RESUMO
Respiratory syncytial virus (RSV) is the cause of one-fifth of all lower respiratory tract infections worldwide and is increasingly being recognized as a serious threat to patient groups with poorly functioning immune systems. Our approach to finding a novel inhibitor of this virus was to screen a 20 000-member diverse library in a whole cell XTT assay. Parallel assays were carried out in the absence of virus in order to quantify any associated cell toxicity. This identified 100 compounds with IC(50)'s less than 50 muM. A-33903 (18), a 1,4-benzodiazepine analogue, was chosen as the starting point for lead optimization. This molecule was moderately active and demonstrated good pharmacokinetic properties. The most potent compounds identified from this work were A-58568 (47), A-58569 (44), and A-62066 (46), where modifications to the aromatic substitution enhanced potency, and A-58175 (42), where the amide linker was modified.
Assuntos
Antivirais/síntese química , Benzodiazepinas/síntese química , Vírus Sinciciais Respiratórios/efeitos dos fármacos , Animais , Antivirais/farmacocinética , Antivirais/farmacologia , Benzodiazepinas/química , Benzodiazepinas/farmacologia , Linhagem Celular Tumoral , Técnicas de Química Combinatória , Ensaio de Imunoadsorção Enzimática , Ratos , Ratos Sprague-Dawley , Relação Estrutura-Atividade , Ensaio de Placa ViralRESUMO
Respiratory syncytial virus (RSV) is the most common cause of lower respiratory tract infections worldwide, yet no effective vaccine or antiviral treatment is available. Here we report the discovery and initial development of RSV604, a novel benzodiazepine with submicromolar anti-RSV activity. It proved to be equipotent against all clinical isolates tested of both the A and B subtypes of the virus. The compound has a low rate of in vitro resistance development. Sequencing revealed that the resistant virus had mutations within the nucleocapsid protein. This is a novel mechanism of action for anti-RSV compounds. In a three-dimensional human airway epithelial cell model, RSV604 was able to pass from the basolateral side of the epithelium effectively to inhibit virus replication after mucosal inoculation. RSV604, which is currently in phase II clinical trials, represents the first in a new class of RSV inhibitors and may have significant potential for the effective treatment of RSV disease.