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Front Immunol ; 12: 750386, 2021.
Article in English | MEDLINE | ID: covidwho-1515534


Antibodies targeting Receptor Binding Domain (RBD) of SARS-CoV-2 have been suggested to account for the majority of neutralizing activity in COVID-19 convalescent sera and several neutralizing antibodies (nAbs) have been isolated, characterized and proposed as emergency therapeutics in the form of monoclonal antibodies (mAbs). However, SARS-CoV-2 variants are rapidly spreading worldwide from the sites of initial identification. The variants of concern (VOC) B.1.1.7 (Alpha), B.1.351 (Beta), P.1 (Gamma) and B.1.167.2 (Delta) showed mutations in the SARS-CoV-2 spike protein potentially able to cause escape from nAb responses with a consequent reduction of efficacy of vaccines and mAbs-based therapy. We produced the recombinant RBD (rRBD) of SARS-CoV-2 spike glycoprotein from the Wuhan-Hu 1 reference sequence in a mammalian system, for mice immunization to isolate new mAbs with neutralizing activity. Here we describe four mAbs that were able to bind the rRBD in Enzyme-Linked Immunosorbent Assay and the transmembrane full-length spike protein expressed in HEK293T cells by flow cytometry assay. Moreover, the mAbs recognized the RBD in supernatants of SARS-CoV-2 infected VERO E6 cells by Western Blot under non-reducing condition or in supernatants of cells infected with lentivirus pseudotyped for spike protein, by immunoprecipitation assay. Three out of four mAbs lost their binding efficiency to completely N-deglycosylated rRBD and none was able to bind the same recombinant protein expressed in Escherichia coli, suggesting that the epitopes recognized by three mAbs are generated by the conformational structure of the glycosylated native protein. Of particular relevance, three mAbs were able to inhibit Wuhan SARS-CoV-2 infection of VERO E6 cells in a plaque-reduction neutralization test and the Wuhan SARS-CoV-2 as well as the Alpha, Beta, Gamma and Delta VOC in a pseudoviruses-based neutralization test. These mAbs represent important additional tools for diagnosis and therapy of COVID-19 and may contribute to the understanding of the functional structure of SARS-CoV-2 RBD.

Antibodies, Monoclonal/pharmacology , Antibodies, Neutralizing/pharmacology , Antibodies, Viral/pharmacology , Epitopes/immunology , SARS-CoV-2/drug effects , Spike Glycoprotein, Coronavirus/immunology , Angiotensin-Converting Enzyme 2/genetics , Animals , Binding Sites, Antibody/immunology , COVID-19/drug therapy , Cell Line, Tumor , Chlorocebus aethiops , Female , Glycosylation , HEK293 Cells , Humans , Mice, Inbred BALB C , Neutralization Tests , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/genetics , Vero Cells
Hum Vaccin Immunother ; 17(10): 3348-3354, 2021 Oct 03.
Article in English | MEDLINE | ID: covidwho-1258722


Vaccination is a key protective factor against COVID-19. Some vaccines have already received emergency authorization from Health Agencies, but growing skepticism and vaccine hesitancy will probably affect COVID-19 vaccination campaigns. In the attempt to shed light on this issue, we conducted an online survey in a population of parents referring to 4 pediatric practices in Naples, Italy in whom we evaluated potential vaccine acceptability in relation to socio-demographic characteristics, perception of personal health and of the impact of COVID-19, and attitudes toward general vaccination practices. Vaccination rates were analyzed also in the corresponding pediatric population.Almost 27% of participants declared they were in favor of vaccinations, and in fact real life vaccination rates in children exceeded the national mean. Only 26.5% of respondents declared they would receive COVID-19 vaccine. Vaccine refusal was attributed to safety concerns in 76% of parents. Specific vaccine attributes further reduced the acceptance rate. Female gender, younger age and lower education level were associated with non-adherence to vaccination. Among extrinsic factors of COVID-19 vaccination, only information from National Health Authorities was significantly associated to vaccine acceptance.The rate of potential COVID-19 vaccine acceptability was very poor in our population of parents. Vaccine hesitancy was mainly due to safety concerns. Demographic and educational factors were correlated to vaccine acceptability. Health education and communication strategies are needed to achieve large-scale vaccine acceptability and finally herd immunity.

COVID-19 , Vaccines , COVID-19 Vaccines , Child , Cross-Sectional Studies , Female , Humans , SARS-CoV-2 , Surveys and Questionnaires , Vaccination