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Updated: Jan 1, 2026
An Electroporation Method to Transform Rickettsia spp. with a Fluorescent Protein-Expressing Shuttle Vector in Tick Cell Lines
Published on: October 11, 2022
New Spotted Fever Group Rickettsia Isolate, Identified by Sequence Analysis of Conserved Genomic Regions
Dar Klein1, Adi Beth-Din1, Regev Cohen2,3
1Israel Institute for Biological Research, P.O. Box 19, Ness-Ziona 74100, Israel.
Abstract:
The clinical features of spotted fever group (SFG) Rickettsia induced disease range from a mild to severe illness. The clinical complexity is even greater due to the fact that the disease can be caused by different species with varying degrees of virulence. Current knowledge asserts that the Israeli SFG (ISF) strain Rickettsia conorii israelensis is the only human pathogenic SFG member in Israel. Current diagnostic procedures distinguish between SFG and the typhus group rickettsiosis, assuming all SFG-positive clinical samples positive for ISF. Molecular studies on questing ticks over the past decade have uncovered the existence of other SFG strains besides ISF in Israel and the region. This study describes the first documented analysis of SFG-positive samples from Israeli patients with the goal of distinguishing between ISF and non-ISF SFG strains. We managed to identify a new Rickettsia isolate from three independent clinical samples in Israel which was shown to be an as-yet unknown SFG member, showing no absolute identity with any known Rickettsia species present in the NCBI database.
Insights
This study identified a novel spotted fever group (SFG) Rickettsia strain in Israeli patients, challenging the assumption that only the Israeli SFG (ISF) strain causes disease. This finding necessitates updated diagnostic approaches for SFG rickettsiosis.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Genomics
Background:
- Spotted fever group (SFG) rickettsiosis presents with diverse clinical manifestations, complicated by various virulent Rickettsia species.
- Current diagnostics in Israel assume only Rickettsia conorii israelensis (ISF) is pathogenic, overlooking other SFG strains.
- Recent tick studies indicate the presence of diverse SFG strains in Israel and surrounding regions.
Purpose of the Study:
- To differentiate between ISF and non-ISF SFG strains in clinical samples from Israeli patients.
- To identify and characterize novel SFG Rickettsia species circulating in Israel.
Main Methods:
- Molecular analysis of SFG-positive clinical samples from Israeli patients.
- Comparison of identified Rickettsia isolates against the NCBI database for species identification.
Main Results:
- Identification of a novel Rickettsia isolate from three independent clinical samples.
- The new isolate represents an unknown SFG member, distinct from all known Rickettsia species in the NCBI database.
- This discovery challenges the current diagnostic paradigm in Israel.
Conclusions:
- The existence of previously unrecognized SFG Rickettsia strains in Israel necessitates a re-evaluation of diagnostic strategies.
- This finding has significant implications for the accurate diagnosis and treatment of SFG rickettsiosis in the region.
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