Isolation and characterization of bacteriophages for Neisseria.

Sixteen bacteriophages for several strains of Neisseria perflava were isolated from throat washings and lysogenic organisms. The phages are placed into five groups based on serological and host-range characteristics. Group I, host strain c r, has phages NI, N2, mutant N2C, N5, N6, and NI3. N I is virulent, all others temperate for the host. Plaque size is about 1.5 mm., the largest for Neisseria phages. Group II, host strains s, T and u, has phage N4 and mutant N4c. The neutralizable antigens of these phages are modified when the host is changed. The group III phages, N3, N7, N8, N 9 and NI I, are temperate for host strain T. Group IIIA has a single member, N I0, which is temperate for its host, strain u. The group IV phages, NI2, NI55 , N 159 and N208, w e r e all isolated from strains of N. flavescens on host strain s. Plaque size is about o.I mm., the smallest for the phages. All phages within a group are apparently serologically identical. Groups II, III and IIIA are serologically related, the others are distinct. The most remarkable feature is the extremely limited host range of each phage. Since the original chance isolations of the hosts given above, no additional phage-sensitive Neisseria have been found in over 30o strains tested.