Biology subjects

Labarrere, C.

Publications and source records attributed to Labarrere, C..

3 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

Description of Rickettsia senegalensis sp. nov.: a new Rickettsia species detected worldwide

Members of the genus Rickettsia are widespread obligate intracellular bacteria with high medical and veterinary relevance. While Rickettsia senegalensis was previously isolated from cat fleas, Ctenocephalides felis, in Senegal, a comprehensive polyphasic characterization is required for its formal taxonomic validation. This study aims to provide the first detailed phenotypic, ultrastructural, and genomic characterization of the type strain PU01-02. Cultivation assays demonstrated that strain PU01-02 grows aerobically in XTC-2, SF9, and LD652 cell lines at 28 {degrees}C in a CO2-free atmosphere. Ultrastructural examination via scanning electron microscopy using a backscattered electron detector confirmed its free cytoplasmic localization and a typical rickettsial morphology characterized by rod-shaped cells approximately 1.5 {micro}m in length and 0.3 {micro}m in width. Whole-genome sequencing yielded a 1.62-Mb genome with a G+C content of 33.2%, and three plasmids were detected. Genomic analyses confirmed its status as a distinct species, placing it within the transitional Rickettsia group, specifically inside the Rickettsia felis cluster. A review of epidemiological data revealed that rickettsial genes identical to those of R. senegalensis had already been identified in several hematophagous arthropods, including fleas and ticks parasitizing various hosts such as cats, dogs, opossums, and rodents worldwide. It has also been detected in cat tissues, suggesting a potential host-pathogen association. Based on these comprehensive characterization data, we formally propose Rickettsia senegalensis sp. nov. as a new species, with PU01-02 (= CSUR R184 = DSM 28250) as the type strain. RepositoriesThe genome sequence of Rickettsia senegalensis sp. nov. strain PU01-02T has been deposited in GenBank under accession number JBVYTQ000000000, and the rrs, gltA, ompB and sca4 gene sequences under accession numbers KF666476, KF666472, KF666470, KF666474, respectively. The plasmid accession numbers are PZ272915, PZ272916, and PZ272917, for pRS01, pRS02 and pRS03, respectively.

microbiology↗

bioRxiv2026

Silent Footprints of Ebolavirus in the Forest: Serological Clues from Wild Non-Human Primates in the Democratic Republic of Congo

Filoviruses, particularly Ebola virus (EBOV), remain a major public health concern in Central Africa. However, their circulation in wildlife during inter-epidemic periods remains poorly documented. Non-human primates (NHPs) may serve as ecological sentinels of viral dynamics at human-forest interfaces, yet surveillance is constrained by the limitations of invasive sampling. We conducted a non-invasive investigation of EBOV exposure in free-ranging NHPs from the Mabali Forest Reserve (Equateur Province, Democratic Republic of Congo) for Ebola virus disease. A total of 630 fecal samples were collected and screened for active infection by PCR targeting the EBOV nucleoprotein gene; all samples tested negative. Molecular identification of host species was achieved in 569 samples (90.3%). Fecal serology using an automated capillary western blot platform (JESS), targeting EBOV nucleoprotein, glycoprotein and viral protein 40 antigens, identified four seropositive individuals (0.70%), including two Cercopithecus ascanius and two C. wolfi. The detection of discrete immunoreactive bands consistent with EBOV-specific antibodies suggests prior exposure despite the absence of active outbreaks. These findings provide the first serological evidence compatible with EBOV exposure in these two Cercopithecus species and support the hypothesis of low-level or cryptic viral circulation in forest ecosystems. The study highlights the feasibility and value of fecal serology as a non-invasive One Health surveillance tool for monitoring zoonotic pathogens at wildlife-human interfaces.

microbiology↗