Semen CD4+ T cells and macrophages are productively infected at all stages of SIV infection in macaques.

International audienceThe mucosal events of HIV transmission have been extensively studied, but the role of infected cells present in the genital and rectal secretions, and in the semen, in particular, remains a matter of debate. As a prerequisite to a thorough in vivo investigation of the early transmission events through infected cells, we characterized in detail by multi-parameter flow cytometry the changes in macaque seminal leukocytes during SIVmac251 infection, focusing on T cells, macrophages and dendritic cells. Using immunocytofluorescence targeting SIV proteins and real-time quantitative PCR targeting SIV DNA, we investigated the nature of the infected cells on sorted semen leukocytes from macaques at different stages of infection. Finally, we cocultured semen CD4(+) T cells and macrophages with a cell line permissive to SIV infection to assess their infectivity in vitro. We found that primary infection induced strong local inflammation, which was associated with an increase in the number of leukocytes in semen, both factors having the potential to favor cell-associated virus transmission. Semen CD4(+) T cells and macrophages were productively infected at all stages of infection and were infectious in vitro. Lymphocytes had a mucosal phenotype and expressed activation (CD69 & HLA-DR) and migration (CCR5, CXCR4, LFA-1) markers. CD69 expression was increased in semen T cells by SIV infection, at all stages of infection. Macrophages predominated at all stages and expressed CD4, CCR5, MAC-1 and LFA-1. Altogether, we demonstrated that semen contains the two major SIV-target cells (CD4+ T cells and macrophages). Both cell types can be productively infected at all stages of SIV infection and are endowed with markers that may facilitate transmission of infection during sexual exposure

Additional Haplogroups of Toxoplasma gondii out of Africa: Population Structure and Mouse-Virulence of Strains from Gabon

Prevalence of human toxoplasmosis in tropical African countries usually exceeds 50%. Its role as a major opportunistic infection of AIDS patients is regularly described. Due to the lack of investigation, congenital infection is certainly underestimated in Africa. Incidence of Toxoplasma ocular disease is higher in Africa and South America than in Europe. Severe cases in immunocompetent patients were described after infection acquired in Amazonia, but nothing is known about such cases in Africa. Several studies argued for a role of genotypes in the clinical expression of human toxoplasmosis, and for a geographical structuration of Toxoplasma across continents. Genetic data concerning isolates from Africa are scarce. Here, apart from the worldwide Type III, we described two main haplogroups, Africa 1 and 3. We detected genetic exchanges between urban centers favored by trade exchange and transportation. It shows how important human influence is, even in shaping the genetic structure of a zoonotic disease agent. Finding of identical haplogroups in South America suggested that these African and American strains share a common ancestor. As a higher pathogenicity in human of South American genotypes has been described, this similarity of genotypes should encourage further clinical studies with genotype analysis in Africa

Caractéristiques génétiques, morphométriques et flore fongique associée à Ips typographus (Coleoptera : Scolytinae) (application à l'estimation des niveaux de population du ravageur)

La composition de la flore fongique associée à Ips typographus et ses caractéristiques morphométriques et génétiques ont été comparées entre populations latentes et épidémiques dans diverses localités françaises. Le niveau des populations a été évalué grâce à un relevé des dommages dans chacun des peuplements suivis. Les conditions épidémiques ont eu un effet négatif sur la taille des insectes, probablement suite à une intensification de la compétition intraspécifique. Aucun effet n'a pu être détecté sur les deux autres paramètres. La flore fongique a toutefois montré une composition spécifique particulière, une variabilité intraspécifique importante et une possible influence sur l'agressivité des populations d'insectes. L'étude de génétique, suite au développement de marqueurs microsatellites, a permis de mettre en évidence une faible structuration des populations à l'échelle française.ORLEANS-BU Sciences (452342104) / SudocSudocFranceF

Stimulation of tree defenses by Ophiostomatoid fungi can explain attack success of bark beetles on conifers

• Our aim is to present why the hypothesis, that Ophiostomatoid fungi play an important role in the establishment of most bark beetle species on living conifers, is valuable. • After summarizing knowledge about the relationships of bark beetles with conifers and fungi, we conclude that controversy results from misinterpretations when using fungal pathogenicity to demonstrate the role of Ophiostomatoid fungi in beetle establishment on host trees. • We demonstrate that fungal pathogenicity is not the right parameter to appreciate the role of fungus in beetle establishment on host trees. We argue that artificial low density inoculations that allow the appreciation of fungus ability to stimulate tree defenses and thus to help beetles in overcoming tree resistance must be used in complement to mass inoculations. In both cases, results must be expressed in terms of tree defense stimulation rather than in terms of tree killing. (i

On the importance of getting fine-scale temperature records near any surface

Commentary on “SoilTemp: a global database of near-surface temperature” by Lembrechts et al.International audienceThe pressing need to identify the ecological consequences of climate changes boosted the development of macroecological approaches as well as climatological tools. Nevertheless, the major pitfall remains that the actual climatic conditions experienced by organisms in their microhabitat and across their home range are largely ignored. In this context, Lembrechts et al. (2020) are initiating a new global database of near-surface temperatures, especially focusing on above ground (up to 2 m) and below ground soil temperatures. This approach is welcome to assess the amplitude of microclimate change around the world and across biomes. Here, I extend this approach by highlighting that fine-scale temperature heterogeneity can be large over short times frames (minutes to hours) and short distances (centimeters to meters) in forest covers. This mosaic of microclimates likely influences the response of organisms to climate change. Further, the SoilTemp database could be expanded to the other interfaces with atmosphere

Population structure of Toxoplama gondii in gabon

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Effect of temperature on the reproductive success, developmental rate and brood characteristics of Ips sexdentatus (Boern.)

1- Global warming is predicted to enhance the development rate and increase the number of generations in multivoltine insects. For secondary forest pests, such as the pine bark beetle Ips sexdentatus, the resulting increase in population level could trigger more frequent outbreaks. However, this positive effect could be outweighed by a temperature-dependent decrease in offspring quality.2- To test these hypotheses, we carried out a laboratory rearing experiment with maritime pine logs at six temperature regimes reproducing hourly fluctuations and averaging 12–25.5 °C. We estimated the thermal requirements for a complete development of the beetle and the number of offspring per female. The offspring quality was estimated using three traits: dry body weight, elytra length and lipid content.3- The minimum and maximum developmental threshold were estimated at 10.9 and 36 °C, respectively, and the thermal requirements for complete development were estimated at 517 degree-days. We predicted a mean of two generations per year in southwestern France, although an additional generation could occur during warmer years. The number of offspring increased exponentially with temperature, although we observed a curvilinear response of offspring traits to temperature, with optima at 15–18 °C.4- This suggests that there are trade-offs between productivity and quality of offspring. Global warming is therefore likely to result in higher number of generations of I. sexdentatus per year, with larger broods but of reduced fitness at high temperatures

Isolation and genotyping of Toxoplasma gondii from different areas in Gabon.

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Human and animal seroprevalence of Toxoplasma gondii comparison between a rural and urban area in Gabon.

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