Infection ofStreptococcus oralisNCTC 11427 by pneumococcal phages

To the question of the relevance of the development and prospects for the use of the bacteriophage <i>Streptococcus pneumoniae</i>

Introduction. The prevalence of Streptococcus pneumoniae strains causing invasive forms of pneumococcal infection and the growing rates of antibiotic resistance of individual serotypes of the pathogen pose a number of urgent and socially significant tasks the search for new antimicrobial agents for prevention and treatment. Objective. To analyze the data of scientific publications of domestic and foreign authors on the problems of practical use and prospects for the development of the bacteriophage S. pneumoniae drug aimed at the actual serotypes of the pathogen. Results. Analysis of literary sources in scientific electronic databases and publishing houses eLibrary.Ru, ScienceDirect, Scopus, PubMed, Springerlink, Wiley Online Library, Annual reviews allowed us to summarize information about four isolated lytic bacteriophages of S. pneumoniae and their endolysins, as well as about two lysogenic phages, to present data on the clinical efficacy of streptococcal bacteriophage in pneumococcal infection in animals and humans. The results of search queries on the most significant and widespread serotypes of S. pneumoniae in the territory of the Russian Federation have established the predominance in the structure of variants 19F, 14, 9V/A, 15 A/F, 6 A/B/C/D, 3 and 23F. Some of them are characterized by a high level of antibiotic resistance and cause invasive forms of the disease, and serotypes 15 A/F/C, 6 C/D are not represented in modern vaccines, which increases the relevance of the development and use of pneumococcal bacteriophage, including intraspecific typing of significant and common serotypes. Conclusion. Based on the analysis of the current state of the issue of pneumococcal bacteriophages, the information obtained on the circulation of topical strains of S. pneumoniae on the territory of the Russian Federation and their serotype landscape, it is concluded that the development of the bacteriophage S. pneumoniae drug is relevant as a means of targeted action for the prevention, diagnosis and personalized therapy of human diseases of pneumococcal etiology.

Genomics and Genetics of Streptococcus pneumoniae

Ninety years after the discovery of pneumococcal Transformation, and 74 years after the work of Avery and colleagues that identified DNA as the genetic material, Streptococcus pneumoniae is still one of the most important model organism to understand Bacterial Genetics and Genomics. In this Chapter special emphasis has been given to Genomics and to Mobile Genetic Elements (the Mobilome) which greatly contribute to the dynamic variation of pneumococcal genomes by horizontal gene transfer. Other topics include molecular mechanisms of Genetic Transformation, Restriction/Modification Systems, Mismatch DNA Repair, and techniques for construction of genetically engineered pneumococcal strains.

The use of bacteriophages to biocontrol oral biofilms

Infections induced by oral biofilms include caries, as well as periodontal, and peri-implant disease, and may influence quality of life, systemic health, and expenditure. As bacterial biofilms are highly resistant and resilient to conventional antibacterial therapy, it has been difficult to combat these infections. An innovative alternative to the biocontrol of oral biofilms could be to use bacteriophages or phages, the viruses of bacteria, which are specific, non-toxic, self-proliferating, and can penetrate into biofilms. Phages for Actinomyces naeslundii, Aggregatibacter actinomycetemcomitans, Enterococcus faecalis, Fusobacterium nucleatum, Lactobacillus spp., Neisseria spp., Streptococcus spp., and Veillonella spp. have been isolated and characterised. Recombinant phage enzymes (lysins) have been shown to lyse A. naeslundii and Streptococcus spp. However, only a tiny fraction of available phages and their lysins have been explored so far. The unique properties of phages and their lysins make them promising but challenging antimicrobials. The genetics and biology of phages have to be further explored in order to determine the most effective way of applying them. Studying the effect of phages and lysins on multispecies biofilms should pave the way for microbiota engineering and microbiota-based therapy.

Diverse virulent pneumophages infect Streptococcus mitis

Streptococcus mitis has emerged as one of the leading causes of bacterial endocarditis and is related to Streptococcus pneumoniae. Antibiotic resistance has also increased among strains of S. mitis and S. pneumoniae. Phages are being reinvestigated as alternatives to antibiotics for managing infections. In this study, the two virulent phages Cp-1 (Podoviridae) and Dp-1 (Siphoviridae), previously isolated from S. pneumoniae, were found to also infect S. mitis. Microbiological assays showed that both pneumophages could not only replicate in S. mitis but also produced more visible plaques on this host. However, the burst size and phage adsorption data were lower in S. mitis as compared to S. pneumoniae. A comparison of the genomes of each phage grown on both hosts produced identical nucleotide sequences, confirming that the same phages infect both bacterial species. We also discovered that the genomic sequence of podophage Cp-1 of the Félix d'Hérelle collection is different than the previously reported sequence and thus renamed SOCP.

The proteome and interactome of Streptococcus pneumoniae phage Cp-1

Mass spectrometry analysis of Streptococcus pneumoniae bacteriophage Cp-1 identified a total of 12 proteins, and proteome-wide yeast two-hybrid screens revealed 17 binary interactions mainly among these structural proteins. On the basis of the resulting linkage map, we suggest an improved structural model of the Cp-1 virion.

Genome sequence of the temperate bacteriophage PH10 from Streptococcus oralis

Exponential growing cultures of Streptococcus oralis strain OMZ 1038, isolated from human supragingival dental plaque, were found to release a bacteriophage (designated PH10) upon treatment with mitomycin C. The complete genome sequence of phage PH10 was determined. The genome was 31276 bp in size and contained 54 open reading frames. The module encoding structural proteins was highly similar to that of Streptococcus pneumoniae prophage PhiSpn_3. The most abundant phage structural protein was encoded by ORF35 and was likely processed by proteolytic cleavage. The putative endolysin from PH10, which contained a muramidase domain and a choline-binding domain, was purified and shown to have lytic activity with S. oralis, S. pneumoniae and Streptococcus mitis, but not with other streptococcal species.

Postinoculation protozoan establishment and association patterns of methanogenic archaea in the ovine rumen

Association patterns between archaea and rumen protozoa were evaluated by analyzing archaeal 16S rRNA gene clone libraries from ovine rumen inoculated with different protozoa. Five protozoan inoculation treatments, fauna free (negative control), holotrich and cellulolytic protozoa, Isotricha and Dasytricha spp., Entodinium spp., and total fauna (type A) were tested. We used denaturing gradient gel electrophoresis, quantitative PCR, and phylogenetic analysis to evaluate the impact of the protozoan inoculants on the respective archaeal communities. Protozoan 18S ribosomal DNA clone libraries were also evaluated to monitor the protozoal population that was established by the inoculation. Phylogenetic analysis suggested that archaeal clones associated with the fauna-free, the Entodinium, and the type A inoculations clustered primarily with uncultured phylotypes. Polyplastron multivesiculatum was the predominant protozoan strain established by the holotrich and cellulolytic protozoan treatment, and this resulted predominantly in archaeal clones affiliated with uncultured and cultured methanogenic phylotypes (Methanosphaera stadtmanae, Methanobrevibacter ruminantium, and Methanobacterium bryantii). Furthermore, the Isotricha and Dasytricha inoculation treatment resulted primarily in archaeal clones affiliated with Methanobrevibacter smithii. This report provides the first assessment of the influence of protozoa on archaea within the rumen microbial community and provides evidence to suggest that different archaeal phylotypes associate with specific groups of protozoa. The observed patterns may be linked to the evolution of commensal and symbiotic relationships between archaea and protozoa in the ovine rumen environment. This report further underscores the prevalence and potential importance of a rather large group of uncultivated archaea in the ovine rumen, probably unrelated to known methanogens and undocumented in the bovine rumen.

Recent trends on the molecular biology of pneumococcal capsules, lytic enzymes, and bacteriophage

Streptococcus pneumoniae has re-emerged as a major cause of morbidity and mortality throughout the world and its continuous increase in antimicrobial resistance is rapidly becoming a leading cause of concern for public health. This review is focussed on the analysis of recent insights on the study of capsular polysaccharide biosynthesis, and cell wall (murein) hydrolases, two fundamental pneumococcal virulence factors. Besides, we have also re-evaluated the molecular biology of the pneumococcal phage, their possible role in pathogenicity and in the shaping of natural populations of S. pneumoniae. Precise knowledge of the topics reviewed here should facilitate the rationale to move towards the design of alternative ways to combat pneumococcal disease.

Proteins PblA and PblB of Streptococcus mitis, which promote binding to human platelets, are encoded within a lysogenic bacteriophage

The binding of platelets by bacteria is a proposed central mechanism in the pathogenesis of infective endocarditis. Platelet binding by Streptococcus mitis strain SF100 (an endocarditis isolate) was recently shown to be mediated in part by the surface proteins PblA and PblB. The genes encoding PblA and PblB are clustered with genes nearly identical to those of streptococcal phages r1t, 01205, and Dp-1, suggesting that pblA and pblB might reside within a prophage. To address this possibility, cultures of SF100 were exposed to either mitomycin C or UV light, both of which are known to induce the lytic cycle of many temperate phages. Both treatments caused a significant increase in the transcription of pblA. Treatment with mitomycin C or UV light also caused a substantial increase in the expression of PblA and PblB, as detected by Western blot analysis of proteins in the SF100 cell wall. By electron microscopy, phage particles were readily visible in the supernatants from induced cultures of SF100. The phage, designated SM1, had a double-stranded DNA genome of approximately 35 kb. Southern blot analysis of phage DNA indicated that pblA and pblB were contained within the SM1 genome. Furthermore, Western blot analysis of phage proteins revealed that both PblA and PblB were present in the phage particles. These findings indicate that PblA and PblB are encoded by a lysogenic bacteriophage, which could facilitate the dissemination of these potential virulence determinants to other bacterial pathogens.

Bacteriophages of Streptococcus pneumoniae: a molecular approach

We have characterized four families of pneumococcal phages with remarkable morphologic and physiological differences. Dp-1 and Cp-1 are lytic phages, whereas HB-3 and EJ-1 are temperate phages. Interestingly, Cp-1 and HB-3 have a terminal protein covalently linked to the 5' ends of their lineal DNAs. In the case of Dp-1, we have found that the choline residues of the teichoic acid were essential components of the phage receptors. We have also developed a transfection system using mature DNAs from Dp-4 and Cp-1. In the later case, the transfecting activity of the DNA was destroyed by treatment with proteolytic enzymes, a feature also shared by the genomes of several small Bacillus phages. DNA replication was investigated in the case of Dp-4 and Cp-1 phages. The terminal protein linked to Cp-1 DNA plays a key role in the peculiar mechanism of DNA replication that has been coined as protein-priming. Recently, the linear 19,345-bp double-stranded DNA of Cp-1 has been completely sequenced, several of its gene products have been analyzed, and a complete transcriptional map has been ellaborated. Most of the pneumococcal lysins exhibit an absolute dependence of the presence of choline in the cell wall substrate for activity, and phage lysis requires, as reported for other systems, the action of a second phage-encoded protein, the holin, which presumably forms some kind of lesion in the membrane. The two lytic gene cassettes, from EJ-1 and Cp-1 phages, have been cloned and expressed in heterologous and homologous systems. The finding that some lysogenic strains of Streptococcus pneumoniae harbor phage remnants has provided important clues on the interchanges between phage and bacteria and supports the view of the chimeric origin of phages.

EJ-1, a temperate bacteriophage of Streptococcus pneumoniae with a Myoviridae morphotype

The first temperate bacteriophage (EJ-1) of Streptococcus pneumoniae with Myoviridae morphotype A1 isolated from a clinical atypical strain has been purified and characterized. This phage has a double-stranded linear genome about 42 kb long, but in contrast to the other pneumococcal temperate phages that have been characterized so far, EJ-1 does not contain any protein covalently linked to it. We have sequenced a fragment of EJ-1 DNA containing the ejl gene, encoding a cell wall lytic enzyme (EJL amidase). This gene has been cloned and expressed in Escherichia coli, and the EJL enzyme was purified and biochemically characterized as an N-acetylmuramyl-L-alanine amidase that shares many similarities with the major pneumococcal autolysin. The EJL amidase is a choline-dependent enzyme that needs the process of conversion to achieve full enzymatic activity, but in contrast to the wild-type pneumococcal LYTA amidase, this process was found to be reversible. Comparisons of the primary structure of this new lytic enzyme with that of the other cell wall lytic enzymes of S. pneumoniae and its bacteriophages characterized so far provided new insights as to the evolutionary relationships between phages and bacteria. The nucleotide sequences of the attachment site (attP) on the phage genome and one of the junctions created by the insertion of the prophage were determined. Interestingly, the attP site was located near the ejl gene, as previously observed for the pneumococcal temperate bacteriophage HB-3 (A. Romero, R. López, and P. García, J. Virol. 66:2860-2864, 1992). A stem-and-loop structure, some adjacent direct and inverted repeats, and two putative integration host factor-binding sites were found in the att sites.