Li Xiangzhong, Fang Fang, Song Yunlong, Yan Hongli, Chang Haiyan, Sun Shuhan, Chen Ze
College of Life Sciences, Hunan Normal University, Changsha, Hunan, People's Republic of China.
DNA Cell Biol. 2006 Apr;25(4):197-205. doi: 10.1089/dna.2006.25.197.
Neuraminidase (NA) is one of the surface glycoproteins of influenza virus. The immune response induced by NA DNA in the mouse model has been proved, in our previous study, to be able to provide an adequate protection against the challenge with a homologous virus and a crossprotection against the challenge with a heterologous virus of the same subtype. In this paper, a series of NA plasmid truncates, with the nucleotides at the 5'- or 3'-terminal of A/PR/8/34 (H1N1) NA deleted serially, were constructed by PCR. BALB/c mice were immunized with the plasmid truncates and challenged with homologous virus at a lethal dosage. The essential sequence of NA DNA to provide protection against the influenza virus was explored by observing the survival rates, serum anti-NA antibody titers, and lung virus titers of the mice. The result showed that, along with the increasing number of nucleotides deleted serially at the 5'- or 3'-terminal of NA DNA, the antibody titer induced by NA DNA decreased. NA DNA lost its protection against the influenza virus when 60 nucleotides (or 20 amino acids) at the 5'-terminal or 66 nucleotides (or 22 amino acids) at the 3'-terminal were deleted. The nt58-1299 of NA DNA may play an important role in protection against influenza virus.
神经氨酸酶（NA）是流感病毒的表面糖蛋白之一。在我们之前的研究中已证明，在小鼠模型中由NA DNA诱导的免疫反应能够提供针对同源病毒攻击的充分保护以及针对相同亚型异源病毒攻击的交叉保护。在本文中，通过聚合酶链式反应（PCR）构建了一系列A/PR/8/34（H1N1）NA的5'-或3'-末端核苷酸被连续缺失的NA质粒截短体。用这些质粒截短体免疫BALB/c小鼠，并用致死剂量的同源病毒进行攻击。通过观察小鼠的存活率、血清抗NA抗体滴度和肺病毒滴度，探索了NA DNA提供抗流感病毒保护的关键序列。结果表明，随着NA DNA 5'-或3'-末端连续缺失核苷酸数量的增加，NA DNA诱导的抗体滴度降低。当NA DNA的5'-末端缺失60个核苷酸（或20个氨基酸）或3'-末端缺失66个核苷酸（或22个氨基酸）时，NA DNA失去了对流感病毒的保护作用。NA DNA的nt58 - 1299可能在抗流感病毒保护中起重要作用。
