Freshwater blue-green algae of the genera Lyngbya, Plectonema, and Phormidium are susceptible to a virus recently isolated from a waste-stabilization pond. Electron micrographs of a partially purified preparation show that the viral particle has an icosahedral structure about 66 mmicro in diameter.

SAFFERMAN, ROPERT S. (Robert A. Taft Sanitary Engineering Center, Cincinnati, Ohio), AND MARY-ELLEN MORRIS. Growth characteristics of the blue-green algal virus LPP-1. J. Bacteriol. 88:771-775. 1964.-The blue-green algal (BGA) virus, strain LPP-1, formed two distinct plaque variants. D)uring subsequent propagation, each of the isolated variants eventually reverted to a mixture of both plaque types. The large-plaquieformer, multiplying at a somewhat faster rate, showed maximal virus production within 60 hr after infection; maximal titer of the small-plaque mutant was reached after a 76-hr incubation period. No differences were observed in either their host spectra or their pH and thermal stability. Evidence was presented which demonstrated that BGA virus samples could be assayed with reasonable accuracy from plaque counts. Vrariations resulting from this plating technique were within the range of experimental error that has been generally reported for such a system.

A recently proposed polythetic definition of virus species appears easily applicable to bacteriophages. Criteria for classification of tailed phages are evaluated. Morphology, DNA homology, and serology are the most important criteria for delineation of species, but no single criterion is satisfactory. Dot-blot hybridization and seroneutralization may suggest false relationships by detecting common sequences in the DNA of otherwise unrelated phages. Species of tailed phages can be defined by a combination of morphology and DNA homology or serology. A procedure for identification of novel phages is outlined. Phage names should include elements of host names.

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