Specific detection of Salmonella enterica and Escherichia coli strains by using ELISA with bacteriophages as recognition agents.

The use of bacteriophages, instead of antibodies, in the ELISA-based detection of bacterial strains was tested. This procedure appeared to be efficient, and specific strains of Salmonella enterica and Escherichia coli could be detected. The sensitivity of the assay was about 10(5) bacterial cells/well (10(6)/ml), which is comparable with or outperforms other ELISA tests detecting intact bacterial cells without an enrichment step. The specificity of the assay depends on the kind of bacteriophage used. We conclude that the use of bacteriophages in the detection and identification of bacteria by an ELISA-based method can be an alternative to the use of specific antibodies. The advantages of the use of bacteriophages are their environmental abundance (and, thus, a possibility to isolate various phages with different specificities) and the availability of methods for obtaining large amounts of phage lysates, which are simple, rapid, cheap, and easy.

Role of the bacteriophage lambda exo-xis region in the virus development.

Various processes of bacteriophage lambda development in Escherichia coli cells bearing either the whole lambda exo-xis region (with truncated, thus nonfunctional, exo and xis genes) or particular genes from this region were investigated. The presence of either the exo-xis region or the ea8.5 gene on a plasmid resulted in formation of fuzzy plaques by infecting phage. Both efficiency of plating and efficiency of lysogenization were decreased in such hosts. On the other hand, neither the efficiency of adsorption nor intracellular lytic development of the infecting phage (measured in one-step-growth experiments) was affected while significantly more host cells survived the infection, when containing the exo-xis region. Although no effects of the exo-xis region on the activity of the p (L) promoter was detected, this region contributed to a decreased transcription from the cII-stimulated promoters p (I), p (aQ) and p (E). These results, together with the results of measurement of efficiency of plating of phages bearing mutations in cI, cII and cIII genes on hosts containing the exo-xis region, strongly suggest that genes from this region (especially ea8.5) are involved in the regulation of bacteriophage lambda development at the stage of the lysis-vs.-lysogenization decision.

Rapid detection of viruses using electrical biochips and anti-virion sera.

AIMS: Rapid detection and quantification of viruses is crucial in clinical practice, veterinary medicine, agriculture, basic research as well as in biotechnological factories. However, although various techniques were described and are currently used, development of more rapid, more sensitive and quantitative methods seems to be still important. METHODS AND RESULTS: Here we describe a method for rapid detection of viruses (using bacteriophages as model viruses), based on electrical biochip array technology with the use of antibodies against capsid proteins. CONCLUSIONS: Using the procedure developed in this work, we were able to detect 2 x 10(4) virions on the chip. The whole assay procedure takes c. 50 min and the assay is quantitative. SIGNIFICANCE AND IMPACT OF THE STUDY: This procedure may be useful in various approaches, including detection of bacteriophage contamination in bioreactors and possibly detection of toxin gene-bearing phages or other viruses in food samples.