Camilli Romina, Spencer Brady L, Moschioni Monica, Pinto Vittoria, Berti Francesco, Nahm Moon H, Pantosti Annalisa
Department of Infectious, Parasitic and Immune-mediated Diseases, Istituto Superiore di Sanità, Rome, Italy.
Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America.
PLoS One. 2014 Jun 26;9(6):e100722. doi: 10.1371/journal.pone.0100722. eCollection 2014.
Recent studies have identified Streptococcus pneumoniae serotype 11E and serovariant 11Av among isolates previously typed as 11A by classical serotyping methods. Serotype 11E and serovariant 11Av differ from serotype 11A by having totally or partially inactive wcjE, a gene in cps locus coding for an O-acetyl transferase. Serotype 11E is rare among carriage isolates but common among invasive isolates suggesting that it survives better during invasion. Aim of this work was to investigate the epidemiology of serotype 11A in a pneumococcal collection using a new serotyping approach based on High-Resolution Magic Angle Spinning Nuclear Magnetic Resonance (HR-MAS NMR) spectroscopy to distinguish serotypes 11A and 11E.
A collection of 48 (34 invasive and 14 carriage) S. pneumoniae isolates from Italy, previously identified as serotype 11A by the Quellung reaction, were investigated by wcjE sequencing, HR-MAS NMR spectroscopy and the reference flow cytometric serotyping assay (FCSA) based on monoclonal antibodies.
HR-MAS NMR spectra from serotypes 11A and 11E showed different NMR peaks indicating that HR-MAS NMR could be used to distinguish these serotypes, although HR-MAS NMR could not distinguish serotype 11Av from serotype 11E unambiguously. Thirty-eight isolates were confirmed to be serotype 11A, 8 isolates with a mutated wcjE were serotype 11E, 1 isolate belonged to serovariant 11Av, and 1 isolate was a mixed population 11A/11Av. All 11E isolates were identified among invasive isolates.
We proved that HR-MAS NMR can be of potential use for pneumococcal serotyping. The detection of serotype 11E among invasive isolates in our collection, supports previous epidemiological studies suggesting that mutations in wcjE can represent a mechanism promoting pneumococcal survival during invasion. The discovery of a spectrum of immunochemical diversity within established serotypes should stimulate efforts to develop new serotyping approaches.
最近的研究在先前通过经典血清分型方法鉴定为11A的分离株中发现了肺炎链球菌11E血清型和11Av血清变异株。11E血清型和11Av血清变异株与11A血清型的不同之处在于，它们的wcjE基因完全或部分失活，wcjE基因位于cps位点，编码一种O-乙酰基转移酶。11E血清型在携带菌株中较为罕见，但在侵袭性菌株中较为常见，这表明它在侵袭过程中存活得更好。这项工作的目的是使用基于高分辨率魔角旋转核磁共振（HR-MAS NMR）光谱的新血清分型方法，研究肺炎链球菌菌株库中11A血清型的流行病学，以区分11A和11E血清型。
收集了48株来自意大利的肺炎链球菌分离株（34株侵袭性菌株和14株携带菌株），这些菌株先前通过荚膜肿胀反应鉴定为11A血清型，通过wcjE基因测序、HR-MAS NMR光谱和基于单克隆抗体的参考流式细胞术血清分型检测（FCSA）进行研究。
11A和11E血清型的HR-MAS NMR光谱显示出不同的核磁共振峰，表明HR-MAS NMR可用于区分这些血清型，尽管HR-MAS NMR无法明确区分11Av血清变异株和11E血清型。38株分离株被确认为11A血清型，8株wcjE基因发生突变的分离株为11E血清型，1株属于11Av血清变异株，1株为11A/11Av混合群体。所有11E分离株均在侵袭性菌株中鉴定到。
我们证明了HR-MAS NMR在肺炎链球菌血清分型中具有潜在用途。在我们的菌株库中侵袭性菌株中检测到11E血清型，支持了先前的流行病学研究，表明wcjE基因的突变可能是促进肺炎链球菌在侵袭过程中存活的一种机制。在既定血清型中发现一系列免疫化学多样性，应促使人们努力开发新的血清分型方法。
