generalized transduction, random host-cell DNA is carried by the defective (tranducing) phage. In specialized transduction, specific genes and gene sequences are carried. Some bacteria, when infected by a specialized transducing phage, become pathogenic, since the genes for virulence (ability to cause disease) are carried by the phage. This process is called lysogenic conversion, since the infected bacteria are not forced to enter into the lytic viral replication cycle. Examples of bacteria that become pathogens in this way include Clostridium botulinum, Staphylococcus aureus, Legionella pneumophila, Escherichia coli O157:H7 and Yersinia pestis.