Influenza B virus causes milder pathogenesis and weaker inflammatory responses in ferrets than influenza A virus.
Abstract It is unknown why the influenza B virus causes less severe clinical signs than the influenza A virus in humans. Here we show that influenza B virus induces a lower levels of inflammatory cytokines in the lungs of infected ferrets, and causes less pathological damage to their lung tissues than does influenza A virus. The copy numbers of inflammatory cytokine genes, such as TNF-alpha and IFN-alpha, was significantly lower in the lungs of ferrets infected with influenza B virus than in those infected with influenza A virus. There were also significantly lower viral titers in the lungs of ferrets infected with the influenza B virus than with the influenza A virus. In addition, the duration of viral presence was shorter in the lungs of ferrets infected with influenza B virus than with influenza A virus. Taken together, our results suggest that the lower induction of inflammatory cytokines and lower viral titers in the lungs may be responsible for the milder clinical signs seen in ferrets or humans infected with influenza B virus.
Kim
Yun Hee
YH
Laboratory of Influenza Research, Chungnam National University, Daejeon, Korea 305-764.
Kim
Hyun Soo
HS
Cho
Sung Hwan
SH
Seo
Sang Heui
SH
D000818:Animals; D016207:Cytokines / Q000096:biosynthesis / Q000235:genetics; D003588:Cytopathogenic Effect, Viral; D005289:Ferrets / Q000276:immunology / Q000502:physiology / Q000821:virology*; D005334:Fever / Q000209:etiology; D018628:Gene Dosage; D055809:Illness Behavior; D007249:Inflammation / Q000209:etiology; D053118:Influenza A Virus, H1N1 Subtype / Q000472:pathogenicity*; D009981:Influenza B virus / Q000472:pathogenicity*; D008168:Lung / Q000378:metabolism / Q000473:pathology / Q000821:virology; D023421:Models, Animal; D009976:Orthomyxoviridae Infections / Q000378:metabolism / Q000473:pathology / Q000821:virology*; D012912:Sneezing; D013045:Species Specificity; D014774:Virulence; D015431:Weight Loss
D016207:Cytokines