Immune responses of infants to infection with respiratory viruses and live attenuated respiratory virus candidate vaccines

Respiratory viruses such as respiratory syncytial virus (RSV), the parainfluenza viruses (PIV), and the influenza viruses cause severe lower respiratory tract diseases in infants ann children throughout the world. Experimental live attenuated vaccines for each of these viruses are being developed for intranasal administration I in the first weeks or months of life. A variety of promising RSV PIV-3, and influenza virus vaccine strains have been developed by classical biological methods, evaluated extensively in preclinical and clinical studies, and shown to be! attenuated ann genetically stable, The ongoing clinical evaluation of these vaccine candidates: coupled with recent major advances in the ability to develop genetically engineered Viruses with specified mutations, may allow the rapid development of respiratory virus strains that possess ideal levels of replicative capacity and genetic stability in vivo. A major remaining obstacle to successful immunization of infants against respiratory virus associated disease may be rite relatively poor immune response of very young infants to primary virus infection, This paper reviews the immune correlates of protection against disease caused by these viruses, immune responses of infants to naturally-acquired infection, and immune responses of infants to experimental infection with candidate vaccine viruses. (C) 1998 Elsevier Science ltd. All rights reserved.