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Bovine herpesvirus-1 (BoHV-1) uses many mechanisms to elude the immune system; one of them is spreading intracellularly, even in the presence of specific antiviral antibodies. Cytotoxic T lymphocytes (CTLs) are necessary to eliminate the virus. The main preventive strategy is vaccination based on inactivated virus. These vaccines are poor inducers of cellular immune responses, and complicate serological diagnosis and determination of the real prevalence of infection. DNA vaccines are a good option because of the capacity of Differentiating Infected from Vaccinated Animals-(DIVA vaccine)-and may be the best way to induce cytotoxic responses. Although this type of vaccines leads to only weak "

Foot-and-Mouth Disease (FMD) is an acute viral disease that causes important economy losses. Vaccines with new low-cost adjuvants that stimulate protective immune responses are needed and can be assayed in a mouse model to predict their effectiveness in cattle. Immunostimulant Particle Adjuvant (ISPA), also known as cage-like particle adjuvant, consisting of lipid boxes of dipalmitoyl-phosphatidylcholine, cholesterol, sterylamine, alpha-tocopherol, and QuilA saponin, was shown to enhance protection of a recombinant vaccine against Trypanosoma cruzi in a mouse model. Thus, in the present work, we studied the effects on the magnitude and type of immunity elicited in mice and cattle in response to a vaccine based on inactivated FMD virus (iFMDV) formulated with ISPA. It was demonstrated that iFMDV–ISPA induced protection in mice against challenge and elicited a specific antibody response in sera, characterized by a balanced Th1/Th2 profile. In cattle, the antibody titers reached corresponded to an expected percentage of protection (EPP) higher than 80%. EPP calculates the probability that livestock would be protected against a 10,000 bovine infectious doses challenge after vaccination. Moreover, in comparison with the non-adjuvanted iFMDV vaccine, iFMDV–ISPA elicited an increased specific T-cell response against the virus, including higher interferon gamma (IFNγ)+/CD8+ lymphocyte production in cattle. In this work, we report for first time that an inactivated FMDV serotype A vaccine adjuvanted with ISPA is capable of inducing protection against challenge in a murine model and of improving the specific immune responses against the virus in cattle. Fil: Bidart, Juan Esteban. Instituto Nacional de Tecnologia Agropecuaria. Centro de Investigacion En Ciencias Veterinarias y Agronomicas. Instituto de Virologia E Innovaciones Tecnologicas. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Pque. Centenario. Instituto de Virologia E Innovaciones Tecnologicas.; Argentina Fil: Kornuta, Claudia Alejandra. Instituto Nacional de Tecnologia Agropecuaria. Centro de Investigacion En Ciencias Veterinarias y Agronomicas. Instituto de Virologia E Innovaciones Tecnologicas. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Pque. Centenario. Instituto de Virologia E Innovaciones Tecnologicas.; Argentina Fil: Gammella, Mariela Vanesa. Instituto Nacional de Tecnologia Agropecuaria. Centro de Investigacion En Ciencias Veterinarias y Agronomicas. Instituto de Virologia E Innovaciones Tecnologicas. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Pque. Centenario. Instituto de Virologia E Innovaciones Tecnologicas.; Argentina Fil: Gnazzo, Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú; Argentina Fil: Soria, Ivana. Instituto Nacional de Tecnologia Agropecuaria. Centro de Investigacion En Ciencias Veterinarias y Agronomicas. Instituto de Virologia E Innovaciones Tecnologicas. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Pque. Centenario. Instituto de Virologia E Innovaciones Tecnologicas.; Argentina Fil: Langellotti, Cecilia Ana. Instituto Nacional de Tecnologia Agropecuaria. Centro de Investigacion En Ciencias Veterinarias y Agronomicas. Instituto de Virologia E Innovaciones Tecnologicas. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Pque. Centenario. Instituto de Virologia E Innovaciones Tecnologicas.; Argentina Fil: Mongini, Claudia. Instituto Nacional de Tecnologia Agropecuaria. Centro de Investigacion En Ciencias Veterinarias y Agronomicas. Instituto de Virologia E Innovaciones Tecnologicas. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Pque. Centenario. Instituto de Virologia E Innovaciones Tecnologicas.; Argentina Fil: Galarza, Roxana. Instituto Nacional de Tecnologia Agropecuaria. Centro Regional Buenos Aires Sur. Estacion Experimental Agropecuaria Cuenca del Salado. Agencia de Extension Rural Chascomus.; Argentina Fil: Calvinho, Luis Fernando. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Rafaela; Argentina Fil: Lupi, Giuliana Antonella. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral; Argentina Fil: Quattrocchi, Valeria. Instituto Nacional de Tecnologia Agropecuaria. Centro de Investigacion En Ciencias Veterinarias y Agronomicas. Instituto de Virologia E Innovaciones Tecnologicas. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Pque. Centenario. Instituto de Virologia E Innovaciones Tecnologicas.; Argentina Fil: Marcipar, Iván Sergio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral; Argentina Fil: Zamorano, Patricia Ines. Instituto Nacional de Tecnologia Agropecuaria. Centro de Investigacion En Ciencias Veterinarias y Agronomicas. Instituto de Virologia E Innovaciones Tecnologicas. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Pque. Centenario. Instituto de Virologia E Innovaciones Tecnologicas.; Argentina

T-cell lymphomas include diverse malignancies. They are rare, some have low survival rates and they lack curative therapies. The aim of this work was to assess whether employing the TLR7 agonist imiquimod and the T-cell costimulatory molecule CD40 or the combination of both as adjuvants of a cell lysate vaccine could enhance the antitumor immune response using a murine T-cell lymphoma model. Immunization with LBC-lysate and imiquimod protected almost all vaccinated animals. A specific humoral and a Th1-type cellular immunity were induced in mice that rejected the lymphoma, characterized by an elevated number of CD4 + T-cells and secretion of IFN-γ, locally and systemically. In contrast, CD40 alone or in combination with imiquimod did not improve the protective response obtained with LBC-lysate and imiquimod. Systemic administration of imiquimod proved to have high potential to serve as a vaccine adjuvant for the treatment of T-cell lymphomas and was effective in this immunotherapy model. Fil: Di Sciullo, Maria Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos. Universidad de Buenos Aires. Facultad de Medicina. Centro de Estudios Farmacológicos y Botánicos; Argentina Fil: Menay, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos. Universidad de Buenos Aires. Facultad de Medicina. Centro de Estudios Farmacológicos y Botánicos; Argentina Fil: Cocozza, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos. Universidad de Buenos Aires. Facultad de Medicina. Centro de Estudios Farmacológicos y Botánicos; Argentina Fil: Gravisaco, María José. Instituto Nacional de Tecnología Agropecuaria; Argentina Fil: Waldner, Claudia Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos. Universidad de Buenos Aires. Facultad de Medicina. Centro de Estudios Farmacológicos y Botánicos; Argentina Fil: Mongini, Claudia. Instituto Nacional de Tecnología Agropecuaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos. Universidad de Buenos Aires. Facultad de Medicina. Centro de Estudios Farmacológicos y Botánicos; Argentina

Extracellular vesicles (EVs), including endosome-derived nanovesicles (exosomes), are involved in cell–cell communication. Through transfer of their molecular contents, extracellular nanovesicles can alter the function of recipient cells. Due to these characteristics, EVs have shown potential as a new alternative for cancer immunotherapy. Tumor exosomes isolated from malignant ascites can activate dendritic cells, thereby priming the immune system to recognize and kill cancer cells. However, a suppressive role on tumor immune response has also been reported, suggesting that the neoplastic stage of carcinogenesis and the microenvironment where tumor cells grow may influence the amount of EVs released by the cell. This neoplastic stage and microenvironment may also impact EVs’ components such as proteins and miRNA, determining their biological behavior. Most T-cell lymphomas have an aggressive clinical course and poor prognosis. Consequently, complementary alternative therapies are needed to improve the survival rates achieved with conventional treatments. In this work, we have characterized EVs isolated from ascites of mice bearing a very aggressive murine T-cell lymphoma and have studied their immunogenic properties. Small EVs were isolated by differential centrifugation, ultrafiltration, and ultracentrifugation at 100,000 × g on a sucrose cushion. The EVs were defined as exosomes by their morphology and size analyzed by electron microscopy, their floating density on a sucrose gradient, as well as their expression of endosome marker proteins ALIX, TSG-101; the tetraspanins CD63, CD9, and CD81. In addition, they contain tumor antigens, the marker for malignancy CD24, the heat shock protein HSP-70, and an unusual surface expression of HSP-90 was demonstrated. The administration of EVs isolated from ascites (EVs A) into naïve-syngeneic mice induced both humoral and cellular immune responses that allowed the rejection of subsequent tumor challenges. However, the immunization had no effect on a non-related mammary adenocarcinoma, demonstrating that the immune response elicited was specific and also it induced immune memory. In vitro analysis demonstrated that T-cells from EVs A-immunized mice secrete IFN-γ in response to tumor stimulation. Furthermore, tumor-specific CD4+ and CD8+ IFN-γ secreting cells could be efficiently expanded from mice immunized with EVs A, showing that a T helper 1 response is involved in tumor rejection. Our findings confirm exosomes as promising defined acellular tumor antigens for the development of an antitumor vaccine. Inst. de Biotecnología Fil: Menay, Florencia. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Virología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Estudios Farmacológicos y Botánicos; Argentina. Universidad de Buenos. Facultad de Medicina, Aires; Argentina Fil: Herschlik, Leticia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Estudios Farmacológicos y Botánicos; Argentina. Universidad de Buenos. Facultad de Medicina, Aires; Argentina Fil: Cocozza, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Estudios Farmacológicos y Botánicos; Argentina. Universidad de Buenos. Facultad de Medicina, Aires; Argentina Fil: Tsacalian, Rodrigo Farid. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Estudios Farmacológicos y Botánicos; Argentina. Universidad de Buenos. Facultad de Medicina, Aires; Argentina Fil: Gravisaco, Marí­a José. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Biotecnología; Argentina Fil: Di Sciullo, Maria Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Estudios Farmacológicos y Botánicos; Argentina. Universidad de Buenos. Facultad de Medicina; Argentina Fil: Vendrell, Alejandrina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Estudios Farmacológicos y Botánicos; Argentina. Universidad de Buenos. Facultad de Medicina, Aires; Argentina Fil: Waldner, Claudia Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Estudios Farmacológicos y Botánicos; Argentina. Universidad de Buenos. Facultad de Medicina, Aires; Argentina Fil: Mongini, Claudia. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Virología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Estudios Farmacológicos y Botánicos; Argentina. Universidad de Buenos. Facultad de Medicina; Argentina

Primary tumor excision is one of the most widely used therapies of cancer. However, the risk of metastases development still exists following tumor resection. The liver is a common site of metastatic disease for numerous cancers. Breast cancer is one of the most frequent sources of metastases to the liver. The aim of this work was to evaluate the efficacy of the orally administered Salmonella Typhi vaccine strain CVD 915 on the development of liver metastases in a mouse model of breast cancer. To this end, one group of BALB/c mice was orogastrically immunized with CVD 915, while another received PBS as a control. After 24 h, mice were injected with LM3 mammary adenocarcinoma cells into the spleen and subjected to splenectomy. This oral Salmonella-based vaccine produced an antitumor effect, leading to a decrease in the number and volume of liver metastases. Immunization with Salmonella induced an early cellular immune response in mice. This innate stimulation rendered a large production of IFN-γ by intrahepatic immune cells (IHIC) detected within 24 h. An antitumor adaptive immunity was found in the liver and celiac and portal lymph nodes (LDLN) 21 days after oral bacterial inoculation. The antitumor immune response inside the liver was associated with increased CD4(+) and dendritic cell populations as well as with an inflammatory infiltrate located around liver metastatic nodules. Enlarged levels of inflammatory cytokines (IFN-γ and TNF) were also detected in IHIC. Furthermore, a tumor-specific production of IFN-γ and TNF as well as tumor-specific IFN-γ-producing CD8 T cells (CD8(+)IFN-γ(+)) were found in the celiac and portal lymph nodes of Salmonella-treated mice. This study provides first evidence for the involvement of LDLN in the development of an efficient cellular immune response against hepatic tumors, which resulted in the elimination of liver metastases after oral Salmonella-based vaccination. Fil: Vendrell, Alejandrina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos. Universidad de Buenos Aires. Facultad de Medicina. Centro de Estudios Farmacológicos y Botánicos; Argentina Fil: Mongini, Claudia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos. Universidad de Buenos Aires. Facultad de Medicina. Centro de Estudios Farmacológicos y Botánicos; Argentina Fil: Gravisaco, Maria Jose Federica. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Biotecnología; Argentina Fil: Canellada, Andrea Mercedes. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni; Argentina Fil: Tesone, Agustina Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos. Universidad de Buenos Aires. Facultad de Medicina. Centro de Estudios Farmacológicos y Botánicos; Argentina Fil: Goin, Juan Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos. Universidad de Buenos Aires. Facultad de Medicina. Centro de Estudios Farmacológicos y Botánicos; Argentina Fil: Waldner, Claudia Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos. Universidad de Buenos Aires. Facultad de Medicina. Centro de Estudios Farmacológicos y Botánicos; Argentina

We investigated the use of a live, attenuated Salmonella enterica serovar Typhi vaccine strain as an antitumor immunotherapy. Mice bearing a subcutaneous tumor (LM3 mammary adenocarcinoma) were immunized on three occasions with S. Typhi strain CVD 915 by injection into the tumor, the peritumoral tissue and the draining lymph node areas; this procedure was termed Salmonella multiple treatment (Salmonella MT). Tumor-bearing mice subjected to the Salmonella MT exhibited reduced tumor growth, prolonged survival and reduced incidence of lung metastases, compared to untreated mice. We examined the mechanisms mediating this effect and found that Salmonella MT promoted an antitumor Th1-type response characterized by increased frequencies of IFN-γ-secreting CD4(+) T and CD8(+) T cells with reduction of regulatory T cells in tumor draining lymph nodes. The main cells infiltrating bacteria-treated tumors were activated neutrophils, which can exert an antitumor effect through the secretion of TNF-α. These results demonstrate for the first time the efficacy of an attenuated S. Typhi vaccine strain as a cancer immunotherapeutic agent. By potentiating the host antitumor immune response, this approach could be a powerful adjunct tool for cancer therapy.

Foot and Mouth Disease (FMD) is an acute disease caused by Foot and Mouth Disease Virus (FMDV) which causes important economy losses, this is why it is necessary to obtain a vaccine that stimulates a rapid and long-lasting protective immune response. Cliptox is a mineral microparticle that in earlier studies has shown adjuvant activity against different antigens. In this study we have examined the effects of Cliptox on the magnitude and type of immunity elicited in response to inactivated FMDV (iFMDV) vaccine. It was demonstrated that iFMDV-Cliptox stimulates a specific antibody response detected in mucosal and in sera. The different isotype profiles elicited by inoculation with this vaccine indicate a Th1/Th2 response. Also, an increase in dendritic cells and macrophages in the spleen in comparison with the iFMDV vaccine iFMDV-Cliptox was detected. The Cliptox-iFMDV formulation was non toxic by using egg embryos and yielded increased protection against challenge with FMDV in the murine model. Our results show that the incorporation of Cliptox into FMDVi vaccine induces an increase of the specific protective immune response in mice and clearly indicate that Cliptox TM exert an (important) up-regulation on DC and MPhi. Additionally, Cliptox TM adjuvant can be used in vaccines for induction of mucosal immune response.

It is well documented that adjuvants improve the immune response generated by traditional viral vaccines, but less is known about the effects of adjuvants on the immune response elicited by DNA vaccines. In this study, we have investigated the use of RN-205 (immunomodulator containing a membrane rich in lipopolysaccharide from gram-negative bacteria) as an adjuvant and analyzed the humoral and cellular specific immune responses elicited by DNA vaccines based on the bovine herpesvirus-1 (BHV-1) glycoprotein D (gD). The comparison of the antibody response induced in mice by a mixture of the three different versions of DNA gD (membrane-anchored, secreted and cytosolic) formulated with or without RN-205 showed that the immunomodulator did not affect the total specific humoral response. The cellular immune response induced in mice immunized with vaccines plus RN-205 was higher than that obtained in mice vaccinated without RN-205, not only in the indexes of proliferation tests but in the number of IL-4 and gammaIFN secreting cells. When total spleen cells were marked with specific monoclonal antibodies against surface markers, a significant increase in the macrophage population of all the groups receiving RN-205 was observed. CD8 and CD4 positive cells were also increased but to a lesser extent. Our results indicate that the incorporation of RN-205 into DNA vaccines induces an increase of the cellular specific immune response in mice.

As it has been suggested that an autocrine mechanism may control tumour cell growth, in this work cells from a spontaneous murine T lymphocyte leukaemia (LB) expressing the interleukin-2 receptor (IL-2R) (CD25) were evaluated in vitro for IL-2-mediated autocrine growth. Cells grew readily in culture and proliferation was enhanced by the addition of recombinant IL-2 but inhibited by monoclonal antibodies against either IL-2 or IL-2 receptor, in the absence of exogenous IL-2. Cyclosporin A also inhibited LB cell growth. However, when exogenous IL-2 was added together with cyclosporin A, cell proliferation proved similar to controls. Using reverse transcription polymerase chain reaction (PCR), mRNA for IL-2 was found to be present in tumour cells. Our findings support the hypothesis that LB tumour cell proliferation is mediated by an autocrine pathway involving endogenous IL-2 generation, despite the fact that these cells are not dependent on exogenous IL-2 to grow in culture. Images Figure 5

In this study, we assessed the effectiveness of a live, attenuated Salmonella enterica serovar Typhi (S. Typhi) vaccine strain as a cancer immunotherapy in a mouse model of metastatic T-cell lymphoma. EL4 tumor-bearing C57BL/6J mice immunized with S. Typhi strain CVD 915, by injection into the tumor and the draining lymph node areas, displayed a significant decrease in tumor growth, a reduction in the mitotic index (MI) of tumors, a delayed development of palpable lymph node metastases and most importantly improved survival, compared to untreated mice. Besides, complete tumor regression was achieved in a small number of bacteria-treated mice. A successful therapeutic response associated with a significant reduction of tumor mass was evident as early as 5 days after treatment. The administration of Salmonella to tumor-bearing mice promoted early cellular infiltration (mainly neutrophils) within the tumor, and was accompanied by a decreased intratumoral interleukin 10 production as well as by leukocyte expansion in tumor draining lymph nodes. A tumor-specific memory immune response was induced in most of cured animals, as evidenced by the lack of tumor growth after a rechallenge with the same tumor. EL4 cells cultured with live Salmonella failed to proliferate and underwent apoptosis in a dose-dependent, timedependent, and contact-dependent manner. To our knowledge, these results demonstrate for the first time the efficacy of a S. Typhi vaccine strain as an oncolytic and immunotherapeutic agent against a highly malignant tumor and support the use of S. Typhi-based vaccine strains in cancer therapy. Fil: Vendrell, Alejandrina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos; Argentina. Universidad de Buenos Aires. Facultad de Medicina; Argentina Fil: Gravisaco, María J.. Instituto Nacional de Tecnologia Agropecuaria. Centro Nacional de Inv. Agropecuarias; Argentina Fil: Goin, Juan Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos; Argentina. Universidad de Buenos Aires. Facultad de Medicina; Argentina Fil: Pasetti, Marcela F.. University of Maryland; Estados Unidos Fil: Herschllik, Leticia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos; Argentina. Universidad de Buenos Aires. Facultad de Medicina; Argentina Fil: de Toro, Julieta. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos; Argentina. Universidad de Buenos Aires. Facultad de Medicina; Argentina Fil: Rodriguez, Carla Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos; Argentina. Comision Nacional de Energia Atomica; Argentina. Universidad de Buenos Aires. Facultad de Medicina; Argentina Fil: Larotonda, Gerardo. Lavet Lab Argentina; Argentina Fil: Mongini, Claudia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos; Argentina. Universidad de Buenos Aires. Facultad de Medicina; Argentina Fil: Waldner, Claudia Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos; Argentina. Universidad de Buenos Aires. Facultad de Medicina; Argentina

A live system to release heterologous antigens using an attenuated Salmonella strain was developed. We transformed Salmonella typhimurium LVR03 (S. LVR03) with a recombinant pTECH2 vector encoding 0, 1, 2, and 4 tandem copies of an imunogenic peptide of bovine herpes virus-1 (BoHV-1) glycoprotein D (gD). The system used yielded peptides fused to the non-toxic C fragment of the tetanus toxin (TetC), which has been shown to have adjuvant properties. Inoculation of BALB/c mice with the transformed Salmonella strains gave rise to a mild self-limited infection, with primary replication of bacteria occurring in Peyer's patches, even when the bacteria was administered intranasally. Humoral and cellular immune responses directed against the BoHV-1 antigens were evaluated after oral or intranasal administration of the recombinant bacteria. The results showed that the S. LVR03-dimer vaccine induced specific humoral (IgG in serum and IgG(1) and IgA in saliva), and cellular immune responses (lymphoproliferation and lymphokine secretion), against not only the selected peptide and whole gD, but also against BoHV-1, when administered intranasally. This is the first time Salmonella has been used as an expression vector to induce immunity against BoHV-1. This work demonstrates the feasibility of using this antigen-release system and encourages future experimentation with a bovine experimental model.

The effect of sera from mice bearing a T cell lymphoid leukaemia (LB) and the supernatants from short term cultures of the tumour cells were studied on cell proliferation using syngeneic and allogeneic normal and tumour cells. An inhibitory activity was demonstrated in 24–48 h supernatants of LB cells in culture and disappeared after 4 days of culture. Inhibitory activity was cytostatic but not cytotoxic and was non-specific since it inhibited the growth of both syngeneic and allogeneic normal and tumour cells. Such activity was found in the 105–1.3 × 105 Mr serum fraction after a Sephacryl S200 chromatography. Though sensitive to protease, trypsine or neuraminidase treatment, which indicated its glycoprotein nature, it remained stable after heating or freezing-thawing cycles as well as after alkaline, acid or hyaluronidase treatment. Addition of exogenous IL-2 abrogated inhibitory activity. ELISA showed the presence of soluble IL-2R both in LB conditioned medium and in above serum fraction. It is demonstrated that the inhibitory factor, soluble IL-2R, is produced by LB leukaemia cells, then secreted into blood and ascitic fluid or released into culture supernatants. Soluble IL-2R exerts inhibitory activity blocking cell proliferation and modulating immune response by binding to free IL-2.