Weak SARS-CoV-2-specific responses of TIGIT-expressing CD8 + T cells in people living with HIV after a third dose of a SARS-CoV-2 inactivated vaccine / 中华医学杂志(英文版)

BACKGROUND@#T-cell immunoreceptor with immunoglobulin and immunoreceptor tyrosine-based inhibition motif domains (TIGIT), an inhibitory receptor expressed on T cells, plays a dysfunctional role in antiviral infection and antitumor activity. However, it is unknown whether TIGIT expression on T cells influences the immunological effects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) inactivated vaccines.@*METHODS@#Forty-five people living with HIV (PLWH) on antiretroviral therapy (ART) for more than two years and 31 healthy controls (HCs), all received a third dose of a SARS-CoV-2 inactivated vaccine, were enrolled in this study. The amounts, activation, proportion of cell subsets, and magnitude of the SARS-CoV-2-specific immune response of TIGIT + CD4 + and TIGIT + CD8 + T cells were investigated before the third dose but 6 months after the second vaccine dose (0W), 4 weeks (4W) and 12 weeks (12W) after the third dose.@*RESULTS@#Compared to that in HCs, the frequency of TIGIT + CD8 + T cells in the peripheral blood of PLWH increased at 12W after the third dose of the inactivated vaccine, and the immune activation of TIGIT + CD8 + T cells also increased. A decrease in the ratio of both T naïve (T N ) and central memory (T CM ) cells among TIGIT + CD8 + T cells and an increase in the ratio of the effector memory (T EM ) subpopulation were observed at 12W in PLWH. Interestingly, particularly at 12W, a higher proportion of TIGIT + CD8 + T cells expressing CD137 and CD69 simultaneously was observed in HCs than in PLWH based on the activation-induced marker assay. Compared with 0W, SARS-CoV-2-specific TIGIT + CD8 + T-cell responses in PLWH were not enhanced at 12W but were enhanced in HCs. Additionally, at all time points, the SARS-CoV-2-specific responses of TIGIT + CD8 + T cells in PLWH were significantly weaker than those of TIGIT - CD8 + T cells. However, in HCs, the difference in the SARS-CoV-2-specific responses induced between TIGIT + CD8 + T cells and TIGIT - CD8 + T cells was insignificant at 4W and 12W, except at 0W.@*CONCLUSIONS@#TIGIT expression on CD8 + T cells may hinder the T-cell immune response to a booster dose of an inactivated SARS-CoV-2 vaccine, suggesting weakened resistance to SARS-CoV-2 infection, especially in PLWH. Furthermore, TIGIT may be used as a potential target to increase the production of SARS-CoV-2-specific CD8 + T cells, thereby enhancing the effectiveness of vaccination.

Adaptive phenotypes of Yersinia pestis induced by successive passages in macrophages / 中华微生物学和免疫学杂志

Objective:To investigate the changes in adaptive phenotypes of Yersinia pestis ( Yp) during successive passages in macrophages. Methods:A Yp strain of 201-MI was induced by 50 successive passages of Yp 201 strain in Raw264.7 cells. Phenotypic characteristics of 201 and 201-MI strains were compared by analyzing their survival rates in macrophages, growth curves, biofilm formation abilities, acid and hydrogen peroxide-stress tolerance, and virulence to mammal cells (Raw264.7 and HeLa cells) and mice. Results:Comparing with 201 strain, 201-MI strain showed various phenotypic changes, including higher survival rate in Raw264.7 cells, faster growth in iron-deficient medium, higher tolerance to acid and hydrogen peroxide, decreased biofilm formation ability, and less damages to Raw264.7 and HeLa cells. More-over, 201-MI strain showed decreased virulence to mice in both subcutaneous and intraperitoneal challenges. Preliminary comparative genomics analysis revealed some indel and nonsense mutations in 201-MI strain, which might account for its phenotype changes.Conclusions:After successive passages in macrophages, Yp showed some phenotypic changes, which might reflect its adaptive evolution under the pressure of macrophages. Detailed multi-omics analysis would be of great help to understand the underlying genetic mechanisms of these changes, and the related Yp-macrophage interaction processes as well.