Some properties of mycoplasma virus Br1

Abstract

Morphologically mycoplasma virus Br1 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. Br1 was closely associated with its host cell and assays reflected infectious centres. During growth of Br1 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 Br1 infection and did not seem to be carrying the virus. Br1 formed plaques onM. bovirhinis but failed to produce plaques on strains of 8Mycoplasma, 2Acholeplasma and 4 bacterial species.