High-Quality Complete Genome Resource of Pathogenic Bacterium Pectobacterium atrosepticum Strain Green1 Isolated from Potato (Solanum tuberosum L.) in Greenland.

Pectobacterium atrosepticum is a narrow-host-range, pectinolytic, plant-pathogenic bacterium causing blackleg of potato (Solanum tuberosum L.) worldwide. Till present, several P. atrosepticum genomes have been sequenced and characterized in detail; however, all of these genomes have come from P. atrosepticum isolates from plants grown in temperate zones, not from hosts cultivated under different climatic conditions. Herewith, we present the first complete, high-quality genome of the P. atrosepticum strain Green1 isolated from potato plants grown under a subarctic climate in Greenland. The genome of P. atrosepticum strain Green1 consists of one chromosome of 4,959,719 bp, with a GC content of 51% and no plasmids. The genome contains 4,531 annotated features, including 4,179 protein-coding genes, 22 ribosomal RNA genes, 70 transfer RNA genes, 8 noncoding RNA genes, 2 CRISPRs, and 126 pseudogenes. We believe that the information in this first high-quality, complete, closed genome of P. atrosepticum strains isolated from host plants grown in a subarctic agricultural region will provide resources for comparative genomic studies and for analyses targeting climatic adaptation and ecological fitness mechanisms present in P. atrosepticum.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Entomopathogenic fungi recorded from the harlequin ladybird, Harmonia axyridis.

Entomopathogenic fungi were recorded from field samples of the harlequin ladybird Harmonia axyridis, an invasive coccinellid that has recently arrived in Denmark. Larvae, pupae and adults were found to be infected by Isaria farinosa, Beauveria bassiana and species of Lecanicillium. This is the first record of entomopathogenic fungi infecting larvae and pupae. Winter mortality due to fungal infection reached 17.9% in adults collected at one location. The larval stage was most susceptible to fungal infection, as confirmed through bioassay with I. farinosa.

Alefacept selectively promotes NK cell-mediated deletion of CD45R0+ human T cells.

Modulation of the immune response using immunoglobulin fusion proteins has shown great promise for clinical immunotherapy of autoimmune diseases. Alefacept is an immunoglobulin fusion protein composed of the first extracellular domain of human LFA-3 fused to the hinge, C(H)2 and C(H)3 domains of human IgG(1). Alefacept has previously been reported to inhibit T cell proliferation. Here, we analyzed the effects of alefacept on lymphocytes in vitro and characterized the role of autologous NK cells in its mechanism of action. Alefacept, but not a C(H)2 binding mutant of Alefacept, inhibited CD3-induced T cell proliferation only in the presence of live NK cells, consistent with an important role for FcgammaR engagement. Alefacept caused preferential depletion of CD69+CD45R0+CD25+ T cell subsets. Cytotoxicity assays revealed that alefacept, but not the C(H)2 binding mutant, induced NK cell-mediated death of activated T cells and sorting into CD45R0+ and CD45RA+ subpopulations showed that lymphocyte deletion occurred preferentially in the CD45R0+ subset. Activated CD45R0+ cells expressed higher levels of CD2 than CD45R0- cells, providing a possible explanation for the selective targeting of this subset. Our results suggest that selective targeting of CD45R0+ T cells by NK cells represents a potential therapeutic mechanism of action of alefacept.

A therapeutic CD4 monoclonal antibody inhibits TCR-zeta chain phosphorylation, zeta-associated protein of 70-kDa Tyr319 phosphorylation, and TCR internalization in primary human T cells.

The molecular mechanisms mediating the inhibitory effects of a humanized CD4 mAb YHB.46 on primary human CD4(+) T cells were investigated. Preincubation of T cells with soluble YHB.46 caused a general inhibition of TCR-stimulated protein tyrosine phosphorylation events, including a reduction in phosphorylation of p95(vav), linker for activation of T cells, and Src homology 2 domain-containing leukocyte protein of 76-kDa signaling molecules. A marked reduction in activation of the Ras/mitogen-activated protein kinase pathway was also observed. Examination of the earliest initiation events of TCR signal transduction showed that YHB.46 inhibited TCR-zeta chain phosphorylation together with recruitment and tyrosine phosphorylation of the zeta-associated protein of 70-kDa tyrosine kinase, particularly at Tyr(319), as well as reduced recruitment of p56(lck) to the TCR-zeta and zeta-associated protein of 70-kDa complex. These inhibitory events were associated with inhibition of TCR endocytosis. Our results show that the YHB.46 mAb is a powerful inhibitor of the early initiating events of TCR signal transduction.