Clonal structure and the specificity of vaccine-induced T cell response to SARS-CoV-2 Spike protein

Adenovirus vaccines, particularly the COVID-19 Ad5-nCoV adenovirus vaccine, have emerged as promising tools in the fight against infectious diseases. In this study, we investigated the structure of the T cell response to the Spike protein of the SARS-CoV-2 virus used in the COVID-19 Ad5-nCoV adenoviral vaccine in a phase 3 clinical trial (NCT04540419). In 69 participants, we collected peripheral blood samples at four time points after vaccination or placebo injection. Sequencing of T cell receptor repertoires from Spike-stimulated T cell cultures at day 14 from 17 vaccinated revealed a more diverse CD4+ T cell repertoire compared to CD8+. Nevertheless, CD8+ clonotypes accounted for more than half of the Spike-specific repertoire. Our longitudinal analysis showed a peak T cell response at day 14, followed by a decline until month 6. Remarkably, multiple T cell clonotypes persisted for at least 6 months after vaccination, as demonstrated by ex vivo stimulation. Examination of CDR3 regions revealed homologous sequences in both CD4+ and CD8+ clonotypes, with major CD8+ clonotypes sharing high similarity with annotated sequences specific for the NYNYLYRLF peptide, suggesting potential immunodominance. In conclusion, our study demonstrates the immunogenicity of the Ad5-nCoV adenoviral vaccine and highlights its ability to induce robust and durable T cell responses. These findings provide valuable insight into the efficacy of the vaccine against COVID-19 and provide critical information for ongoing efforts to control infectious diseases

Concentration, temperature and deformation dependences of martensite lattice parameters in binary Ti-Ni shape memory alloys

X-ray diffractometric study of Ti-47.0 te 50.7 at. % Ni alloys has been performed. A concentration dependence of B19$'$ Martensite Lattice Parameters (MLP) exists in the range from 50.0 to 50.7 % Ni. MLP in Ti-47.0 and 50.0 % Ni coincide. Temperature dependence of MLP exists; MLP change in Ti-50.0%Ni alloy is enhanced in the B19$'$ to B2 transformation range. In the Ti-50.0% Ni, MLP are different for the quenched martensite and for the one formed from the austenite containing well-developed dislocation substructure. In Ti-50.0% Ni alloy, MLP do not change after its deformation up to 25% strain. Changes in MLP in the case of hyper-equiatomic nickel concentration or due to the presence of highly-dislocated initial austenite are independent of the presence of the R phase during martensite formation