Disparities in detection of antibodies against hepatitis E virus in US blood donor samples using commercial assays.

BACKGROUND: Reported hepatitis E virus (HEV) antibody assay performance characteristics are variable. Using a subset of surplus US blood donation samples, we compared assays for detecting anti-HEV immunoglobulin M (Ig)M and IgG or total anti-HEV antibodies. STUDY DESIGN AND METHODS: Samples from 5040 random blood donations, all HEV-RNA negative, collected primarily in the midwestern United States in 2015 were tested for anti-HEV IgM and IgG or total anti-HEV using assays manufactured by Diagnostic Systems, Wantai, and MP Biomedicals. RESULTS: Overall, the percentage of detection for anti-HEV IgG and total anti-HEV was 11.4%, and for anti-HEV IgM was 1.8%. Nine samples were reactive for anti-HEV IgM by all assays, giving a recent infection rate of 0.18%. Anti-HEV IgG/total anti-HEV detection rates increased with age. Interassay agreement was higher among the IgG anti-HEV/total anti-HEV assays (84%) than the IgM assays (22%). Regression analyses of signal-to-cutoff ratios from IgG/total antibody assay were heteroskedastic, indicating no constant variance among these assays, suggesting they may detect different epitopes or were affected by waning or less avid antibodies in the US donor population. CONCLUSIONS: Although similar percentages of IgG anti-HEV/total anti-HEV detection were observed across the three commercial assays, each assay detected a unique sample subpopulation and was heteroskedastic when compared pairwise. Discordance was higher among anti-HEV IgM assays, but a recent HEV infection rate of at least 0.18% was estimated based on assay concordance.

αvß3 Integrin drives fibroblast contraction and strain stiffening of soft provisional matrix during progressive fibrosis.

Fibrosis is characterized by persistent deposition of extracellular matrix (ECM) by fibroblasts. Fibroblast mechanosensing of a stiffened ECM is hypothesized to drive the fibrotic program; however, the spatial distribution of ECM mechanics and their derangements in progressive fibrosis are poorly characterized. Importantly, fibrosis presents with significant histopathological heterogeneity at the microscale. Here, we report that fibroblastic foci (FF), the regions of active fibrogenesis in idiopathic pulmonary fibrosis (IPF), are surprisingly of similar modulus as normal lung parenchyma and are nonlinearly elastic. In vitro, provisional ECMs with mechanical properties similar to those of FF activate both normal and IPF patient-derived fibroblasts, whereas type I collagen ECMs with similar mechanical properties do not. This is mediated, in part, by αvß3 integrin engagement and is augmented by loss of expression of Thy-1, which regulates αvß3 integrin avidity for ECM. Thy-1 loss potentiates cell contractility-driven strain stiffening of provisional ECM in vitro and causes elevated αvß3 integrin activation, increased fibrosis, and greater mortality following fibrotic lung injury in vivo. These data suggest a central role for αvß3 integrin and provisional ECM in overriding mechanical cues that normally impose quiescent phenotypes, driving progressive fibrosis through physical stiffening of the fibrotic niche.