人类已经存在甲型H1N1流感部分免疫能力
PNAS：人类已经存在甲型H1N1流感部分免疫能力生物谷
人体后天性免疫是阻止病原体入侵的重要防线，一旦病原体感染机体，如流感病毒，免疫系统便会产生抗体并记忆。最新研究表明此前的流感感染很可能提供了抵抗当前的H1N1流感病毒大流行的一些免疫力。这些发现可能有助于平息一种担心，即这种H1N1病毒与此前的人类季节流感毒株如此不同，以至于人群没有已经存在的免疫力。
Bjoern Peters及其同事使用Immune Epitope Database比较了这种H1N1病毒的哪些分子标记可能与此前的季节流感毒株表面上的分子标记类似。这组作者发现了人类的免疫系统能识别这种H1N1病毒表面上与最近的季节流感病毒共享的大约17%的标记。另一种称为T细胞的免疫细胞也能探测被病毒感染的细胞，它能够识别这种甲型H1N1 病毒的69%的标记。这种高比例的识别提示人类和动物预先存在的免疫力可能提供一个阻止大流行毒株的屏障，而且可能有助于削弱广泛感染的影响。然而，这组作者说，仍然需要疫苗来应对这种H1N1流感病毒表面携带的独特标记。（生物谷Bioon.com）
生物谷推荐原始出处：
PNAS November 16, 2009, doi: 10.1073/pnas.0911580106
Pre-existing immunity against swine-origin H1N1 influenza viruses in the general human population
Jason A. Greenbauma,1, Maya F. Kotturia,1, Yohan Kima, Carla Oseroffa, Kerrie Vaughana, Nima Salimia, Randi Vitaa, Julia Ponomarenkob, Richard H. Scheuermannc, Alessandro Settea and Bjoern Petersa,2
aDivision of Vaccine Discovery, La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037;
bSan Diego Supercomputer Center, University of California at San Diego, La Jolla, CA 92093; and
cDepartment of Pathology and Division of Biomedical Informatics, University of Texas Southwestern Medical Center, Dallas, TX 75390
A major concern about the ongoing swine-origin H1N1 influenza virus (S-OIV) outbreak is that the virus may be so different from seasonal H1N1 that little immune protection exists in the human population. In this study, we examined the molecular basis for pre-existing immunity against S-OIV, namely the recognition of viral immune epitopes by T cells or B cells/antibodies that have been previously primed by circulating influenza strains. Using data from the Immune Epitope Database, we found that only 31% (8/26) of B-cell epitopes present in recently circulating H1N1 strains are conserved in the S-OIV, with only 17% (1/6) conserved in the hemagglutinin (HA) and neuraminidase (NA) surface proteins. In contrast, 69% (54/78) of the epitopes recognized by CD8+ T cells are completely invariant. We further demonstrate experimentally that some memory T-cell immunity against S-OIV is present in the adult population and that such memory is of similar magnitude as the pre-existing memory against seasonal H1N1 influenza. Because protection from infection is antibody mediated, a new vaccine based on the specific S-OIV HA and NA proteins is likely to be required to prevent infection. However, T cells are known to blunt disease severity. Therefore, the conservation of a large fraction of T-cell epitopes suggests that the severity of an S-OIV infection, as far as it is determined by susceptibility of the virus to immune attack, would not differ much from that of seasonal flu. These results are consistent with reports about disease incidence, severity, and mortality rates associated with human S-OIV. 传染病流行一段时间以后，人群通常都会产生免疫力，这就是免疫系统的神奇所在。 通过本次流行，已经有很多人产生了免疫力，只是所占比例还不够大，不足以形成有效的免疫屏障。
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