Biology subjects

Martineau, A.

Publications and source records attributed to Martineau, A..

4 recordsLinked to original sources

bioRxiv2025

Digital PCR detection of Mycobacterium tuberculosis and HIV-1 co-localization in spinal tuberculosis biopsies

BackgroundMycobacterium tuberculosis (Mtb) and HIV-1 co-infection in tissues is suggested to favour reciprocal replication, infection and reservoir expansion. Yet, confirmation of this detrimental synergism in diseased tissues is limited. MethodsIn this prospective study of 25 adults investigated for spinal tuberculosis (STB) in South Africa (13 (52%) people living with HIV-1 (PLWH), on antiretroviral treatment) 25 open surgery or CT-guided biopsies were collected and portioned into 93 segments. Extracted DNA was analysed by droplet digital PCR (ddPCR) to detect and quantify Mtb complex (MTBC) (rpoB, IS6110), HIV-1 (pol, gag) and Human (RPP30) gene copies. ddPCR sensitivity for Mtb was validated against Xpert-Ultra and culture. Total biopsy and intra-biopsy variation in pathogen DNA abundance, co-detection, and relationships to human cellularity, HIV status, and peripheral viral load (VL) evaluated. ResultsddPCR detected MTBC DNA in biopsies from 10/10 (100%) culture-confirmed STB, 5/6 (83%) Xpert Ultra-confirmed STB and 4/9 (44%) diagnosed Not STB (all 4 with previous pulmonary TB). Detected MTBC ranged from 8-59,144 rpoB copies/biopsy. RpoB copies/million human cells were higher in biopsies from PLWH (p=0.0096) and positively correlated with matched-segment HIV-1 pol copies/million cells (r=0.40; p=0.0003), but not VL. HIV-1 DNA was detected in all PLWH biopsies, four with undetectable VL. HIV-1 pol copies/million cells were higher in segments with MTBC DNA co-detected (p=0.011) and also correlated with VL (r=0.91; p=0.0003). ConclusionsReciprocal relationships exists between Mtb and HIV-1 abundance in spinal tissue. Findings support investigating TB-HIV co-infected tissue segments to characterise how the immune microenvironment impacts HIV-1/Mtb reservoir persistence and/or expansion.

molecular biology↗

bioRxiv2024

Conserving steppe-land birds under climate change: a gap analysis for the Eurasian Stone-curlew (Burhinus oedicnemus) in the Western Palearctic

Climate change is having dramatic impacts on the distribution of animals. Birds, and especially steppe-land birds, are particularly sensitive to climate change and identifying areas that are critical for their conservation is pivotal, as well as estimating the expected impact on these areas under different climate and land use change scenarios. In-situ climate refugia (areas suitable under both current and future climates) are especially valuable for the conservation of climate-sensitive species, and is therefore important to identify them and evaluate their coverage by protected areas. Via species distribution modelling, we aimed to identify in-situ climate refugia in the Western Palearctic for the Eurasian Stone-curlew Burhinus oedicnemus, an umbrella steppic species of conservation concern. We used a comprehensive dataset of occurrences in the breeding period to fine-tune a Maxent species distribution model and project it under three carbon emission scenarios of increasing severity for the year 2050. We then identified in-situ climate refugia and performed a gap analysis estimating the percentage of refugia falling within the network of currently protected areas. In all modelled future scenarios a northward expansion of suitable breeding habitats was predicted, and suitable areas had similar extents, with a slight increase of the overall suitability under more severe scenarios. According to our results, the Eurasian Stone-curlew has the potential to maintain viable populations in the Western Palearctic, even though dispersal limitations might hinder the colonization of newly suitable breeding areas. In-situ climate refugia were mainly identified outside protected areas, particularly in Northern Africa and the Middle East. Therefore, we advocate targeted actions in climate refugia to promote the conservation of this and other steppe-land species under global environmental change.

ecology↗

bioRxiv2021

Projected dynamics of breeding habitat suitability for a steppe-land bird warrant anticipatory conservation actions

Understanding spatial and temporal variations of habitat suitability is fundamental for species conservation under global change. Steppic species are particularly sensitive to anthropogenic change and have undergone large declines in the last decades. We aimed to describe current and future breeding habitat suitability for the Eurasian stone-curlew Burhinus oedicnemus, a steppic species of conservation concern, and to identify critical areas for its conservation. We collected 1628 presence records covering the period 1992-2016. We developed a species distribution model using a dynamic Maxent algorithm and a set of pseudo-absences with a spatial density weighted on a fixed kernel density estimated on the presences, to mitigate the potential sampling bias. We projected this model under a set of carbon emission, socioeconomic and land-use/land-cover scenarios for the years 2030, 2050, 2070 and 2090. Finally, we described the cell-wise and mean change of breeding habitat suitability through consecutive time intervals and identified the areas critical for the species conservation. All scenarios predicted a short-term northward shift of suitable areas, followed by a period of stability. We found no consistent trends in the mean change of breeding habitat suitability, and similar extents of suitable areas under current and future scenarios. Critical areas for the conservation of the species are mainly located in Northern Europe, Israel and parts of North Africa, the Iberian Peninsula and Italy. According to our results, the Eurasian stone-curlew has the potential to maintain viable populations in the Western Palearctic, but dispersal limitations might hinder the colonization of shifted suitable areas. Targeted conservation interventions in the critical areas are therefore recommended to secure the future of the species under global change.

ecology↗

bioRxiv2020

Cellular and Cytokine Responses in the Granulomas of Asymptomatic Cattle naturally infected with Mycobacterium bovis in Ethiopia

Cellular (CD3+ T cell and CD68+ macrophages), cytokines (IFN-{gamma}+ and TNF-+) and effector molecule (iNOS+) responses were evaluated in the lymph nodes and tissue of cattle naturally infected with Mycobacterium bovis. Detailed post mortem and immunonohistochemical examinations of lesions were performed on 16 cows positive for single intradermal cervical comparative tuberculin test (SICCTT) and identified from dairy farms located around the Addis Ababa City. The severity of the gross lesion was significantly higher (p=0.003) in M. bovis culture positive (n=12) cows than in culture negative (n=4). Immunohistochemical techniques showed that the mean percentage labelling of CD3+ T cells decreased as the stage of granuloma increased from stage I to stage IV in culture positive cows (p<0.001). On the other hand, the proportional fraction of CD68+ macrophages and the concentrations of IFN-{gamma}+, TNF-+ and iNOS+ increased significantly from stage I to stage IV (p< 0.001) in culture positive cows. At the early stage of the granuloma, the culture negative cows showed significantly higher mean proportions of CD68+ macrophages (p=0.03) as well as the concentrations of iNOS+ (p=0.007) compared to culture positive cows. Similarly, at advanced granuloma stages, culture negative cows demonstrated significantly higher mean proportions of CD3+ T cells (p< 0.001) compared to culture positive cows. Thus, the present study demonstrated that following natural infection of cows with M. bovis, as the stage of granuloma increases from stage I to stage IV, the proportion of CD3+ cells decreases while the immunolabeling fraction of CD68+ macrophages, IFN-{gamma}+, TNF- and iNOS+ increases.

immunology↗