Some properties of mycoplasma virus Br 1.

Morphologically mycoplasma virus Br 1 is a typical contractile-tailed bacteriophage with a head 77 nm in diameter and a tail 104 nm long. Its type of nucleic acid was not determined. Br 1 was closely associated with its host cell and assays reflected infectious centres. During growth of Br 1 in mycoplasma cultures at multiplicities of infection (MOI) greater than 0.001, there was a lag period: this was up to 23 hours at an MOI of 35. The mean generation time of a mycoplasma culture infected at MOI up to 235 was 2 hours, compared with 1 hour for an uninfected culture. However in these infected cultures there were viable mycoplasmas all of which appeared to be fully susceptible to Br 1 infection and did not seem to be carrying the virus. Br 1 formed plaques on M. bovirhinis but failed to produce plaques on strains of 8 Mycoplasma, 2 Acholeplasma and 4 bacterial species.