Proteomic analysis of Rickettsia akari proposes a 44 kDa-OMP as a potential biomarker for Rickettsialpox diagnosis

Abstract

Background: Rickettsialpox is a febrile illness caused by the mite-borne pathogen Rickettsia akari. Several cases of this disease are reported worldwide annually. Nevertheless, the relationship between the immunogenicity of R. akari and disease development is still poorly understood. Thus, misdiagnosis is frequent. Our study is aiming to identify immunogenic proteins that may improve disease recognition and enhance subsequent treatment. To achieve this goal, two proteomics methodologies were applied, followed by immunoblot confirmation. Results: Three hundred and sixteen unique proteins were identified in the whole-cell extract of R. akari. The most represented protein groups were found to be those involved in translation, post-translational modifications, energy production, and cell wall development. A significant number of proteins belonged to amino acid transport and intracellular trafficking. Also, some proteins affecting the virulence were detected. In silico analysis of membrane enriched proteins revealed 25 putative outer membrane proteins containing beta-barrel structure and 11 proteins having a secretion signal peptide sequence. Using rabbit and human sera, various immunoreactive proteins were identified from which the 44 kDa uncharacterized protein (A8GP63) has demonstrated a unique detection capability. It positively distinguished the sera of patients with Rickettsialpox from other rickettsiae positive human sera. Conclusion: Our proteomic analysis certainly contributed to the lack of knowledge of R. akari pathogenesis. The result obtained may also serve as a guideline for a more accurate diagnosis of rickettsial diseases. The identified 44 kDa uncharacterized protein can be certainly used as a unique marker of rickettsialpox or as a target molecule for the development of more effective treatment.

Genomic evolution and adaptation of arthropod-associated Rickettsia

“…Our work has shed light on the complex genomic history of the obligate intracellular Rickettsia spp. It represents a comprehensive overview into post-genomic and experimental studies such as RNAseq and small regulatory RNAs 91 – 94 , proteomics 27 , 95 – 98 , genetic transformation 9 and gene functions 16 , 99 – 101 aiming at better understanding the molecular mechanisms of critical genes driven by evolutionary processes, which have influenced the adaptation, survival and virulence of Rickettsia spp.…”

Detection of Coxiella antibodies in ruminants using a SucB recombinant antigen

“…Liquid chromatography–tandem mass spectrometry (LC-MS/MS) was performed as described previously. 6,15 Briefly, an electrophoresis band was cut using a scalpel blade and destained in 50 mM ammonium bicarbonate buffer and 50% acetonitrile. Using 10 mM dithiothreitol and 50 mM iodoacetamide, the sample was reduced and alkylated.…”