Analysis of polymorphic membrane protein expression in cultured cells Identifies PmpA and PmpH of Chlamydia psittaci as candidate factors in pathogenesis and immunity to infection

The polymorphic membrane protein (Pmp) paralogous families of Chlamydia trachomatis, Chlamydia pneumoniae and Chlamydia abortus are putative targets for Chlamydia vaccine development. To determine whether this is also the case for Pmp family members of C. psittaci, we analyzed transcription levels, protein production and localization of several Pmps of C. psittaci. Pmp expression profiles were characterized using quantitative real-time PCR (RT-qPCR), immunofluorescence (IF) and immuno-electron microscopy (IEM) under normal and stress conditions. We found that PmpA was highly produced in all inclusions as early as 12 hpi in all biological replicates. In addition, PmpA and PmpH appeared to be unusually accessible to antibody as determined by both immunofluorescence and immuno-electron microscopy. Our results suggest an important role for these Pmps in the pathogenesis of C. psittaci, and make them promising candidates in vaccine development

Heparin-mediated inhibition of Chlamydia psittaci adherence to HeLa cells

The adherence of human strains ofChlamydia trachomatishas been recently shown to be inhibitable by heparin and heparitinase, leading to the proposal thatChlamydiabinding to host cells may be mediated by a glycosaminoglycan (GAG)-dependent mechanism. We here describe the adherence of the guinea-pig pathogen,Chlamydia psittaciGPIC, to HeLa cells, which was measured by cytofluorometry with chlamydiae whose DNA was fluorescently labelled. Adherence could be inhibited by heat or trypsin pretreatment of the bacteria, and binding was much faster at 37°C (reaching a plateau within 1 h) than 4°C. Little binding remained when host cells were pre-fixed with paraformaldehyde, suggesting that host cell receptor mobility may be required for effective adherence. Visualization by confocal microscopy confirmed that the bacteria were at or near the host cell surface during the entire time-course of these experiments. Adherence increased as a function of pH between pH 6 and pH 8.0–8.5. Both adherence and infection of HeLa cells could be inhibited with heparin when the adherence step was performed at 4°C, but only infection was inhibited when the adherence step was performed at 37°C, even though heparitinase could block adherence at either 4°C or 37°C. Even at 4°C, heparin-mediated inhibition was significantly lower at pH 8 than pH 7.4, suggesting that GAG-independent mechanisms may play a role in the higher adherence observed at basic pH. These results therefore demonstrate that a GAG-dependent adherence step may be operative inC. psittaci, and raise the possibility that other adherence mechanisms may also contribute to binding by this chlamydial strain. Furthermore, they suggest that there may not be a strict correlation betweenC. psittaciadherence and the ability to cause productive infections

Isolation of a new Chlamydia species from the feral Sacred Ibis (Threskiornis aethiopicus): Chlamydia ibidis

Investigations conducted on feral African Sacred Ibises (Threskiornis aethiopicus) in western France led to the isolation of a strain with chlamydial genetic determinants. Ultrastructural analysis, comparative sequence analysis of the 16S rRNA gene, ompA, and of a concatenate of 31 highly conserved genes, as well as determination of the whole genome sequence confirmed the relatedness of the new isolate to members of the Chlamydiaceae, while, at the same time demonstrating a unique position outside the currently recognized species of this family. We propose to name this new chlamydial species Chlamydia ibidis

Characteristics of children with Kawasaki disease requiring intensive care: 10 years' experience at a tertiary pediatric hospital

Background/Purpose: Kawasaki disease (KD) is a febrile systemic vasculitis, and some patients may develop serious complications requiring intensive care. We aim to ascertain the clinical presentations and outcomes of these patients. Methods: From October 2004 to October 2014, children with KD who had stayed in the pediatric intensive care unit (ICU) for acute stage treatment were defined as case patients; for each case, three age/sex-matched patients with KD but without ICU stay, if identified, were selected as control patients. Clinical data were retrospectively collected and analyzed. Results: Among the total of 1065 KD patients, we identified 26 case patients and 71 controls for statistical analysis. ICU patients had a longer fever duration, and tended to have hemoglobin level 10%, peak serum C-reactive protein level > 200 mg/L, serum albumin value < 3 g/dL, and often presented with multiorgan system involvement. Time from symptom onset to the diagnosis of KD was similar between the two groups, but ICU patients were less likely to have KD as a leading admission diagnosis. Shock (73.1%, n = 19) was the most common reason for ICU admission. ICU patients were more likely to receive antibiotics, albumin infusion, and require a second dose of intravenous immunoglobulin or steroid therapy. No in-hospital mortality was observed. Conclusion: Patients with KD requiring ICU admission are significantly associated with multiorgan involvement, abnormal hematological and biochemistry biomarkers, KD recognition difficulty at the time of admission, and intravenous immunoglobulin-refractory KD. Keywords: intensive care, Kawasaki disease, Kawasaki disease shock syndrome, shock, Taiwa