Viruses reproduction begins when the virion comes into contact with a suitable host cell. The DNA or RNA enters the host cell and begins to function as genetic information by directing the synthesis of specific types of proteins that have enzymatic and structural roles. The infectious cycle usually consists of two different stages. In the first, the proteins are produced that are required for the reproduction of the viral DNA or RNA in conjunction with components of the host cell. In the second stage, proteins that make up the virion are produced; these combine with the DNA or RNA to form mature virions, which are the released from the cell. In some cases this release involves the complete disruption and death of the cell, a process known as lysis. In other cases individual virions are released through the cell membrane without killing the cell.
A virus contains the information needed to reproduce itself coded in its nucleic acid. Because it lacks its own protein producing machinery, however, the virus must use the machinery of the host cell in order to multiply. A bacteriophage virion attaches to a bacterial cell and injects its DNA into the bacterium. Using bacterial ribosomes enzyme the viral DNA direct the synthesis of messenger RNA (mRNA), enzymes that break up bacterial DNA, and enzymes that allow replication of viral DNA. Protein synthesized, using mRNA, from the DNA code, these proteins from heads, tails, and tail fibers, and the virus parts assemble into complete virions. An enzymes break up the bacterial cell and liberates the new virions, which can infect other bacterial cells. The information that bring by DNA will procude a virus with the same virus characteristic.