contigs

Whole genome sequencing reads for the 212 French Campylobacter jejuni isolates referred to in the associated publication

Anti-<i>Campylobacter</i> IgY antibodies in the sera of chickens after vaccination and challenge.

<p>The chicks were immunized by the IM route, on day 5 with DNA and on day 12 with proteins. They were then orally infected on day 19 by <i>Campylobacter</i>. The specific systemic immune response was assessed weekly from blood samples until the end of the experiment on day 42 ± 1 day (data from day 1 to day 14 not shown) by ELISAs which reveal the IgY antibodies (OD 490nm) (A) YP562, YP1115, YP9769, YP437, YP9817, and YP9838 antigens were individually injected in the first experiment along with a combination of antigens (Pool) and compared to a DNA/protein control group (injected with adjuvants only). (B) Four antigens (YP562, YP437, YP9817, and YP9838) were tested again in a second experiment and compared to a DNA/protein control group (injected with adjuvants only). The negative control group was administered with PBS only. Each dot corresponds to the OD of an individual chicken. Bars represent the medians for each group. *: statistically significant differences from the control group at the same time point (p < 0.05).</p

Promising new vaccine candidates against <i>Campylobacter</i> in broilers

<div><p><i>Campylobacter</i> is the leading cause of human bacterial gastroenteritis in the European Union. Birds represent the main reservoir of the bacteria, and human campylobacteriosis mainly occurs after consuming and/or handling poultry meat. Reducing avian intestinal <i>Campylobacter</i> loads should impact the incidence of human diseases. At the primary production level, several measures have been identified to reach this goal, including vaccination of poultry. Despite many studies, however, no efficient vaccine is currently available. We have recently identified new vaccine candidates using the reverse vaccinology strategy. This study assessed the <i>in vivo</i> immune and protective potential of six newly-identified vaccine antigens. Among the candidates tested on Ross broiler chickens, four (YP_001000437.1, YP_001000562.1, YP_999817.1, and YP_999838.1) significantly reduced cecal <i>Campylobacter</i> loads by between 2 and 4.2 log₁₀ CFU/g, with the concomitant development of a specific humoral immune response. In a second trial, cecal load reductions results were not statistically confirmed despite the induction of a strong immune response. These vaccine candidates need to be further investigated since they present promising features.</p></div

Anti-<i>Campylobacter</i> IgY antibodies in sera and <i>Campylobacter</i> loads in chicken ceca after DNA vaccination alone or protein vaccination alone and challenged using the YP9817 antigen.

<p>Birds were vaccinated with the DNA vaccine alone on day 5 or with proteins alone on day 12 and then infected on day 19. (A) The IgY levels in blood samples were assessed by ELISAs each week until the end of the experiment on day 42 ± 1 day (data from day 1 to day 14 not shown). Each dot corresponds to the OD of an individual chicken. Bars represent the medians for each group. (B) <i>Campylobacter</i> counts were evaluated at the end of the experiment from ceca samples by qPCR (Log GenEq/g). The detection limit was set at 1.88 log₁₀ GenEq/g. Samples with counts under the threshold were set at 0.94 log₁₀ GenEq/g. No significant differences were observed between groups.</p

<i>Campylobacter</i> loads in chicken ceca after vaccination and challenge.

<p>After two vaccinations on days 5 and 12, chickens were then orally infected on day 19. <i>Campylobacter</i> counts were evaluated at the end of the experiment from ceca samples. (A) YP562, YP1115, YP9769, YP437, YP9817, and YP9838 antigens were individually injected in the first experiment along with a combination of antigens (Pool) and compared to a DNA/protein control group (injected with adjuvants only). Ceca samples were cultured on mCCDA for <i>Campylobacter</i> counts (Log CFU/g). Groups without common letters (a-c) differed significantly (p < 0.05). (B) Four antigens (YP562, YP437, YP9817, and YP9838) were tested again in a second experiment and compared to DNA/protein control group (injected with adjuvant only) and negative control group administered with PBS only. Quantitative PCR on ceca samples was used for <i>Campylobacter</i> counts (Log GenEq/g). The detection limit was determined to lie at 1.88 log₁₀ GenEq/g. Samples with counts under the threshold were set at 0.94 log₁₀ GenEq/g. No significant differences were observed between groups.</p

Cecal persistence and colonization levels of <i>S.</i> Senftenberg isolates in infected chicks.

<p>Number of CFU of <i>Salmonella</i> Senftenberg rifampicin-resistant strains per gram of cecum of chicks orally infected with 10⁵ CFU. (A) Enumeration was performed up to 33 days post-infection for strains SS304, SS308, SS270, SS267, and 26 days p.i for strains SS17, SS291, SS209, SS13, SS48, SS47, SS278, SS41. (B) Cecal load of chicks inoculated with four selected strains (SS308, SS209, SS304, SS278) in a second experiment up to 26 days p.i. The data presented correspond to the mean of positive and negative cecum samples ± SEM.</p

Measurement of proximal cecal villus height and crypt depth of control chicks and animals infected with persistent SS308 and non-persistent SS304 strains of <i>S.</i> Senftenberg at 5 and 26 days post-infection (infection at 1 day of age).

a,b<p>The mean of proximal cecal villus heights and crypt depths ±SD. Different letters in the same line indicate a significant difference with the Mann -Whitney test (P≤0.05).</p

Mouse infection by S. Senftenberg strains.

<p>Groups of BALB/c mice were orally infected with 5×10⁸ bacteria of persistent (SS308, SS209), non-persistent (SS304, SS278) and human (SS291) <i>S.</i> Senftenberg strains (n = 10 for each group). (A) At day 3 p.i., the number of bacteria detected in the ileum, colon and mesenteric lymph nodes (MLN) was determined. The <i>S.</i> Enteritidis LA5 strain was used as a positive control (n = 6). The results of two independent experiments were pooled for analysis. The frequency of MLN colonization by <i>Salmonella</i> strains was calculated after direct detection (<b>black</b>) or enrichment (<b>grey</b>). <b>White</b> histogram corresponds to negative MLN samples. (B) Number of bacteria in the same organs determined 28 days p.i. Data correspond to the mean of positive and negative animals ± SEM of two independent experiments. Letters (a–e) indicate a significant difference between the different groups of infected mice (<i>P</i><0.05).</p

Cell invasion capacity of <i>S.</i> Senftenberg strains.

<p>In vitro invasion and intracellular multiplication were performed in epithelial cell lines (HT29 and LMH) and macrophages (HD11 and J774). Persistent (P) (SS308, SS209) and non-Persistent (NP) (SS304, SS278) strains were analyzed in addition to a human isolate (H) (SS291). Cells were infected at a MOI of 10 CFU/cell and the number of intracellular bacteria was determined 2 h (<b>black</b>) and 20 h (<b>grey</b>) post-infection. Data representing the mean ± SD of at least two independent experiments carried out in duplicate. The invasive strain of <i>Salmonella</i> Enteriditis LA5 was used as a positive control.</p

Spleen colonization of chicks infected with <i>S.</i> Senftenberg.

<p>Broiler chikens were orally infected with 10⁵ CFU. A) Frequency of spleen colonization by persistent (SS308, SS209) and non-persistent (SS278, SS304) strains of <i>S.</i> Senftenberg at different times post-infection. B) Number of CFU of <i>S.</i> Senftenberg per gram of spleen. Spleen samples which were positive after enrichment were given a value of 33 CFU. These results correspond to the mean of 15 animals (positives and negatives) ± SEM.* Letters (a–b) indicate a significant difference in means of spleen colonization levels between the groups of persistent (SS308, SS209) and non-persistent strains (SS304, SS278) at the 0.05 level.</p