Conservation of T cell epitopes between seasonal influenza viruses and the novel influenza A H7N9 virus

A novel avian influenza A(H7N9) virus recently emerged in the Yangtze River delta and caused diseases, often severe, in over 130 people. This H7N9 virus appeared to infect humans with greater ease than previous avian influenza virus subtypes such as H5N1 and H9N2. While there are other potential explanations for this large number of human infections with an avian influenza virus, we investigated whether a lack of conserved T-cell epitopes between endemic H1N1 and H3N2 influenza viruses and the novel H7N9 virus contributes to this observation. Here we demonstrate that a number of T cell epitopes are conserved between endemic H1N1 and H3N2 viruses and H7N9 virus. Most of these conserved epitopes are from viral internal proteins. The extent of conservation between endemic human seasonal influenza and avian influenza H7N9 was comparable to that with the highly pathogenic avian influenza H5N1. Thus, the ease of inter-species transmission of H7N9 viruses(compared with avian H5N1 viruses) cannot be attributed to the lack of conservation of such T cell epitopes. On the contrary, our findings predict significant T-cell based cross-reactions in the human population to the novel H7N9 virus. Our findings also have implications for H7N9 virus vaccine design.

Development of T cell antigen-based human coronavirus vaccinesagainst nAb-escaping SARS-CoV-2 variants

Currently approved vaccines have been successful in preventing the severity of COVID-19 and hospitalization. These vaccines primarily induce humoral immune responses;however, highly transmissible and mutated variants, such as the Omicron variant, weaken the neutralization potential of the vaccines, thus,raising serious concerns about their efficacy. Additionally, while neutralizing antibodies(nAbs) tend to wane more rapidly than cell-mediated immunity, long-lasting T cells typically prevent severe viral illness by directly killing infected cells or aiding other immune cells. Importantly, T cells are more cross-reactive than antibodies, thus, highly mutated variants are less likely to escape lasting broadly cross-reactive T cell immunity. Therefore, T cell antigen-based human coronavirus(HCoV) vaccines with the potential to serve as a supplementary weapon to combat emerging SARS-CoV-2 variants with resistance to n Abs are urgently needed. Alternatively, T cell antigens could also be included in B cell antigen-based vaccines to strengthen vaccine efficacy. This review summarizes recent advancements in research and development of vaccines containing T cell antigens or both T and B cell antigens derived from proteins of SARS-CoV-2 variants and/or other HCo Vs based on different vaccine platforms.

T Cell Vaccination as an Immunotherapy for Autoimmune Diseases

Immunization with inactivated autoreactive T cells(T cell vaccination) selected from individual's own T cell repertoire provides a unique in vivo setting for testing immune regulation that is known to involve interactions of a variety of related surface molecules(1).It induces regulatory immune responses that closely resemble the in vivo situation where the immune system is challenged by clonal activation and expansion of given T cell populations in various autoimmune diseases.T cell vaccination provides a powerful means of eliciting natural reactions of the immune system in response to clonal expansion of T cells,which can be used as a therapeutic approach to suppress or eliminate specific pathogenic autoreactive T cells in autoimmune conditions.Clinical trials using T cell vaccination to deplete autoreactive T cells in human autoimmune conditions have begun to reveal the pathologic relevance of various autoimmune T cell populations in the disease processes,providing a unique opportunity to test the autoimmune theories in a clinical setting.Cellular & Molecular Immunology. 2004;1(5):321-327.

Therapeutic antitumor response to cervical cancer in mice immunized with U14 vaccines transfected with costimulatory B7 gene

Objective To investigate the effect of U14 vaccine transfected with the B7 gene in inducing antitumor immune response to murine cervical carcinoma in Chinese 615-strain mice.Methods A recombinant retroviral plasmid vector expressing mouse B7-1 gene (pLNSX-mB7) was transfected into 615-strain mouse cervical carcinoma cell line No. 14 (U14) by electroporation to set up a highly-expressed mB7-1 U14 cell clonal strain (B7+U14). In vivo experiments: (1) B7+U14 vaccine was primed to protect the 615-strain mice against U14 re-challenge. (2) B7+U14 vaccine was injected into tumor-bearing mice with different tumor sizes. Lifetimes and tumor sizes were recorded. In vitro cytotoxicity assay: Mice were immunized with B7+U14 or U14 vaccine and 2 weeks later, spleen cells of those mice were cultured for 2 days. The cytotoxicity of these cells against U14 was detected by 5-diphenyl tetrazolium bromide assay.Results We obtained several B7-1 high expression clonal U14 lines. In vivo experiment, we did not find tumor growing in 3 of the 6 mice primed by B7+U14 vaccine during their entire life after re-challenge with U14. The other 3 mice developed tumors and their average survival time was longer than that of the control group (P<0.01). All 6 mice grew tumors in the control group. When the transplanted tumors became palpable, the mice were randomly divided into 3 groups to be injected with B7+U14 vaccine. It was effective for tumor-bearing mice only when the tumor diameters were <3?mm. When the diameters were ≥3?mm, it was not efficacious to inject B7+U14 vaccine (P<0.05). In vitro cytotoxicity assay, cytotoxic T lymphocytes induced by B7+U14 vaccine had a higher cytotoxicity against U14 than that induced by U14 vaccine (F=310.8, P<0.001).Conclusions Vaccines of cervical cancer cells transfected with the costimulatory molecule B7 gene can induce antitumor immune protection in host mice against U14 re-challenge. This treatment may cure part of the tumor-bearing mice but be restricted by tumor size. The results suggest that transfecting the B7 gene into cervical cancer as a cell vaccine may be an efficient supplementary method to treat cervical cancer after operation.

Anti-Idiotypic Regulatory Responses Induced by Vaccination with DNA Encoding Murine TCR Vα5 and Vβ2

There is evidence suggesting that anti-idiotypic regulation against T cells plays a role in maintaining homeostasis in the immune system, although its mechanism is not fully understood. By using DNA constructs encoding the TCR Vα5.2 and Vβ2.1 chains derived from ：in ovalbumin （OVA）-specific T cdl clone （OVA-T）, we herein demonstrated that vaccination with TCR-DNA effectively induced anti-idiotypic cellular as well as humoral responses. Serum samples from the TCR-DNA-vaccinated BALB/c mice were able to stain T cells in an idiotype-specific manner. CD4^＋ T cells from the TCR-DNA-vaccinated mice proliferated in response to stimulation with irradiated syngeneic OVA-T calls and secreted interferon-y but very little IL-4. Splenocytes from the TCR-DNA-vaccinated mice showed strong idiotype-specific CTL activity against the OVA-T cdls. Furthermore, adoptive transfer of the CD4^＋ or CD8^＋ T cells from the TCR-DNA-vaccinated mice resulted in hyporesponsiveness of syngeneic recipients. These results demonstrated that vaccination with DNA encoding TCR can effectively activate anti-idiotypic regulatory responses in vivo and thus providing a useful way for immunological intervention.