Monocyte-Derived Dendritic Cells Exhibit Increased Levels of Lysosomal Proteolysis as Compared to Other Human Dendritic Cell Populations

Fine control of lysosomal degradation for limited processing of internalized antigens is a hallmark of professional antigen presenting cells. Previous work in mice has shown that dendritic cells (DCs) contain lysosomes with remarkably low protease content. Combined with the ability to modulate lysosomal pH during phagocytosis and maturation, murine DCs enhance their production of class II MHC-peptide complexes for presentation to T cells.In this study we extend these findings to human DCs and distinguish between different subsets of DCs based on their ability to preserve internalized antigen. Whereas DCs derived in vitro from CD34+ hematopoietic progenitor cells or isolated from peripheral blood of healthy donors are protease poor, DCs derived in vitro from monocytes (MDDCs) are more similar to macrophages (M Phis) in protease content. Unlike other DCs, MDDCs also fail to reduce their intralysosomal pH in response to maturation stimuli. Indeed, functional characterization of lysosomal proteolysis indicates that MDDCs are comparable to M Phis in the rapid degradation of antigen while other human DC subtypes are attenuated in this capacity.Human DCs are comparable to murine DCs in exhibiting a markedly reduced level of lysosomal proteolysis. However, as an important exception to this, human MDDCs stand apart from all other DCs by a heightened capacity for proteolysis that resembles that of M Phis. Thus, caution should be exercised when using human MDDCs as a model for DC function and cell biology

Sequencing of the Sea Lamprey (Petromyzon marinus) Genome Provides Insights into Vertebrate Evolution

Lampreys are representatives of an ancient vertebrate lineage that diverged from our own ∼500 million years ago. By virtue of this deeply shared ancestry, the sea lamprey (P. marinus) genome is uniquely poised to provide insight into the ancestry of vertebrate genomes and the underlying principles of vertebrate biology. Here, we present the first lamprey whole-genome sequence and assembly. We note challenges faced owing to its high content of repetitive elements and GC bases, as well as the absence of broad-scale sequence information from closely related species. Analyses of the assembly indicate that two whole-genome duplications likely occurred before the divergence of ancestral lamprey and gnathostome lineages. Moreover, the results help define key evolutionary events within vertebrate lineages, including the origin of myelin-associated proteins and the development of appendages. The lamprey genome provides an important resource for reconstructing vertebrate origins and the evolutionary events that have shaped the genomes of extant organisms

HIV transmitted/founder vaccines elicit autologous tier 2 neutralizing antibodies for the CD4 binding site

<div><p>Here we report the construction, antigenicity and initial immunogenicity testing of DNA and modified vaccinia Ankara (MVA) vaccines expressing virus-like particles (VLPs) displaying sequential clade C Envelopes (Envs) that co-evolved with the elicitation of broadly neutralizing antibodies (bnAbs) to the CD4 binding site (CD4bs) in HIV-infected individual CH0505. The VLP-displayed Envs showed reactivity for conformational epitopes displayed on the receptor-binding form of Env. Two inoculations of the DNA-T/F vaccine, followed by 3 inoculations of the MVA-T/F vaccine and a final inoculation of the MVA-T/F plus a gp120-T/F protein vaccine elicited nAb to the T/F virus in 2 of 4 rhesus macaques (ID50 of ~175 and ~30). Neutralizing Ab plateaued at 100% neutralization and mapped to the CD4bs like the bnAbs elicited in CH0505. The nAb did not have breadth for other tier 2 viruses. Immunizations with T/F followed by directed-lineage vaccines, both with and without co-delivery of directed-lineage gp120 boosts, failed to elicit tier 2 neutralizing Ab for the CD4bs. Thus, pulsed exposures to DNA and MVA-expressed VLPs plus gp120 protein of a T/F Env can induce autologous tier 2 nAbs to the CD4bs.</p></div

Immunization schema¹.

<p>Immunization schema<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0177863#t001fn001" target="_blank">¹</a>.</p

Antigenicity of Env expressed by the 505 vaccines.

<p>The vaccines being tested are indicated at the top of the schematic and the recombinant Ab and their specificities on the left side. See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0177863#sec002" target="_blank">Methods</a> for procedures.</p

Antibody responses.

<p>(A) Patterns of binding Ab for the 3 immunization groups. Vertical dotted lines indicate immunizations. The horizontal dashed line compares troughs across immunizations. (B) Temporal peak titers of neutralizing Ab compared to peak titers of binding Ab (gray dashed line) in Group 1 animals. The patterns for A11R011 and A10L002 are typical for all animals that did not develop nAb to the CD4bs. (C). Mapping of neutralizing activity using mutants that knock out the V1V2 target for bnAb (N160A and N160A.N173A); the CH0505 target for bnAb to the CD4bs (N280D and G458Y); and the V3-glycan target for bnAb (N301A and N334A).</p

Electron micrographs of VLPs expressed by the DNA and MVA vaccines.

<p>Thin section electron micrographs were immunogold stained for Env using the PGT145 and PGT151 Ab that bind native trimers (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0177863#sec002" target="_blank">methods</a>). The DNA vaccine is expressed in transiently transfected 293T cells and the MVA vaccine in infected DF1 cells. The VLPs being analyzed and nanometer (nm) size markers are indicated in the panels. Arrows, indicate examples of immunogold staining on VLPs. The triangles point to examples of immunogold staining on the plasma membranes of vaccine infected cells.</p