Listeria monocytogenes prevalence and genomic diversity along the pig and pork production chain.

The facultative intracellular bacterium Listeria monocytogenes (L. monocytogenes) is the causative agent of listeriosis, a severe invasive illness. This ubiquitous species is widely distributed in the environment, but infection occurs almost exclusively through ingestion of contaminated food. The pork production sector has been heavily affected by a series of L. monocytogenes-related foodborne outbreaks in the past around the world. Ready-to-eat (RTE) pork products represent one of the main food sources for strong-evidence listeriosis outbreaks. This pathogen is known to be present throughout the entire pig and pork production chain. Some studies hypothesized that the main source of contamination in final pork products was either living pigs or the food-processing environment. A detailed genomic picture of L. monocytogenes can provide a renewed understanding of the routes of contamination from pig farms to the final products. This review provides an overview of the prevalence, the genomic diversity and the genetic background linked to virulence of L. monocytogenes along the entire pig and pork production chain, from farm to fork.

Controlled Experimental Infection in Pigs with a Strain of Yersinia enterocolitica Harboring Genetic Markers for Human Pathogenicity: Colonization and Stability.

Yersinia enterocolitica (Ye) is one of the major causes of foodborne zoonosis. The BT4/O:3 bioserotype is most commonly isolated in human infections. Pigs are considered the main reservoir of Ye, and hence, understanding the dynamics of infection by this pathogen at the individual and group levels is crucial. In the present study, an experimental model was validated in Large White pigs infected with a BT4/O:3 strain. This study showed that Ye contamination in pigs may occur via the introduction of the bacteria not only by mouth but also by snout, with a colonization process consisting of three periods corresponding to three contamination statuses of pigs: P1, corresponding to the 24 h following ingestion or inhalation of Ye with the appearance of bacteria in tonsils or in feces; P2, from 2 days postinoculation (dpi), corresponding to expansion of Ye and colonization of the digestive system and extraintestinal organs associated with an IgG serological response; and P3, after 21 dpi, corresponding to regression of colonization with intermittent Ye detection in tonsils and feces. Although the inoculated strain persisted up to 56 dpi in all pigs, genetic variations with the loss of the gene yadA (a gene involved in human infection) and the emergence of two new multilocus variable-number tandem-repeat analysis (MLVA) profiles were observed in 33% of the 30 isolates studied. This experimental infection model of pigs by Ye provides new insights into the colonization steps in pigs in terms of bacterial distribution over time and bacterial genetic stability.

Characterization of Clostridioides difficile strains isolated from manure and digestate in five agricultural biogas plants.

Clostridioides difficile strains were isolated from manure and digestate samples from five biogas plants in France. The objective of this study was to characterize these isolates using PCR ribotyping, wgMLST, a multiplex PCR targeting genes encoding for the main virulence factors, i.e. tcdA, tcdB, cdtA and cdtB, and antimicrobial susceptibility assays. The 54 strains characterized were all positive for tcdA and tcdB and 83% (45/54) were positive for the binary toxin genes. PCR ribotypes 126 (59%) and 078 (37%) were predominant, and wgMLST analysis of 18 isolates showed close proximity of strains within a single biogas plant. Samples from the biogas plant supplied with cattle and poultry manure displayed the largest variety in PCR ribotypes. The in vitro activities of nine antimicrobial agents were determined. All the strains were susceptible to vancomycin and metronidazole, which are currently considered first-line treatments for C. difficile infection in humans. All the strains were resistant to clindamycin. The results of this study show that a high percentage of C. difficile strains present in the French biogas plants investigated are toxigenic strains from PCR ribotypes also commonly found in humans.

Colonization of Pigs Experimentally Infected with a Monophasic Variant of Salmonella Typhimurium.

The monophasic variant of Salmonella Typhimurium is highly prevalent in human and in pork. However, little is known about colonization dynamics and serology in pigs. We orally inoculated 24 seven-week-old piglets with 109 CFU/pig of a porcine strain of monophasic Salmonella Typhimurium in an experimental trial. Three groups of eight piglets were orally inoculated and monitored for 21, 49, or 84 days post-inoculation until necropsied. From 3 days post-inoculation to necropsy, individual feces were sampled twice weekly and blood once weekly. At necropsy, the tonsils, mesenteric lymph nodes, and the contents of the duodenum, jejunum, ileum, and cecum were collected from each pig. We determined the number of CFU/g in all the samples and measured also Salmonella antibodies in OD% in all blood samples. At different times during the trial, we tested by MLVA (Multilocus Variable Number Tandem Repeat Analysis) the genomic stability of the strain after passing through the intestinal tract. Salmonella was continuously excreted by pigs, ranging from 1.4 to 5.8 log10 CFU/g. At necropsy, Salmonella was present in all samples, but the tonsils were particularly infected. Salmonella antibodies were detected in five pigs 7 days post-inoculation. At 49 days post-inoculation, all the pigs were seropositive. We observed new MLVA types for 3.3% of the isolates tested over the trial. Our study allowed us to show the serovar's ability to persist in pigs after infection up to 84 days post-inoculation. We demonstrated that Salmonella seroconversion appeared earlier than in naturally infected pigs and that the strain's genome can evolve after passing through the digestive tract of pigs.

Genetic diversity and antimicrobial resistance profiles of Salmonella enterica serotype derby isolated from pigs, pork, and humans in France.

In France, Salmonella enterica serotypes Typhimurium and Derby are the most often isolated serotypes in pigs. Moreover, serotype Derby usually ranks between third and fourth in prevalence among human isolates in France. The aim of this study was to evaluate the genetic relationships between human and pig Salmonella Derby isolates based on their pulsed-field gel electrophoresis (PFGE) patterns after XbaI, BlnI, and SpeI restriction and on their antimicrobial resistance profiles. The 196 studied isolates were isolated in 2006 and 2007: 73 from fattening pigs, 27 from pork, and 96 from humans. Forty-four PFGE XbaI patterns were identified. A major pattern (SDX01) was identified for 96 isolates (49%). This pattern was common to pig, pork, and human isolates. Among the 146 isolates tested for their antimicrobial resistance, 84.2% (n=123) showed resistance to at least one antibiotic and 69.2% (n=101) were simultaneously resistant to at least streptomycin, sulfonamides, and tetracycline. Most of the isolates that are resistant to these three antibiotics also displayed the major SDX01 pattern. The use of two other restriction enzymes on a part of the panel (155 isolates) brought a significant increase in the discriminatory index, in particular for SDX01 strains. As Salmonella Derby is essentially isolated from pigs, and major resistance and PFGE patterns of isolates from pigs and pork were very similar to human isolates, human salmonellosis due to Salmonella Derby may be related to pigs.

Monophasic Variant of Salmonella Typhimurium Infection Affects the Serum Metabolome in Swine.

Salmonella is the most relevant foodborne zoonotic agent found in swine, and its presence in French herds is significant. Its carriage is asymptomatic, which makes it difficult to detect during rearing, thus increasing the risk of its presence on pork meat. Studies have shown that enteric infection in animals could be associated with changes in the serum metabolome composition, through the immune response or changes in the digestive microbiota composition. We hypothesized that these changes in the serum metabolome composition could be used as markers for the detection of asymptomatic animals infected by Salmonella. Using untargeted analysis by liquid chromatography coupled with mass spectrometry, we showed that significant differences in the composition of the serum metabolome could be detected between infected or noninfected animals both 1 and 21 days after experimental infection. This serum metabolome composition significantly changed during the 21 days postinfection in the infected animal groups, suggesting an evolution of the impact of infection with time. Despite this evolution, differences in the serum metabolome composition persisted between infected and noninfected animals 21 days after the initial infection. We also showed a possible difference between high-shedding and low-shedding animals 21 days postinfection. Finally, some of the variations in the metabolome were found to be significantly associated with variations of specific members of the fecal microbiota. Thus, excreting and asymptomatic animals, but also high-shedding animals, could be identified on the basis of their serum metabolome composition.

Effects of Major Families of Modulators on Performances and Gastrointestinal Microbiota of Poultry, Pigs and Ruminants: A Systematic Approach.

Considering the ban on the use of antibiotics as growth stimulators in the livestock industry, the use of microbiota modulators appears to be an alternative solution to improve animal performance. This review aims to describe the effect of different families of modulators on the gastrointestinal microbiota of poultry, pigs and ruminants and their consequences on host physiology. To this end, 65, 32 and 4 controlled trials or systematic reviews were selected from PubMed for poultry, pigs and ruminants, respectively. Microorganisms and their derivatives were the most studied modulator family in poultry, while in pigs, the micronutrient family was the most investigated. With only four controlled trials selected for ruminants, it was difficult to conclude on the modulators of interest for this species. For some modulators, most studies showed a beneficial effect on both the phenotype and the microbiota. This was the case for probiotics and plants in poultry and minerals and probiotics in pigs. These modulators seem to be a good way for improving animal performance.

Comparative Analysis of Campylobacter jejuni and C. coli Isolated from Livestock Animals to C. jejuni and C. coli Isolated from Surface Water Using DNA Sequencing and MALDI-TOF.

This study evaluated the contribution of cattle, sheep, poultry and pigs to the contamination of surface water from rivers by Campylobacter jejuni and C. coli using MLST, cgMLST and considered MALDI-TOF MS as an alternative technique. The 263 strains isolated from cattle (n = 61), sheep (n = 42), poultry (n = 65), pigs (n = 60) and surface water (n = 35) were distributed across 115 sequence types (STs), 49 for C. jejuni and 66 for C. coli. Considering MLST data, 14.2%, 11.4% and 2.8% of the surface water strains could be attributed to cattle, poultry and sheep, respectively, none to pigs, and 85.7% were non-attributed. Analysis of cg-MLST data with STRUCTURE indicated that C. jejuni strains from water were predominantly attributed to poultry (93.5%), weakly to sheep (<1%) and 6.3% non-attributed, and that conversely, C. coli strains from water were predominantly non-attributed (94.3%) and 5.7% attributed to poultry. Considering the protein profiles with a threshold of 94% and 97% of similarity, respectively, strains from surface water could be attributed to poultry (31.4% and 17.1%), and to cattle (17.1% and 5.7%); 54.1% and 77.1% were non-attributed. This study confirmed these livestock animals might contribute to the contamination of surface water, with a level of contribution depending on the typing technique and the method of analysis. MALDI-TOF could potentially be an alternative approach for source attribution.

Quantification of indicator and pathogenic bacteria in manures and digestates from three agricultural biogas plants over a one-year period.

Interest in the conversion of manure in biogas via anaerobic digestion (AD) is growing, but questions remain about the biosafety of digestates. For a period of one year, we monitored the impact of three mesophilic agricultural biogas plants (BPs) mainly fed with pig manure (BP1, BP3) or bovine manure (BP2) on the physicochemical parameters, the composition of the microbial community and the concentration of bacteria (E. coli, enterococci, Salmonella, Campylobacter, Listeria monocytogenes, Clostridium perfringens, Clostridium botulinum and Clostridioides difficile). The BP2 digestate differed from those of the two other BPs with a higher nitrogen content, more total solids and greater abundance of Clostridia MBA03 and Disgonomonadacea. Persistence during digestion ranked from least to most, was: Campylobacter (1.6 to >2.9 log10 reduction, according to the BP) < E. coli (1.8 to 2.2 log10) < Salmonella (1.1 to 1.4 log10) < enterococci (0.2 to 1.2 log10) and C. perfringens (0.2 to 1 log10) < L. monocytogenes (-1.2 to 1.6 log10) < C. difficile and C. botulinum (≤0.5 log10). No statistical link was found between the reduction in the concentration of the targeted bacteria and the physicochemical and operational parameters likely to have an effect (NH3, volatile fatty acids and total solids contents, hydraulic retention time, presence of co-substrates), underlining the fact that the fate of the bacteria during mesophilic digestion depends on many interacting factors. The reduction in concentrations varied significantly over the sampling period, underlining the need for longitudinal studies to estimate the impact of AD on pathogenic microorganisms.

Inflammatory Responses Induced by the Monophasic Variant of Salmonella Typhimurium in Pigs Play a Role in the High Shedder Phenotype and Fecal Microbiota Composition.

Pigs infected with Salmonella may excrete large amounts of Salmonella, increasing the risk of spread of this pathogen in the food chain. Identifying Salmonella high shedder pigs is therefore required to mitigate this risk. We analyzed immune-associated markers and composition of the gut microbiota in specific-pathogen-free pigs presenting different shedding levels after an oral infection with Salmonella. Immune response was studied through total blood cell counts, production of anti-Salmonella antibodies and cytokines, and gene expression quantification. Total Salmonella shedding for each pig was estimated and hierarchical clustering was used to cluster pigs into high, intermediate, and low shedders. Gut microbiota compositions were assessed using 16S rRNA microbial community profiling. Comparisons were made between control and inoculated pigs, then between high and low shedders pigs. Prior to infection, high shedders had similar immunological profiles compared to low shedders. As soon as 1 day postinoculation (dpi), significant differences on the cytokine production level and on the expression level of several host genes related to a proinflammatory response were observed between high and low shedders. Infection with Salmonella induced an early and profound remodeling of the immune response in all pigs, but the intensity of the response was stronger in high shedders. In contrast, low shedders seroconverted earlier than high shedders. Just after induction of the proinflammatory response (at 2 dpi), some taxa of the fecal microbiota were specific to the shedding phenotypes. This was related to the enrichment of several functional pathways related to anaerobic respiration in high shedders. In conclusion, our data show that the immune response to Salmonella modifies the fecal microbiota and subsequently could be responsible for shedding phenotypes. Influencing the gut microbiota and reducing intestinal inflammation could be a strategy for preventing Salmonella high shedding in livestock. IMPORTANCE Salmonellosis remains the most frequent human foodborne zoonosis after campylobacteriosis and pork meat is considered one of the major sources of human foodborne infections. At the farm, host heterogeneity in pig infection is problematic. High Salmonella shedders contribute more significantly to the spread of this foodborne pathogen in the food chain. The identification of predictive biomarkers for high shedders could help to control Salmonella in pigs. The purpose of the present study was to investigate why some pigs become super shedders and others low shedders. We thus investigated the differences in the fecal microbial composition and the immune response in orally infected pigs presenting different Salmonella shedding patterns. Our data show that the proinflammatory response induced by S. Typhimurium at 1 dpi could be responsible for the modification of the fecal microbiota composition and functions observed mainly at 2 and 3 dpi and to the low and super shedder phenotypes.

One Health surveillance-A cross-sectoral detection, characterization, and notification of foodborne pathogens.

Introduction: Several Proficiency Test (PT) or External Quality Assessment (EQA) schemes are currently available for assessing the ability of laboratories to detect and characterize enteropathogenic bacteria, but they are usually targeting one sector, covering either public health, food safety or animal health. In addition to sector-specific PTs/EQAs for detection, cross-sectoral panels would be useful for assessment of the capacity to detect and characterize foodborne pathogens in a One Health (OH) perspective and further improving food safety and interpretation of cross-sectoral surveillance data. The aims of the study were to assess the cross-sectoral capability of European public health, animal health and food safety laboratories to detect, characterize and notify findings of the foodborne pathogens Campylobacter spp., Salmonella spp. and Yersinia enterocolitica, and to develop recommendations for future cross-sectoral PTs and EQAs within OH. The PT/EQA scheme developed within this study consisted of a test panel of five samples, designed to represent a theoretical outbreak scenario. Methods: A total of 15 laboratories from animal health, public health and food safety sectors were enrolled in eight countries: Denmark, France, Italy, the Netherlands, Poland, Spain, Sweden, and the United Kingdom. The laboratories analyzed the samples according to the methods used in the laboratory and reported the target organisms at species level, and if applicable, serovar for Salmonella and bioserotype for Yersinia. Results: All 15 laboratories analyzed the samples for Salmonella, 13 for Campylobacter and 11 for Yersinia. Analytical errors were predominately false negative results. One sample (S. Stockholm and Y. enterocolitica O:3/BT4) with lower concentrations of target organisms was especially challenging, resulting in six out of seven false negative results. These findings were associated with laboratories using smaller sample sizes and not using enrichment methods. Detection of Salmonella was most commonly mandatory to notify within the three sectors in the eight countries participating in the pilot whereas findings of Campylobacter and Y. enterocolitica were notifiable from human samples, but less commonly from animal and food samples. Discussion: The results of the pilot PT/EQA conducted in this study confirmed the possibility to apply a cross-sectoral approach for assessment of the joint OH capacity to detect and characterize foodborne pathogens.

Development of a rapid and sensitive method combining a cellulose ester microfilter and a real-time quantitative PCR assay to detect Campylobacter jejuni and Campylobacter coli in 20 liters of drinking water or low-turbidity waters.

Investigations of Campylobacter jejuni and Campylobacter coli in samples of drinking water suspected of being at the origin of an outbreak very often lead to negative results. One of the reasons for this failure is the small volume of water typically used for detecting these pathogens (10 to 1,000 ml). The efficiencies of three microfilters and different elution procedures were determined using real-time quantitative PCR to propose a procedure allowing detection of Campylobacter in 20 liters of drinking water or low-turbidity water samples. The results showed that more than 80% of the bacteria inoculated in 1 liter of drinking water were retained on each microfilter. An elution with a solution containing 3% beef extract, 0.05 M glycine at pH 9, combined with direct extraction of the bacterial genomes retained on the cellulose ester microfilter, allowed recovery of 87.3% (±22% [standard deviation]) of Campylobacter per 1 liter of tap water. Recoveries obtained from 20-liter volumes of tap water spiked with a C. coli strain were 69.5% (±10.3%) and 78.5% (±15.1%) for 91 CFU and 36 CFU, respectively. Finally, tests performed on eight samples of 20 liters of groundwater collected from an alluvial well used for the production of drinking water revealed the presence of C. jejuni and C. coli genomes, whereas no bacteria were detected with the normative culture method in volumes ranging from 10 to 1,000 ml. In the absence of available epidemiological data and information on bacterial viability, these last results indicate only that the water resource is not protected from contamination by Campylobacter.

Occurrence and Diversity of Listeria monocytogenes Isolated from Two Pig Manure Treatment Plants in France.

The presence of Listeria monocytogenes in piggery effluents intended for irrigation crops may be a source of bacterial dissemination in agriculture. The occurrence and diversity of L. monocytogenes in the farm environment were examined in two pig manure treatment systems (S1 and S2). Samples collected over the course of one year consisted of manure, the liquid fraction of treated manure (lagoon effluent), and soil surrounding the lagoon. L. monocytogenes was enumerated using the Most Probable Number (MPN) method, serotyped by PCR, genotyped by pulsed-field gel electrophoresis (PFGE), and sequenced for multilocus sequence typing (MLST). L. monocytogenes was detected in 92% of manure samples and in approximately 50% of lagoon effluent and soil samples. Concentrations ranged between 5 and 103 MPN 100| |mL-1. Serogroups IIa, IIb, and IVb were identified. Diversity was high with 44 PFGE profiles (252 isolates) and 17 clonal complexes (CCs) (96 isolates) with higher diversity in manure at site S1 supplied by four farms. Some PFGE profiles and CCs identified in manure or in pig feces from a previous study were also detected in lagoons and/or soil, reflecting pig L. monocytogenes circulation throughout the manure treatment and in the vicinity of the sampling sites. However, some PFGE profiles and CCs were only found in the lagoon and/or in soil, suggesting an origin other than pigs. The present study highlights the limited ability of biological treatments to eliminate L. monocytogenes from pig manure. The persistence of some PFGE profiles and CCs throughout the year in the lagoon and soil shows the ability of L. monocytogenes to survive in this type of environment.

Immune response after a single vaccination against 2009 influenza A H1N1 in USA: a preliminary report of two randomised controlled phase 2 trials.

BACKGROUND: Data are needed from large clinical trials of paediatric, adult, and elderly people to find the appropriate antigen dose and vaccination schedule for the 2009 pandemic influenza A H1N1. We therefore report preliminary safety and immunogenicity results after one injection of a licensed monovalent pandemic H1N1 vaccine in the USA. METHODS: We randomly assigned healthy children (aged 6-35 months and 3-9 years) and adults (18-64 years and >or=65 years) to vaccine containing per dose 7.5 microg (children and adults), 15 microg (children and adults), or 30 microg (adults only) haemagglutinin in two placebo-controlled, observer-masked, multicentre phase 2 studies done in the USA. Participants were allocated with an interactive voice-response system or computer-generated randomisation lists with opaque scratchable patches. Primary outcome was haemagglutination inhibition antibody response 21 days after the first of two planned vaccinations (interim analysis of studies in progress). Analyses were by full-analysis set. The trials are registered with ClinicalTrials.gov as NCT00953524 and NCT00952419. FINDINGS: 410 of 423 children and 724 of 750 adults given an active vaccine, and 50 of 51 children and 95 of 99 adults given placebo were assessed for immunogenicity on day 21. After active vaccination, 45 of 101 (45%; 95% CI 35-55) to 47 of 94 (50%; 40-61) infants aged 6-35 months, 75 of 109 (69%; 59-77) to 80 of 106 (75%; 66-83) 3-9-year-old children, 134 of 141 (95%; 90-98) to 144 of 144 (100%; 98-100) of 18-64-year-old adults, and 93 of 100 (93%; 86-96) to 93 of 98 (95%; 89-98) elderly adults were seroprotected (proportion with titres >or=1:40). No vaccine-related serious adverse events occurred. Injection-site and systemic reactions were reported by up to about 50% of every age and vaccine group, with no noticeable differences between vaccine and placebo groups. INTERPRETATION: One dose of vaccine was highly immunogenic in adults, suggesting that it afforded sufficient protection against this pandemic influenza A H1N1 virus. Two doses of vaccine will probably be needed in children younger than 9 years. Safety and reactogenicity of the vaccine were acceptable and similar to those of seasonal vaccine. FUNDING: Office of the Assistant Secretary for Preparedness and Response, and Biomedical Advanced Research and Development Authority.

Rapid identification and quantification of Campylobacter coli and Campylobacter jejuni by real-time PCR in pure cultures and in complex samples.

BACKGROUND: Campylobacter spp., especially Campylobacter jejuni (C. jejuni) and Campylobacter coli (C. coli), are recognized as the leading human foodborne pathogens in developed countries. Livestock animals carrying Campylobacter pose an important risk for human contamination. Pigs are known to be frequently colonized with Campylobacter, especially C. coli, and to excrete high numbers of this pathogen in their faeces. Molecular tools, notably real-time PCR, provide an effective, rapid, and sensitive alternative to culture-based methods for the detection of C. coli and C. jejuni in various substrates. In order to serve as a diagnostic tool supporting Campylobacter epidemiology, we developed a quantitative real-time PCR method for species-specific detection and quantification of C. coli and C. jejuni directly in faecal, feed, and environmental samples. RESULTS: With a sensitivity of 10 genome copies and a linear range of seven to eight orders of magnitude, the C. coli and C. jejuni real-time PCR assays allowed a precise quantification of purified DNA from C. coli and C. jejuni. The assays were highly specific and showed a 6-log-linear dynamic range of quantification with a quantitative detection limit of approximately 2.5 × 10² CFU/g of faeces, 1.3 × 10² CFU/g of feed, and 1.0 × 10³ CFU/m² for the environmental samples. Compared to the results obtained by culture, both C. coli and C. jejuni real-time PCR assays exhibited a specificity of 96.2% with a kappa of 0.94 and 0.89 respectively. For faecal samples of experimentally infected pigs, the coefficients of correlation between the C. coli or C. jejuni real-time PCR assay and culture enumeration were R² = 0.90 and R² = 0.93 respectively. CONCLUSION: The C. coli and C. jejuni real-time quantitative PCR assays developed in this study provide a method capable of directly detecting and quantifying C. coli and C. jejuni in faeces, feed, and environmental samples. These assays represent a new diagnostic tool for studying the epidemiology of Campylobacter by, for instance, investigating the carriage and excretion of C. coli and C. jejuni by pigs from conventional herds.

Immunodominant epitopes in herpes simplex virus type 2 glycoprotein D are recognized by CD4 lymphocytes from both HSV-1 and HSV-2 seropositive subjects.

In human recurrent cutaneous herpes simplex, there is a sequential infiltrate of CD4 and then CD8 lymphocytes into lesions. CD4 lymphocytes are the major producers of the key cytokine IFN-gamma in lesions. They recognize mainly structural proteins and especially glycoproteins D and B (gD and gB) when restimulated in vitro. Recent human vaccine trials using recombinant gD showed partial protection of HSV seronegative women against genital herpes disease and also, in placebo recipients, showed protection by prior HSV1 infection. In this study, we have defined immunodominant peptide epitopes recognized by 8 HSV1(+) and/or 16 HSV2(+) patients using (51)Cr-release cytotoxicity and IFN-gamma ELISPOT assays. Using a set of 39 overlapping 20-mer peptides, more than six immunodominant epitopes were defined in gD2 (two to six peptide epitopes were recognized for each subject). Further fine mapping of these responses for 4 of the 20-mers, using a panel of 9 internal 12-mers for each 20-mers, combined with MHC II typing and also direct in vitro binding assay of these peptides to individual DR molecules, showed more than one epitope per 20-mers and promiscuous binding of individual 20-mers and 12-mers to multiple DR types. All four 20-mer peptides were cross-recognized by both HSV1(+)/HSV2(-) and HSV1(-)/HSV2(+) subjects, but the sites of recognition differed within the 20-mers where their sequences were divergent. This work provides a basis for CD4 lymphocyte cross-recognition of gD2 and possibly cross-protection observed in previous clinical studies and in vaccine trials.

Quantitative and qualitative evaluation of Campylobacter spp. contamination of turkey cecal contents and carcasses during and following the slaughtering process.

The present study aimed to document quantitatively and qualitatively the contamination by thermotolerant Campylobacter spp. of turkey samples during slaughtering. Four Campylobacter-positive turkey flocks were investigated at the slaughterhouse at three different stages: evisceration (cecal content), after carcass rinses but before chilling (neck skin), and after breast meat cut (meat). In each case, the studied flock was slaughtered first thing in the morning any given day of the week. The efficiency of cleaning and disinfecting operations was examined in the facility prior to processing the studied flock. For each flock, 90 samples were collected from cecal contents, neck skins, and meat pieces and checked quantitatively and qualitatively for Campylobacter. Identification of Campylobacter species was determined by PCR, and genetic patterns were determined by pulsed-field gel electrophoresis. Campylobacter contamination levels of ceca range from 2 to more than 7 Log CFU/g, while those of neck skin range from 0.5 to 3.5 Log CFU/g and those of meat range from 0.1 to 1.9 Log CFU/g. These differences in Campylobacter counts were not associated with a modification of Campylobacter species ratio; however, in the Campylobacter jejuni population, four genetic groups identified from the ceca were not recovered during slaughtering operations and two other genetic groups were only detected after chilling at the cutting stage of the breast meat. The present study suggests that the slaughtering process did not affect Campylobacter species populations; however, it might have influenced the strain population. Finally, the Campylobacter populations found on breast meat were similar to those isolated from the digestive tract of the birds.

Similar immunogenicity of the A/H1N1 2009 pandemic influenza strain when used as a monovalent or a trivalent vaccine.

BACKGROUND: The WHO recommended including the A (H1N1) 2009 pandemic strain in the influenza vaccines for use in the 2010-2011 northern hemisphere (NH) influenza season. The immunogenicity and safety of the trivalent split inactivated vaccine (Vaxigrip®) NH 2010-2011 formulation was compared to that observed for the corresponding non-adjuvanted monovalent A (H1N1) pandemic vaccine (Panenza®), when tested in similar populations of adult and elderly volunteers. METHODS: The monovalent vaccine was evaluated in two clinical trials, conducted respectively in both adult and elderly subjects and in a population of adults. The trivalent vaccine was evaluated in a clinical study that enrolled both adult and elderly subjects. Antibody titers were measured in serum samples drawn at day 0 (before vaccination) and 21 days after one vaccine injection using the same hemagglutination inhibition (HI) assay method. The occurrence of adverse events was reported up to 21 days after vaccination. RESULTS: Before immunization in the three studies, most of the volunteers had antibody titers below seroprotective levels against the pandemic A(H1N1) 2009 virus. After vaccination, in each trial and in each age group, high seroprotection rates, GMT ratios and seroconversion rates were observed. Seroprotection rates after administration of the monovalent vaccine reached 93% and 98% in the adult groups, and 83.7% in the elderly group. After administration of the trivalent vaccine, seroprotection rates of 92.2% and 81.3% were obtained respectively in the adult and the elderly groups. No related serious adverse events and no safety signals were detected either with the monovalent or trivalent vaccine. CONCLUSION: Comparable immunogenicity profiles were observed in three clinical trials of the pandemic A(H1N1) 2009 strain when formulated either as a monovalent or as a component of a seasonal trivalent vaccine.

Diversity of Yersinia enterocolitica isolated from pigs in a French slaughterhouse over 2 years.

The pig is one of the main reservoirs of Yersinia enterocolitica strains pathogenic to humans. A description of the Y. enterocolitica population in this reservoir, and accurate discriminatory techniques for typing isolates are needed for prevention, outbreak investigation, and surveillance. This study investigates the genetic diversity of pathogenic Y. enterocolitica isolates obtained from pig tonsils in a French pig slaughterhouse in 2009 (S1) and 2010 (S2). The use of Pulsed-Field Gel Electrophoresis (PFGE) and MLVA as typing techniques was also compared and evaluated. First, a total of 167 isolates (12 of biotype 3 recovered during S1, and 155 of biotype 4 recovered during S1 and S2) were typed by PFGE using the XbaI enzyme. MLVA was then tested on all the biotype 3 isolates in addition to 70 selected biotype 4 isolates recovered over the 2 years. PFGE generated two specific XbaI-PFGE profiles for biotype 3 isolates. Nine XbaI profiles were obtained for biotype 4, with a higher diversity (ID = 0.599) than biotype 3 (ID = 0.167). Two out of the nine XbaI profiles were reported during both surveys and at different months. MLVA improved the differentiation between isolates; the index of diversity reached 0.621 and 0.958, respectively, for biotype 3 (three MLVA types) and biotype 4 (32 MLVA types). The MLVA types for biotype 4 differed over the two surveys, but some isolates with different MLVA types were genetically closely related. This study provides an initial evaluation of the genetic diversity of Y. enterocolitica strains isolated from pigs in France. We show that some PFGE profiles are maintained in the pig production sector, and, through MLVA, that part of the Y. enterocolitica population remained genetically close over the two years. MLVA proved its effectiveness as a tool for investigating pathogenic Y. enterocolitica strains isolated from pigs.

An overview of the immunogenicity and effectiveness of current human rabies vaccines administered by intradermal route.

Pre- as well as post-exposure prophylaxis plays an important role in controlling the number of deaths associated with human rabies. Rabies vaccines, classically injected intramuscularly, are now also administered by intradermal (ID) route. Vaccines to be administered by the ID route should meet the same quality, safety and efficacy specifications as vaccines for intramuscular (IM) use. The aim of this paper is to provide information based on publicly available data regarding the ID use of rabies vaccines and to identify potential needs for further analysis of the potency, immunogenicity and effectiveness of rabies vaccines administered by this route. A first literature search, focused on the immunogenicity of rabies vaccines given by ID route, identified 338 publications in the period 1997-2018, 40 of which were included in our analyses. A second search investigating the effectiveness of ID vaccination resulted in 371 hits for the period 2007-2018, of which 13 suitable publications were retained. The immunogenicity of current rabies vaccines was analyzed in 3 ways: proportion of subjects reaching the antibody threshold of 0.5 IU/ml after ID vaccination, relationship between potency and immunogenicity of the vaccine given intradermally, and comparison of antibody responses after IM or ID vaccination. Overall, vaccines administered intradermally were found immunogenic. Post-exposure prophylaxis by ID route appeared at least as immunogenic as by IM regimens. By contrast, ID pre-exposure prophylaxis trended towards lower antibody titers than IM vaccination, but the observation was not associated with any clinical relevance. Vaccine effectiveness was assessed by investigating survival after exposure. Data from more than 30,000 patients who sought rabies post-exposure prophylaxis did not indicate that current vaccines administered by ID route lack efficacy. These results support current recommendations for ID vaccination against rabies. However, published data on ID performance were associated with significant weaknesses that future research should better address.