Order of authorship in the original publication: Luria, Human. Luria and Human discovered the restriction modification system found in bacteria and other prokaryotic organisms. This system provides a defense against foreign DNA such as that carried by bacteriophages. They found that bacteriophage growing within an infected bacterium could be modified, so that upon their release and re-infection of a related bacterium the bacteriophage’s growth is restricted (inhibited). 

"It was found that, for a bacteriophage λ that can grow well in one strain of Escherichia coli, for example E. coli C, when grown in another strain, for example E. coli K, its yields can drop significantly, by as much as 3-5 orders of magnitude. The host cell, in this example E. coli K, is known as the restricting host and appears to have the ability to reduce the biological activity of the phage λ. If a phage becomes established in one strain, the ability of that phage to grow also becomes restricted in other strains" (Wikipedia article on Restriction enzyme, accessed 3-2020). 

Digital facsimile from PubMedCentral at this link.