mRNA in the Context of Protein Replacement Therapy.

Protein replacement therapy is an umbrella term used for medical treatments that aim to substitute or replenish specific protein deficiencies that result either from the protein being absent or non-functional due to mutations in affected patients. Traditionally, such an approach requires a well characterized but arduous and expensive protein production procedure that employs in vitro expression and translation of the pharmaceutical protein in host cells, followed by extensive purification steps. In the wake of the SARS-CoV-2 pandemic, mRNA-based pharmaceuticals were recruited to achieve rapid in vivo production of antigens, proving that the in vivo translation of exogenously administered mRNA is nowadays a viable therapeutic option. In addition, the urgency of the situation and worldwide demand for mRNA-based medicine has led to an evolution in relevant technologies, such as in vitro transcription and nanolipid carriers. In this review, we present preclinical and clinical applications of mRNA as a tool for protein replacement therapy, alongside with information pertaining to the manufacture of modified mRNA through in vitro transcription, carriers employed for its intracellular delivery and critical quality attributes pertaining to the finished product.

Serum Proteome Signatures of Anti-SARS-CoV-2 Vaccinated Healthcare Workers in Greece Associated with Their Prior Infection Status.

Over the course of the pandemic, proteomics, being in the frontline of anti-COVID-19 research, has massively contributed to the investigation of molecular pathogenic properties of the virus. However, data on the proteome on anti-SARS-CoV-2 vaccinated individuals remain scarce. This study aimed to identify the serum proteome characteristics of anti-SARS-CoV-2 vaccinated individuals who had previously contracted the virus and comparatively assess them against those of virus-naïve vaccine recipients. Blood samples of n = 252 individuals, out of whom n = 35 had been previously infected, were collected in the "G. Gennimatas" General Hospital of Thessaloniki, from 4 January 2021 to 31 August 2021. All participants received the BNT162b2 mRNA COVID-19 vaccine (Pfizer/BioNTech). A label-free quantitative proteomics LC-MS/MS approach was undertaken, and the identified proteins were analyzed using the GO (Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes) databases as well as processed by bioinformatics tools. Titers of total RBD-specific IgGs against SARS-CoV-2 were also determined using the SARS-CoV-2 IgG II Quant assay. A total of 47 proteins were significantly differentially expressed, the majority of which were down-regulated in sera of previously infected patients compared to virus-naïve controls. Several pathways were affected supporting the crucial role of the humoral immune response in the protection against SARS-CoV-2 infection provided by COVID-19 vaccination. Overall, our comprehensive proteome profiling analysis contributes novel knowledge of the mechanisms of immune response induced by anti-SARS-CoV-2 vaccination and identified protein signatures reflecting the immune status of vaccine recipients.

Immunogenicity of the BNT162b2 mRNA Covid-19 vaccine in elderly people over 85 years of age in Greece: the GREVAXIMO study.

BACKGROUND: Elderly people aged over 85 years were among the first groups to receive the BNT162b2 mRNA Covid-19 vaccine in Greece according to the national priority assignment policy. AIM: The aim of this study was to provide useful insight into the antibody generation taking place post-immunization in elderly individuals aged over 85. METHODS: In the first phase of our study, antibody levels were monitored in a total of 400 participants, while our final sample consisted of 297 subjects. Humoral immune responses were recorded in 69.75% (95% CI 65.25-74.25) of vaccinees post-first dose and in 98.99% (95% CI 97.85-100) post-second dose. RESULTS: Overall, a remarkable 40-fold change in IgG levels was observed between the two doses. Subjects displaying low antibody levels after the first dose had significantly higher IgG fold changes than vaccinees whose initial antibody levels were high. CONCLUSION: Taken together, our findings highlighted the high fold change (41.18) recorded in the titers of neutralizing antibodies after the second dose suggesting the need for its timely administration to elderly individuals.

Immunogenicity after the first dose of the BNT162b2 mRNA Covid-19 vaccine: real-world evidence from Greek healthcare workers.

Real-world data regarding the effectiveness, safety and immunogenicity of the Pfizer-BioNTech BNT162b2 mRNA vaccine are accumulating in the literature, suggesting that this vaccine generates high titres of S1-binding IgG antibodies that exhibit potent virus neutralization capacity. This is the first phase IV immunogenicity study to recruit a large number of Greek healthcare workers (n=425) including 63 previously-infected subjects. We measured titres of neutralizing IgGs against the receptor-binding domain of the S1 subunit of the spike protein of SARS-CoV-2 14 days post-immunization with the first dose, employing the SARS-CoV-2 IgG II Quant assay. A total of 92.24 % of our study cohort received a positive assay outcome and titres varied with age. Post-hoc analysis revealed that although titres did not significantly differ among participants aged 20-49 years, a significant decline was marked in the age group of 50-59 years, which was further accentuated in subjects aged over 60. Antibody titres escalated significantly among the previously-infected, indicating the potential booster effect of the first dose in that group.

Second dose of the BNT162b2 mRNA vaccine: Value of timely administration but questionable necessity among the seropositive.

This study monitored titers of neutralizing IgG against the receptor-binding domain of the SARS-CoV-2 S1 subunit 14 days post-injection of each dose of the BNT162b2 mRNA Covid-19 vaccine in 401 Greek healthcare workers aged 20-67. After the first dose, titers varied upon age and history of infection, being lower in the 50+ age group and significantly higher among the seropositive. After the second dose, immunogenicity was significantly boosted in the age 50+ and SARS-CoV-2-naïve individuals, indicating the effectuality of its timely administration, yet questioning its value among the seropositive.