Immunological and Inflammatory Biomarkers of Susceptibility and Severity in Adult Respiratory Syncytial Virus Infections.

<bold>Background: </bold>Respiratory syncytial virus (RSV) is the most common cause of bronchiolitis in young infants. However, it is also a significant pathogen in older adults. Validated biomarkers of RSV disease severity would benefit diagnostics, treatment decisions, and prophylactic interventions. This review summarizes knowledge of biomarkers for RSV disease in adults.<bold>Methods: </bold>A literature review was performed using Ovid Medline, Embase, Global health, Scopus, and Web of Science for articles published 1946-October 2016. Nine articles were identified plus 9 from other sources.<bold>Results: </bold>From observational studies of natural infection and challenge studies in volunteers, biomarkers of RSV susceptibility or disease severity in adults were: (1) lower anti-RSV neutralizing antibodies, where neutralizing antibody (and local IgA) may be a correlate of susceptibility/severity; (2) RSV-specific CD8+ T cells in bronchoalveolar lavage fluid preinfection (subjects with higher levels had less severe illness); and (3) elevated interleukin-6 (IL-6), IL-8, and myeloperoxidase levels in the airway are indicative of severe infection.<bold>Conclusions: </bold>Factors determining susceptibility to and severity of RSV disease in adults have not been well defined. Respiratory mucosal antibodies and CD8+ T cells appear to contribute to preventing infection and modulation of disease severity. Studies of RSV pathogenesis in at-risk populations are needed. [ABSTRACT FROM AUTHOR]