Influence of Humoral Response Against GnRH, Generated by Immunization with a Therapeutic Vaccine Candidate on the Evolution of Patients with Castration-Sensitive Prostate Adenocarcinoma.

BACKGROUND AND AIMS: A gonadotropin-releasing hormone (GnRH)-based therapeutic vaccine candidate against hormone-sensitive prostate cancer has demonstrated its safety and signs of efficacy in phase I/II trials. In this study, we characterized the isotype/subclass profiles of the anti-GnRH humoral response generated by the vaccination and analyzed its association with patients' clinical outcomes. METHODS: The immunoglobulin isotypes and IgG subclasses of the antibody responses of 34 patients included in a randomized, open, prospective phase I/II clinical trial were characterized. Every patient included in the study had a diagnosis of locally advanced prostate adenocarcinoma at stages 3 and 4 and received immunization with the vaccine candidate. Additionally, serum testosterone and prostate specific antigen (PSA) concentrations, serving as indicators of tumor response, were determined. The type of anti-GnRH antibody response was correlated to the time elapsed until the first biochemical recurrence in patients and the outcome of the disease. RESULTS: All patients developed strong and prolonged anti-GnRH antibody responses, resulting in a short- to mid-term decrease in serum testosterone and PSA levels. Following immunizations, anti-GnRH antibodies of the IgM/IgG and IgG1/IgG3 subclasses were observed. Following radiotherapy, the humoral response switched to IgG (IgG1/IgG4). Patients who experienced a short-term biochemical relapse were characterized by significantly higher levels of anti-GnRH IgG titers, particularly IgG1 and IgG4 subclasses. These characteristics, along with a high response of specific IgM antibodies at the end of immunizations and the development of anti-GnRH IgA antibody responses following radiotherapy, were observed in patients whose disease progressed, compared to those with controlled disease. CONCLUSION: The nature of the humoral response against anti-GnRH, induced by vaccination may play a key role in activating additional immunological mechanisms. Collectively, these mechanisms could contribute significantly to the regulation of tumor growth.

Novel chimeric E2CD154 subunit vaccine is safe and confers long lasting protection against classical swine fever virus.

E2CD154 is a vaccine candidate against classical swine fever (CSF) based on a chimeric protein composed of the E2 glycoprotein fused to porcine CD154 antigen, and formulated in the oil adjuvant Montanide™ ISA 50 V2. This vaccine confers early protection in pigs and prevents vertical transmission in pregnant sows. The objectives of this study were to assess the safety of this immunogen in piglets, to compare several doses of antigen in the formulation, and to study the duration of the immunity provided by this vaccine for up to 9 months. Three trials were conducted by immunizing pigs with a two-dose regime of the vaccine. Challenge experiments were carried out with the highly pathogenic Margarita strain. No local or systemic adverse effects were documented, and neither macroscopic nor microscopic pathological findings were observed in the vaccinated animals. The three antigen doses explored were safe and induced CSF protective neutralizing antibodies. The dose of 50 µg was selected for further development because it provided the best clinical and virological protection. Finally, this protective immunity was sustained for at least 9 months. This study demonstrates that E2CD154 vaccine is safe; defines a vaccine dose of 50 µg antigen, and evidences the capacity of this vaccine to confer long term protection from CSFV infection for up to 9 months post- vaccination. These findings complement previous data on the evaluation of this vaccine candidate, and suggest that E2CD154 is a promising alternative to modified live vaccines in CSF endemic areas.

Design of a culture medium for optimal growth of the bacterium Pseudoxanthomonas indica H32 allowing its production as biopesticide and biofertilizer.

Culture medium composition is one of the most important parameters to analyze in biotechnological processes with industrial purposes. The aim of this study was to design of a culture medium for optimal growth of the bacterium Pseudoxanthomonas indica H32 allowing its production as biopesticide and biofertilizer. The influence of several carbon and nitrogen sources and their molar ratios on P. indica H32 growth was investigated. The effect of different micronutrients such as mineral salts and vitamin on P. indica H32 growth was determined as well. A mixture design based on Design-Expert 10.0 Software was performed to optimize the culture medium concentration. Finally, in the designed medium, an attribute of the biological mechanism of action of the P. indica H32 against nematodes, was evaluated: the hydrogen sulfide production. It was found that tested carbon/nitrogen ratios were not a significant influence on P. indica H32 growth. Growth of P. indica H32 was favored with use of sucrose, yeast extract and phosphate buffer without the addition of any tested micronutrients. An optimal concentration of 10 g/L sucrose and 5 g/L yeast extract were obtained at a cost of 0.10 $/L. In this concentration, the specific growth rate (µ) and maximal optical density (Xmax) were equal to 0.439 h- 1 and 8.00 respectively. It was evidenced that under the culture conditions used, P. indica H32 produced hydrogen sulfide. The designed medium led to a 1.08 $/L reduction of costs in comparison to LB medium. These results were critical to carry on with biotechnological development of P. indica H32 as a bioproduct.

Active component of a GnRH based vaccine binds to natural GnRH receptors in Dunning R3327-G cell line and human prostate carcinoma vesicles.

An alternative approach to immunization with native GnRH for the inhibition of gonadotropin secretion and gonadal function is the use of peptidomimetics such as peptides of GnRH that could serve as vaccines when these are joined to more immunogenic molecules. The GnRH sequence of many species is well-known. Reported consensual aminoacid sequence of mammals is: Glu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly. Most of the known GnRH sequences, including birds, fish and reptiles, have the Glycin amino acid residue at position 6. Glycin is the smallest amino acid, and confers flexibility to the polypeptide chain. Glycin substitution by Prolin, to confer rigidity, and the coupling to a Tetanic Toxoid T helper epitope (GnRHm1-TT), increases considerably the immune response towards the autolog GnRH when it is administered using an oily adjuvant. In the present study we also investigate the capacity of GnRHm1-TT (active component of a GnRH based vaccine) to bind the natural GnRH receptor in Dunning R3327-G cell line and vesicles of different tissues when administered without an adjuvant. Results showed that GnRHm1-TT do not lose the binding ability to natural GnRH receptor in vitro and in vivo. We also demonstrated that this molecule behaves as a GnRH agonist analog when administered intraperitoneally to Wistar rats.