第一章 病毒学基础

第四节.病毒的增殖 Viral Multiplication
　　病毒的种类很多，它们的繁殖方式既有共性又有各自的特点，这里以噬菌体为重点，从以下方面来介绍病毒的增殖：

   

　

一.增殖的定义

二.增殖的机制

三.增殖的过程

四.溶原性循环
　 　
　
　 一.增殖的定义 (Definition of multiplication)

　
  　　病毒感染宿主细胞后，利用宿主进行病毒核酸的复制和蛋白质的合成，最后装配成子代病毒，并由宿主细胞释放出来。这个过程称为病毒的增殖。

    The nucleic acid in a virion contains only a few of the genes needed for the synthesis of new viruses. The enzymes used in the viral life cycle are synthesized and functional only when the virus is within the host cell. Thus, for a virus to multiply, it must invade a host cell and take over the host's metabolic machinery (such as enzymes needed for protein synthesis, ribosomes, tRNA, and energy etc.).　

　

　

二. 增殖的机制 Mechanisms of Viral Multiplication

   增殖的基本原理在不同病毒的是类似的。目前了解最清楚的病毒的增殖周期是噬菌体的的增殖过程。
   噬菌体可以通过两种机制增殖：裂解性循环或者溶原性循环。裂解性循环的结果是寄主细胞的裂解和死亡，而在溶原性循环中，寄主细胞仍然存活。
    因为对T-偶数噬菌体(T2, T4, and T6)研究最详细，T-偶数噬菌体与其寄主大肠杆菌（E.coli）常作为描述病毒增殖的例子。
     T-偶数噬菌体病毒粒子体积比较大，无被膜，具有特征性的头部和尾部的结构。

     The basic mechanism of viral multiplication is similar for all viruses. The best-understood viral life cycles are those of the bacteriophages. Phages can multiply by two alternative mechanisms: the lytic cycle or the lysogenic cycle. The lytic cycle ends with the lysis and death of the host cell, whereas the host cell remains alive in the lysogenic cycle.  

   Because the T-even bacteriophages (T2, T4, and T6) have been studied most extensively the multiplication of T-even bacteriophages in their host, E.coli, will be described as an example of the lytic cycle.
   The virions of T-even bacteriophages are large, complex, and nonenveloped, with a characteristic head-and-tail structure.
　

mechanism [5mekEnizEm]n.机械装置, 机构, 机制

lytic [5litik] adj. 溶胞作用的

lysogenic [9laIsEJ`dVenIk]adj.[生]生成细胞溶素的,生成溶胞素的,溶原的,产噬的

lysis [5laisis] n 细胞[菌]溶解

extensively adv.广阔地

temperat[5tempErit]adj.有节制的, 适度的, 戒酒的, (气候)温和的

temperate bacteriophage:温和噬菌体