Single versus dual respiratory virus infections in hospitalized infants: impact on clinical course of disease and interferon-gamma response

Pediatr Infect Dis J. 2005 Jul;24(7):605-10. doi: 10.1097/01.inf.0000168741.59747.2d.


Background: Dual respiratory viral infections are frequently associated with lower respiratory tract illness in infants. This study aimed to determine the impact of a dual respiratory viral infection on specific aspects of the infant's immune response and the clinical course of illness.

Methods: A prospective study was performed with 772 infants hospitalized from October 2000 through July 2004. Sensitive polymerase chain reaction methodology revealed the presence of a single respiratory virus in 443 (57%) of 772 cases, whereas dual infections were identified in 153 (20%) of cases. From 250 infants with confirmed respiratory viral infection, fresh heparinized blood was analyzed for interferon-gamma (IFN-gamma) responses by flow cytometry. Of these, 191 patients had a single infection with respiratory syncytial virus (RSV), rhinoviruses, adenoviruses or influenza viruses; and 59 patients had a dual infection with RSV and rhinoviruses, RSV and adenoviruses, influenza viruses and rhinoviruses or adenoviruses and rhinoviruses. The clinical features and peripheral lymphocyte IFN-gamma responses were compared among infants with single or dual infections.

Results: It was found that dual infections with non-RSV respiratory viruses induced peripheral blood mononuclear cell IFN-gamma responses that mimic those of single infections, whereas coinfection with RSV was associated with reduced IFN-gamma responses and a more severe clinical course of lower respiratory tract disease.

Conclusions: The results indicate that the clinical characteristics and the IFN-gamma response differ significantly in single and dual respiratory viral infection, depending on the nature of the simultaneously detected viruses. In dual infections, RSV involvement was associated with a decreased IFN-gamma response in peripheral blood mononuclear cell and an increase in severity of illness.

MeSH terms

  • Female
  • Hospitalization*
  • Humans
  • Infant, Newborn
  • Infant, Premature
  • Infant, Premature, Diseases* / immunology
  • Infant, Premature, Diseases* / physiopathology
  • Infant, Premature, Diseases* / virology
  • Interferon-gamma / biosynthesis
  • Leukocytes, Mononuclear / immunology
  • Male
  • Prospective Studies
  • Respiratory Tract Infections* / complications
  • Respiratory Tract Infections* / immunology
  • Respiratory Tract Infections* / physiopathology
  • Respiratory Tract Infections* / virology
  • Virus Diseases / complications*
  • Virus Diseases / immunology
  • Virus Diseases / physiopathology
  • Virus Diseases / virology*
  • Viruses / genetics
  • Viruses / isolation & purification


  • Interferon-gamma