190
T. BERGAN
recombinant acquired a different group or type antigen and lost antigens
originally present. Other examples of antigenic changes after transduction
have been mediated by typing phages in a number of studies (Gemski
et al., 1975 : Lhsz16 et al., 1973a, b ; Milch et al., 1968). Parallel changesin the
chemical composition of O-type polysaccharide have been observed by
Financsek et al. (1975).
D. Phage receptor chemistry
In S. dysenteriae, a protein carrier of the O-antigen or common component present in the lipopolysaccharide has been identified as a probable
phage receptor substance (Goldhar et al., 1973, 1974, 1975, 1976).
Burnet and McKie (1930) reported that most phages act similarly on
smooth and rough colonies of the same strains of S. flexneri. On the other
hand the phages selected by Hammarstrom (1949) were mostly lytic against
phase I1 strains, R-phages, and only some had equal or reduced propensity
against phase I strains (R- and S-phages). Pruneda and Farmer (1977)
reported that smooth and rough variants of the same strains had different
lysotypes. They developed their proposed phage typing set for R-colonies.
V. PROPERTIES OF SHIGELLA PHAGES
A. Morphology of phages
The phages of Shigella possess polyhedric heads and tails of varying
appearance according to phage strain. The phages of the international
typing set of S. flexneri and S. sonnei have been subdivided into seven
morphology types (Krzywy et al., 1972). For S. flexneri, six types have been
identified; for S. sonnei, seven morphological types have been described
(Krzywy et al., 1970, 1971). Inhomogeneity of phage strains has been
demonstrated for one S. flexneri and four out of 16 S. sonnei typing phage
preparations (Krzywy et al., 1972). The phages are morphologically similar
to those observed in other species of the Enterobacteriaceae, Brucella, and
Bacillus mycoides (Krzywy et al., 1970, 1971; Quynh, 1968).
The capsids are either icosahedrons or octahedrons. Their uncontracted
tails are long or short, cylindrical or conical. Some have flexible tails. Rare
phage strains have non-contractable, conical tails. Fibrils, collars, and base
plates have been identified in most phages.
B. Serology of phages
Classification of bacteriophages according to serology, has demonstrated
seven groups on the basis of neutralisation assays in S. flexneri phages
(Lhsz16 et al., 1973a) b; Gromkova, 1967). Among the phages of Hammarstrom (1947), Slopek et al. (1961) have demonstrated four immunotypes.
T. BERGAN
recombinant acquired a different group or type antigen and lost antigens
originally present. Other examples of antigenic changes after transduction
have been mediated by typing phages in a number of studies (Gemski
et al., 1975 : Lhsz16 et al., 1973a, b ; Milch et al., 1968). Parallel changesin the
chemical composition of O-type polysaccharide have been observed by
Financsek et al. (1975).
D. Phage receptor chemistry
In S. dysenteriae, a protein carrier of the O-antigen or common component present in the lipopolysaccharide has been identified as a probable
phage receptor substance (Goldhar et al., 1973, 1974, 1975, 1976).
Burnet and McKie (1930) reported that most phages act similarly on
smooth and rough colonies of the same strains of S. flexneri. On the other
hand the phages selected by Hammarstrom (1949) were mostly lytic against
phase I1 strains, R-phages, and only some had equal or reduced propensity
against phase I strains (R- and S-phages). Pruneda and Farmer (1977)
reported that smooth and rough variants of the same strains had different
lysotypes. They developed their proposed phage typing set for R-colonies.
V. PROPERTIES OF SHIGELLA PHAGES
A. Morphology of phages
The phages of Shigella possess polyhedric heads and tails of varying
appearance according to phage strain. The phages of the international
typing set of S. flexneri and S. sonnei have been subdivided into seven
morphology types (Krzywy et al., 1972). For S. flexneri, six types have been
identified; for S. sonnei, seven morphological types have been described
(Krzywy et al., 1970, 1971). Inhomogeneity of phage strains has been
demonstrated for one S. flexneri and four out of 16 S. sonnei typing phage
preparations (Krzywy et al., 1972). The phages are morphologically similar
to those observed in other species of the Enterobacteriaceae, Brucella, and
Bacillus mycoides (Krzywy et al., 1970, 1971; Quynh, 1968).
The capsids are either icosahedrons or octahedrons. Their uncontracted
tails are long or short, cylindrical or conical. Some have flexible tails. Rare
phage strains have non-contractable, conical tails. Fibrils, collars, and base
plates have been identified in most phages.
B. Serology of phages
Classification of bacteriophages according to serology, has demonstrated
seven groups on the basis of neutralisation assays in S. flexneri phages
(Lhsz16 et al., 1973a) b; Gromkova, 1967). Among the phages of Hammarstrom (1947), Slopek et al. (1961) have demonstrated four immunotypes.