Disease Severity in Respiratory Syncytial Virus Infection: Role of Viral and Host Factors

Abstract

Respiratory syncytial virus (RSV) is not only a major cause of severe lower respiratory tract infection (LRTI) in infancy but is increasingly recognised as an important pathogen in later life. RSV infection is associated with a wide spectrum of disease ranging from asymptomatic infection to life-threatening bronchiolitis and pneumonia. Research has demonstrated that there exists a complex interplay between viral and host factors that determines the severity of disease following RSV infection. Several factors determine RSV virulence including the infective properties of individual strains and viral load (VL). Disease outcome from RSV infection is also impacted considerably by a variety of host factors with the host immune response increasingly recognised as pivotal. This chapter outlines our current understanding of these factors and provides an oversight of their relative importance.