21.   Kim said the flu virus infected cells in its host, reproduced inside these cells and then broke out to spread the infection to other cells.

22.   Recently, for example, a group of scientists in Montana discovered that when the virus first infects a cell, it undergoes a slight change in surface configuration.

23.   Researcher Peter S. Kim said a cavity found in one component of HIV could be an ideal target for drugs designed to render it unable to infect human cells.

24.   Scientists have long been experimenting with various types of virus carriers because their ability to infect cells makes them ideal gene-delivery vehicles.

25.   Similarly, in the laboratory, the virus cannot infect their cells.

26.   Some viruses can mask this signal after they infect a cell so that the cell they reside in is not attacked.

27.   Synagis is a genetically engineered antibody that works to stop the virus from fusing with and infecting the cells of the respiratory tract.

28.   The idea was to pinpoint how the milk blocks bacteria from infecting other cells.

29.   The influenza virus is enclosed in a membrane, and in order to infect a cell its membrane and that of the target cell must fuse.

30.   The method depends on first infecting the cells with a tumor gene that makes them divide.