The exo–xis region, present in genomes of lambdoid bacteriophages, contains highly conserved genes of largely unknown functions. In this report, using bacteriophage λ and Shiga toxin-converting bacteriophage ϕ24Β, we demonstrate that the presence of this region on a multicopy plasmid results in impaired lysogenization of Escherichia coli and delayed, while more effective, induction of prophages following stimulation by various agents (mitomycin C, hydrogen peroxide, UV irradiation). Spontaneous induction of λ and ϕ24Β prophages was also more efficient in bacteria carrying additional copies of the corresponding exo–xis region on plasmids. No significant effects of an increased copy number of genes located between exo and xis on both efficiency of adsorption on the host cells and lytic development inside the host cell of these bacteriophages were found. We conclude that genes from the exo–xis region of lambdoid bacteriophages participate in the regulation of lysogenization and prophage maintenance.

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Mixed infections of a single host with different variants of influenza

Gram-positive and nonpathogenic lactic acid bacteria (LAB) are considered to be promising candidates for the development of new, safe systems of heterologous protein expression. Recombinant LAB has been shown to induce specific local and systemic immune response against selected pathogens, and could be a good alternative to classical attenuated carriers. The main goal of our study was to express the avian influenza haemagglutinin (H5) and chicken interleukin 2 (chIL-2) in Lactococcus lactis. Results of this study were anticipated to lead to construction of lactococcal strain(s) with potential vaccine properties against the avian influenza A (H5N1) virus. Expression of the cloned H5 gene, its His-tagged variant and chIL-2 gene, under the control of the ptcB gene promoter was attested by RT-PCR on transcriptional level and Western or dot blot analysis on translational level, demonstrating that system can be an attractive solution for production of heterologous proteins. The results of the preliminary animal trial conducted in mice are a promising step toward development of a vaccine against avian bird flu using Lactococcus lactis cells as antigen carriers.

Pandemic influenza A(H1N1)pdm09 virus is a global health threat and between 2009-2011 it became the predominant influenza virus subtype circulating in the world. The research describes the MSSCP (Multitemperature Single Strand Conformation Polymorphism) analysis of the hemagglutinin (HA) region encompassing major neutralizing epitope in pandemic influenza isolates from Taiwan. Several genetically distinct changes appeared in isolates obtained in 2010 and 2011. The majority of changes in HA protein did not result in significant modifications, however three modifications were localized in epitope E of H1 and one was part of the interface binding antibodies BH151 and HC45 possibly making the current vaccine less effective.-Taking into account the possibility of the emergence of influenza A with antibody evading potential, the MSSCP method provides an alternative approach for detection of minor variants which escape detection by conventional Sanger sequencing.