Substituted N-(4-amino-2-chlorophenyl)-5-chloro-2-hydroxybenzamide analogues potently inhibit respiratory syncytial virus (RSV) replication and RSV infection-associated inflammatory responses

Recent Progress toward the Discovery of Small Molecules as Novel Anti-Respiratory Syncytial Virus Agents

Respiratory syncytial virus (RSV) stands as the foremost cause of infant hospitalization globally, ranking second only to malaria in terms of infant mortality. Although three vaccines have recently been approved for the prophylaxis of adults aged 60 and above, and pregnant women, there is currently no effective antiviral drug for treating RSV infections. The only preventive measure for infants at high risk of severe RSV disease is passive immunization through monoclonal antibodies. This Perspective offers an overview of the latest advancements in RSV drug discovery of small molecule antivirals, with particular focus on the promising findings from agents targeting the fusion and polymerase proteins. A comprehensive reflection on the current state of RSV research is also given, drawing inspiration from the lessons gleaned from HCV and HIV, while also considering the impact of the recent approval of the three vaccines.

Therapeutic potential of salicylamide derivatives for combating viral infections

Since time immemorial human beings have constantly been fighting against viral infections. The ongoing and devastating coronavirus disease 2019 pandemic represents one of the most severe and most significant public health emergencies in human history, highlighting an urgent need to develop broad-spectrum antiviral agents. Salicylamide (2-hydroxybenzamide) derivatives, represented by niclosamide and nitazoxanide, inhibit the replication of a broad range of RNA and DNA viruses such as flavivirus, influenza A virus, and coronavirus. Moreover, nitazoxanide was effective in clinical trials against different viral infections including diarrhea caused by rotavirus and norovirus, uncomplicated influenza A and B, hepatitis B, and hepatitis C. In this review, we summarize the broad antiviral activities of salicylamide derivatives, the clinical progress, and the potential targets or mechanisms against different viral infections and highlight their therapeutic potential in combating the circulating and emerging viral infections in the future.

Monoterpene-Containing Substituted Coumarins as Inhibitors of Respiratory Syncytial Virus (RSV) Replication

Respiratory syncytial virus (RSV) is a critical cause of infant mortality. However, there are no vaccines and adequate drugs for its treatment. We showed, for the first time, that O-linked coumarin-monoterpene conjugates are effective RSV inhibitors. The most potent compounds are active against both RSV serotypes, A and B. According to the results of the time-of-addition experiment, the conjugates act at the early stages of virus cycle. Based on molecular modelling data, RSV F protein may be considered as a possible target.

Exchange Protein Directly Activated by cAMP 2 Enhances Respiratory Syncytial Virus-Induced Pulmonary Disease in Mice

Respiratory syncytial virus (RSV) is the most common cause of lower respiratory tract infection in young children. It is also a significant contributor to upper respiratory tract infections, therefore, a major cause for visits to the pediatrician. High morbidity and mortality are associated with high-risk populations including premature infants, the elderly, and the immunocompromised. However, no effective and specific treatment is available. Recently, we discovered that an exchange protein directly activated by cyclic AMP 2 (EPAC2) can serve as a potential therapeutic target for RSV. In both lower and upper epithelial cells, EPAC2 promotes RSV replication and pro-inflammatory cytokine/chemokine induction. However, the overall role of EPAC2 in the pulmonary responses to RSV has not been investigated. Herein, we found that EPAC2-deficient mice (KO) or mice treated with an EPAC2-specific inhibitor showed a significant decrease in body weight loss, airway hyperresponsiveness, and pulmonary inflammation, compared with wild-type (WT) or vehicle-treated mice. Overall, this study demonstrates the critical contribution of the EPAC2-mediated pathway to airway diseases in experimental RSV infection, suggesting the possibility to target EPAC2 as a promising treatment modality for RSV.