RESPIRATORY SYNCYTIAL VIRUS-VACCINES

Respiratory syncytial virus (RSV) is the most important cause of viral lower respiratory tract illness (LRI) in infants and children worldwi de and causes significant LRI in the elderly and in immunocompromised patients. The goal of RSV vaccination is to prevent serious RSV-associ ated LRI. There are several obstacles to the development of successful RSV vaccines, including the need to immunize very young infants, who may respond inadequately to vaccination; the existence of two antigeni cally distinct RSVgroups, A and B; and the history of disease enhancem ent following administration of a formalin-inactivated vaccine. It is likely that more than one type of vaccine will be needed to prevent RS V LRI in the various populations at risk. Although vector delivery sys tems, synthetic peptide, and immune-stimulating complex vaccines have been evaluated in animal models, only the purified F protein (PFP) sub unit vaccines and live attenuated vaccines have been evaluated in rece nt clinical trials. PFP-2 appears to be a promising vaccine for the el derly and for RSV-seropositive children with underlying pulmonary dise ase, whereas live cold-passaged (cp), temperature-sensitive (ts) RSV v accines (denoted cpts vaccines) would most probably be useful in young infants. The availability of cDNA technology should allow further ref inement of existing live attenuated cpts candidate vaccines to produce engineered vaccines that are satisfactorily attenuated immunogenic, a nd phenotypically stable.