Patents are designed to protect creations and designs, but how long a patent lasts for is dependent on a number of factors. The length of time that a patent offers protection, depends largely on what type of patent is issued and whether required maintenance fees are paid to keep the patent active. slide 1 of 6.
A viral infection is a disease that can be caused by different kinds of viruses, of which the influenza-virus is best known.
Viral Infections Viruses have two methods of infection once inside a host cell. In a lytic infection, a virus enters a cell, makes copies of itself, and causes the cell to burst, releasing new virus particles that can attack other cells.