PD-L1 Blockade Differentially Impacts Regulatory T Cells from HIV-Infected Individuals Depending on Plasma Viremia

Blocking the PD-1/PD-L1 pathway has emerged as a potential therapy to restore impaired immune responses in human immunodeficiency virus (HIV)-infected individuals. Most reports have studied the impact of the PD-L1 blockade on effector cells and neglected possible effects on regulatory T cells (Treg cells), which play an essential role in balancing immunopathology and antiviral effector responses. The aim of this study was to define the consequences of ex vivo PD-L1 blockade on Treg cells from HIV-infected individuals. We observed that HIV infection led to an increase in PD-1+ and PD-L1+ Treg cells. This upregulation correlated with disease progression and decreased under antiretroviral treatment. Treg cells from viremic individuals had a particularly high PD-1 expression and impaired proliferative capacity in comparison with Treg cells from individuals under antiretroviral treatment. PD-L1 blockade restored the proliferative capacity of Treg cells from viremic individuals but had no effect on its suppressive capacity. Moreover, it increased the viral production in cell cultures from viremic individuals. This increase in viral production correlated with an increase in Treg cell percentage and a reduction in the CD4/Treg and CD8/Treg cell ratios. In contrast to the effect of the PD-L1 blockade on Treg cells from viremic individuals, we did not observe a significant effect on the proliferative capacity of Treg cells from individuals in whom viremia was controlled (either spontaneously or by antiretroviral treatment). However, PD-L1 blockade resulted in an increased proliferative capacity of HIV-specific-CD8 T cells in all subjects. Taken together, our findings suggest that manipulating PD-L1 in vivo can be expected to influence the net gain of effector function depending on the subject’s plasma viremia.     

Reassessment of the vocal repertoire of a nest-building gladiator frog,Boana pardalis (Anura,Hylidae, Cophomantinae): implications for its diagnosis within the B. faber species group

In this study, we re-describe the advertisement and territorial calls of Boana pardalis, carry out an acoustic comparison between the studied species and the other congeners of the B. faber group, and report for the first time the tympanic amplexus for the studied species. The advertisement call of B. pardalis can be used to supplement its diagnosis in the B. faber group based on temporal call traits, e.g. emission rate and emission pattern, as well as the call envelope.     

Modelling the effect of forest cover on shallow landslides at the river basin scale

The potential for reducing the occurrence of shallow landslides through targeted reforestation of critical parts of a river basin is explored through mathematical modelling. Through the systematic investigation of land management options, modelling allows the optimum strategies to be selected ahead of any real intervention in the basin. Physically based models, for which the parameters can be evaluated using physical reasoning, offer particular advantages for predicting the effects of possible future changes in land use and climate. Typically a physically based landslide model consists of a coupled hydrological model (for soil moisture) and a geotechnical slope stability model, along with an impact model, such as basin sediment yield. An application of the SHETRAN model to the 65.8-km² Guabalcón basin in central Ecuador demonstrates a technique for identifying the areas of a basin most susceptible to shallow landsliding and for quantifying the effects of different vegetation covers on landslide incidence. Thus, for the modelled scenario, increasing root cohesion from 300 to 1500 Pa causes a two-thirds reduction in the number of landslides. Useful information can be obtained even on the basis of imperfect data availability but model output should be interpreted carefully in the light of parameter uncertainty.     

A phylogenetic study of the Thygater‐Trichocerapis group and new scopes for the subgenera of Thygater Holmberg, (Hymenoptera,Apidae)

The bee tribe Eucerini is a large monophyletic taxon occurring in all continents, except Oceania and Antarctica, but far more diverse in the Americas and, especially, in the Neotropics. The phylogenetic relationships within its subtribe Eucerina, which contains the bulk of Eucerini diversity, is poorly understood, this being especially true for the relationships among its Neotropical representatives, which have been poorly represented in all phylogenetic studies, including Eucerini, to date. This leads to a generalized lack of confidence on the monophyly of the groups currently accepted as genera and subgenera. Here, a phylogenetic study based on three molecular markers (COI, 18S, and 28S, totalling about 1700 bp) and 58 morphological characters is presented as a contribution to the understanding of the relationships of the so‐called Thygater‐Trichocerapis group, and especially of the genus Thygater Holmberg, which has not previously been extensively sampled. Representatives of Trichocerapis, including its monotypic subgenus T. (Dithygater), are included for the first time in a phylogenetic study. The main results were: (i) support for the monophyly of the Thygater‐Trichocerapis group; (ii) support for the monophyly of Thygater; (iii) recognition of two main clades in Thygater, each one containing the type species of one of the previously recognized subgenera; and (iv) additional support for the position of Alloscirtetica as sister to all remaining Eucerina. Based on these results a redefinition of the scope of the two subgenera of Thygater is proposed, with changes in the subordination of three of its species, T. (Nectarodiaeta) chaetaspis comb.n. , T. (Nectarodiaeta) paranaensis comb.n. and T. (Thygater) mexicana comb.n.     

Host-cell invasion by Trypanosomacruzi: Role of cell surface galactose residues

Alpha-galactosidase treatment of blood, insect and intracellular forms of $\text{T.}\text{cruzi}$ enhanced their ability to associate with mouse peritoneal macrophages or rat heart myoblasts as evidenced by significant increases in both the percentage of infected cells and the number of parasites per cell. The magnitude of the enhancement was greater with invasive (blood and insect) than with noninvasive (intracellular) forms of the parasite. The enzyme effect was reversible, attaining total recovery in 2.5 hr. By contrast, when either host cell was pretreated with the enzyme, the extent of cell-parasite association was significantly reduced. These results indicate that galactose residues on $\text{T.}\text{cruzi}$ and host cells modulate their association in opposite ways.     

Molecular phylogeny of the New World Dipsadidae (Serpentes: Colubroidea): a reappraisal

We present a phylogenetic analysis of the New World dipsadids based on an expanded data matrix that includes 246 terminal taxa including 196 dipsadids. The species are sampled for eight genes (12S, 16S, cytb, nd2, nd4, bdnf, c‐mos, rag2). The data are explored using two distinct optimality procedures—maximum parsimony and maximum likelihood—and two alignment strategies—dynamic homology and static homology. Two previously unsampled dipsadid genera, Sordellina and Rhachidelus, are now included in the analysis. The definitions of the genera, Erythrolamprus, Clelia, Hypsirhynchus, Philodryas and Phimophis, and the tribes Alsophiini, Echinantherini and Conophiini, are revised. In order to maintain monophyly, the genus Umbrivaga is synonymized with Erythrolamprus, and two new genera are erected to accommodate Phimophis iglesiasi and Clelia rustica, as well as their closely related species. The West Indian genera Schwartzophis, Darlingtonia, Antillophis and Ocyophis are resurrected. © The Willi Hennig Society 2012.