Single versus dual respiratory virus infections in hospitalized infants: impact on clinical course of disease and interferon-gamma response.
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.
Institute of Virology, Medical University of Vienna, Vienna, Austria. Judith.aberle@meduniwien.ac.at
Judith H
JH
Aberle
Stephan W
SW
Aberle
Elisabeth
E
Pracher
Hans-Peter
HP
Hutter
Michael
M
Kundi
Therese
T
Popow-Kraupp
D005260:Female; D006760:Hospitalization; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D007235:Infant, Premature, Diseases / Q000276:immunology / Q000503:physiopathology / Q000821:virology; D007371:Interferon-gamma / Q000096:biosynthesis; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008297:Male; D011446:Prospective Studies; D012141:Respiratory Tract Infections / Q000150:complications / Q000276:immunology / Q000503:physiopathology / Q000821:virology; D014777:Virus Diseases / Q000150:complications* / Q000276:immunology / Q000503:physiopathology / Q000821:virology*; D014780:Viruses / Q000235:genetics / Q000302:isolation & purification
D007371:Interferon-gamma