有记载的人类社会发展历程中，曾经有过几次流感大流行。这些灾难都是由某些致命流感病毒引发的，那么，这次引爆全球的甲型H1N1病毒是否也具有致命流感病毒的某些标记呢？美国科学家在最新一期《BMC Microbiology》上发表研究报告说，经过与以往造成流感大流行的致命流感病毒进行对比，他们认为甲型H1N1流感病毒并不像人们担心的那么严重。
美国利弗莫尔劳伦斯国家实验所的乔纳森·艾伦和汤姆·斯莱扎克从被保留下来的、造成以往几次流感大流行的病毒毒株中鉴别出34种基因标记物，这些标记物与病毒宿主特异性和高致死率有关，影响着流感的严重程度；与此同时，他们从甲型H1N1流感病毒毒株样本中鉴别出17种影响流感严重程度的基因标记物。在对这些基因标记物进行对比后发现，甲型H1N1流感病毒样本中的基因标记物与致命流感病毒中的基因标记物没有相似性。
研究人员认为，这表明甲型H1N1流感病毒缺少以往出现的致命流感病毒所具有的特性。但他们也同时强调说，这一研究结果并不表示目前的甲型H1N1流感不严重，而且，对此作出定论还有待进一步研究。
BMC Microbiology 2009, 9:77doi:10.1186/1471-2180-9-77
Conserved amino acid markers from past influenza pandemic strains
Jonathan E Allen , Shea N Gardner , Elizabeth A Vitalis and Tom R Slezak
Abstract
Background
Finding the amino acid mutations that affect the severity of influenza infections remains an open and challenging problem. Of special interest is better understanding how current circulating influenza strains could evolve into a new pandemic strain. Influenza proteomes from distinct viral phenotype classes were searched for class specific amino acid mutations conserved in past pandemics, using reverse engineered linear classifiers.
Results
Thirty-four amino acid markers associated with host specificity and high mortality rate were found. Some markers had little impact on distinguishing the functional classes by themselves, however in combination with other mutations they improved class prediction. Pairwise combinations of influenza genomes were checked for reassortment and mutation events needed to acquire the pandemic conserved markers. Evolutionary pathways involving H1N1 human and swine strains mixed with avian strains show the potential to acquire the pandemic markers with a double reassortment and one or two amino acid mutations.
Conclusion
The small mutation combinations found at multiple protein positions associated with viral phenotype indicate that surveillance tools could monitor genetic variation beyond single point mutations to track influenza strains. Finding that certain strain combinations have the potential to acquire pandemic conserved markers through a limited number of reassortment and mutation events illustrates the potential for reassortment and mutation events to lead to new circulating influenza strains.
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