Evolution of prophylaxis: MoAb, siRNA, vaccine, and small molecules.

Despite the considerable impact that respiratory syncytial virus (RSV) infections have in the health of children and adults, the development of therapeutic interventions has been remarkably slow. In the 1980s, advances in the characterisation of neutralising antibodies against RSV led to the development and clinical application of a polyclonal immunoglobulin preparation with high titres of neutralising antibodies against RSV (RSV IVIG). The next step was the development of neutralising monoclonal antibodies. Only palivizumab demonstrated clinical efficacy and was licensed in 1998 by the US FDA, and subsequently by the different world drug regulatory agencies. Motavizumab (MEDI-524) is a novel recombinant humanised IgG1 mAb derived from palivizumab with enhanced anti-RSV neutralising activity. In recent years, in addition to the anti-RSV antibodies, a number of alternative strategies against RSV are being developed. The most innovative approach is the use of siRNAs (small inhibitory RNAs) with specific anti-RSV activity.