV was then evaluated for its efficacy in SARS-CoV-2-infected K18-hACE2 mice after repeated intranasal administration at 10 mg/kg/bid for 5 days. Veklury® given intraperitoneally at 20 mg/kg/bid was used for comparison. Mice receiving LRDV remained alive up to 15 days post-infection (dpi). On the other hand, the control groups receiving PBS and empty liposomes showed 100 % death at 6 dpi and the Veklury® group had 62.5 % death at 8 dpi. Intranasal LRDV also promoted a strong reduction in viral loads in the brain and lungs of mice and prevented the inflammatory response induced by SARS-CoV-2 in the lungs. This is in contrast with Veklury®, which did not significantly reduce the viral titer in the brain and was poorly effective in preventing the inflammatory response in the lungs. Intranasal LRDV emerges as a promising therapeutic strategy for COVID-19, including "Long COVID".

Recent Advances in Antiviral Drug Delivery Strategies

Viral infectious diseases have long posed significant challenges to public health, leading to substantial morbidity and mortality worldwide. Recent outbreaks, including those caused by coronaviruses, have highlighted the urgent need for more effective antiviral treatments. Existing therapies, while numerous, face limitations such as drug resistance, toxicity, poor bioavailability, and non-specific targeting, which hinder their effectiveness against new and emerging viruses. This review focuses on the latest advances in nanoplatform technologies designed to enhance drug solubility, provide sustained or targeted delivery, and improve the efficacy of antiviral therapies. Additionally, we explore how these technologies can be integrated with novel strategies like genetic modulation to combat viral infections more effectively. The review also discusses the potential of these innovations in addressing the challenges posed by current antiviral therapies and their implications for future clinical applications.

Development of Vincristine‐Loaded Nano Graphene Oxides for Dual Therapies Against Canine Anaplastic Carcinoma Cells Obtained From a Dog with Spontaneous Mammary Tumor

Among pet species, mammary tumors are most commonly encountered in dogs. In the traditional treatment of mammary tumors in dogs; surgical operation, chemotherapy, immunotherapy, cryotherapy, radiotherapy and homeopathy are used. Herein, we reported vincristine loaded nano graphene oxide (Vin@nGO) for simultaneous photothermal therapy (PTT) and chemotherapy under near infrared laser (NIR, 808 nm), whereas GO was used both as a platform for vincristine and as a photothermal (PT) agent, and vincristine was used as a chemotherapeutic agent. Spontaneous mammary tumor masses of a dog were removed and primary tumor cells were obtained and propagated by tissue culture from tumor tissue samples under appropriate conditions. Then, these cells were incubated with Vin@nGO and exposed to NIR laser. NIR laser irradiation at 808 nm was converted to heat by nGO, then the target cancer cells were destroyed by both hyperthermia and chemotherapy. MTS analysis was performed to test the effectiveness of this dual therapy on cell proliferation and a statistically significant (p < 0.05) decrease in cell proliferation/viability was found (90% reduction compared to the control group (p < 0.0001)). Our study data also shed light on usability of Vin@nGO in the in vivo model for future work.