Comparison of IgA, IgG and neutralizing antibody responses following immunization with Moderna, BioNTech, AstraZeneca, Sputnik-V, Johnson and Johnson, and Sinopharm’s COVID-19 vaccines.

BACKGROUNDSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and the resulting coronavirus disease 2019 (COVID-19) have afflicted millions of people in a worldwide pandemic. Several vaccines have been developed to prevent infection and illness. However, the safety and efficacy of most of the vaccines currently available are still being questioned by part of the public opinion. Even if vaccine-resistant individuals represent a minority in most countries, their hesitancy is sufficient to delay the highly desired ‘herd-immunity threshold.’ METHODSIn an ongoing multinational trial, we collected blood samples from 365 adults, 18 years of age or older, vaccinated with mRNA vaccines (Moderna, BioNTech), viral DNA-vectored vaccines (AstraZeneca, Sputnik-V, and Johnson and Johnson), or the attenuated virus vaccine from Sinopharm. Out of the 365 vaccinated individuals included in the study, 41 received two doses of Moderna Biotech's Spikevax, 92 received two doses of BioNTech’s Comirnaty, 52 were vaccinated with two doses of Oxford-AstraZeneca’s Vaxzevria, 34 received one dose of Johnson and Johnson’s Jansen, 35 two doses of Gamaleja’s Sputnik-V and 28 two doses of Sinopharm’s BBIBP-CorV. In addition, 40 received a prime dose of AstraZeneca followed by BioNTech as a booster, whereas 43 received Moderna’s vaccine as a booster after a prime dose of AstraZeneca. After collecting reactogenicity data, the expression of S-Protein binding IgG and IgA were analyzed before and after full vaccination in each group using an automated sandwich ELISA system. In addition, the neutralizing capacity of sera from individuals from all groups was investigated using an ACE-2-RBD neutralizing assay. RESULTSThe main side effects reported included short-term mild-to-moderate pain at the injection site, fatigue, and headache. More severe side effects were reported by vaccinees in the Moderna (10%), AstraZeneca (11%), Johnson and Johnson (5.9%), and Sputnik-V (7.2%) groups. No severe adverse reaction was reported in the BioNTech group, and the Sinopharm vaccinees presented the mildest reactogenicity profile, with 93.8% of the vaccinees declaring no adverse reactions. Moderna’s vaccine induced the highest amounts of SARS-CoV-2 specific IgG, IgA, and serum neutralization activity compared to the other groups. In contrast, people vaccinated with Sinopharm and Johnson and Johnson’s vaccines have the lowest SARS-CoV-2-specific antibody titers. Vaccinees from the Johnson and Johnson group presented significant levels of SARS-CoV-2 specific IgA but not IgG compared to the controls before vaccination. In the Sinopharm group, neither IgG nor IgA expression was significant. In addition, sera from vaccinees of these two groups presented no significant neutralization potential compared to the unvaccinated controls. Significant negative correlations between age and SARS-CoV-2- specific IgG expression were observed in the Johnson and Johnson (r=-0.4414, p=0.009) and Sinopharm (r=-0.6108, p=0.0006) groups. Remarkably, younger vaccinees (18-60 years old) in both Sinopharm and Johnson and Johnson groups produced substantial SARS-CoV-2 specific antibody expression and exhibited significant neutralization potential. While the AstraZeneca vaccine alone induced moderate IgG and IgA expression, the combination with Moderna or BioNTech mRNA vaccines induced higher antibody levels than a double dose of AstraZeneca and similar IgG expression and neutralization potential compared to Moderna, or BioNTech used alone. CONCLUSIONThe results suggest that the Moderna vaccine is the most immunogenic after two doses. AstraZeneca and Sputnik-V presented moderate but significant antibody expression and virus neutralizing properties. Low antibody and neutralization potential was observed in the elderly vaccinated with Sinopharm or Johnson and Johnson vaccines. The data also suggest that heterologous vaccination strategies combining the AstraZeneca DNA vectored vaccines and mRNA vaccines Moderna or BioNTech booster induced more robust antibody and virus neutralization potential compared to their homologous counterparts.

TBIO-14. CHARACTERISATION OF THE ARGININE PATHWAY ENZYMES IN PAEDIATRIC BRAIN TUMOURS TO DETERMINE SUSCEPTIBILITY TO THERAPEUTIC ARGININE DEPLETION

INTRODUCTION Extracellular arginine dependency (auxotrophy) is increasingly being recognised in several tumours. This is due to the inability of cancer cells to recycle or synthesise intracellular arginine through the urea cycle pathway compared to normal cells. Whilst adult glioblastoma is known to exhibit this, the expression of the arginine pathway enzymes has not been delineated in paediatric brain tumours. METHODS We used immunohistochemical methods to stain for arginine pathway enzymes in Paediatric High grade glioma (pHGG), low grade glioma (pLGG) and medulloblastoma (MB) tumour tissue microarrays (TMAs). The antibodies detected protein expression of the metaboliser Arginase (Arg2), recycling enzymes ornithine transcarbamoylase (OTC), Arginosuccinate synthetase (ASS1) and arginosuccinate lyase (ASL) as well as the transporter SLC7A1. RESULTS Deficiency of OTC, ASS1 and ASL were seen in 92%, 98% and 93% of pHGG samples (n=156) respectively, with deficiency defined as low (<20%) or negative antibody expression. Identical results were seen in pLGG (n=98) - 83%, 97% and 95% were deficient in OTC, ASS1 and ASL. Both pHGG and pLGG highly expressed SLC7A1 and Arg2, demonstrating that they could transport and utilise arginine. In MB (n=82), this auxotrophic signature was again seen in 90% of TMAs with absent or low expression of OTC, ASS1 and ASL and high Arg2 and SLC7A1 expression. CONCLUSIONS These results show that pHGG, pLGG and MB are arginine auxotrophs. Pegylated arginase (BCT-100) is currently in Phase I/II trials in relapsed pHGG. Our results suggest that therapeutic arginine depletion may also be useful in MB and pLGG.

The role of antibody expression and their association with bladder cancer recurrence: a single-centre prospective clinical-pilot study in 35 patients

Background Bladder cancer (BC) is the 10th most common cancer in the UK, with about 10,000 new cases annually. About 75–85% of BC are non-muscle invasive (NMIBC), which is associated with high recurrence and progression rates (50–60% within 7–10 years). There are no routine biomarkers currently available for identifying BC patients at increased risk of developing recurrence. The focus of this research study was to evaluate antibody expression in BC patients and their association with cancer recurrence. Methods 35 patients scheduled for TURBT were recruited after written informed consent. Ethical approval for the project was granted via IRAS (REC4: 14/WA/0033). Following surgical procedure, tissues were preserved in 10% buffered formalin and processed within 24 h in FFPE blocks. 7 sections (4 µm each) were cut from each block and stained for CD31, Human epidermal growth factor receptor-2 (HER-2), S100P, Cyclooxygenase-2 (COX-2), VEGFR-3 thrombomodulin and CEACAM-1 using immunohistochemistry. Clinical outcome measures (obtained via cystoscopy) were monitored for up to 6 months following surgical procedure. Results There was significantly increased expression of CD31 (p < 0.001), HER-2 (p = 0.032), S100P (p < 0.001), COX-2 (p < 0.001), VEGFR-3 (p < 0.001) and decreased expression of thrombomodulin (p = 0.010) and CEACAM-1 (p < 0.001) in bladder tumours compared to normal bladder tissues. HER-2 expression was also significantly associated with cancer grade (p = 0.003), especially between grade 1 and grade 2 (p = 0.002) and between grade 1 and grade 3 (p = 0.004). There was also a significant association between cancer stage and HER-2 expression (p < 0.001). Although recurrence was significantly associated with cancer grade, there was no association with antibody expression. Conclusion Findings from the present study may indicate an alternative approach in the monitoring and management of patients with BC. It is proposed that by allowing urological surgeons access to laboratory markers such as HER-2, Thrombomodulin and CD31 (biomarker profile), potentially, in the future, these biomarkers may be used in addition to, or in combination with, currently used scoring systems to predict cancer recurrence. However, verification and validation of these biomarkers are needed using larger cohorts.