Heterogeneous virulence of pandemic 2009 influenza H1N1 virus in mice.
BACKGROUND
Understanding the pathogenesis of influenza infection is a key factor leading to the prevention and control of future outbreaks. Pandemic 2009 Influenza H1N1 infection, although frequently mild, led to a severe and fatal form of disease in certain cases that make its virulence nature debatable. Much effort has been made toward explaining the determinants of disease severity; however, no absolute reason has been established.


RESULTS
This study presents the heterogeneous virulence of clinically similar strains of pandemic 2009 influenza virus in human alveolar adenocarcinoma cells and mice. The viruses were obtained from patients who were admitted in a local hospital in China with a similar course of infection and recovered. The A/Nanchang/8002/2009 and A/Nanchang/8011/2009 viruses showed efficient replication and high lethality in mice while infection with A/Nanchang/8008/2009 was not lethal with impaired viral replication, minimal pathology and modest proinflammatory activity in lungs. Sequence analysis displayed prominent differences between polymerase subunits (PB2 and PA) of viral genomes that might correlate with their different phenotypic behavior.


CONCLUSIONS
The study confirms that biological heterogeneity, linked with the extent of viral replication, exists among pandemic H1N1 strains that may serve as a benchmark for future investigations on influenza pathogenesis.
Division of Immunology, International Institute of Infection and Immunity, Shantou University Medical College, 22 Xinling Road, Shantou, Guangdong 515041, China.
Amber
A
Farooqui
Alberto J
AJ
Leon
Yanchang
Y
Lei
Pusheng
P
Wang
Jianyun
J
Huang
Raquel
R
Tenorio
Wei
W
Dong
Salvatore
S
Rubino
Jie
J
Lin
Guishuang
G
Li
Zhen
Z
Zhao
David J
DJ
Kelvin
D000818:Animals; D002460:Cell Line; D002681:China; D004195:Disease Models, Animal; D006761:Hospitals; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000472:pathogenicity*; D007251:Influenza, Human / Q000821:virology*; D051379:Mice; D008969:Molecular Sequence Data; D009976:Orthomyxoviridae Infections / Q000473:pathology* / Q000821:virology*; D011110:Polymorphism, Genetic; D012367:RNA, Viral / Q000235:genetics; D012324:RNA-Dependent RNA Polymerase; D017422:Sequence Analysis, DNA; D014764:Viral Proteins; D014774:Virulence; D014779:Virus Replication
C061290:PA protein, influenza viruses; C057027:PB2 protein, Influenzavirus A; D012367:RNA, Viral; D014764:Viral Proteins; D012324:RNA-Dependent RNA Polymerase