Longitudinal comparison of automated SARS-CoV-2 serology assays in assessing virus neutralization capacity in COVID-19 convalescent sera

CONTEXT.–

Serological tests on automated immunology analyzers are increasingly used to monitor the acquired immunity against SARS-CoV-2. The heterogeneity of assays raises concerns about their diagnostic performance and comparability.

OBJECTIVE.–

To test sera from formerly infected individuals for SARS-Cov-2 antibodies utilizing six automated serology assays and a pseudoneutralization test (PNT).

DESIGN.–

Six SARS-CoV-2 serology assays were utilized to assess 954 samples collected during a 12 months period from 315 COVID-19 convalescents. The tests determined either antibodies against the viral nucleocapsid (anti-NC) or spike protein (anti-S). Two assays did not distinguish between antibody classes whereas the others selectively measured immunoglubulins G (IgG) antibodies. PNT was used to detect the presence of neutralizing antibodies.

RESULTS.–

Comparison of qualitative results showed only slight to moderate concordance between the assays (Cohen's kappa < 0.57). Significant correlations (P < .001) were observed between the antibody titers from all quantitative assays. However, titer changes were not detected equally. A total anti-S assay measured an increase in 128 out of 172 cases (74%) of a suitable subset, whereas all IgG anti-S tests reported decreases in at least 118 (69%). Regarding the PNT results, diagnostic sensitivities ≥89% were achieved with PPVs ≥93%. In contrast, specificity changed substantially over time varying from 20 to 100%.

CONCLUSIONS.–

Comparability of serological SARS-CoV-2 antibody tests is rather poor. Due to different diagnostic specificities, the tested assays were not equally capable of capturing changes in antibody titers. However, with thoroughly validated cut-offs, IgG-selective anti-S assays are a reliable surrogate test for SARS-CoV-2 neutralizing antibodies in former COVID-19 patients.

Lower incidence of macrovascular complications in patients on insulin glargine versus those on basal human insulins: a population-based cohort study in Italy

BACKGROUND AND AIM

The aim of this study was to compare the use of insulin glargine and intermediate/long-acting human insulin (HI) in relation to the incidence of complications in diabetic patients.

METHODS AND RESULTS

A population-based cohort study was conducted using administrative data from four local health authorities in the Abruzzo Region (900,000 inhabitants). Diabetic patients without macrovascular diseases and treated with either intermediate/long-acting HI or glargine were followed for 3-years; the incidence of diabetic (macrovascular, microvascular and metabolic) complications was ascertained by hospital discharge claims and estimated using Cox proportional hazard models. Propensity score (PS) matching was also used to adjust for significant differences in the baseline characteristics between the two groups.

RESULTS

Overall, 1921 diabetic patients were included: 744 intermediate/long-acting HI and 1177 glargine users. During the 3-year follow-up, 209 (28.1%) incident events of any diabetic complication occurred in the intermediate/long-acting HI and 159 (13.5%) in the glargine group. After adjustment for covariates, glargine users had an HR (95% CI) of 0.57 (0.44-0.74) for any diabetic complication and HRs of 0.61 (0.44-0.84), 0.58 (0.33-1.04) and 0.35 (0.18-0.70) for macrovascular, microvascular and metabolic complications, respectively, compared to intermediate/long-acting HI users. PS analyses supported these findings.

CONCLUSIONS

The use of glargine is associated with a lower risk of macrovascular complications compared with traditional basal insulins. However, limitations inherent to the study design including the short length of observation and the lack of data on metabolic control or diabetes duration, do not allow us to consider this association as a proof of causality.

Protein delivery by subviral particles of human cytomegalovirus

Direct protein delivery is an emerging technology in vaccine development and gene therapy. We could previously show that subviral dense bodies (DB) of human cytomegalovirus (HCMV), a beta-herpesvirus, transport viral proteins into target cells by membrane fusion. Thus these non-infectious particles provide a candidate delivery system for the prophylactic and therapeutic application of proteins. Here we provide proof of principle that DB can be modified genetically. A 55 kDa fusion protein consisting of the green fluorescent protein and the neomycin phosphotransferase could be packed in and delivered into cells by recombinant DB in a functional fashion. Furthermore, transfer of protein into fibroblasts and dendritic cells by DB was efficient, leading to exogenous loading of the MHC-class I antigen presentation pathway. Thus, DB may be a promising basis for the development of novel vaccine strategies and therapeutics based on recombinant polypeptides.

Induction of CMV-specific T-cell lines using Ag-presenting cells pulsed with CMV protein or peptide

BACKGROUND

CMV disease is still associated with a high morbidity and mortality in recipients of a solid organ or stem cell graft, especially in patients undergoing allogenic stem cell transplantation. Reconstitution of CMV-specific CD4(+) and CD8(+) cytotoxic T cell responses are essential to control CMV infection following allogenic stem cell transplantation. The transfer of unselected populations of lymphocytes from the peripheral blood of a CMV-scropositive donor to a transplant recipient can be used to control CMV infection. However, such transfer of unselected donor lymphocytes is limited by potentially fatal complications that arise from alloreactive T cells, also present in the unselected donor lymphocytes. Thus to make infusion of donor T cells safe and also more effective in controlling CMV infection in the recipient of the T cell infusion, T cells are manipulated in vitro to deplete alloreactive T cells and to enrich for CMV-specific T cells.

METHODS

Using various antigen-presenting cells (monocytes/PBMNCs/dendritic cells) and different modes of antigen presentation (infected APCs, pulsing of protein or peptide antigen) different CMV-specific T cell populations can be generated and expanded.

RESULTS

Using protein-/or peptide-pulsed DCs CMV-specific CD8(+) cytoxic T cell lines (can be generated and expanded) in addition CMV-specific CD4(+) T cell lines can be generated when CMV-protein-pulsed DCs are used as antigen-presenting cells. When peripheral blood mononuclear cells were stimulated with CMV lysates predominantly CMV-specific CD4(+) T cells are generated and expanded ex vivo.

DISCUSSION

Depending on the APC used (monocytes versus DC) and the mode of antigen presentation (protein versus peptide pulsing) different CMV-specific T cell populations of varying purity can be generated which show preserved function when tested for specific proliferation, cytokine production and cytotoxicity.

Ex vivo generation of human cytomegalovirus-specific cytotoxic T cells by peptide-pulsed dendritic cells

Adoptive transfer of donor-derived human cytomegalovirus (HCMV)-specific T-cell clones can restore protective immunity after stem cell transplantation. Ex vivo induction of HCMV-specific T cells using HCMV-infected fibroblasts as stimulator cells confines this approach to HCMV-seropositive donors and requires the presence of infectious virus during the stimulation procedure. In this study, we describe a potential alternative strategy to generate HCMV-specific T cells ex vivo for adoptive immunotherapy. Generation of HCMV-specific cytotoxic T lymphocytes (CTLs) ex vivo was investigated using peptide-pulsed dendritic cells as antigen-presenting cells. HCMV-specific T cells were generated and sufficiently expanded for adoptive immunotherapy in 6 out of 14 HCMV-seropositive and 2 out of 11 HCMV-seronegative donors. The CTLs recognized HCMV-infected autologous fibroblasts. No lysis was observed with either non-infected autologous or HLA-mismatched infected fibroblasts. Staining with tetrameric HLA/peptide complexes revealed significant enrichment for peptide-specific T cells of up to 28% and > 90% of CD8(+) T cells after three and five specific stimulations respectively. In addition, the expansion rates indicated that ex vivo generation of > 1 x 10(9) HCMV-specific T cells was possible after 6--7 weeks when cultures were initiated with 1--5 x 10(6) responder cells. Thus, the approach with peptide-pulsed DCs to generate HCMV-specific CTLs is feasible for clinical application after allogeneic stem cell transplantation.

Human cytomegalovirus infection of immature dendritic cells and macrophages

A central aspect of human cytomegalovirus (HCMV) pathogenesis is the interaction of the virus with different antigen-presenting cell (APC) types of the host. In principle, a number of various cell types have the potential of antigen presentation when MHC II expression is induced by appropriate stimuli. The most potent antigen presenters are monocytes/macrophages and dendritic cells (DCs), therefore called professional APCs. Interestingly, these cells seem to be targets of productive HCMV infection. The susceptibility of the monocyte/macrophage system has been analyzed intensively during the past decade. Investigation of the role of DCs during HCMV infection, however, has begun only recently.

Monocyte-derived dendritic cells are permissive to the complete replicative cycle of human cytomegalovirus

The susceptibility of monocyte-derived immature dendritic cells (DC) to infection by various strains of human cytomegalovirus (HCMV) was analysed. Immature DC were generated by incubation of peripheral blood monocytes with interleukin-4 and granulocyte-macrophage colony-stimulating factor for 7 days and were characterized by a CD1a+/CD40+/CD80+/CD86+/HLA-DR+/CD14- phenotype. Viral antigen expression and production of infectious progeny virus were analysed in infected immature DC cultures. Immature DC were 80-90 % susceptible to HCMV strains that had been propagated in endothelial cell culture, whereas the infection rate was negligible with fibroblast-adapted HCMV strains. Immature DC infection resulted in expression of viral immediate early, early and late genes. Productive infection was proven by the detection of infectious virus in single-step growth curves and in infectious centre assays. It is concluded that HCMV might interfere with the host immune reaction by permissive, lytic infection of immature DC.

Assessing the outcomes of nursing-home patients

This paper describes the development of multidimensional measures of nursing-home patients' functioning. The technique was designed to gather information directly from the patients, using demonstrated ability in place of self-report wherever possible. Six domains are tapped: physiologic, activities of daily living, affective, cognitive, social, and satisfaction. Test-retest reliability ranges from .59 for social interaction to .85 for affect. Validity was tested by replication on successive waves of data as well as discriminant and content validity.