Presence of Chlamydia/Chlamydophila spp in pigs with and without conjunctivitis.

ABSTRACT Chlamydia and Chlamydophila are species of a family of bacteria (Chlamydiaceae) that cause a range of diseases, including conjunctivitis, in a variety of animals including pigs and humans. Some species cause zoonotic disease. This study examined the occurrence of Chlamydiaceae in samples taken from the lower eyelid conjunctiva in pigs with and without conjunctivitis. The study was initiated based on a herd investigation aimed to examine the experienced increase of conjunctivitis in some finisher herds. This study was conducted as a case-control study, by collecting samples from 62 case pigs (16-26 weeks old) and an equal number of controls, from three herds in Uppland, Sweden. The samples were analysed by real-time PCR (23S rRNA gene of Chlamydiaceae). When employing a threshold value of Ct 36, a significant difference in the occurrence of Chlamydiaceae between the entire case group (83% positive samples) and the control group (65% positive samples) was detected. In one of the herds a significantly higher occurrence of Chlamydiaceae was shown in pigs with conjunctivitis, compared to pigs without conjunctivitis. In the other two herds no significant difference was shown. The study revealed no significant difference in the occurrence of Chlamydiaceae between the herds. When employing av threshold value of Ct 38, the difference between the case and the control group were no longer significant. Hence, a relationship between Chlamydiaceae spp and conjunctivitis in pigs could not be convincingly demonstrated in the present study. However, based on the total results of this study, it is possible that such a relationship exist but with varying expression of clinical signs. The variation in clinical expression could be due to differences in infectious dose, differences in virulence between sub-species of Chlamydia/Chlamydophila, mixed infections of Chlamydia/Chlamydophila or mixed infection with other microorganisms such as Mycoplasma spp or virus. Conjunctivitis caused by Chlamydiaceae could at reinfections be a delayed hyper-sensitivity reaction, be caused by the fact that several species within the Chlamydiaceae exhibit the ability to induce a delayed hyper-sensitivity reaction in the host. The presence of Chlamydiaceae in pigs, their pathogenicity and the pig's immune response to the microorganism is not well studied and these fields require both extended and advanced studies.SAMMANFATTNING Chlamydia spp och Chlamydophila spp är arter i en familj bakterier (Chlamydiaceae) som orsakar en rad sjukdomar, bl a konjunktivit, hos ett stort antal djur inklusive gris och människa. En del av arterna har även zoonotisk potential. Denna studie har undersökt förekomsten av Chlamydiaceae i prover tagna från nedre ögonlockets konjunktiva hos grisar med och utan konjunktivit. Studien initierades efter en besättningsutredning föranledd av en ökad förekomst av konjunktivit i vissa besättningar. Undersökningen har genomförts som en fall-kontrollstudie, genom provtagning av 62 stycken slaktsvin och lika många kontroller i åldern 16-26 veckor, från tre stycken uppländska besättningar. Proverna har analyserats med realtids-PCR av 23S rRNA-genen hos Chlamydiaceae. När Ct <36 användes som tröskelvärde, påvisades en signifikant skillnad i klamydiaförekomst mellan fall (83 % positiva prov) och kontroll (65 % positiva prov) totalt i det undersökta materialet, samt i en av de tre provtagna besättningarna. Hos de övriga två besättningarna sågs ingen signifikant skillnad i klamydiaförekomst mellan fall och kontroller. Det sågs heller ingen signifikant skillnad i klamydiaförekomst mellan besättningarna. När Ct <38 användes som tröskelvärde, sågs inga signifikanta skillnader mellan fall- och kontrollgrupperna. Studien kunde därför inte påvisa något distinkt samband mellan klamydiaförekomst och konjunktivit. Dock tolkas resultatet som att Chlamydiaceae spp sannolikt orsakar konjunktivit hos grisar, men med varierad uttrycksgrad av kliniska symtom. Variationen i kliniskt uttryck skulle kunna bero på skillnader i infektionsdos, skillnader i virulens hos olika underarter av Chlamydia/Chlamydophila, blandinfektioner av olika Chlamydia/Chlamydophila eller blandinfektion med andra mikroorganismer som exempelvis mykoplasmer eller virus, samt när i inflammationsförloppet grisen provtas. Konjunktivit orsakad av Chlamydiaceae skulle, vid reinfektioner, kunna bero på en fördröjd hypersensibilitetsreaktion hos värddjuret, då flera arter inom Chlamydiaceae förmår utlösa en sådan reaktion. Då förekomsten av Chlamydiaceae hos gris samt deras patogenicitet och hur grisens immunförsvar hanterar mikroorganismerna är ett tämligen outforskat område krävs både utvidgade och fördjupade studier inom området

The occurrence of Chlamydia spp. in pigs with and without clinical disease

<p>Abstract</p> <p>Background</p> <p>Within the genera <it>Chlamydia</it>, the development of refined diagnostic techniques has allowed the identification of four species that are capable of infecting pigs. The epidemiology, clinical, and zoonotic impacts of these species are however largely unknown. The study aimed to investigate the presence of <it>Chlamydia </it>spp. in the intestines of growing pigs and in conjunctival swabs from finisher pigs, and relate the findings to clinical signs.</p> <p>Results</p> <p>By histology, 20 of 48 pigs had intestinal lesions that may be consistent with chlamydial infection. By PCR, forty-six of the pigs were positive whereas two samples were inhibited. Sequencing of 19 DNA extracts identified these as <it>Chlamydia suis</it>. By immunohistochemistry, 32 of 44 samples were positive and a significant relationship was detected between macroscopically visible intestinal lesions and a high degree of infection. By real-time PCR, a significant difference was detected between pigs with and without conjunctivitis when a Ct value of 36 was employed but not when a Ct value of 38 was employed.</p> <p>Conclusions</p> <p><it>Chlamydia suis </it>was demonstrated in most samples and overall, no correlation to clinical signs was detected. However, a correlation was noted between samples with a high degree of infection and the presence of clinical signs. It is possible, that the intensive pig production systems studied might predispose for the transmission and maintenance of the infection thus increasing the infectious load and the risk for disease in the pig.</p

Coherent diffractive imaging of microtubules using an X-ray laser

X-ray free electron lasers (XFELs) create new possibilities for structural studies of biological objects that extend beyond what is possible with synchrotron radiation. Serial femtosecond crystallography has allowed high-resolution structures to be determined from micro-meter sized crystals, whereas single particle coherent X-ray imaging requires development to extend the resolution beyond a few tens of nanometers. Here we describe an intermediate approach: the XFEL imaging of biological assemblies with helical symmetry. We collected X-ray scattering images from samples of microtubules injected across an XFEL beam using a liquid microjet, sorted these images into class averages, merged these data into a diffraction pattern extending to 2 nm resolution, and reconstructed these data into a projection image of the microtubule. Details such as the 4 nm tubulin monomer became visible in this reconstruction. These results illustrate the potential of single-molecule X-ray imaging of biological assembles with helical symmetry at room temperature

Atomistic characterization of the active-site solvation dynamics of a model photocatalyst

The interactions between the reactive excited state of molecular photocatalysts and surrounding solvent dictate reaction mechanisms and pathways, but are not readily accessible to conventional optical spectroscopic techniques. Here we report an investigation of the structural and solvation dynamics following excitation of a model photocatalytic molecular system [Ir-2(dimen)(4)](2+), where dimen is para-diisocyanomenthane. The time-dependent structural changes in this model photocatalyst, as well as the changes in the solvation shell structure, have been measured with ultrafast diffuse X-ray scattering and simulated with Born-Oppenheimer Molecular Dynamics. Both methods provide direct access to the solute-solvent pair distribution function, enabling the solvation dynamics around the catalytically active iridium sites to be robustly characterized. Our results provide evidence for the coordination of the iridium atoms by the acetonitrile solvent and demonstrate the viability of using diffuse X-ray scattering at free-electron laser sources for studying the dynamics of photocatalysis.1

Flow-aligned, single-shot fiber diffraction using a femtosecond X-ray free-electron laser

A major goal for X-ray free-electron laser (XFEL) based science is to elucidate structures of biological molecules without the need for crystals. Filament systems may provide some of the first single macromolecular structures elucidated by XFEL radiation, since they contain one-dimensional translational symmetry and thereby occupy the diffraction intensity region between the extremes of crystals and single molecules. Here, we demonstrate flow alignment of as few as 100 filaments (Escherichia coli pili, F-actin, and amyloid fibrils), which when intersected by femtosecond X-ray pulses result in diffraction patterns similar to those obtained from classical fiber diffraction studies. We also determine that F-actin can be flow-aligned to a disorientation of approximately 5 degrees. Using this XFEL-based technique, we determine that gelsolin amyloids are comprised of stacked β-strands running perpendicular to the filament axis, and that a range of order from fibrillar to crystalline is discernable for individual α-synuclein amyloids

Structure of a photosynthetic reaction centre determined by serial femtosecond crystallography

Serial femtosecond crystallography is an X-ray free-electron-laser-based method with considerable potential to have an impact on challenging problems in structural biology. Here we present X-ray diffraction data recorded from microcrystals of the Blastochloris viridis photosynthetic reaction centre to 2.8 angstrom resolution and determine its serial femtosecond crystallography structure to 3.5 angstrom resolution. Although every microcrystal is exposed to a dose of 33MGy, no signs of X-ray-induced radiation damage are visible in this integral membrane protein structure