Detection of a characteristic melting profile of a SARS-CoV-2 Kappa variant in Italy using the SARS-CoV-2 Variants ELITe MGB® Kit.

BACKGROUND: Although more than a year has passed since the start of the pandemic, SARS-CoV-2 infection still represents a major challenge for public health all over the world due to viral genome capability of gaining rapid mutations. Whole-genome sequencing (WGS) is the gold standard for variant identification, but it is time consuming and relatively expensive. For this reason, assays targeting multiple regions of the SARS-CoV-2 genome may be useful for a rapid traceability of either known or new variants, anyway, not all the manufacturers are able to sustain the rapid development of variants. OBJECTIVE: We tested forty nasopharyngeal swabs, resulted positive for the presence of SARS-CoV-2 RNA at low cycle threshold (CT < 25), with SARS-CoV-2 Variants ELITe MGB® Kit, which was designed to identify Nigerian variant, possible UK variant and South African or Brazilian variant. RESULTS: During the analysis, we noted an atypical melting curve, different from the other variants recognizable by the kit. The subsequent WGS reported this variant as Kappa, so we assess the possibility of "suspecting" the presence of a Kappa variant using SARS-CoV-2 Variants ELITe MGB® Kit. CONCLUSIONS: Rapid variant screening followed by WGS offers the opportunity to study mutation dynamics and quickly identify possible variants of interest (VOI) and/or variants of concern (VOC), which is crucial in virus spreading control. Furthermore, an accurate analysis of the melting peak could be useful to suspect the presence of new variants.

Recombinant human monoclonal HLA antibodies of different IgG subclasses recognising the same epitope: Excellent tools to study differential effects of donor-specific antibodies.

In the field of transplantation, the humoural immune response against mismatched HLA antigens of the donor is associated with inferior graft survival, but not in every patient. Donor-specific HLA antibodies (DSA) of different immunoglobulin G (IgG) subclasses may have differential effects on the transplanted organ. Recombinant technology allows for the generation of IgG subclasses of a human monoclonal antibody (mAb), while retaining its epitope specificity. In order to enable studies on the biological function of IgG subclass HLA antibodies, we used recombinant technology to generate recombinant human HLA mAbs from established heterohybridomas. We generated all four IgG subclasses of a human HLA class I and class II mAb and showed that the different subclasses had a comparable affinity, normal human Fc glycosylation, and retained HLA epitope specificity. For both mAbs, the IgG1 and IgG3 isotypes were capable of binding complement component 3d (C3d) and efficient in complement-dependent cell lysis against their specific targets, while the IgG2 and IgG4 subclasses were not able to induce cytotoxicity. Considering the fact that the antibody-binding site and properties remained unaffected, these IgG subclass HLA mAbs are excellent tools to study the function of individual IgG subclass HLA class I and class II-specific antibodies in a controlled fashion.