An update on respiratory syncytial virus antiviral agents.

Respiratory syncytial virus (RSV), the most common cause of lower respiratory tract disease in infants and young children, is a ubiquitous respiratory pathogen, infecting or reinfecting much of the population every year and causing severe, sometimes fatal disease in high-risk populations of infants and adults, particularly in developing countries. Spurred by the medical and economic burdens of RSV disease and enticed by the economic potential of therapeutic drugs, particularly in the absence to date of a safe and effective RSV vaccine, scientists in many industrial, academic and government laboratories have developed a wide variety of candidate RSV antiviral agents. Most of these have been screened thus far only in cell culture, a few in animal models. Aside from ribavirin, however, none has proven effective in therapeutic clinical trials and even ribavirin usage has declined precipitously in recent years due to concerns over efficacy, safety, ease of use and cost. All of the antiviral compounds discussed in this review were evaluated primarily for their ability to reduce viral load, with little or no attention paid to the role of host inflammation in the pathogenesis of RSV disease. Recent research has highlighted the prominent role of inflammatory mediators and an increasing number of reports suggest that a therapeutic strategy that combines antiviral and anti-inflammatory components will be the most effective way of treating RSV disease.