virulent bacteriophage

vir·u·lent bac·te·ri·o·phage

a bacteriophage that regularly causes lysis of the bacteria that it infects; it may exist in one or the other of only two forms, vegetative or mature; it does not have a probacteriophage form (that is, its genome does not incorporate with that of the host bacterium), therefore it does not effect lysogenization.

vir·u·lent bac·te·ri·o·phage

(vir'yū-lĕnt bak-tēr'ē-ō-fāj) A bacteriophage that regularly causes lysis of the bacteria that it infects.