8月5日，由美国和日本等国科学家组成的研究小组报告说，他们发现甲型H1N1流感病毒能适应人体并高效复制的原因。这一研究成果发表在最新一期美国《公共科学图书馆·病原体》（PLoS Pathogens）杂志上。
一般情况下，流感病毒要实现从宿主细胞进入包括人在内的哺乳动物体内并进行有效复制，其PB2蛋白质的特定位置上需要存在两种氨基酸——赖氨酸和天冬酰胺酸。一直以来，研究人员并未在甲型流感病毒PB2蛋白质的这一特定位置上发现这两种氨基酸，因此对甲型H1N1流感能在人际间传播感到费解。
研究小组发现，甲型流感病毒是过去90年中出现的4种禽流感和猪流感病毒“杂交”的产物，它甚至还包含1918年西班牙流感病毒的部分残余，其赖氨酸存在于PB2蛋白质的另一特殊位置。甲型流感病毒的这种特殊结构使其能很好地适应人体细胞，从而在人体内有效复制。
研究人员表示，这一发现为预测将来的流感大流行提供了另一可用的遗传标记。（生物谷Bioon.com）
生物谷推荐原文出处：
PLoS Pathog 6(8): e1001034. doi:10.1371/journal.ppat.1001034
Biological and Structural Characterization of a Host-Adapting Amino Acid in Influenza Virus
Shinya Yamada1, Masato Hatta2, Bart L. Staker3,4, Shinji Watanabe2, Masaki Imai2, Kyoko Shinya5, Yuko Sakai-Tagawa1, Mutsumi Ito1, Makoto Ozawa2,6, Tokiko Watanabe2, Saori Sakabe1,7, Chengjun Li2, Jin Hyun Kim2, Peter J. Myler4,8,9, Isabelle Phan4,8, Amy Raymond3,4, Eric Smith3,4, Robin Stacy4,8, Chairul A. Nidom10,11, Simon M. Lank12, Roger W. Wiseman12, Benjamin N. Bimber12, David H. O'Connor12,13, Gabriele Neumann2, Lance J. Stewart3,4*, Yoshihiro Kawaoka1,2,5,6,7,14*
1 Division of Virology, Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, Tokyo, Japan, 2 Influenza Research Institute, Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, United States of America, 3 Emerald BioStructures, Inc., Bainbridge Island, Washington, United States of America, 4 Seattle Structural Genomics Center for Infectious Disease, Washington, United States of America, 5 Department of Microbiology and Infectious Diseases, Kobe University, Hyogo, Japan, 6 Department of Special Pathogens, International Research Center for Infectious Diseases, Institute of Medical Science, University of Tokyo, Tokyo, Japan, 7 ERATO Infection-Induced Host Responses Project, Saitama, Japan, 8 Seattle Biomedical Research Institute, Seattle, Washington, United States of America, 9 Departments of Global Health and Medical Education & Biomedical Informatics, University of Washington, Seattle, Washington, United States of America, 10 Faculty of Veterinary Medicine, Tropical Disease Centre, Airlangga University, Surabaya, Indonesia, 11 Collaborating Research Center-Emerging and Reemerging Infectious Diseases, Tropical Disease Centre, Airlangga University, Surabaya, Indonesia, 12 Wisconsin National Primate Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America, 13 Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, Wisconsin, United States of America, 14 Creative Research Initiative, Sousei, Hokkaido University, Sapporo, Japan
Two amino acids (lysine at position 627 or asparagine at position 701) in the polymerase subunit PB2 protein are considered critical for the adaptation of avian influenza A viruses to mammals. However, the recently emerged pandemic H1N1 viruses lack these amino acids. Here, we report that a basic amino acid at position 591 of PB2 can compensate for the lack of lysine at position 627 and confers efficient viral replication to pandemic H1N1 viruses in mammals. Moreover, a basic amino acid at position 591 of PB2 substantially increased the lethality of an avian H5N1 virus in mice. We also present the X-ray crystallographic structure of the C-terminus of a pandemic H1N1 virus PB2 protein. Arginine at position 591 fills the cleft found in H5N1 PB2 proteins in this area, resulting in differences in surface shape and charge for H1N1 PB2 proteins. These differences may affect the protein's interaction with viral and/or cellular factors, and hence its ability to support virus replication in mammals.
