The therapeutic potential of monoclonal antibodies against respiratory syncytial virus.

Attempts to develop a vaccine against respiratory syncytial virus (RSV), the major cause of lower respiratory tract disease in infants and young children, have been unsuccessful. Passive immunisation with antibody to RSV has been found to be an effective alternative method for prophylaxis. The product currently in use for RSV passive immunisation, a preparation of purified human IgG containing virus-neutralising activity, requires monthly iv. infusions. Monoclonal antibodies (mAbs) are currently under development as an alternative means of treatment that would require lower doses. The first such mAb was recently approved for RSV prophylaxis in the USA. The mucosal delivery of antibodies is also effective and a mAb nose drop treatment for immunoprophylaxis is under development. The potential of passive immunisation for the treatment of existing RSV infections is not clear. Antibody treatment following infection clearly suppresses viral replication but it may not reduce disease once inflammatory processes have been initiated.