[Ambivalent bacteriophages of different species active on Escherichia coli K12 and Salmonella sps. strains].

A study was made of several bacteriophages (including phages U2 and LB related to T-even phages of Escherichia coli) that grow both on E. coli K12 and on some Salmonella strains. Such phages were termed ambivalent. T-even ambivalent phages (U2 and LB) are rare and have a limited number of hosts among Salmonella strains. U2 and LB are similar to canonical E. coli-specific T-even phages in morphological type and size of the phage particle and in reaction with specific anti-T4 serum. Phages U2 and LB have identical sets of structural proteins, some of which are similar in size to structural proteins of phages T2 and T4. DNA restriction patterns of phages U2 and LB differ from each other and from those of T2 and T4. Still, DNAs of all four phages have considerable homology. Unexpectedly, phages U2 and LB grown on Salmonella bungori were unstable during centrifugation in a CsCl gradient. Ambivalent bacteriophages were found in species other than T-even phages and were similar in morphotype to lambdoid and other E. coli phages. One of the ambivalent phages was highly similar to well-known Felix01, which is specific for Salmonella. Ambivalent phages can be used to develop a new set for phage typing in Salmonella. An obvious advantage is that ambivalent phages can be reproduced in the E. coli K12 laboratory strain, which does not produce active temperate phages. Consequently, the resulting typing phage preparation is devoid of an admixture of temperate phages, which are common in Salmonella. The presence of temperate phages in phage-typing preparations may cause false-positive results in identifying specific Salmonella strains isolated from the environment or salmonellosis patients. Ambivalent phages are potentially useful for phage therapy and prevention of salmonellosis in humans and animals.

Sequence comparison of the genes for immunity, DNA replication, and cell lysis of the P22-related Salmonella phages ES18 and L.

Complementation and hybridization experiments with the generalized transducing Salmonella phages P22, ES18 and L revealed strong similarity between the phages L and P22; the genome of ES18 shows a mosaic structure. About half of its genome, including the early genes, is similar or completely homologous to P22; the other half of the morphologically different ES18 does not show any similarity to P22 nor to E. coli phage lambda. Sequence comparison of the early genes has confirmed that the C-immunity region of ES18 is identical with that of P22, whereas the same region of phage L shows poor (repressor gene) or no similarity. The 5'-terminus of the DNA replication gene 12 of ES18, however, is homologous to the same section of gene O of phage lambda. The lysis genes of ES18 again are identical to those of P22; only gene 15 is mosaic-like and has more similarity to gene Rz of phage lambda. These results will be discussed in terms of the theory of modular genome organization.

Biological characteristics of Salmonella weltevreden typing phages.

The important biological characteristics of Salmonella weltevreden (3, 10 : r :Z6) typing phages were studied. On the basis of these, the phages could be classified into three groups: phages phi I and phi II, phages phi III, phi IV and phi VI, and phage phi V.

Characterization of Salmonella enterica serotype typhimurium in the Czech Republic: phage types, antimicrobial and plasmid profiles.

In this study a collection of 547 S. Typhimurium strains isolated in the years 2000 and 2001 both of the human and non-human origin were analysed. 21 different phage types were detected, the most frequent one was DT104 (46%) followed by DT141 (28%) and DT68 (3%). Resistance to one or more antimicrobial agents was found mainly in DT104 (77.4%). S. Typhimurium isolates resistant to 5 and more antimicrobial agents were found in three phagetypes DT104 (57%), DT120 and DT155. Plasmid profiling of DT104 isolates showed 10 different profiles. Pattern A found in 30.5% of tested strains was predominant and carried serovar specific plasmid and one additional small plasmid of approx. 2.5 kb.

[Erythrocyte diagnostica made from salmonellal phagolysates]. / Eritrotsitarnye diagnostikumy iz fagolizatov sal'monell.

For the first time O antigens obtained from phagolysates were proved to be suitable for use as material for the production of highly specific erythrocyte diagnostic preparations. O antigens obtained from Salmonella by two methods, i.e. phage disintegration and Grasset's method, were subjected to comparative chemical analysis and found to have no essential difference. Nevertheless, the sensitizing potency of O antigens obtained from phagolysates were experimentally shown to be 3 times greater than that of O antigens obtained by Grasset's method. The optimum sensitizing doses established in the passive hemagglutination test for O antigens obtained by both methods indicated that these antigens were highly sensitive and specific.

Conservation of the N-terminus of some phage tail proteins.

To study the interaction between lipopolysaccharide and protein, a comparative approach was employed using seven Salmonella enterica serovar Typhimurium typing phages as the protein model systems. This interaction has been studied in detail in the Salmonella enterica serovar Typhimurium phage P22 system and involves only the viral tailspike protein. Similarity between these phages and phage P22 was monitored in this Report by assaying restriction endonuclease digestions, capsid size, reactivity to the P22 tailspike protein monoclonal antibody, mAb92, which reacts with the N-terminus of the P22 tail protein and the ability to produce a PCR fragment using primers made to the ends of the P22 tailspike gene. The data indicate that tailspike similarity exists between most of these phages and a scheme reclassifying them is presented and that the N-terminus of the P22 tailspike protein may be a motif for many phage systems and may serve as a aid in the taxonomy of phages. The data suggest a classification scheme in which the N-terminus of some tailspike proteins (head-binding region in some tail proteins) may play a critical element role in the classification of Salmonella viruses.

Plaque morphology and antigenic relationship of the Salmonella weltevreden typing phages.

The plaque morphology and antigenic relationship of the six typing phages of Salmonella weltevreden were studied. Under identical conditions of plating, the phages could be classified into three groups based on plaque morphology. Neutralization tests with anti-phage sera showed that typing phages phi I and phi II were antigenically similar. Phages phi III, phi IV and phi VI also showed antigenic similarity. Typing phage phi V was antigenically distinct from all other phages. Thus the phages could be classified into three groups on the basis of both plaque morphology on their respective indicator strains and velocities of neutralization by homologous/heterologous anti-sera.