1:20, 2.9-fold lower; BNT162b2/BNT162b2: 1:640 vs. as an antigen), a surrogate neutralisation test (sVNT), and a Vero-cell-based virus-neutralisation test (cVNT) with the B.1.1.7 variant of concern (VOC; alpha) as antigen. Investigation was carried out before and after heterologous (= 30 and 42) or homologous booster vaccination (AZD1222/AZD1222, = 8/9; BNT162b2/BNT162b2, = 8/8). After the second immunisation, a subgroup of 26 age- and gender-matched sera (AZD1222/mRNA, = 9; AZD1222/AZD1222, = 9; BNT162b2/BNT162b2, = 8) was also tested for VNA against VOC B.1.617.2 (delta) in the cVNT. The strength of IgG binding to separate SARS-CoV-2 antigens was measured by avidity. Results After the first vaccination, the prevalence of IgG directed against the (trimeric) SARS-CoV-2 S-protein and its receptor binding domain name (RBD) varied from 55C95% (AZD1222) to 100% (BNT162b2), depending on the vaccine regimen and the SARS-CoV-2 antigen used. The booster vaccination resulted in 100% seroconversion and the occurrence of highly avid IgG, which is Zalcitabine usually directed against the S-protein subunit 1 and the RBD, as well as VNA against VOC B.1.1.7, while anti-NP IgGs were not detected. The results of the three anti-SARS-CoV-2 IgG assessments showed an excellent correlation to the VNA titres against this VOC. The agreement of cVNT and sVNT results was good. However, the sVNT seems to overestimate non- and poor B.1.1.7-neutralising titres. The anti-SARS-CoV-2 IgG concentrations and the B.1.1.7-neutralising titres were significantly higher after heterologous vaccination compared to the homologous AZD1222 scheme. If VOC B.1.617.2 was used as antigen, significantly lower VNA titres were measured in the cVNT, and three (33.3%) vector vaccine recipients had a VNA titre Rabbit Polyclonal to CBLN2 the messenger ribonucleic acid (mRNA) vaccines from Pfizer/BioNTech (BNT162b2) and Zalcitabine Moderna (mRNA-1273), the genetic information for the S-protein was optimised and the mRNA was packaged in liposomes. After inoculation, the muscle mass cells directly expressed this stable and highly immunogenic viral surface protein [2, 6]. In vector vaccines, replication-deficient human (Ad26.COV2; Janssen) or chimpanzee adenoviruses (ChAdOx1 nCoV-19/AZD1222, Vaxzevria; AstraZeneca, hereinafter referred to as AZD1222) are used to introduce the genetic information of the SARS-CoV-2 S-protein into the cells, followed by transcription of deoxyribonucleic acid into mRNA and expression of the S-protein [2, 6]. Due to Zalcitabine the widespread use of these vaccines, rare.