https://doi.org/10.1016/j.talanta.2022.123409

Review of COVID-19 testing and diagnostic methods

The checkpoint inhibitor therapy that blocks programmed death-1 (PD-1) and its major ligand PD-L1 has achieved encouraging clinical efficacy in certain cancers. However, the binding of checkpoint inhibitors with other immune cells that express PD-L1 often results in a low response rate to the blockade and severe adverse effects. Herein, an LyP1 polypeptide-modified outer-membrane vesicle (LOMV) loaded with a PD-1 plasmid is developed to achieve self-blockade of PD-L1 in tumor cells. The nanocarriers accumulate in the tumor tissue through OMV-targeting ability and are internalized into the tumor cells via the LyP1-mediated target, subsequently delivering PD-1 plasmid into the nucleus, leading to the expression of PD-1 by the tumor cells. In addition, a magnetic particle chemiluminescence kit is developed to quantitatively detect the binding rate of PD-1/PD-L1. The self-expressed PD-1 bonded with the PD-L1 is expressed by both autologous and neighboring tumor cells, achieving self-blockade. Simultaneously, the outer-membrane protein of LOMV recruits cytotoxic lymphocyte cells and natural killer cells to tumor tissues and stimulates them to secrete IFN-γ , improving the antitumor activity of the PD-1/PD-L1 self-blocking therapy. 

Self‐Blockade of PD‐L1 with Bacteria‐Derived Outer‐Membrane Vesicle for Enhanced Cancer Immunotherapy

Sensitive detection of the SARS-CoV-2 protein remains a great research interest in clinical screening and diagnosis owing to the coronavirus epidemic. Here, an ultrasensitive chemiluminescence (CL) imaging strategy was developed through proximity hybridization to trigger the formation of a rolling circle-amplified G-quadruplex/hemin DNAzyme for the detection of the SARS-CoV-2 protein. The target protein was first recognized by a pair of DNA-antibody conjugates, Ab-1 and Ab-2, to form a proximity-ligated complex, Ab-1/SARS-CoV-2/Ab-2, which contained a DNA sequence complemental to block DNA and thus induced a strand displacement reaction to release the primer from a block/primer complex. The released primer then triggered a rolling circle amplification to form abundant DNAzyme units in the presence of hemin, which produced a strong chemiluminescent signal for the detection of the target protein by catalyzing the oxidation of luminol by hydrogen peroxide. The proposed assay showed a detectable concentration range over 5 orders of magnitude with the detection limit down to 6.46 fg/mL. The excellent selectivity, simple procedure, acceptable accuracy, and intrinsic high throughput of the imaging technique for analysis of serum samples demonstrated the potential applicability of the proposed detection method in clinical screening and diagnosis.

A Rolling Circle-Amplified G-Quadruplex/Hemin DNAzyme for Chemiluminescence Immunoassay of the SARS-CoV-2 Protein.

Immune response to two SARS-CoV-2 mRNA vaccine doses among kidney transplant recipients (KTRs) is limited. We aimed to evaluate humoral and cellular response to a third BNT162b2 dose. In this prospective study, 190 KTRs were evaluated before and ∼3 weeks after the third vaccine dose. The primary outcomes were anti-spike antibody level >4160 AU/ml (neutralization-associated cutoff) and any seropositivity. Univariate and multivariate analyses were conducted to identify variables associated with antibody response. T-cell response was evaluated in a subset of participants. Results were compared to a control group of 56 healthcare workers. Among KTRs, we found a seropositivity rate of 70% (133/190) after the third dose (37%, 70/190, after the second vaccine dose); and 27% (52/190) achieved levels above 4160 AU/ml after the third dose, compared to 93% of controls. Variables associated with antibody response included higher antibody levels after the second dose (odds ratio [OR] 30.8 per log AU/ml, 95% confidence interval [CI]11–86.4, p < 0.001); and discontinuation of antimetabolite prior to vaccination (OR 9.1,95% CI 1.8–46.5, p = 0.008). T-cell response was demonstrated in 13% (7/53). In conclusion, third dose BNT162b2 improved immune response among KTRs, however 30% still remained seronegative. Pre-vaccination temporary immunosuppression reduction improved antibody response. Graphical Abstract

/pdf/immune-response-to-third-dose-bnt162b2-covid-19-vaccine-1zl2jjua.pdf

Immune Response to Third Dose BNT162b2 COVID-19 Vaccine Among Kidney Transplant Recipients—A Prospective Study

To describe the humoral immune response to COVID-19 vaccines in people living with HIV and identify factors associated with the magnitude of anti-SARS-CoV-2 antibody concentrations. Retrospective analysis of electronic patient files in a big single HIV center in Munich, Germany. Non-parametric methods were used for descriptive and comparative statistics. Generalized linear models were used to analyze associations of general and HIV-specific variables with anti-SARS-CoV-2 antibody concentrations after standard vaccination. Overall, 665 people living with HIV were included into the analysis (median age: 53 [IQR: 43; 59]), 560 [84.2%] males). Median concentration of anti-SARS-CoV-2-antibodies was 1400 (IQR 664; 2130) BAU/mL. In 18 (2.7%) subjects, antibody concentrations below the threshold of 34 BAU/mL were found. Among PLWH with CD4 cell count < 200 cells/µL, median anti-SARS-CoV-2-Abs were 197 (IQR 44.6; 537.2) as compared to 1420 (IQR 687; 2216) for the group ≥ 200 cells/µL (p < 0.001). In a cumulative logit model, a vaccination scheme including an mRNA vaccine [OR: 4.64 (3.58; 6.02)], being female [OR: 2.14 (1.76; 2.61)], and having higher CD4 cells [OR per 100 cells/µL: 1.06 (1.04; 1.08)] were significantly associated with anti-SARS-CoV-2 antibody concentrations in higher quartiles, when adjusted for the time after vaccination. We found a robust antibody response in people living with HIV undergoing standard vaccination against SARS-CoV-2. mRNA-containing vaccination schemes, being female, and having a higher CD4 cell count was associated with a higher concentration of antibodies in people living with HIV in our study sample. Particularly in the subgroup with CD4 cell counts < 200 cells/µL, antibody response was poor.

/pdf/humoral-response-to-sars-cov-2-vaccines-in-people-living-2iwxgn7j53.pdf

Humoral response to SARS-CoV-2 vaccines in people living with HIV.

The development of vaccines to prevent SARS-CoV-2 infection has mainly relied on the induction of neutralizing antibodies (nAbs) to the Spike protein of SARS-CoV-2, but there is growing evidence that T cell immune response can contribute to protection as well. In this study, an anti-receptor binding domain (RBD) antibody assay and an INFγ-release assay (IGRA) were used to detect humoral and cellular responses to the Pfizer-BioNTech BNT162b2 vaccine in three separate cohorts of COVID-19-naive patients: 108 healthcare workers (HCWs), 15 elderly people, and 5 autoimmune patients treated with immunosuppressive agents. After the second dose of vaccine, the mean values of anti-RBD antibodies (Abs) and INFγ were 123.33 U/mL (range 27.55–464) and 1513 mIU/mL (range 145–2500) in HCWs and 210.7 U/mL (range 3–500) and 1167 mIU/mL (range 83–2500) in elderly people. No correlations between age and immune status were observed. On the contrary, a weak but significant positive correlation was found between INFγ and anti-RBD Abs values (rho = 0.354, p = 0.003). As to the autoimmune cohort, anti-RBD Abs were not detected in the two patients with absent peripheral CD19+B cells, despite high INFγ levels being observed in all 5 patients after vaccination. Even though the clinical relevance of T cell response has not yet been established as a correlate of vaccine-induced protection, IGRA testing has showed optimal sensitivity and specificity to define vaccine responders, even in patients lacking a cognate antibody response to the vaccine.

/pdf/assessment-of-humoral-and-cellular-immunity-induced-by-the-48u8fsecvu.pdf

Assessment of humoral and cellular immunity induced by the BNT162b2 SARS-CoV-2 vaccine in healthcare workers, elderly people, and immunosuppressed patients with autoimmune disease.

Long-term decay of anti-RBD IgG titers after BNT162b2 vaccination is not mirrored by loss of neutralizing bioactivity against SARS-CoV-2.

Diagnostic performance of an automated chemiluminescence immunoassay for SARS-CoV-2 IgG and IgM antibodies detection: A real life experience

New-Generation Quantitative Immunoassays for SARS-CoV-2 Antibody Detection: Need for Harmonization

QuantiFERON -TB Gold plus (QFT-plus) represents the latest generation of interferon-gamma release assays (IGRAs), eliciting a response from CD8 T- cells in addition to CD4-T cells, with the aim to improve detection of latent M.tuberculosis infection (LTBI) with respect to its predecessor QuantiFERON-TB Gold In-Tube (QFT-GIT), even if no significant differences have been shown between the two tests (1, 2).….

Anna Moratto

Papers

Assessment of humoral and cellular immunity induced by the BNT162b2 SARS-CoV-2 vaccine in healthcare workers, elderly people, and immunosuppressed patients with autoimmune disease.

Long-term decay of anti-RBD IgG titers after BNT162b2 vaccination is not mirrored by loss of neutralizing bioactivity against SARS-CoV-2.

Diagnostic performance of an automated chemiluminescence immunoassay for SARS-CoV-2 IgG and IgM antibodies detection: A real life experience

New-Generation Quantitative Immunoassays for SARS-CoV-2 Antibody Detection: Need for Harmonization

QuantiFERON-TB Gold Plus: High qualitative and quantitative agreement between ELISA and CLIA assays.