malT knockout mutation invokes a stringent type gene-expression profile in Actinobacillus pleuropneumoniae in bronchoalveolar fluid

Actinobacillus pleuropneumoniae causes contagious pleuropneumonia, an economically important disease of commercially reared pigs throughout the world. To cause this disease, A. pleuropneumoniae must rapidly overcome porcine pulmonary innate immune defenses. Since bronchoalveolar fluid (BALF) contains many of the innate immune and other components found in the lungs, we examined the gene expression of a virulent serovar 1 strain of A. pleuropneumoniae after exposure to concentrated BALF for 30 min.Peer reviewed: YesNRC publication: Ye

Comparative variation within the genome of Campylobacter jejuni NCTC 11168 in human and murine hosts

Sherpa Romeo green journal. Open access, distributed under the terms of the Creative Commons Attibution License.Campylobacteriosis incited by C. jejuni is a significant enteric disease of human beings. A person working with two reference strains of C. jejuni National Collection of Type Cultures (NCTC) 11168 developed symptoms of severe enteritis including bloody diarrhea. The worker was determined to be infected by C. jejuni . In excess of 50 isolates were recovered from the worker’s stool. All of the recovered isolates and the two reference strains were indistinguishable from each other based on comparative genomic fingerprint subtyping. Whole genome sequence analysis indicated that the worker was infected with a C. jejuni NCTC 11168 obtained from the American Type Culture Collection; this strain (NCTC 11168-GSv) is the genome sequence reference. After passage through the human host, major genetic changes including indel mutations within twelve contingency loci conferring phase variations were detected in the genome of C. jejuni . Specific and robust single nucleotide polymorphism (SNP) changes in the human host were also observed in two loci (Cj0144c, Cj1564). In mice inoculated with an isolate of C. jejuni NCTC 11168-GSv from the infected person, the isolate underwent further genetic variation. At nine loci, mutations specific to inoculated mice including five SNP changes were observed. The two predominant SNPs observed in the human host reverted in mice. Genetic variations occurring in the genome of C. jejuni in mice corresponded to increased densities of C. jejuni cells associated with cecal mucosa. In conclusion, C. jejuni NCTC 11168-GSv was found to be highly virulent in a human being inciting severe enteritis. Host-specific mutations in the person with enteritis occurred/were selected for in the genome of C. jejuni , and many were not maintained in mice. Information obtained in the current study provides new information on host-specific genetic adaptation by C. jejuni .Ye

Modulation of gene expression in Actinobacillus pleuropneumoniae exposed to bronchoalveolar fluid

Background: Actinobacillus pleuropneumoniae, the causative agent of porcine contagious pleuropneumonia, is an important pathogen of swine throughout the world. It must rapidly overcome the innate pulmonary immune defenses of the pig to cause disease. To better understand this process, the objective of this study was to identify genes that are differentially expressed in a medium that mimics the lung environment early in the infection process. Methods and Principal Findings: Since bronchoalveolar lavage fluid (BALF) contains innate immune and other components found in the lungs, we examined gene expression of a virulent serovar 1 strain of A. pleuropneumoniae after a 30 min exposure to BALF, using DNA microarrays and real-time PCR. The functional classes of genes found to be up-regulated most often in BALF were those encoding proteins involved in energy metabolism, especially anaerobic metabolism, and in cell envelope, DNA, and protein biosynthesis. Transcription of a number of known virulence genes including apxIVA and the gene for SapF, a protein which is involved in resistance to antimicrobial peptides, was also up-regulated in BALF. Seventynine percent of the genes that were up-regulated in BALF encoded a known protein product, and of these, 44 % had been reported to be either expressed in vivo and/or involved in virulence. Conclusions: The results of this study suggest that in early stages of infection, A. pleuropneumoniae may modulate expression of genes involved in anaerobic energy generation and in the synthesis of proteins involved in cell wal

<i>Campylobacter jejuni</i> Colonization Is Associated with a Dysbiosis in the Cecal Microbiota of Mice in the Absence of Prominent Inflammation

<div><p>Background</p><p><i>Campylobacter jejuni</i> causes enterocolitis in humans, but does not incite disease in asymptomatic carrier animals. To survive in the intestine, <i>C. jejuni</i> must successfully compete with the microbiota and overcome the host immune defense. <i>Campylobacter jejuni</i> colonization success varies considerably amongst individual mice, and we examined the degree to which the intestinal microbiota was affected in mice (i.e. a model carrier animal) colonized by <i>C. jejuni</i> at high relative to low densities.</p> <p>Methods</p><p>Mice were inoculated with <i>C. jejuni</i> or buffer, and pathogen shedding and intestinal colonization were measured. Histopathologic scoring and quantification of mRNA expression for α-defensins, toll-like receptors, and cytokine genes were conducted. Mucosa-associated bacterial communities were characterized by two approaches: multiplexed barcoded pyrosequencing and terminal restriction fragment length polymorphism analysis.</p> <p>Results</p><p>Two <i>C. jejuni</i> treatments were established based on the degree of cecal and colonic colonization; <i>C. jejuni</i> Group A animals were colonized at high cell densities, and <i>C. jejuni</i> Group B animals were colonized at lower cell densities. Histological examination of cecal and colonic tissues indicated that <i>C. jejuni</i> did not incite visible pathologic changes. Although there was no significant difference among treatments in expression of mRNA for α-defensins, toll-like receptors, or cytokine genes, a trend for increased expression of toll-like receptors and cytokine genes was observed for <i>C. jejuni</i> Group A. The results of the two methods to characterize bacterial communities indicated that the composition of the cecal microbiota of <i>C. jejuni</i> Group A mice differed significantly from <i>C. jejuni</i> Group B and Control mice. This difference was due to a reduction in load, diversity and richness of bacteria associated with the cecal mucosa of <i>C. jejuni</i> Group A mice.</p> <p>Conclusions</p><p>High density colonization by <i>C. jejuni</i> is associated with a dysbiosis in the cecal microbiota independent of prominent inflammation.</p> </div

Study of early post -operative atrial fibrillation after valvular heart surgery.

Objectives: 1) To study the incidence and timing of development of atrial fibrillation after valvular replacement surgery; 2) To know various risk factors for development of this Arrhythmia. Material and Methods: 80 patients of either sex, with rheumatic valvular heart disease undergoing Mitral Valve, Aortic Valve and both Mitral and Aortic Valve replacement with normal preoperative sinus rhythm, operated under cardiopulmonary bypass by standard technique were observed by continuous ECG monitoring (DATA SCOPE SPECTRUM USA) to note the incidence and timing of development of atrial fibrillation. Age, sex, systemic and pulmonary hypertension, preoperative history of intermittent atrial fibrillation, preoperative left atrial and left ventricular systolic and diastolic dimensions, left ventricular ejection fractions and duration of aortic cross clamp were studied as risk factors in patients who developed Atrial fibrillation. Results: 28 patients (35%) developed atrial fibrillation in the post operative period. In majority of cases 13 (46.42%) it occurred between 24- 48 hours post operatively. 7% (14.28%) had more than one episode. It was benign and self-limiting in majority of patients. Age more than 55 years, systemic hypertension, left atrial size more than 50mm, history of pre operative intermittent atrial fibrillation, left ventricular ejection fraction below 35%, duration of aortic cross clamp > 50 minutes were significant risk factors, (P<0.01). Conclusion: Atrial fibrillation develops in significant number of patients post operatively after valvular replacement surgery. In majority of the patients it is benign and self limiting

Histopathologic changes.

<p>Mean histological scores of cecal and colonic tissues for combined necrosis, neutrophils, macrophages and lymphocytes, and fibrosis, and goblet cell size and number. Treatments are: (A) <i>C</i>. <i>jejuni</i> Group A (8.8 log₁₀ copy number of <i>C</i>. <i>jejuni</i> g^-1 of cecal tissue); (B) <i>C</i>. <i>jejuni</i> Group B (6.4 log₁₀ copy number of <i>C</i>. <i>jejuni</i> g^-1 of cecal tissue); and (C) control (not inoculated with <i>C</i>. <i>jejuni</i>). Vertical lines associated with histogram bars are standard error of the means (n=6). There were no significant differences for cecal (P≥0.20) or colonic (P≥0.34) tissues among treatments. Scores were categorized as no effect to negligible changes (score of 0 to 4), mild to moderate changes (score of 5 to 9), and marked changes (score of 10 to 19).</p

Richness and diversity of bacterial communities.

<p>(A) Richness; (B) Chao1 diversity; (C) Shannon diversity; and (D) phylogenetic diversity. Treatments are: (A) <i>C</i>. <i>jejuni</i> Group A (8.8 log₁₀ copy number of <i>C</i>. <i>jejuni</i> g^-1 of cecal tissue); (B) <i>C</i>. <i>jejuni</i> Group B (6.4 log₁₀ copy number of <i>C</i>. <i>jejuni</i> g^-1 of cecal tissue); and (C) control (not inoculated with <i>C</i>. <i>jejuni</i>). Vertical lines associated with markers are standard error of the means (n=6).</p

Prevalence of <i>Campylobacter jejuni</i> sequences.

<p>Prevalence of sequences (%) identified as <i>C</i>. <i>jejuni</i> by treatment. Treatments are: (A) <i>C</i>. <i>jejuni</i> Group A (8.8 log₁₀ copy number of <i>C</i>. <i>jejuni</i> g^-1 of cecal tissue); (B) <i>C</i>. <i>jejuni</i> Group B (6.4 log₁₀ copy number of <i>C</i>. <i>jejuni</i> g^-1 of cecal tissue); and (C) control (not inoculated with <i>C</i>. <i>jejuni</i>). Vertical lines associated with histogram bars are standard error of the means (n=6). Number associated with histogram bars are the mean number of sequences (± standard error of the means) that were identified as <i>C</i>. <i>jejuni</i> by treatment.</p

Messenger RNA expression of cytokines.

<p>Relative mRNA expression of cytokines in cecal tissue where: (A) interleukin (IL)-1β; (B) IL-6; (C) IL-10; (D) interferon-γ; and (E) tumor necrosis factor-α. Treatments are: (A) <i>C</i>. <i>jejuni</i> Group A (8.8 log₁₀ copy number of <i>C</i>. <i>jejuni</i> g^-1 of cecal tissue); (B) <i>C</i>. <i>jejuni</i> Group B (6.4 log₁₀ copy number of <i>C</i>. <i>jejuni</i> g^-1 of cecal tissue); and (C) control (not inoculated with <i>C</i>. <i>jejuni</i>). Vertical lines associated with histogram bars are standard error of the means (n=6).</p