Recent developments in the treatment and prevention of respiratory syncytial virus infection

The Discovery of Small Allosteric and Active Site Inhibitors of the SARS-CoV-2 Main Protease via Structure-Based Virtual Screening and Biological Evaluation

The main protease enzyme (M^pro) of SARS-CoV-2 is one of the most promising targets for COVID-19 treatment. Accordingly, in this work, a structure-based virtual screening of 3.8 million ligand libraries was carried out. After rigorous filtering, docking, and post screening assessments, 78 compounds were selected for biological evaluation, 3 of which showed promising inhibition of the M^pro enzyme. The obtained hits (CB03, GR04, and GR20) had reasonable potencies with K_i values in the medium to high micromolar range. Interestingly, while our most potent hit, GR20, was suggested to act via a reversible covalent mechanism, GR04 was confirmed as a noncompetitive inhibitor that seems to be one of a kind when compared to the other allosteric inhibitors discovered so far. Moreover, all three compounds have small sizes (~300 Da) with interesting fittings in their relevant binding sites, and they possess lead-like characteristics that can introduce them as very attractive candidates for the future development of COVID-19 treatments.

Respiratory syncytial virus fusion inhibitors. Part 3: Water-soluble benzimidazol-2-one derivatives with antiviral activity in vivo

The introduction of acidic and basic functionality into the side chains of respiratory syncytial virus (RSV) fusion inhibitors was examined in an effort to identify compounds suitable for evaluation in vivo in the cotton rat model of RSV infection following administration as a small particle aerosol. The acidic compounds 2r, 2u, 2v, 2w, 2z, and 2aj demonstrated potent antiviral activity in cell culture and exhibited efficacy in the cotton rat comparable to ribavirin. In a BALB/c mouse model, the oxadiazolone 2aj reduced virus titers following subcutaneous dosing, whilst the ester 2az and amide 2aab exhibited efficacy following oral administration. These results established the potential of this class of RSV fusion inhibitors to interfere with infection in vivo following topical or systemic administration.

Respiratory syncytial virus inhibitors. Part 2: Benzimidazol-2-one derivatives

Structure-activity relationships for a series of benzimidazol-2-one-based inhibitors of respiratory syncytial virus are described. These studies focused on structural variation of the benzimidazol-2-one substituent, a vector inaccessible in a series of benzotriazole derivatives on which 2 is based, and revealed a broad tolerance for substituent size and functionality.

Fundamental structure-activity relationships associated with a new structural class of respiratory syncytial virus inhibitor

Structure-activity relationships surrounding the dialkylamino side chain of a series of benzotriazole-derived inhibitors of respiratory syncytial virus fusion based on the screening lead 1a were examined. The results indicate that the topology of the side chain is important but the terminus element offers considerable latitude to modulate physical properties.

Palivizumab in the prevention of respiratory syncytial virus disease

Respiratory syncytial virus (RSV) infection is the leading cause of lower respiratory tract infection in infants and young children. Premature infants and infants with underlying lung disease are at increased risk for severe RSV infection in the first 1 - 2 years of life. Monthly prophylaxis with palivizumab (Synagis) during RSV season has been proven safe and effective in this population and these effects have persisted over the 4 years since the drug was approved by the US FDA in 1998. Issues remain regarding the optimal candidates for palivizumab prophylaxis and whether additional groups of high-risk individuals, for example infants with congenital heart disease or cystic fibrosis, and immunocompromised hosts, might benefit from such preventive therapy. It is possible that palivizumab in combination with antiviral or anti-inflammatory agents might also prove to be beneficial in the treatment of RSV disease. Newer monoclonal antibodies to RSV in development may offer the potential for less frequent dosing, increased efficacy and a role in treatment of RSV disease, but pending further evaluation of such products palivizumab provides significant protection for high-risk infants against a major pathogen.