How many types of bacteriophage are there ?
--- bacteriophage hk022 --- bacteriophage lambda --- bacteriophage m13 --- bacteriophage mu --- bacteriophage n4 --- bacteriophage p1 --- bacteriophage p2 --- bacteriophage phi x 174 --- bacteriophage prd1 --- leviviridae --- allolevivirus --- levivirus --- t-phages --- bacteriophage t3 --- bacteriophage t4 --- bacteriophage t7