Characterization of Brucellaphages

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Abstract
Eleven brucella-phages of Russian or Polish origin were examined to determine their biological, biochemical and physical characteristics. All the phages gave clear plaques of variable size (0-5-3-5mm.) on the host Brucella abortus strain 19. Plaque formation occurred with all smooth cultures of B. abortus and B. neotomae. Brucella suis cultures were incompletely lysed or inhibited by high-titre (about 1 x 109 plaque-forming units/ml.) phage. This was shown to be true phage lysis since small (0-5mm.) turbid plaques were later observed with this host. A partial ingibition or lysis of cultures of Brucella melitensis by high-titre phage was noted and could be associated with the presence of intact phage. Replication of phage on this host without plaque formation was observed by means of an elution technique. The phages reacted serologically as a group and comparative studies by electron microscopy indicated a very similar if not identical morphology. The average dimensions of the phage head were 59 x 66 m[mu] and it presented an outline consistent with that of a regular icosahedron. Attached to the phage head was a short (10 x 23 m[mu]) tail having a somewhat wedge-shaped terminal end. The % guanine+ cytosine of the DNA from B. abortus, B. melitensis, B. suis and the eleven brucellaphages was determined from the thermal denaturation temperature of their nucleic acids. These were 57-3% for B. abortus, 57-9% for B. melitensis, and 58.5% for B. suis. The base compositions of the phage nucleic acids were 45.3[long dash]46.7% guanine+cytosine. On the basis of their similar fundamental characteristics these phages may be considered as closely related if not identical.