The development of antivirals for respiratory viruses has advanced markedly in response to the growing threat of pathogens such as Influenzavirus (IAV), respiratory syncytial virus (RSV), and SARS-CoV-2. This article reviews the advances and challenges in this field, highlighting therapeutic strategies that target critical stages of the viral replication cycle, including inhibitors of viral entry, replication, and assembly. In addition, innovative approaches such as inhibiting host cellular proteins to reduce viral resistance and repurposing existing drugs are explored, using advanced bioinformatics tools that optimize the identification of antiviral candidates. The analysis also covers emerging technologies such as nanomedicine and CRISPR gene editing, which promise to improve the stability and efficacy of treatments. While current antivirals offer valuable options, they face challenges such as viral evolution and the need for accessible treatments for vulnerable populations. This article underscores the importance of continued innovation in biotechnology to overcome these limitations and provide safe and effective treatments. Combining traditional and advanced approaches in developing antivirals is essential in order to address respiratory viral diseases that affect global health.

RNA viruses remain a significant public health concern due to their rapid evolution, genetic variability, and capacity to trigger recurrent epidemics and pandemics. Over the last decade, natural products have gained attention as a valuable source of antiviral candidates, offering structural diversity, accessibility, and favorable safety profiles. This review highlights key replication mechanisms of RNA viruses and their associated therapeutic targets, including RNA-dependent RNA polymerase, viral proteases, and structural proteins mediating entry and maturation. We summarize recent advances in the identification of bioactive compounds such as flavonoids, alkaloids, terpenes, lectins, and polysaccharides that exhibit inhibitory activity against clinically relevant pathogens, including the Influenza A virus (IAV), human immunodeficiency viruses (HIV), dengue virus (DENV), Zika virus (ZIKV), and Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Special emphasis is placed on the integration of in silico screening, in vitro validation, and nanotechnology-based delivery systems that address challenges of stability, bioavailability, and specificity. Furthermore, the growing role of artificial intelligence, drug repurposing strategies, and curated antiviral databases is discussed as a means to accelerate therapeutic discovery. Despite persistent limitations in clinical translation and standardization, natural products represent a promising and sustainable platform for the development of next-generation antivirals against RNA viruses.

Nuclear transport of proteins larger than 60 kDa occurs via energy-dependent active transport, whereas smaller proteins diffuse into the nucleus through nuclear pore complexes via passive nuclear transport. Although the dengue virus (DENV) replication cycle primarily takes place in the cytoplasm, the capsid protein and non-structural protein 5 (NS5) are imported into the nucleus through a nuclear localization sequence-dependent mechanism. However, given its small molecular weight (14 kDa), the DENV capsid protein may also enter the nucleus via passive diffusion. While some drugs primarily inhibit active nuclear transport, few are known to block passive diffusion. Notably, biguanides have been associated with inhibitory effects on passive nuclear transport. Since biguanides such as metformin (MET) exhibit anti-DENV properties, we investigated the effects of MET on the nuclear transport of DENV proteins. Our results suggest that MET induces changes in the nuclear membrane of Huh-7 cells and reduces capsid nuclear localization without affecting NS5 nuclear import. Furthermore, MET treatment did not alter capsid nuclear import in BHK-21 cells. Additionally, mimicking MET’s effects using a non-hydrolyzable ATP analogue increased capsid cytoplasmic retention and decreased DENV-2 replication. Finally, the inhibition of the classical active nuclear transport pathway did not block capsid nuclear transport, suggesting that DENV-2 capsid enters the nucleus in Huh-7 and Vero cells independently of this pathway.

Dengue is a viral disease caused by the dengue virus (DENV), which continues to pose a significant global public health challenge. This concern is particularly heightened by the rising incidence of dengue over the last two decades. While many infected individuals experience mild symptoms, a subset can progress to severe dengue, characterized by life-threatening hemorrhagic complications. Addressing this critical public health issue requires the development of new, safe, and effective treatments. In this study, the therapeutic potential of various metformin and phenformin analogs against DENV infection was evaluated. The antiviral effect was assessed by measuring the percentage of infected cells, as well as the levels of viral proteins and infectious viral particles. Additionally, DENV-infected AG129 mice were treated with two selected analogs and monitored for survival, weight changes, clinical signs, and viral RNA copies. The results demonstrated that these analogs effectively inhibited the number of infected cells, reduced viral protein levels, and decreased the formation of infectious viral particles. Furthermore, when compared to metformin (MET), certain analogs exhibited enhanced antiviral efficacy. Notably, we also found that the antiviral activity of the analogs correlated with increased levels of phosphorylated AMPK (pAMPK). In vivo treatments yielded significant antiviral effects, as evidenced by reduced clinical symptoms, lower mortality rates compared to untreated controls, and a marked reduction in viral load. These findings underscore the potential of biguanides derivatives as promising therapeutic agents against dengue infection, providing a foundation for further exploration of their antiviral properties.

Dengue, transmitted by Aedes mosquitoes, can progress to severe symptoms like hemorrhagic fever and shock syndrome. While the virus and host immune response contribute to severity, other factors, such as small extracellular vesicles (sEVs), may play a role. sEVs mediate intercellular communication by transferring cellular components; however, their role in vivo infection remains unclear. We isolated and characterized sEVs from DENV-infected C6/36 mosquito cells, finding that they interact with mammalian cells and internalize the content. Using sEVs populations (with a size between 100 and 200 nm), we demonstrated enhanced infection in in vitro and in vivo murine models, including immunocompetent and immunosuppressed mice, which developed severe dengue-like symptoms. Our study reveals that sEVs from DENV-infected mosquito cells contribute to dengue pathogenesis, inducing severe symptoms in in vivo models, highlighting their potential role in disease progression and severe outcomes.