Respiratory syncytial virus (RSV) RNA loads in peripheral blood correlates with disease severity in mice.
BACKGROUND
Respiratory Syncytial Virus (RSV) infection is usually restricted to the respiratory epithelium. Few studies have documented the presence of RSV in the systemic circulation, however there is no consistent information whether virus detection in the blood correlates with disease severity.


METHODS
Balb/c mice were inoculated with live RSV, heat-inactivated RSV or medium. A subset of RSV-infected mice was treated with anti-RSV antibody 72 h post-inoculation. RSV RNA loads were measured by PCR in peripheral blood from day 1-21 post-inoculation and were correlated with upper and lower respiratory tract viral loads, the systemic cytokine response, lung inflammation and pulmonary function. Immunohistochemical staining was used to define the localization of RSV antigens in the respiratory tract and peripheral blood.


RESULTS
RSV RNA loads were detected in peripheral blood from day 1 to 14 post-inoculation, peaked on day 5 and significantly correlated with nasal and lung RSV loads, airway obstruction, and blood CCL2 and CXCL1 expression. Treatment with anti-RSV antibody reduced blood RSV RNA loads and improved airway obstruction. Immunostaining identified RSV antigens in alveolar macrophages and peripheral blood monocytes.


CONCLUSIONS
RSV RNA was detected in peripheral blood upon infection with live RSV, followed a time-course parallel to viral loads assessed in the respiratory tract and was significantly correlated with RSV-induced airway disease.
Torres
Juan Pablo
JP
Department of Pediatrics, Division of Infectious Diseases, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390, USA.
Gomez
Ana M
AM
Khokhar
Shama
S
Bhoj
Vijay G
VG
Tagliabue
Claudia
C
Chang
Michael L
ML
Kiener
Peter A
PA
Revell
Paula A
PA
Ramilo
Octavio
O
Mejias
Asuncion
A
D000818:Animals; D002460:Cell Line; D004195:Disease Models, Animal; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D012367:RNA, Viral / Q000097:blood*; D012129:Respiratory Function Tests / Q000379:methods; D018357:Respiratory Syncytial Virus Infections / Q000097:blood* / Q000175:diagnosis / Q000821:virology*; D012136:Respiratory Syncytial Viruses / Q000235:genetics / Q000378:metabolism*; D012720:Severity of Illness Index; D019562:Viral Load / Q000235:genetics*
D012367:RNA, Viral