Virally delivered cytokines alter the immune response to future lung infections.
Respiratory syncytial virus (RSV) is an important cause of infant morbidity and mortality worldwide and is increasingly recognized to have a role in the development and exacerbation of chronic lung diseases. There is no effective vaccine, and we reasoned that it might be possible to skew the immune system towards beneficial nonpathogenic responses by selectively priming protective T-cell subsets. We therefore tested recombinant RSV (rRSV) candidates expressing prototypic murine Th1 (gamma interferon [IFN-gamma]) or Th2 (interleukin-4 [IL-4]) cytokines, with detailed monitoring of responses to subsequent infections with RSV or (as a control) influenza A virus. Although priming with either recombinant vector reduced viral load during RSV challenge, enhanced weight loss and enhanced pulmonary influx of RSV-specific CD8+ T cells were observed after challenge in mice primed with rRSV/IFN-gamma. By contrast, rRSV/IL-4-primed mice were protected against weight loss during secondary challenge but showed airway eosinophilia. When rRSV/IL-4-primed mice were challenged with influenza virus, weight loss was attenuated but was again accompanied by marked airway eosinophilia. Thus, immunization directed toward enhancement of Th1 responses reduces viral load but is not necessarily protective against disease. Counter to expectation, Th2-biased responses were more beneficial but also influenced the pathological effects of heterologous viral challenge.
Harker
James
J
Department of Respiratory Medicine, MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, National Heart and Lung Institute, Imperial College London, St. Mary's Campus, London W2 1PG, United Kingdom.
Bukreyev
Alexander
A
Collins
Peter L
PL
Wang
Belinda
B
Openshaw
Peter J M
PJ
Tregoning
John S
JS
D000276:Adjuvants, Immunologic / Q000235:genetics; D000818:Animals; D001835:Body Weight; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000235:genetics / Q000276:immunology; D015847:Interleukin-4 / Q000235:genetics / Q000276:immunology; D008168:Lung / Q000473:pathology / Q000821:virology; D051379:Mice; D011657:Pulmonary Eosinophilia; D018357:Respiratory Syncytial Virus Infections / Q000276:immunology* / Q000517:prevention & control*; D022261:Respiratory Syncytial Virus Vaccines / Q000235:genetics* / Q000276:immunology*; D012136:Respiratory Syncytial Viruses / Q000235:genetics / Q000276:immunology*; D014614:Vaccines, Synthetic / Q000235:genetics / Q000276:immunology
D000276:Adjuvants, Immunologic; D022261:Respiratory Syncytial Virus Vaccines; D014614:Vaccines, Synthetic; D015847:Interleukin-4; D007371:Interferon-gamma