Biology subjects

Davoust, B.

Publications and source records attributed to Davoust, B..

8 recordsLinked to original sources

bioRxiv2026

Continental-scale survey of Treponema pallidum in African nonhuman primates: expanding the range to the Mediterranean basin

Background: Treponema pallidum, the causative agent of yaws, bejel, and syphilis, is a significant pathogen affecting both humans and nonhuman primates (NHPs). While its presence is documented in several African NHP species, the continental-scale distribution, ecological drivers, and status in North African populations remain poorly understood. We conducted a large-scale, non-invasive survey to investigate the circulation of T. pallidum across African NHP populations and evaluate geographical and ecological patterns of exposure. Results: A total of 1,696 fecal samples from 11 wild NHP species collected across five African countries were screened for anti-T. pallidum antibodies using an automated chemiluminescent Simple Western assay, and fecal and dipteran samples were analyzed by molecular methods. Widespread seropositivity was observed across all African sites and multiple primate taxa, including great apes and cercopithecids. We provide the first evidence of T. pallidum antibodies in Barbary macaques (Macaca sylvanus) from North Africa, extending the known distribution of the pathogen to the Mediterranean basin. In West Africa, chimpanzees (Pan troglodytes verus) from Senegal and Guinea exhibited particularly high seroprevalence, confirming this region as a major endemic hotspot. In Central Africa, substantial circulation was documented in Cercopithecus wolfi, Cercopithecus ascanius, and western lowland gorillas (Gorilla gorilla gorilla). Arid/savanna biomes showed significantly higher exposure than Mediterranean and tropical rainforest biomes. No T. pallidum DNA was detected in fecal or dipteran samples. Conclusion: Our findings demonstrate widespread circulation of T. pallidum among African NHPs, reveal its presence in North African primate populations for the first time. The observed high seroprevalence, coupled with significant variations across species and geographical regions, suggests the existence of multiple transmission pathways adapted to specific host behaviors and environmental constraints. These results support the existence of a broad multihost sylvatic reservoir and provide new insights into the ecology of T. pallidum, with important implications for wildlife health, One Health surveillance, and yaws eradication efforts.

microbiology↗

bioRxiv2026

Ecological Drivers of Nontuberculous Mycobacteria in Aquatic Systems: Biodiversity, Niche Competition, and Pathogen Emergence

Microbial diversity remains largely unexplored across environments and scales, notably because at local scales many microbial taxa exist under a dormant state. Microbial biogeography is shaped by edaphic and ecological drivers, and shifts in microbial community composition are frequently associated with host community structure and health. Nontuberculous mycobacteria represent a striking example of environmental microorganisms with opportunistic pathogenic potential. Unfortunately, data on their diversity, distribution, and ecological interactions in aquatic environments remain limited. However, understanding competition for niche space and the role of abiotic and biotic factors shaping their biogeography is crucial for predicting disease emergence and transmission. Here we aimed at i) identifying microhabitat abiotic and biotic drivers influencing their distribution, ii) assessing the predictability of their diversity and distribution across continents, and iii) examining potential exclusion or associations between pathogenic and nonpathogenic mycobacterial species. By deploying an eDNA-based metabarcoding approach from freshwater samples collected in urban and rural sites in French Guiana and Cote dIvoire, we have boosted our understanding of environmental mycobacteria ecology by highlighting the influence of habitat type, abiotic factors, and microbial interactions on mycobacterial distribution. In addition, the detection of pathogenic species further highlighted the importance of environmental reservoirs in mycobacterial disease transmission.

ecology↗

bioRxiv2022

Evidence of antibodies against SARS-CoV-2 in wild mustelids from Brittany (France)

In the French region of Brittany, mainly in the department of the Cotes dArmor, during the first semester of 2021, seropositivity for SARS-CoV-2 was detected in five wild mustelids out of 32 animals tested. Anti-SARS-CoV-2 IgG against at least four out of five recombinant viral proteins (S1 receptor binding domain, nucleocapsid, S1 subunit, S2 subunit and spike) were detected using automated western blot technique in three martens (Martes martes) and two badgers (Meles meles). An ELISA test also objectified seropositivities. Although the 171 qPCRs carried out on samples from the 33 mustelids were all negative, these preliminary results (observational study) nevertheless bear witness to infections of unknown origin. The epidemiological surveillance of Covid-19 in wildlife must continue, in particular with the tools of efficient serology.

microbiology↗

bioRxiv2020

Stool serology: development of a non-invasive immunological method for the detection of Enterovirus-specific antibodies in Congo gorilla feces

The incidence of poliovirus has significantly reduced by as much as 99.9% globally. Alongside this, however, vaccine-associated paralytic poliomyelitis has emerged. Recently, a new recombinant virus (Enterovirus C/Poliovirus) was identified in humans working as eco-guards and in gorillas in Democratic Republic of Congo, including one gorilla with polio-like sequelae. A strain of this recombinant virus (Ibou002) was also isolated from gorilla faeces. In order to assess the potential role of poliovirus infection, we have developed and optimised a protocol, based on the lyophilisation and solubilisation of small volumes of stool extracts, to detect specific antibodies. First, total immunoglobulins was detected in the concentrated stool extracts. Specific antibodies were then detected in 4/16 gorilla samples and 2/3 human samples by western blot using both the polio vaccine antigen and the Ibou002 antigen and by ELISA using the polio vaccine antigen. Humoral responses were greater with the Ibou002 antigen. We therefore suggest that this recombinant virus could lead to a polio-like disease in the endangered western lowland gorilla. The development of a non-invasive method to detect microorganism-specific immunoglobulins from faecal samples opens up new perspectives for the exploration of humoral responses of pathogens in animals and a greater understanding of zoonotic infectious diseases.

microbiology↗

bioRxiv2020

Stool methanogens in intestine mammal species.

Methanogens are being members of anaerobe microbiota of the digestive tract of both human and mammals. However, the sources, modes of acquisition and dynamics of digestive tract methanogens remain poorly investigated. In this study, we aimed to expand the spectrum of animals which could be sources of methanogens for human, by exploring methanogen carriage in animals in contact with the general population or with some restricted populations; comparing the repertoire of animal methanogens with the one of human methanogens in order to question methanogens as zoonotic microorganisms. We used RT-PCR, PCR-sequencing and multispacer sequence typing to investigate the presence of methanogens in 407 fecal specimens collected from nine different mammalian species. We detected by RT-PCR, the presence of methanogen DNA in all mammals here investigated and none of the negative controls. We obtained by sequencing, seven different species of methanogens, of which three (Methanobrevibacter smithii, Methanobrevibacter millerae and Methanomassiliicoccus luminyensis) are known to be part of the methanogens present in the human digestive tract. We obtained 24 M. smithii by PCR-sequencing including 12/24 (50%) in pigs, 6/24 (25%) in dogs, 4/24 (16.66%) in cats, and 1/24 (4.16%) in both sheep and horses. Genotyping these 24 M. smithii revealed five different genotypes, all know in humans. Our results are fairly representative of the methanogen community present in the digestive tract of certain animals domesticated by humans and other future studies must be done to try to cultivate methanogens here detected by molecular biology to better understand the dynamics of methanogens in animals and also the likely acquisition of methanogens in humans through direct contact with these animals or through consumption of the meat and/or milk of certain animals, in particular cows.

microbiology↗

bioRxiv2019

Development of a multiplexed qPCRs-based approach for the diagnosis of Dirofilaria immitis, D. repens, Acanthocheilonema reconditum and the others filariosis

BackgroundThe frequent canine filariosis are caused by zoonotic filarial nematodes called Dirofilaria immitis, D. repens and Acanthocheilonema reconditum (Spirurida: Onchocercidae). The absence of reliable diagnostic tools to diagnose and discriminate between these infections as well as their different forms constitutes a major obstacle to their control. The serological diagnosis of heartworm disease has recently shown both sensitivity and specificity problems. FindingsHerein, we developed and set up a novel molecular approach for an improved detection of the occult and non-occult filarioses, especially those caused by A. reconditum, D. immitis and D. repens as well as their differential diagnosis based on qPCRs assays. This approach designated the "Combined multiplex approach", proceeds as follows: Filaria and wolbachia identification using the newly customized 28S-based pan-filarial and 16S-based pan-wolbachia qPCRs, respectively, followed by the fast typing method of positive samples using the triplex qPCR targeting A. reconditum, D. immitis and D. repens, and a duplex qPCR targeting Wolbachia of D. immitis and that of D. repens. The analytical sensitivity of the newly qPCR systems was confirmed by the detection limit of wolbachia and filaria DNA ranged from 5E-1 to 1.5E-4 mf/ml of blood with an R{superscript 2} higher than 0.99, Cohens Kappa agreement ranged from 0.98 to 1. The approach was complemented by a pan-filarial COI and pan-Wolbachia ftsZ PCR for the identification of other filarial parasites and their Wolbachia, respectively. When tested on clinical samples, the results are as follows: 29.2 % (49/168) tested positive to at least filariae or wolbachiae DNA. 19 samples of them tested positive for filarial DNA, 9 for wolbachia DNA and 21 for both. Filarial species and Wolbachia genotype were also identified by the combined multiplex approach from all the positive samples. The single DNA of D. immitis was identified in 12 samples, D. repens in 7, and A. reconditum in 15 samples, the co-infection was observed in 5 samples, 4 for both Dirofilaria and one harbored the three species. Therefore, 22 samples were positive for Wolbachia endosymbiont of D. immitis, 3 for that of D. repens and 5 for both genotypes. A newly duplex qPCR developed for the differential diagnosis of heartworm and French heartworm (Angiostrongylus vasorum) was successfully validated in vitro. However, no DNA of this latter was detected in canine blood samples used in this study. The immunochromatographic test for dirofilariasis antigen during evaluation before and after thermal pretreatment of sera showed substantial agreement (K=0.6) and weak agreement (K=0.15), respectively. ConclusionThe proposed molecular tool targeting filarial genes and associated Wolbachia genes is a reliable tool for the exploration and diagnosis of occult and non-occult canine filariasis. We believe that the current diagnosis of heartworm based on antigen detection should be always confirmed by qPCR-based essays; the heat-pretreatment of sera is useless and strongly discouraged.

molecular biology↗

bioRxiv2019

Mycobacteria fecal shedding in wild boars (Sus scrofa), South-eastern France

The recent recrudescence of tuberculosis in cattle has implicated wild boar as a reservoir and vector of this disease, which led to the investigation of fecal shedding of the causative Mycobacterium bovis. In the Provence region of France, wild boars are very abundant, and the current study was carried out to assess the presence of tuberculous and nontuberculous mycobacteria in feces of wild boar population. W e developed an original protocol allowing the fast isolation of mycobacteria by combining a 1%-chlorhexidine decontamination of fecal matter with culture on MOD9 medium. Colonies were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, combined with DNA sequencing. This protocol yielded no tuberculous mycobacteria among ninety-nine wild boar fecal samples collected in the Provence region. However, non-tuberculous mycobacteria were isolated from five samples (5.05%), including Mycobacterium peregrinum, Mycobacterium vaccae and Mycobacterium setense, the last species being previously unreported in the wild boar; in addition to two positive samples for Nocardia spp. In conclusion, wild boars in southeastern France are not shedding tuberculosis agents, but they could constitute a reservoir of human non-tuberculous mycobacteriosis in selected populations directly exposed to wild boars.

microbiology↗

bioRxiv2017

African Nonhuman Primates Are Infected With The Yaws Bacterium Treponema pallidum subsp. pertenue

Treponema pallidum subsp. pertenue (TPE) is the causative agent of yaws. The disease was subject to global eradication efforts in the mid 20th century but reemerged in West Africa, Southern Asia, and the Pacific region. Despite its importance for eradication, detailed data on possible nonhuman disease reservoirs are missing. A number of African nonhuman primates (NHPs) have been reported to show skin ulcerations suggestive of treponemal infection in humans. Furthermore antibodies against Treponema pallidum (TP) have been repeatedly detected in wild NHP populations. While genetic studies confirmed that NHPs are infected with TP strains, subspecies identification was only possible once for a strain isolated in 1966, pinpointing the involvement of TPE. We therefore collected a number of recently isolated simian TP strains and determined eight whole genome sequences using hybridization capture or long-range PCR combined with next-generation sequencing. These new genomes were compared with those of known human TP isolates. Our results show that naturally occurring simian TP strains circulating in three African NHP species all cluster with human TPE strains and show the same genomic structure as human TPE strains. These data indicate that humans are not the exclusive host for the yaws bacterium and that a One Health approach is required to achieve sustainable eradication of human yaws.

microbiology↗