Two scientists Alfred Hershey and Martha Chase in 1952 did a famous experiment to prove whether the protein coat, or the viral DNA was responsible for hijacking a host cell's reproductive machinery, producing more viruses. Since protein contains sulfur, some radioactive sulfur was put into one batch of T2 virus and its host cell E.Coli bacteria. Since DNA contains phosphorus, radioactive phosphorus was placed in a second batch of T2 virus with E.Coli. Depending on which one the bacteria cell(host) incorporated, would determine which part of the virus was taking over the cell's reproductive equipment. As it turned out, the phosphorus showed up inside the bacteria cell therefore, it is DNA that a virus injects into a host cell, which in turn, directs the host into replicating more viruses.