Biology subjects

Aboudharam, G.

Publications and source records attributed to Aboudharam, G..

5 recordsLinked to original sources

bioRxiv2022

Dental pulp metagenomics reveals ancient human Herpesviridae.

Following a recent report on ancient human Herpesviridae (HHV), we adapted a standard protocol used for the high-throughput sequencing of modern DNA to recover ancient DNA (aDNA) from dental pulp specimens collected at two historical burial sites. Investigation of 36 soldiers buried in Sevastopol, Crimea, during the 1853-1856 Crimean War yielded genomic sequences covering 8.5% of the herpes simplex virus (HSV)-1 genome, 15.7% of the HSV-2 genome, 1.9% of the Epstein-Barr virus (EBV) genome and 3.9% of the cytomegalovirus genome. Further investigation of 16 civilians buried in the 17th century in Amiens, France, yielded genomic sequences covering 9.8% of the HHV-1 genome and 2.2% of the HHV-6A genome; all data obtained with parallel negative controls was appropriately negative. Specific qPCRs confirmed the presence of four HSV-1, two HSV-2 and one EBV sequences in Sevastopol and two HSV-1 and one HHV-6 sequences in Amiens. HHV-6 was further detected by fluorescent in situ hybridization. These results demonstrated the usefulness of modern metagenomic protocols for high-throughput sequencing of aDNA in dental pulp.

microbiology↗

bioRxiv2020

Human dental pulp stem cells: a sanctuary for relapsing Bartonella quintana.

Bartonella quintana is a facultative intracellular bacterium responsible for relapsing fever, an example of non-sterilizing immunity. The cellular sanctuary of B. quintana in-between febrile relapses remains unknown but repeated detection of B. quintana in dental pulp specimens suggested long-term half-life dental pulp stem cells (DPSCs) as candidates. As the capacity of DPSCs to internalize microscopic particles was unknown, we confirmed that DPSCs internalized B. quintana bacteria: Gimenez staining and fluorescence microscopy localized B. quintana bacteria inside DPSCs and this internalization did not affect the cellular multiplication of DPSCs during a one-month follow-up despite the increase in the bacterial load. B. quintana-infected DPSCs did not produce Tumor Necrosis Factor- whereas an important production of Monocytes Chemoattractant Protein-1 was observed. These unprecedented observations suggested the possibility that DPSCs were shelters for the long-term persistence of B. quintana in the host, warranting further experimental and clinical investigations.

microbiology↗

bioRxiv2020

A 2,000-year-old specimen with intraerythrocytic Bartonella quintana

Photogrammetry and cascading microscopy investigations of dental pulp specimens collected from 2,000-year-old individuals buried in a Roman necropolis in Besancon, France, revealed unprecedented preserved tissular and cellular morphology. Photogrammetry yielded 3-D images of the smallest archaeological human remain ever recovered. Optical microscopy examinations after standard hematoxylin-phloxine-saffron staining and anti-glycophorin A immunohistochemistry exposed dental pulp cells, in addition erythrocytes were visualized by electron microscopy, which indicated that the ancient dental pulp trapped a blood drop. Fluorescence in situ hybridization applied on red blood cells revealed the louse-borne pathogen Bartonella quintana, a finding confirmed by polymerase chain reaction assays. Through paleohistology and paleocytology, we demonstrate that ancient dental pulp preserved intact blood cells at the time of the individuals death, offering an unprecedented opportunity to engage in direct and indirect tests to diagnose pathogens in ancient buried individuals.

microbiology↗

bioRxiv2020

Five millennia of Bartonella quintana bacteremia.

Bartonella quintana caused trench fever in the framework of two World Wars and is now recognized as an agent of re-emerging infection. Many reports indicated the popularity of B. quintana exposure since the 90s. For evaluating its prevalence in ancient populations, we used real-time PCR to detect B. quintana DNA in 400 teeth collected from 145 individuals dating from the 1st to 19th centuries in nine archeological sites with the presence of negative controls. Fishers exact test was used to compare the prevalence of B. quintana detection in civil and military populations. B. quintana DNA was confirmed in a total of 28/145 (19.3%) individuals, comprising 78 citizens and 67 soldiers, 20.1% and 17.9% of which were positive for B. quintana bacteremia, respectively. This study collected previous studies on these ancient samples and showed that the presence of B. quintana infection followed the course of time in human history; a total of 14/15 sites from five European countries had a positive prevalence. The positive rate in soldiers was higher than those of citizens, with 20% and 18.8%, respectively, in the 18th - 19th centuries, but the difference in frequency was not significant. These results confirmed the role of dental pulp in diagnosing B. quintana bacteremia in ancient populations and showed the incidence of B. quintana in both citizens and soldiers. Many recent findings contributed to understanding the coevolution of the relationship between B. quintana and humans.

microbiology↗

bioRxiv2019

Culture of salivary methanogens assisted by chemically produced hydrogen

Methanogen cultures require hydrogen produced by fermentative bacteria such as Bacteroides thetaiotaomicron (biological method). We developed an alternative method for hydrogen production using iron filings and acetic acid with the aim of cultivating methanogens more efficiently and more quickly (chemical method). We developed this new method with a reference strain of Methanobrevibacter oralis, compared the method to the biological reference method with a reference strain of Methanobrevibacter smithii and finally applied the method to 50 saliva samples. Methanogen colonies counted using ImageJ software were identified using epifluorescence optical microscopy, real-time PCR and PCR sequencing. For cultures containing the pure strains of M. oralis and M. smithii, colonies appeared three days postinoculation with the chemical method versus nine days with the biological method. The average number of M. smithii colonies was significantly higher with the chemical method than with the biological method. There was no difference in the delay of observation of the first colonies in the saliva samples between the two methods. However, the average number of colonies was significantly higher when using the biological method than when using the chemical method at six days and nine days postinoculation (Students test, p = 0.005 and p = 0.04, respectively). The chemical method made it possible to isolate four strains of M. oralis and three strains of M. smithii from the 50 saliva samples. Establishing the chemical method will ease the routine isolation and culture of methanogens.

microbiology↗