| environ. |
virus Submicroscopic agents that infect plants, animals and bacteria, and are unable to reproduce outside the tissues of the host. A fully formed virus consists of nucleic acid (DNA or RNA) surrounded by a protein and lipid (fat) coat. The nucleic acid of the virus interferes with nucleic acid-synthesizing mechanism of the host cell, organizing it to produce more viral nucleic acid. Viruses cause many diseases (e.g., mosaic diseases of many cultivated plants, myxomatosis, foot and mouth disease, the common cold, influenza, measles, poliomyelitis). Many plant viruses are transmitted by insects, some by eelworms. Animal viruses are spread by contact, droplet infection or by insect vectors and some are spread by the exchange of body fluids (感染植物、动物和细菌，并在宿主组织外无法复制的亚显微媒介。一个完全形成的病毒由蛋白质和脂质(脂肪)所包裹的核酸(DNA或RNA)组成，病毒的核酸干扰宿主细胞的核酸合成机制，促使它产生出更多的病毒核酸。病毒能引起很多疾病(例如，许多栽培植物的花叶病、多发粘液瘤病、手足口病、普通感冒，流行性感冒、麻疹、小儿麻痹症)。许多植物病毒是由昆虫传播的，有一些是由线虫传播的。动物病毒是通过接触、飞沫感染或昆虫媒介传播的，有些是由体液交换传播的。) |
