Campylobacter jejuni group III phage CP81 contains many T4-like genes without belonging to the T4-type phage group: implications for the evolution of T4 phages

Application of Bacteriophages to Limit Campylobacter in Poultry Production

Campylobacter is a major foodborne pathogen with over a million United States cases a year and is typically acquired through the consumption of poultry products. The common occurrence of Campylobacter as a member of the poultry gastrointestinal tract microbial community remains a challenge for optimizing intervention strategies. Simultaneously, increasing demand for antibiotic-free products has led to the development of several alternative control measures both at the farm and in processing operations. Bacteriophages administered to reduce foodborne pathogens are one of the alternatives that have received renewed interest. Campylobacter phages have been isolated from both conventionally and organically raised poultry. Isolated and cultivated Campylobacter bacteriophages have been used as an intervention in live birds to target colonized Campylobacter in the gastrointestinal tract. Application of Campylobacter phages to poultry carcasses has also been explored as a strategy to reduce Campylobacter levels during poultry processing. This review will focus on the biology and ecology of Campylobacter bacteriophages in poultry production followed by discussion on current and potential applications as an intervention strategy to reduce Campylobacter occurrence in poultry production.

Isolation and Characterization of Group III Campylobacter jejuni-Specific Bacteriophages From Germany and Their Suitability for Use in Food Production

Campylobacter spp. are a major cause of bacterial foodborne diarrhea worldwide. While thermophilic Campylobacter species asymptomatically colonize the intestines of chickens, most human infections in industrial countries have been attributed to consumption of chicken meat or cross-contaminated products. Bacteriophages (phages) are natural predators of bacteria and their use at different stages of the food production chain has been shown to reduce the public health burden of human campylobacteriosis. However, regarding regulatory issues, the use of lytic phages in food is still under discussion and evaluation. This study aims to identify lytic phages suitable for reducing Campylobacter bacteria along the food production chain. Therefore, four of 19 recently recovered phages were further characterized in detail for their lytic efficacy against different Campylobacter field strains and their suitability under food production settings at different temperatures and pH values. Based on the results of this study, the phages vB_CjM-LmqsCP1-4 and vB_CjM-LmqsCP1-5 appear to be promising candidates for the reduction of Campylobacter jejuni in food production settings.

Two Distinct Modes of Lysis Regulation in Campylobacter Fletchervirus and Firehammervirus Phages

Campylobacter phages are divided into two genera; Fletchervirus and Firehammervirus, showing only limited intergenus homology. Here, we aim to identify the lytic genes of both genera using two representative phages (F352 and F379) from our collection. We performed a detailed in silico analysis searching for conserved protein domains and found that the predicted lytic genes are not organized into lysis cassettes but are conserved within each genus. To verify the function of selected lytic genes, the proteins were expressed in E. coli, followed by lytic assays. Our results show that Fletchervirus phages encode a typical signal peptide (SP) endolysin dependent on the Sec-pathway for translocation and a holin for activation. In contrast, Firehammervirus phages encode a novel endolysin that does not belong to currently described endolysin groups. This endolysin also uses the Sec-pathway for translocation but induces lysis of E. coli after overexpression. Interestingly, co-expression of this endolysin with an overlapping gene delayed and limited cell lysis, suggesting that this gene functions as a lysis inhibitor. These results indicate that Firehammervirus phages regulate lysis timing by a yet undescribed mechanism. In conclusion, we found that the two Campylobacter phage genera control lysis by two distinct mechanisms.

Application of Campylobacter jejuni Phages: Challenges and Perspectives

Bacteriophages (phages) are the most abundant and diverse biological entities in the biosphere. Due to the rise of multi-drug resistant bacterial strains during the past decade, phages are currently experiencing a renewed interest. Bacteriophages and their derivatives are being actively researched for their potential in the medical and biotechnology fields. Phage applications targeting pathogenic food-borne bacteria are currently being utilized for decontamination and therapy of live farm animals and as a biocontrol measure at the post-harvest level. For this indication, the United States Food and Drug Administration (FDA) has approved several phage products targeting Listeria sp., Salmonella sp. and Escherichia coli. Phage-based applications against Campylobacter jejuni could potentially be used in ways similar to those against Salmonella sp. and Listeria sp.; however, only very few Campylobacter phage products have been approved anywhere to date. The research on Campylobacter phages conducted thus far indicates that highly diverse subpopulations of C. jejuni as well as phage isolation and enrichment procedures influence the specificity and efficacy of Campylobacter phages. This review paper emphasizes conclusions from previous findings instrumental in facilitating isolation of Campylobacter phages and improving specificity and efficacy of the isolates.

Campylobacter Phage Isolation and Characterization: What We Have Learned So Far

Lytic Campylobacter phages, which can be used to combat this pathogen in animals and on food products, have been studied for more than 30 years. Though, due to some peculiarities of the phages, which hampered their isolation and particularly their molecular analysis for a long time, progress in this research field was rather slow. Meanwhile, the situation has changed and much more is known about the biology and genetics of those phages. In this article, we address specific issues that should be considered when Campylobacter phages are studied, starting with the isolation and propagation of the phages and ending with a thorough characterization including whole-genome sequencing. The basis for advice and recommendations given here is a careful review of the scientific literature and experiences that we have had ourselves with Campylobacter phages.

Comparative genomics of Cp8viruses with special reference to Campylobacter phage vB_CjeM_los1, isolated from a slaughterhouse in Ireland

Campylobacter phage vB_CjeM_Los1 was recently isolated from a slaughterhouse in the Republic of Ireland using the host Campylobacter jejuni subsp. jejuni PT14, and full-genome sequencing and annotation were performed. The genome was found to be 134,073 bp in length and to contain 169 predicted open reading frames. Transmission electron microscopy images of vB_CjeM_Los1 revealed that it belongs to the family Myoviridae, with tail fibres observed in both extended and folded conformations, as seen in T4. The genome size and morphology of vB_CjeM_Los1 suggest that it belongs to the genus Cp8virus, and seven other Campylobacter phages with similar size characteristics have also been fully sequenced. In this work, comparative studies were performed in relation to genomic rearrangements and conservation within each of the eight genomes. None of the eight genomes were found to have undergone internal rearrangements, and their sequences retained more than 98% identity with one another despite the widespread geographical distribution of each phage. Whole-genome phylogenetics were also performed, and clades were shown to be representative of the differing number of tRNAs present in each phage. This may be an indication of lineages within the genus, despite their striking homology.

A multiplex real-time PCR for the detection and differentiation of Campylobacter phages

Campylobacter jejuni and C. coli are important food-borne pathogens that are widespread in animal husbandry. To combat Campylobacter along the food chain, the application of lytic phages has been shown to be a promising tool. Campylobacter phages are currently classified into three groups, of which group II and group III phages are the most common. Members of each group are closely related, whereas the two groups share only little DNA similarity. Moreover, while group III phages are specific for C. jejuni, group II phages additionally infect C. coli. Phage cocktails intended to be used for applications should be composed of various phages that differ in their host range and growth kinetics. The isolation of phages is generally performed by plaque assays. This approach has the limitation that phages are merely identified by their lytic activity on certain indicator strains and that relatively high numbers of phages must be present in a tested sample. Therefore, a more sensitive molecular detection system would be beneficial, which allows a pre-screening of samples and the quick detection and discrimination of group II and group III phages. New phages can then be isolated by use of indicator strains that may be different from those typically applied. On the basis of available Campylobacter phage genome sequences, we developed a multiplex PCR system for group II and group III phages selecting the tail tube gene and the gene for the base plate wedge, respectively, as target. Phages of both groups could be identified with primers deduced from the putative tail fiber gene. Efficient release of phage DNA from capsids was achieved by an extended heat treatment or digestion of phage particles with proteinase K/SDS yielding a detection limit of 1 pfu/ml. Individual detection of group II phages, group III phages and of both groups was studied with artificially contaminated chicken skin. To recover phages that had strongly adhered to the skin, stomaching was the most efficient technique. The developed PCR protocol was employed to detect Campylobacter phages in food and environmental samples. In 50 out of 110 samples group II and/or group III phages were identified.

Prevalence, Host Range, and Comparative Genomic Analysis of Temperate Ochrobactrum Phages

Ochrobactrum and Brucella are closely related bacteria that populate different habitats and differ in their pathogenic properties. Only little is known about mobile genetic elements in these genera which might be important for survival and virulence. Previous studies on Brucella lysogeny indicated that active phages are rare in this genus. To gain insight into the presence and nature of prophages in Ochrobactrum, temperate phages were isolated from various species and characterized in detail. In silico analyses disclosed numerous prophages in published Ochrobactrum genomes. Induction experiments showed that Ochrobactrum prophages can be induced by various stress factors and that some strains released phage particles even under non-induced conditions. Sixty percent of lysates prepared from 125 strains revealed lytic activity. The host range and DNA similarities of 19 phages belonging to the families Myoviridae, Siphoviridae, or Podoviridae were determined suggesting that they are highly diverse. Some phages showed relationship to the temperate Brucella inopinata phage BiPB01. The genomic sequences of the myovirus POA1180 (41,655 bp) and podovirus POI1126 (60,065 bp) were analyzed. Phage POA1180 is very similar to a prophage recently identified in a Brucella strain isolated from an exotic frog. The POA1180 genome contains genes which may confer resistance to chromate and the ability to take up sulfate. Phage POI1126 is related to podoviruses of Sinorhizobium meliloti (PCB5), Erwinia pyrifoliae (Pep14), and Burkholderia cenocepacia (BcepIL02) and almost identical to an unnamed plasmid of the Ochrobactrum intermedium strain LMG 3301. Further experiments revealed that the POI1126 prophage indeed replicates as an extrachromosomal element. The data demonstrate for the first time that active prophages are common in Ochrobactrum and suggest that atypical brucellae also may be a reservoir for temperate phages.

Binding Specificities of the Telomere Phage ϕKO2 Prophage Repressor CB and Lytic Repressor Cro

Temperate bacteriophages possess a genetic switch which regulates the lytic and lysogenic cycle. The genomes of the temperate telomere phages N15, PY54, and ϕKO2 harbor a primary immunity region (immB) comprising genes for the prophage repressor (cI or cB), the lytic repressor (cro) and a putative antiterminator (q). The roles of these products are thought to be similar to those of the lambda proteins CI (CI prophage repressor), Cro (Cro repressor), and Q (antiterminator Q), respectively. Moreover, the gene order and the location of several operator sites in the prototype telomere phage N15 and in ϕKO2 are reminiscent of lambda-like phages. We determined binding sites of the ϕKO2 prophage repressor CB and lytic repressor Cro on the ϕKO2 genome in detail by electrophoretic mobility shift assay (EMSA) studies. Unexpectedly, ϕKO2 CB and Cro revealed different binding specificities. CB was bound to three O_R operators in the intergenic region between cB and cro, two O_L operators between cB and the replication gene repA and even to operators of N15. Cro bound exclusively to the 16 bp operator site O_R3 upstream of the ϕKO2 prophage repressor gene. The ϕKO2 genes cB and cro are regulated by several strong promoters overlapping with the O_R operators. The data suggest that Cro represses cB transcription but not its own synthesis, as already reported for PY54 Cro. Thus, not only PY54, but also phage ϕKO2 possesses a genetic switch that diverges significantly from the switch of lambda-like phages.

Analysis of the First Temperate Broad Host Range Brucellaphage (BiPBO1) Isolated from B. inopinata

Brucella species are important human and animal pathogens. Though, only little is known about mobile genetic elements of these highly pathogenic bacteria. To date, neither plasmids nor temperate phages have been described in brucellae. We analyzed genomic sequences of various reference and type strains and identified a number of putative prophages residing within the Brucella chromosomes. By induction, phage BiPBO1 was isolated from Brucella inopinata. BiPBO1 is a siphovirus that infects several Brucella species including Brucella abortus and Brucella melitensis. Integration of the phage genome occurs adjacent to a tRNA gene in chromosome 1 (chr 1). The bacterial (attB) and phage (attP) attachment sites comprise an identical sequence of 46 bp. This sequence exists in many Brucella and Ochrobactrum species. The BiPBO1 genome is composed of a 46,877 bp double-stranded DNA. Eighty-seven putative gene products were determined, of which 32 could be functionally assigned. Strongest similarities were found to a temperate phage residing in the chromosome of Ochrobactrum anthropi ATCC 49188 and to prophages identified in several families belonging to the order rhizobiales. The data suggest that horizontal gene transfer may occur between Brucella and Ochrobactrum and underpin the close relationship of these environmental and pathogenic bacteria.

A novel DNA-binding protein from Campylobacter jejuni bacteriophage NCTC12673

We previously suggested that the double-stranded genomic DNA of Campylobacter jejuni bacteriophage NCTC12673 was complexed with proteins. Mass spectrometry of peptides obtained from tryptic digests of purified phage DNA indicated that phage protein Gp001 co-purified with the DNA. Gp001 is an acidic protein that lacks any obvious homology or conserved domains found in known DNA-binding proteins. The DNA-binding ability of recombinant Gp001 was examined using an electrophoretic mobility shift assay. Slow DNA-Gp001 complex formation was observed at pH 5.5, but not at neutral or basic pH. This nucleoprotein complex had difficulty entering agarose gels used in the assay while proteinase K pretreatment released the DNA from the complex. No mobility shift was observed when the DNA was immediately subjected to electrophoresis after mixing with Gp001, even if both components were separately pre-incubated at pH 5.5. The complexed DNA was unable to transform chemically competent Escherichia coli cells and was less susceptible to degradation by nucleases. The formation of Gp001-DNA complexes at low pH may provide a mechanism for maintaining DNA integrity while the phage pursues its host through the gastrointestinal tract. Also, this feature can potentially be used to improve DNA delivery protocols applied in gene therapy.

Campylobacter group II phage CP21 is the prototype of a new subgroup revealing a distinct modular genome organization and host specificity

BACKGROUND

The application of phages is a promising tool to reduce the number of Campylobacter along the food chain. Besides the efficacy against a broad range of strains, phages have to be safe in terms of their genomes. Thus far, no genes with pathogenic potential (e.g., genes encoding virulence factors) have been detected in Campylobacter phages. However, preliminary studies suggested that the genomes of group II phages may be diverse and prone to genomic rearrangements.

RESULTS

We determined and analysed the genomic sequence (182,761 bp) of group II phage CP21 that is closely related to the already characterized group II phages CP220 and CPt10. The genomes of these phages are comprised of four modules separated by very similar repeat regions, some of which harbouring open reading frames (ORFs). Though, the arrangement of the modules and the location of some ORFs on the genomes are different in CP21 and in CP220/CPt10. In this work, a PCR system was established to study the modular genome organization of other group II phages demonstrating that they belong to different subgroups of the CP220-like virus genus, the prototypes of which are CP21 and CP220. The subgroups revealed different restriction patterns and, interestingly enough, also distinct host specificities, tail fiber proteins and tRNA genes. We additionally analysed the genome of group II phage vB_CcoM-IBB_35 (IBB_35) for which to date only five individual contigs could be determined. We show that the contigs represent modules linked by long repeat regions enclosing some yet not identified ORFs (e.g., for a head completion protein). The data suggest that IBB_35 is a member of the CP220 subgroup.

CONCLUSION

Campylobacter group II phages are diverse regarding their genome organization. Since all hitherto characterized group II phages contain numerous genes for transposases and homing endonucleases as well as similar repeat regions, it cannot be excluded that these phages are genetically unstable. To answer this question, further experiments and sequencing of more group II phages should be performed.

Primary isolation strain determines both phage type and receptors recognised by Campylobacter jejuni bacteriophages

In this study we isolated novel bacteriophages, infecting the zoonotic bacterium Campylobacter jejuni. These phages may be used in phage therapy of C. jejuni colonized poultry to prevent spreading of the bacteria to meat products causing disease in humans. Many C. jejuni phages have been isolated using NCTC12662 as the indicator strain, which may have biased the selection of phages. A large group of C. jejuni phages rely on the highly diverse capsular polysaccharide (CPS) for infection and recent work identified the O-methyl phosphoramidate modification (MeOPN) of CPS as a phage receptor. We therefore chose seven C. jejuni strains each expressing different CPS structures as indicator strains in a large screening for phages in samples collected from free-range poultry farms. Forty-three phages were isolated using C. jejuni NCTC12658, NCTC12662 and RM1221 as host strains and 20 distinct phages were identified based on host range analysis and genome restriction profiles. Most phages were isolated using C. jejuni strains NCTC12662 and RM1221 and interestingly phage genome size (140 kb vs. 190 kb), host range and morphological appearance correlated with the isolation strain. Thus, according to C. jejuni phage grouping, NCTC12662 and NCTC12658 selected for CP81-type phages, while RM1221 selected for CP220-type phages. Furthermore, using acapsular ∆kpsM mutants we demonstrated that phages isolated on NCTC12658 and NCTC12662 were dependent on the capsule for infection. In contrast, CP220-type phages isolated on RM1221 were unable to infect non-motile ∆motA mutants, hence requiring motility for successful infection. Hence, the primary phage isolation strain determines both phage type (CP81 or CP220) as well as receptors (CPS or flagella) recognised by the isolated phages.

Reduction of Campylobacter jejuni in broiler chicken by successive application of group II and group III phages

BACKGROUND

Bacteriophage treatment is a promising tool to reduce Campylobacter in chickens. Several studies have been published where group II or group III phages were successfully applied. However, these two groups of phages are different regarding their host ranges and host cell receptors. Therefore, a concerted activity of group II and group III phages might enhance the efficacy of a treatment and decrease the number of resistant bacteria.

RESULTS

In this study we have compared the lytic properties of some group II and group III phages and analysed the suitability of various phages for a reduction of C. jejuni in broiler chickens. We show that group II and group III phages exhibit different kinetics of infection. Two group III and one group II phage were selected for animal experiments and administered in different combinations to three groups of chickens, each containing ten birds. While group III phage CP14 alone reduced Campylobacter counts by more than 1 log10 unit, the concomitant administration of a second group III phage (CP81) did not yield any reduction, probably due to the development of resistance induced by this phage. One group of chickens received phage CP14 and, 24 hours later, group II phage CP68. In this group of animals, Campylobacter counts were reduced by more than 3 log10 units.

CONCLUSION

The experiments illustrated that Campylobacter phage cocktails have to be carefully composed to achieve the best results.

A receptor-binding protein of Campylobacter jejuni bacteriophage NCTC 12673 recognizes flagellin glycosylated with acetamidino-modified pseudaminic acid

Bacteriophage receptor-binding proteins (RBPs) confer host specificity. We previously identified a putative RBP (Gp047) from the campylobacter lytic phage NCTC 12673 and demonstrated that Gp047 has a broader host range than its parent phage. While NCTC 12673 recognizes the capsular polysaccharide (CPS) of a limited number of Campylobacter jejuni isolates, Gp047 binds to a majority of C. jejuni and related Campylobacter coli strains. In this study, we demonstrate that Gp047 also binds to acapsular mutants, suggesting that unlike the parent phage, CPS is not the receptor for Gp047. Affinity chromatography and far-western analyses of C. jejuni lysates using Gp047 followed by mass spectrometry indicated that Gp047 binds to the major flagellin protein, FlaA. Because C. jejuni flagellin is extensively glycosylated, we investigated this binding specificity further and demonstrate that Gp047 only recognizes flagellin decorated with acetamidino-modified pseudaminic acid. This binding activity is localized to the C-terminal quarter of the protein and both wild-type and coccoid forms of C. jejuni are recognized. In addition, Gp047 treatment agglutinates vegetative cells and reduces their motility. Because Gp047 is highly conserved among all campylobacter phages sequenced to date, it is likely that this protein plays an important role in the phage life cycle.

Alternative bacteriophage life cycles: the carrier state of Campylobacter jejuni

Members of the genus Campylobacter are frequently responsible for human enteric disease, often through consumption of contaminated poultry products. Bacteriophages are viruses that have the potential to control pathogenic bacteria, but understanding their complex life cycles is key to their successful exploitation. Treatment of Campylobacter jejuni biofilms with bacteriophages led to the discovery that phages had established a relationship with their hosts typical of the carrier state life cycle (CSLC), where bacteria and bacteriophages remain associated in equilibrium. Significant phenotypic changes include improved aerotolerance under nutrient-limited conditions that would confer an advantage to survive in extra-intestinal environments, but a lack in motility eliminated their ability to colonize chickens. Under these circumstances, phages can remain associated with a compatible host and continue to produce free virions to prospect for new hosts. Moreover, we demonstrate that CSLC host bacteria can act as expendable vehicles for the delivery of bacteriophages to new host bacteria within pre-colonized chickens. The CSLC represents an important phase in the ecology of Campylobacter bacteriophage.

Bacteriophage receptor binding protein based assays for the simultaneous detection of Campylobacter jejuni and Campylobacter coli

Campylobacter jejuni and Campylobacter coli are the most common bacterial causes of foodborne gastroenteritis which is occasionally followed by a debilitating neuropathy known as Guillain-Barré syndrome. Rapid and specific detection of these pathogens is very important for effective control and quick treatment of infection. Most of the diagnostics available for these organisms are time consuming and require technical expertise with expensive instruments and reagents to perform. Bacteriophages bind to their host specifically through their receptor binding proteins (RBPs), which can be exploited for pathogen detection. We recently sequenced the genome of C. jejuni phage NCTC12673 and identified its putative host receptor binding protein, Gp047. In the current study, we localized the receptor binding domain to the C-terminal quarter of Gp047. CC-Gp047 could be produced recombinantly and was capable of agglutinating both C. jejuni and C. coli cells unlike the host range of the parent phage which is limited to a subset of C. jejuni isolates. The agglutination procedure could be performed within minutes on a glass slide at room temperature and was not hindered by the presence of buffers or nutrient media. This agglutination assay showed 100% specificity and the sensitivity was 95% for C. jejuni (n = 40) and 90% for C. coli (n = 19). CC-Gp047 was also expressed as a fusion with enhanced green fluorescent protein (EGFP). Chimeric EGFP_CC-Gp047 was able to specifically label C. jejuni and C. coli cells in mixed cultures allowing for the detection of these pathogens by fluorescent microscopy. This study describes a simple and rapid method for the detection of C. jejuni and C. coli using engineered phage RBPs and offers a promising new diagnostics platform for healthcare and surveillance laboratories.

Bacteriophage receptor binding protein based assays for the simultaneous detection of Campylobacter jejuni and Campylobacter coli

Campylobacter jejuni and Campylobacter coli are the most common bacterial causes of foodborne gastroenteritis which is occasionally followed by a debilitating neuropathy known as Guillain-Barré syndrome. Rapid and specific detection of these pathogens is very important for effective control and quick treatment of infection. Most of the diagnostics available for these organisms are time consuming and require technical expertise with expensive instruments and reagents to perform. Bacteriophages bind to their host specifically through their receptor binding proteins (RBPs), which can be exploited for pathogen detection. We recently sequenced the genome of C. jejuni phage NCTC12673 and identified its putative host receptor binding protein, Gp047. In the current study, we localized the receptor binding domain to the C-terminal quarter of Gp047. CC-Gp047 could be produced recombinantly and was capable of agglutinating both C. jejuni and C. coli cells unlike the host range of the parent phage which is limited to a subset of C. jejuni isolates. The agglutination procedure could be performed within minutes on a glass slide at room temperature and was not hindered by the presence of buffers or nutrient media. This agglutination assay showed 100% specificity and the sensitivity was 95% for C. jejuni (n = 40) and 90% for C. coli (n = 19). CC-Gp047 was also expressed as a fusion with enhanced green fluorescent protein (EGFP). Chimeric EGFP_CC-Gp047 was able to specifically label C. jejuni and C. coli cells in mixed cultures allowing for the detection of these pathogens by fluorescent microscopy. This study describes a simple and rapid method for the detection of C. jejuni and C. coli using engineered phage RBPs and offers a promising new diagnostics platform for healthcare and surveillance laboratories.

Use of phages to control Campylobacter spp

The use of phages to control pathogenic bacteria has been investigated since they were first discovered in the beginning of the 1900s. Over the last century we have slowly gained an in-depth understanding of phage biology including which phage properties are desirable when considering phage as biocontrol agents and which phage characteristics to potentially avoid. Campylobacter infections are amongst the most frequently encountered foodborne bacterial infections around the world. Handling and consumption of raw or undercooked poultry products have been determined to be the main route of transmission. The ability to use phages to target these bacteria has been studied for more than a decade and although we have made progress towards deciphering how best to use phages to control Campylobacter associated with poultry production, there is still much work to be done. This review outlines methods to improve the isolation of these elusive phages, as well as methods to identify desirable characteristics needed for a successful outcome. It also highlights the body of research undertaken so far and what criteria to consider when doing in-vivo studies, especially because some in-vitro studies have not been found to translate into to phage efficacy in-vivo.

The complete genome sequence of bacteriophage CP21 reveals modular shuffling in Campylobacter group II phages

Campylobacter group II phages described so far share a high degree of sequence similarity. We report the 182,833-bp genomic sequence of the closely related group II phage CP21 and show that it has a completely different genomic organization. As in other group II phages, the CP21 genome is composed of large modules separated by long DNA repeat regions which obviously trigger recombination and modular shuffling.

Control of Campylobacter spp. and Yersinia enterocolitica by virulent bacteriophages

The efficacy of the Campylobacter (C.) phages NCTC12684 (group II) and CP81 (group III) and of the Yersinia (Y.) phage PY100 to reduce the numbers of Campylobacter and Y. enterocolitica in meat at 4^oC applying different Multiplicities of Infection (MOIs) was analyzed. Initial experiments were carried out in broth at 4^oC and 37^oC to compare cell number reductions under chilling and optimized growth conditions, respectively. The results showed a 1 log₁₀ unit reduction of Campylobacter cell numbers at 37^oC in broth. However, no reduction was observed in broth and meat at 4^oC. In contrast, Y. enterocolitica cell numbers were reduced in broth at 4^oC (up to 3 log₁₀ units after 24hr) and 37^oC (5 log₁₀ units after 1.5hr) and also in meat at 4^oC (2 log₁₀ units after 48hr). The highest cell number reductions were obtained at the highest MOIs.

Quo vadis? - Monitoring Campylobacter in Germany

Campylobacter is a poorly recognized foodborne pathogen, leading the statistics of bacterially caused human diarrhoea in Europe during the last years. In this review, we present qualitative and quantitative German data obtained in the framework of specific monitoring programs and from routine surveillance. These also comprise recent data on antimicrobial resistances of food isolates. Due to the considerable reduction of in vitro growth capabilities of stressed bacteria, there is a clear discrepancy between the detection limit of Campylobacter by cultivation and its infection potential. Moreover, antimicrobial resistances of Campylobacter isolates established during fattening of livestock are alarming, since they constitute an additional threat to human health. The European Food Safety Authority (EFSA) discusses the establishment of a quantitative limit for Campylobacter contamination of broiler carcasses in order to achieve an appropriate level of protection for consumers. Currently, a considerable amount of German broiler carcasses would not comply with this future criterion. We recommend Campylobacter reduction strategies to be focussed on the prevention of fecal contamination during slaughter. Decontamination is only a sparse option, since the reduction efficiency is low and its success depends on the initial contamination concentration.

A novel cyanophage with a cyanobacterial nonbleaching protein A gene in the genome

A cyanophage, PaV-LD, has been isolated from harmful filamentous cyanobacterium Planktothrix agardhii in Lake Donghu, a shallow freshwater lake in China. Here, we present the cyanophage's genomic organization and major structural proteins. The genome is a 95,299-bp-long, linear double-stranded DNA and contains 142 potential genes. BLAST searches revealed 29 proteins of known function in cyanophages, cyanobacteria, or bacteria. Thirteen major structural proteins ranging in size from 27 kDa to 172 kDa were identified by SDS-PAGE and mass-spectrometric analysis. The genome lacks major genes that are necessary to the tail structure, and the tailless PaV-LD has been confirmed by an electron microscopy comparison with other tail cyanophages and phages. Phylogenetic analysis of the major capsid proteins also reveals an independent branch of PaV-LD that is quite different from other known tail cyanophages and phages. Moreover, the unique genome carries a nonbleaching protein A (NblA) gene (open reading frame [ORF] 022L), which is present in all phycobilisome-containing organisms and mediates phycobilisome degradation. Western blot detection confirmed that 022L was expressed after PaV-LD infection in the host filamentous cyanobacterium. In addition, its appearance was companied by a significant decline of phycocyanobilin content and a color change of the cyanobacterial cells from blue-green to yellow-green. The biological function of PaV-LD nblA was further confirmed by expression in a model cyanobacterium via an integration platform, by spectroscopic analysis and electron microscopy observation. The data indicate that PaV-LD is an exceptional cyanophage of filamentous cyanobacteria, and this novel cyanophage will also provide us with a new vision of the cyanophage-host interactions.