A novel proteoliposomal vaccine elicits potent antitumor immunity in mice

Therapeutic vaccination against idiotype is a promising strategy for immunotherapy of B-cell malignancies. Its feasibility, however, is limited by the requirement for a patient-specific product. Here we describe a novel vaccine formulation prepared by simply extracting cell-membrane proteins from lymphoma cells and incorporating them together with IL-2 into proteoliposomes. The vaccine was produced in 24 hours, compared with more labor-intensive and time-consuming hybridoma or recombinant DNA methods. The vaccine elicited T-cell immunity in vivo, as demonstrated by secretion of type 1 cytokines. It protected against tumor challenge at doses of tumor antigen 50 to 100 times lower than that previously observed using either liposomes formulated with IL-2 and secreted lymphoma immunoglobulin or a prototype vaccine consisting of lymphoma immunoglobulin conjugated to keyhole limpet hemocyanin. The increased potency justifies testing similar patient-specific human vaccines prepared using extracts from primary tumor samples.     

Novel antibodies against follicular non-Hodgkin's lymphoma

The anti-CD20 monoclonal antibody rituximab has revolutionized the treatment of patients with follicular B-cell lymphoma. With the combination of chemotherapy and rituximab the overall survival rate has increased with approximately 30%. Unfortunately, there is resistance to rituximab with relapse of the disease in about 60% of the patients during the first five years of treatment and eventually in all patients. To this end, there is a need to develop improved anti-CD20 monoclonal antibodies and antibodies that target other attractive molecules expressed on the follicular lymphoma cell. This review describes the development and clinical achievements so far of next generation anti-CD20 and other antibodies in the treatment of follicular B-cell lymphoma.     

Sm-p80-based DNA vaccine formulation induces potent protective immunity against Schistosoma mansoni

No effective vaccine exists for the human parasitic disease, schistosomiasis. We have targeted a functionally important antigen, Sm-p80 as a vaccine candidate because of its consistent immunogenicity, protective potential and important role in the immune evasion process. In this study we report that a Sm-p80-based DNA vaccine formulation confers 59% reduction in worm burden in mice. Animals immunized with Sm-p80-pcDNA3 exhibited a decrease in egg production by 84%. Sm-p80 DNA elicited strong immune responses that include IgG2A and IgG2B antibody isotypes in vaccinated animals. Splenocytes proliferated in response to Sm-p80 produced appreciably more Th1 response enhancing cytokines (IL-2, IFN-γ) than Th2 response enhancing cytokines (IL-4, IL-10). These data reinforce the potential of Sm-p80 as an excellent vaccine candidate for schistosomiasis.     

Combination lenalidomide-rituximab immunotherapy activates anti-tumour immunity and induces tumour cell death by complementary mechanisms of action in follicular lymphoma

Chemotherapy plus rituximab has been the mainstay of treatment for follicular lymphoma (FL) for two decades but is associated with immunosuppression and relapse. In phase 2 studies, lenalidomide combined with rituximab (R²) has shown clinical synergy in front-line and relapsed/refractory FL. Here, we show that lenalidomide reactivated dysfunctional T and Natural Killer (NK) cells ex vivo from FL patients by enhancing proliferative capacity and T-helper cell type 1 (Th1) cytokine release. In combination with rituximab, lenalidomide improved antibody-dependent cellular cytotoxicity in sensitive and chemo-resistant FL cells, via a cereblon-dependent mechanism. While single-agent lenalidomide and rituximab increased formation of lytic NK cell immunological synapses with primary FL tumour cells, the combination was superior and correlated with enhanced cytotoxicity. Immunophenotyping of FL patient samples from a phase 3 trial revealed that R² treatment increased circulating T- and NK-cell counts, while R-chemotherapy was associated with reduced cell numbers. Finally, using an in vitro model of myeloid differentiation, we demonstrated that lenalidomide caused a reversible arrest in neutrophil maturation that was distinct from a cytotoxic chemotherapeutic agent, which may help explain the lower rates of neutropenia observed with R² versus R-chemotherapy. Taken together, we believe these data support a paradigm shift in the treatment of FL – moving from combination immunochemotherapy to chemotherapy-free immunotherapy.     

T淋巴细胞瘤转基因瘤苗抗肿瘤作用研究

目的观察C57小鼠源性淋巴瘤瘤苗抗肿瘤免疫效果。方法采用电穿孔法将粒细胞—巨噬细胞集落刺激因子（GM-CSF）表达质粒导入T淋巴瘤RMA细胞制作转基因瘤苗,筛选出高表达GM-CSF的细胞克隆（RMA-GM）,经丝裂霉素处理后皮下接种C57小鼠,观察抗肿瘤免疫效果。结果RMA-GM接种C57小鼠后,出瘤时间延长,肿瘤生长速度减慢,生存期延长,40%的小鼠长期生存。结论GM-CSF基因质粒转导的RMA-GM转基因瘤苗具有较好的抗肿瘤免疫效果。     

Enhanced protection against tuberculosis by vaccination with recombinant Mycobacterium microti vaccine that induces T cell immunity against region of difference 1 antigens

Mycobacterium microti, the vole bacillus, which was used as a live vaccine against tuberculosis until the 1970s, confers the same protection in humans as does Mycobacterium bovis bacille Calmette-Guerin (BCG). However, because the efficacy of the BCG vaccine varies considerably, we have tried to develop a better vaccine by reintroducing into M. microti the complete region of difference 1 (RD1), which is required for secretion of the potent T cell antigens early secreted antigen target (ESAT)-6 and culture filtrate protein (CFP)-10. The resultant recombinant strain, M. microti OV254::RD1-2F9, induced specific ESAT-6 and CFP-10 immune responses in mice with CD8(+) T lymphocytes that had strong expression of the CD44(hi) activation marker. This vaccine also displayed better efficacy against disseminated disease in the mouse and the guinea pig models of tuberculosis than was seen in animals vaccinated with M. microti alone or with BCG. The M. microti OV254::RD1-2F9 vaccine was less virulent and persistent in mice and than was BCG::RD1-2F9 may represent a safer alternative to BCG::RD1-2F9.     

A class II MHC-targeted vaccine elicits immunity against SARS-CoV-2 and its variants

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in over 100 million infections and millions of deaths. Effective vaccines remain the best hope of curtailing SARS-CoV-2 transmission, morbidity, and mortality. The vaccines in current use require cold storage and sophisticated manufacturing capacity, which complicates their distribution, especially in less developed countries. We report the development of a candidate SARS-CoV-2 vaccine that is purely protein based and directly targets antigen-presenting cells. It consists of the SARS-CoV-2 Spike receptor-binding domain (Spike_RBD) fused to an alpaca-derived nanobody that recognizes class II major histocompatibility complex antigens (VHH_MHCII). This vaccine elicits robust humoral and cellular immunity against SARS-CoV-2 and its variants. Both young and aged mice immunized with two doses of VHH_MHCII-Spike_RBD elicit high-titer binding and neutralizing antibodies. Immunization also induces strong cellular immunity, including a robust CD8 T cell response. VHH_MHCII-Spike_RBD is stable for at least 7 d at room temperature and can be lyophilized without loss of efficacy.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of COVID-19, has caused a global pandemic, infecting over 230 million people, and leading to millions of deaths (1). Rapid distribution of effective vaccines on a global scale is the most effective means of mitigating the political, social, and economic destabilization caused by the SARS-CoV-2 pandemic.The SARS-CoV-2 spike (S) protein is a trimeric transmembrane protein that binds to the cell surface receptor angiotensin-converting enzyme 2 (ACE2) via its receptor-binding domain (RBD) and mediates fusion with host membranes (2). SARS-CoV-2 S is the primary target for neutralizing antibodies and elicits both CD4 and CD8 T cell responses during infection (3–7). Most vaccines in current use or in development target S, or fragments of S, as the primary antigen (8). Because several variants of concern have emerged, many of which contain mutations in S that partially resist neutralization by vaccine-elicited and COVID-19–elicited antibodies, vaccines that offer protection against new variants are necessary (9–11).Leading vaccine candidates use an array of diverse vaccine platforms. These include inactivated virions, DNA-based vaccines, recombinant subunit preparations, lipid-encapsulated mRNA formulations, as well as live-attenuated, replication-incompetent viral vectored, and replication-competent viral vectored vaccines (8). None of them directly and specifically target antigen-presenting cells (APCs). We hypothesized that targeted delivery of antigen to professional class II MHC⁺ APCs would improve access to the processing and presentation pathways that generate CD4 and CD8 T cell responses, in addition to provoking a robust antibody response. Our earlier efforts to generate an anti-HPV16 CD8 T cell response relied on fusions of an anti-CD11b nanobody to the immunodominant epitope of the HPV16 E7 protein as a vaccine. Its success in eradicating even established tumors inspired us to pursue a similar effort to deliver the RBD of the SARS-CoV2 S protein as a fusion with a nanobody that targets APCs (12). Most vaccines in current use require specialized storage conditions (13–15). The development of vaccines with enhanced stability to allow storage at ambient temperature and rapidly adjustable to emerging variants of the virus therefore remains a priority. Moreover, vaccines that can be produced rapidly in a scalable manufacturing process would improve access.Here we report the development of a recombinant protein vaccine that consists of the SARS-CoV-2 Spike RBD (Spike_RBD) fused to an alpaca-derived nanobody that targets class II major histocompatibility (MHC II) complex antigens (VHH_MHCII-Spike_RBD). This vaccine delivers the antigen directly to class II MHC⁺ APCs. Immunization of both young and aged mice with two doses of VHH_MHCII-Spike_RBD resulted in robust binding and neutralizing antibody responses against SARS-CoV-2 and emerging variants. Immunization also induced prominent CD8 T cell responses against conserved Spike_RBD-derived epitopes. VHH_MHCII-Spike_RBD can be produced in high yield in mammalian cells and tolerates both storage at room temperature for at least 7 d and lyophilization without loss of efficacy.     

The role of antibody-mediated immunity in defense against Mycobacterium tuberculosis: advances toward a novel vaccine strategy

Antibody-mediated immunity has been historically considered to have no role in host-defense against Mycobacterium tuberculosis. In recent years, studies from our group as well as others have challenged this traditional thinking. Using monoclonal antibodies, researchers demonstrated that antibodies can modify various aspects of mycobacterial infection to the benefit of the host. A review of recent experimental evidence in support of a role for antibodies in host-defense against mycobacterial infections is presented. Challenges to the field and an outline of future directions with particular attention to research leading to the development of a novel vaccine strategy, are emphasized.     

Effects of inactivated influenza vaccine on postvaccination immunity against tuberculosis

The importance of inactivated influenza virus vaccines (IIVV) as a risk factor leading to a change of immunologic reactivity in persons earlier revaccinated with BCG once, twice or thrice was studied. The condition of T system was investigated by blast-transformation reaction with PPD-L and PHA in 1 and 3 months after administration of different types of IIVV. If all types of IIVV are administered, there is an inhibition of a specific activity of T cells with a certain stimulation of their nonspecific functions. The intensity of IIVV impact depends on the type, number, and duration of prior BCG vaccinations, as well as the initial condition of T-link.     

Conjugation of lymphoma idiotype to CD40 antibody enhances lymphoma vaccine immunogenicity and antitumor effects in mice

Personalized immunotherapy of lymphoma based on tumor idiotype (Id) has shown anti-idiotype humoral immune responses in 40%-50% and cellular immune responses in 50%-75% of follicular lymphoma patients, indicating that this therapy can be clinically successful. We have developed a novel vaccine against lymphoma consisting of an anti-CD40 Ab (ADX40) chemically conjugated to the tumor idiotype A20 and tested it in a murine lymphoma model. BALB/c mice were immunized with 2 doses of immunogen alone or in conjunction with additional adjuvants before tumor challenge. ADX40-Id vaccination resulted in significantly retarded tumor growth and reduced mouse morbidity. Moreover, similar mouse survival was obtained with 2 injections of ADX40-Id as with 8 injections using the standard therapy of keyhole limpet hemocyanin Id + GM-CSF. Co-administration of ADX40-Id with 3-O-deacyl-4'-monophosphoryl lipid A further significantly enhanced vaccine efficacy, resulting in an increased overall survival. Anti-Id-specific Abs were detected at elevated levels after ADX40-Id immunization; however, in vivo depletion of CD4 and/or CD8 T cells before challenge showed that CD8 effector T cells were the major mediators of tumor protection. The results of the present study show that the ADX40-Id conjugate vaccine is a potential candidate as a stand-alone vaccine or in combination with currently licensed adjuvants for lymphoma immunotherapy.     

Recombinant modified vaccinia virus Ankara-based vaccine induces protective immunity in mice against infection with influenza virus H5N1

Since 2003, the number of human cases of infections with highly pathogenic avian influenza viruses of the H5N1 subtype is still increasing, and, therefore, the development of safe and effective vaccines is considered a priority. However, the global production capacity of conventional vaccines is limited and insufficient for a worldwide vaccination campaign. In the present study, an alternative H5N1 vaccine candidate based on the replication-deficient modified vaccinia virus Ankara (MVA) was evaluated. C57BL/6J mice were immunized twice with MVA expressing the hemagglutinin (HA) gene from influenza virus A/Hongkong/156/97 (MVA-HA-HK/97) or A/Vietnam/1194/04 (MVA-HA-VN/04). Subsequently, recombinant MVA-induced protective immunity was assessed after challenge infection with 3 antigenically distinct strains of H5N1 influenza viruses: A/Hongkong/156/97, A/Vietnam/1194/04, and A/Indonesia/5/05. Our data suggest that recombinant MVA expressing the HA of influenza virus A/Vietnam/1194/04 is a promising alternative vaccine candidate that could be used for the induction of protective immunity against various H5N1 influenza strains.     

A novel therapeutic vaccine approach against RANKL that prevents pathological bone destruction

The vaccination method is used to induce antibody response against disease-related proteins by immunization with modified pathological antigen as preventive therapy to acquire disease resistance. A RANKL vaccine was developed by modifying the soluble TNF-like domain of murine RANKL to incorporate a promiscuous Th epitope. Immunization with RANKL vaccine prevented pathological bone resorption in arthritic mice or ovariactomized mice.     

Generation of antitumor immunity against large colon tumors by repeated runs of electrochemotherapy

BACKGROUND/AIMS: Electrochemotherapy, which uses two parallel electrodes for delivery of electric pulses, may be useful for treatment of tumor nodules. However, in clinical fields, tumors that are larger than the distance between the two electrodes are frequently observed, and it would be difficult in such cases to deliver electric pulses to the tumor. This study was done to define how host antitumor immunity is generated by repeated electrochemotherapy treatments, and whether it is associated with regression of even large tumor nodules. METHODOLOGY: Balb/c mice and Balb/c nude mice were inoculated subcutaneously with colon 26. Electrochemotherapy using bleomycin and electroporation (CUY21) was administered as a treatment for tumor nodules that were larger than the distance between the electrodes. RESULTS: In Balb/c mice, growth of large tumors at the start of treatment is not inhibited by a single electrochemotherapy treatment. However, complete tumor regression was obtained through repeated electrochemotherapy treatments. No tumor cure was observed among Balb/c nude mice under the same therapeutic conditions. Inflammatory cells were accumulated in the tumor tissue seven days after the third electrochemotherapy treatment. CONCLUSIONS: Repeated electrochemotherapy is a promising treatment, even for large tumors, such as are usually encountered in clinical practice, by generating T-cell dependent, antitumor immunity.     

DNA疫苗诱导小鼠细胞免疫及抗肿瘤免疫研究

目的 观察ＨＢＶＤＮＡ疫苗诱导ＢＡＬＢ／Ｃ小鼠（Ｈ－２＾ｄ）的特异性细胞免疫应答及其对稳定表达ＨＢｓＡｇ的小鼠肥大细胞瘤Ｐ８１５细胞（这５－ＨＢＶ－Ｓ）（Ｈ－２＾ｄ）成瘤性的影响。方法 肌肉注射ＤＮＡ疫苗,背部皮下接种Ｐ８１５－ＨＢＶ－Ｓ细胞,观察成瘤情况,４ｈ＾５１Ｃｒ释放法不细胞细胞毒Ｔ淋细胞（ＣＴＬ）活性。结果 ＤＮＡ疫苗可以降低成瘤率,抑制成长小鼠存活期和提高小鼠存活率。ＣＴＬ细胞杀伤活性