Peptides from heptad repeat (HR1 and HR2) regions of gp41 are effective inhibitors of HIV-1 entry that block the fusion of viral and cellular membranes, but the generation of antibodies highly specific for these peptides is challenging. We have previously described a mouse hybridoma that recognizes MT-C34-related peptides derived from HR2. It was used for the selection of HIV-1-resistant CD4 lymphocytes engineered to express the MT-C34 peptide via a CRISPR/Cas9-mediated knock-in into the CXCR4 locus. In this study, we cloned variable domains of this antibody and generated a recombinant chimeric antibody (chAb) by combining it with the constant regions of the humanized antibody Trastuzumab. The new chAb displayed a high specificity and two-fold higher level of affinity than the parental mouse monoclonal antibody. In addition, chAb mediated up to 27–43% of the antibody-dependent cellular cytotoxicity towards cells expressing MT-C34 on their surface. The anti-MT-C34 chAb can be easily generated using plasmids available for the research community and can serve as a valuable tool for the detection, purification, and even subsequent elimination of HIV-1-resistant CD4 cells or CAR cells engineered to fight HIV-1 infection.

FN-y is a cytokine of great clinical significance. The excessive or insufficient function of the signalling pathway triggered by IFN-y is a cause of various pathological states of the immune system and the body in general. At present, clinical practice uses quantitative methods of detection of this protein without taking into account its functional activity. Traditional tests for assessment of the biological activity of IFN-y are technologically complex and their results are poorly quantified. In the course of this work a model system was created representing a cell line with a reporter construct stably integrated into the genome controlled by a STAT-dependent promotor. Processing of the cells of this model system by IFN-y activates the STAT-1-signalling pathway, which causes expression of FFly luciferase gene. Luciferase activity is quantitatively assessed by detection of bioluminescence. Working concentration values (2.5 ng/ml) and time of performing the assay (8 h) were chosen. The effectiveness of using the model system for testing IFN-y bioactivity has been shown.