| 1. | New variants of some plant viruses have been produced artificially in the laboratory by treating pure virus strains with mutagens .
用亚硝酸之类的诱变处理纯病毒株系，能在实验室内人为地使有些植物病毒产生新变种。 |
| 2. | The strain is resistant because of a single mutation
病毒株的抗药性来自单一突变。 |
| 3. | Its mortality rate , in its most virulent strains , is 90 %
最致命的病毒株引起的死亡率达到90 % 。 |
| 4. | The 1957 strain was nearly released by accident in 2005
因为偶然的因素1957病毒株险些在2005年流行。 |
| 5. | That strain , influenza a ( h5n1 ) does not yet pass readily from one person to another
这种禽流感病毒株是一种a型流感病毒，品系为h5n1 。 |
| 6. | Analysis on antigenicity and hi antibody level of influenza virus in zhejiang province
浙江省近年来流感病毒株的抗原性及人群免疫状况分析 |
| 7. | Also , it is based on a irus strain that was circulating in ietnam three years ago
还有，这一疫苗是基于三年前在越南流行的病毒株而研制的。 |
| 8. | The four h5n1 isolates were from two patients who were confirmed to have influenza a h5n1 infection
此四个h5n1病毒株来自两名证实患上甲型流行性h5n1感冒的病人。 |
| 9. | Herpesiruses descended from a strain that once infected a common ancestor of mammals , birds and reptiles
疱疹病毒源于一度感染哺乳动物、鸟类和昆虫的始祖的病毒株。 |
