IS VIRULENCE OF H5N2 INFLUENZA-VIRUSES IN CHICKENS ASSOCIATED WITH LOSS OF CARBOHYDRATE FROM THE HEMAGGLUTININ
IS VIRULENCE OF H5N2 INFLUENZA-VIRUSES IN CHICKENS ASSOCIATED WITH LOSS OF CARBOHYDRATE FROM THE HEMAGGLUTININ
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DOI：
10.1016/0042-6822(84)90376-3
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发表时间：
1984-01-01
期刊：
影响因子：
3.7
通讯作者：
WEBSTER, RG
中科院分区：
文献类型：
--
作者：
KAWAOKA, Y;NAEVE, CW;WEBSTER, RG
对1983年4月在宾夕法尼亚州[美国]鸡群中出现并随后于1983年10月变为强毒株的A/Chick/Penn/83（H5 N2）流感病毒进行了噬斑形成能力和血凝素（HA）分子裂解能力的检查。无毒的病毒产生空斑和切割HA只有在胰蛋白酶的存在下。在胰蛋白酶存在或不存在下，强毒病毒产生噬斑并将HA前体切割成HA 1和HA 2。从无毒病毒的HA 1的表观分子量高于从强毒病毒，但当病毒在衣霉素的存在下生长，HA的分子量是无法区分的。9个单克隆抗体的HA的无毒力的病毒表明，有至少1个表位的HA是不同的毒力和无毒力的病毒。通过对它们各自的HA基因进行测序来比较来自2种病毒的HA的氨基酸序列。编码经加工的HA多肽的核苷酸序列含有1641个核苷酸，确定了547个氨基酸的蛋白质。通过连接肽区域，毒性和无毒力病毒的氨基酸序列是不可区分的，表明H5 HA的可切割性的差异并不直接归因于连接肽的氨基酸序列。7个核苷酸变化中的4个导致HA 1的残基13、69和123以及HA 2多肽的残基501处的氨基酸变化。由于在强毒株或无毒毒株的氨基酸序列中没有缺失或插入，因此存在MW差异是由于强毒株中碳水化合物侧链丢失所致的可能性。强毒株中残基13处的氨基酸变化是可能影响糖基化位点的唯一突变，并且该突变位于连接肽附近。据推测，这种碳水化合物的损失可能允许识别碱性氨基酸序列的酶进入，并导致强毒病毒中HA的裂解激活。
The A/Chick/Penn/83 (H5N2) influenza virus that appeared in chickens in Pennsylvania [USA] in April 1983 and subsequently became virulent in Oct. 1983, was examined for plaque-forming ability and cleavability of the hemagglutinin (HA) molecule. The avirulent virus produced plaques and cleaved the HA only in the presence of trypsin. The virulent virus produced plaques and cleaved the HA precursor into HA1 and HA2 in the presence or absence of trypsin. The apparent MW of the HA1 from the avirulent virus was higher than that from the virulent virus, but when the viruses were grown in the presence of tunicamycin, the MW of HA were indistinguishable. Two of 9 monoclonal antibodies to the HA of the avirulent virus indicate that there is at least 1 epitope on the HA that is different between the virulent and avirulent viruses. The amino acid sequences of the HA from the 2 viruses were compared by sequencing their respective HA gene. The nucleotide sequence coding for the processed HA polypeptide contained 1641 nucleotides specifying a protein of 547 amino acids. The amino acid sequences of the virulent and avirulent viruses were indistinguishable through the connecting peptide region, indicating that the difference in cleavability of the H5 HA is not directly attributed to the amino acid sequence of the connecting peptide. Four of 7 nucleotide changes resulted in amino acid changes at residues 13, 69 and 123 of HA1 and at residue 501 of the HA2 polypeptide. Since there were no deletions or insertions in the amino acid sequence of the virulent or avirulent viruses, the possibility exists that the difference in MW is due to loss of a carbohydrate side chain in the virulent strain. The amino acid change in the virulent strain at residue 13 is the only mutation that could affect a glycosylation site and this is in the vicinity of the connecting peptide. It is postulated that the loss of this carbohydrate may permit access of an enzyme that recognizes the basic amino acid sequences and results in cleavage activation of the HA in the virulent virus.