The epidemic typhus and trench fever are risk for public health due to increased migration in southeast of Turkey.

Pediculus humanus capitis is a small ectoparasitic insect that has lived and feds on human beings for thousands of years. Molecular techniques have been used for Pediculus species identification and evolutionary, phylogenic, and ecological studies. A total of 23 adults of P. h. capitis were collected in Gaziantep, located in southeast Turkey, and DNA was isolated from all P. h. capitis using DNA extraction kit. All DNA samples were screened for investigate of Ricettsia prowazekii, Bartonella quintana and Borrelia recurrentis with real-time polymerase chain reaction. In addition, we investigated genetic variation in DNA samples of Pediculus humanus capitis using the cytochrome oxidase I genetic DNA sequence. We found 4 (17.4%) Ricettsia prowazekii and 3 (13.1%) Bartonella quintana in DNA samples of Pediculus humanus capitis, while we did not find any Bartonella recurrentis in any of the DNA samples. We demonstrated 1.8% genetic variations in DNA samples of Pediculus humanus capitis with Bartonella quintana. The phylogenetic tree based on the cytochrome oxidase I gene revealed that P. h. capitis in southeast Turkey are classified into two clades (clade A, clade B) and Bartonella quintana was found in only clade B. However, we did not find any genetic variations in other DNA samples in this region. The genetic variations may be related to P. h.capitis vector of Bartonella quintana has found in this study. In addition, this study was shown that P. h. capitis do transmit Rickettsia prowazekii and Bartonella quintana to people, epidemic typhus and trench fever may emergence in Gaziantep southeast of Turkey in the future.

Plasmids and rickettsial evolution: insight from Rickettsia felis.

BACKGROUND: The genome sequence of Rickettsia felis revealed a number of rickettsial genetic anomalies that likely contribute not only to a large genome size relative to other rickettsiae, but also to phenotypic oddities that have confounded the categorization of R. felis as either typhus group (TG) or spotted fever group (SFG) rickettsiae. Most intriguing was the first report from rickettsiae of a conjugative plasmid (pRF) that contains 68 putative open reading frames, several of which are predicted to encode proteins with high similarity to conjugative machinery in other plasmid-containing bacteria. METHODOLOGY/PRINCIPAL FINDINGS: Using phylogeny estimation, we determined the mode of inheritance of pRF genes relative to conserved rickettsial chromosomal genes. Phylogenies of chromosomal genes were in agreement with other published rickettsial trees. However, phylogenies including pRF genes yielded different topologies and suggest a close relationship between pRF and ancestral group (AG) rickettsiae, including the recently completed genome of R. bellii str. RML369-C. This relatedness is further supported by the distribution of pRF genes across other rickettsiae, as 10 pRF genes (or inactive derivatives) also occur in AG (but not SFG) rickettsiae, with five of these genes characteristic of typical plasmids. Detailed characterization of pRF genes resulted in two novel findings: the identification of oriV and replication termination regions, and the likelihood that a second proposed plasmid, pRFdelta, is an artifact of the original genome assembly. CONCLUSION/SIGNIFICANCE: Altogether, we propose a new rickettsial classification scheme with the addition of a fourth lineage, transitional group (TRG) rickettsiae, that is unique from TG and SFG rickettsiae and harbors genes from possible exchanges with AG rickettsiae via conjugation. We offer insight into the evolution of a plastic plasmid system in rickettsiae, including the role plasmids may have played in the acquirement of virulence traits in pathogenic strains, and the likely origin of plasmids within the rickettsial tree.

Reductive genome evolution from the mother of Rickettsia.

The Rickettsia genus is a group of obligate intracellular alpha-proteobacteria representing a paradigm of reductive evolution. Here, we investigate the evolutionary processes that shaped the genomes of the genus. The reconstruction of ancestral genomes indicates that their last common ancestor contained more genes, but already possessed most traits associated with cellular parasitism. The differences in gene repertoires across modern Rickettsia are mainly the result of differential gene losses from the ancestor. We demonstrate using computer simulation that the propensity of loss was variable across genes during this process. We also analyzed the ratio of nonsynonymous to synonymous changes (Ka/Ks) calculated as an average over large sets of genes to assay the strength of selection acting on the genomes of Rickettsia, Anaplasmataceae, and free-living gamma-proteobacteria. As a general trend, Ka/Ks were found to decrease with increasing divergence between genomes. The high Ka/Ks for closely related genomes are probably due to a lag in the removal of slightly deleterious nonsynonymous mutations by natural selection. Interestingly, we also observed a decrease of the rate of gene loss with increasing divergence, suggesting a similar lag in the removal of slightly deleterious pseudogene alleles. For larger divergence (Ks > 0.2), Ka/Ks converge toward similar values indicating that the levels of selection are roughly equivalent between intracellular alpha-proteobacteria and their free-living relatives. This contrasts with the view that obligate endocellular microorganisms tend to evolve faster as a consequence of reduced effectiveness of selection, and suggests a major role of enhanced background mutation rates on the fast protein divergence in the obligate intracellular alpha-proteobacteria.