Analysis of the <it>Rickettsia africae </it>genome reveals that virulence acquisition in <it>Rickettsia </it>species may be explained by genome reduction

Background The Rickettsia genus includes 25 validated species, 17 of which are proven human pathogens. Among these, the pathogenicity varies greatly, from the highly virulent R. prowazekii , which causes epidemic typhus and kills its arthropod host, to the mild pathogen R. africae , the agent of African tick-bite fever, which does not affect the fitness of its tick vector. Results We evaluated the clonality of R. africae in 70 patients and 155 ticks, and determined its genome sequence, which comprises a circular chromosome of 1,278,540 bp including a tra operon and an unstable 12,377-bp plasmid. To study the genetic characteristics associated with virulence, we compared this species to R. prowazekii , R. rickettsii and R. conorii . R. africae and R. prowazekii have, respectively, the less and most decayed genomes. Eighteen genes are present only in R. africae including one with a putative protease domain upregulated at 37°C. Conclusion Based on these data, we speculate that a loss of regulatory genes causes an increase of virulence of rickettsial species in ticks and mammals. We also speculate that in Rickettsia species virulence is mostly associated with gene loss. The genome sequence was deposited in GenBank under accession number [GenBank: NZ_AAUY01000001].

Abstract licence: CC BY-NC-ND

1. 3.

   MUSCLE: a multiple sequence alignment method with reduced time and space complexity · 2004

2. 10.

   Rickettsia Phylogenomics: Unwinding the Intricacies of Obligate Intracellular Life · 2008

3. 12.

   Genome Sequence of Rickettsia bellii Illuminates the Role of Amoebae in Gene Exchanges between Intracellular Pathogens · 2006

4. 18.

   The Genome Sequence of Rickettsia felis Identifies the First Putative Conjugative Plasmid in an Obligate Intracellular Parasite · 2005

5. 21.

   Reductive Genome Evolution from the Mother of Rickettsia · 2007

6. 22.

   Detection and Identification of Spotted Fever Group Rickettsiae and Ehrlichiae in African Ticks · 2001

34 more references, whose wording the paper’s licence keeps private.

• Typing methods based on whole genome sequencing data · 2020

• Wholly Rickettsia ! Reconstructed Metabolic Profile of the Quintessential Bacterial Parasite of Eukaryotic Cells · 2017

A person counts once a day per paper. We keep no cookie and no address: a reader is a hash that changes every day. Any month under five reads shows no number.