PROPHYLACTIC ADMINISTRATION OF A COMPLEMENTARITY-DETERMINING REGION DERIVED FROM A NEUTRALIZING MONOCLONAL-ANTIBODY IS EFFECTIVE AGAINST RESPIRATORY SYNCYTIAL VIRUS-INFECTION IN BALB C MICE/

Immunotherapy with antibodies against respiratory syncytial virus (RSV ) is a treatment option given the absence of any vaccine or other avai lable satisfactory treatment. We selected one of our monoclonal antibo dies, RS-348, that is highly neutralizing. We showed that a single pep tide (PEP3H) derived from complementarity-determining region 3 (CDR3) of its heavy chain was capable of neutralizing the virus in vitro. Whe n intranasally administered 24 h before challenge, this peptide protec ted BALB/c mice against RSV lung infection. These results indicate tha t a single CDR can be effective against RSV infection.