Validación de la técnica de determinación de proteínas totales por el método microcoomassie a doble longitud de onda para la muestra de producto terminado del antígeno de la nucleocápsida del virus de la hepatitis C / Validation of the technique of determination of total proteins by microcoomassie method to double wave longitude for the sample of Finished Product of hepatitis C core antigen

En el Centro de Ingeniería Genética y Biotecnología se obtuvo una formulación para un candidato vacunal del virus de la hepatitis C (VHC). Es un plásmido para la inmunización con ADN que contiene los genes de los tres antígenos estructurales del virus, mezclado con una variante truncada recombinante de la nucleocápsida del VHC como adyuvante molecular. Ambos compuestos se formularon en bulbos separados y se mezclaron en el momento de la inmunización. En el laboratorio de Desarrollo Analítica se validó la técnica de determinación de proteínas totales por el método de microcoomassie para la muestra de producto terminado (PT) del antígeno de la nucleocápsida del virus de la hepatitis C (HCcAg). Los parámetros validados fueron: especificidad, linealidad, rango, exactitud, precisión y estabilidad de la muestra de PT, bajo dos condiciones diferentes de almacenamiento. El método resultó ser específico para la cuantificación del HCcAg, sin interferencias del placebo de la muestra, a diluciones superiores a 1:8. La curva del microcoomasie fue lineal en el rango de trabajo de 5-40 µg/mL. Se demostró la exactitud del método (recuperación 100 ± 10por ciento). En la evaluación del sistema se cumplieron los criterios de aceptación establecidos para la precisión: repetibilidad (CV £ 5 por ciento) y precisión intermedia (CV £ 10 por ciento). El PT es estable a (4 ºC y 22-25 ºC) durante los tiempos estudiados sin alteración en la concentración del HCcAg. La validación fue satisfactoria y el método fue adecuado para cuantificar proteínas en la muestra de PT. Este resultado permite dar cumplimiento a las especificaciones establecidas para este producto(AU)

A formulation was obtained for a vaccinal candidate of hepatitis C virus (VHC) in the CIGB. It is a plasmid for the immunization with DNA contianing the genes of the three structural antigens of the virus, blended with a recombinant truncated variant of the protein of the core of the VHC, as molecular adjuvant. Both compounds were formulated in separate vials and were mixed at the moment of the immunization. In the laboratory of Development-analytic the technique of determination of total proteins was validated by the microcoomassie method for the sample of Finished Product (FP) of Hepatitis C core antigen (HCVcoreAg). The validated parameters were: Specificity, Linearity and Range, Accuracy, Precision, Stability of the FP sample under two different conditions of storage. The method was specific for the quantification of the HCcAg without interferences of sample placebo of FP to superior dilutions at 1:8. The curve of the microcoomassie for the FP was lineal in the range of work of 5-40 µg/mL. It demonstrated the accuracy of the method (100±10percent recovery). In the evaluation of the system, the established acceptance criteria were completed for Precision: Repeatability (CV £ 5percent) and Intermediate Precision (CV £ 10 percent). Temperatures studied in stability did not cause alteration in HCcAg concentration, and the FP can be stored for 15 days. Validation was satisfactory. The method is adequate to quantify the sample of the FP. This result allows us to comply with the specifications established for this product(AU)

Immunization with a DNA vaccine candidate in chronic hepatitis C patients is safe, well tolerated and does not impair immune response induction after anti-hepatitis B vaccination.

BACKGROUND: In the present study, we evaluated the safety of CIGB-230, a novel vaccine candidate based on the mixture of a plasmid for DNA immunization, expressing hepatitis C virus (HCV) structural antigens, with a recombinant HCV Core protein. METHODS: Fifteen HCV chronically-infected volunteers with detectable levels of HCV RNA genotype 1b, who were nonresponders to previous treatment with interferon plus ribavirin, were intramuscularly injected with CIGB-230 on weeks 0, 4, 8, 12, 16 and 20. Individuals were also immunized at weeks 28, 32 and 36 with a recombinant vaccine against hepatitis B. Adverse events were recorded and analyzed. Blood samples were taken every 4 weeks up to month 12 for hematological, biochemical, virological and immunological analysis. RESULTS: All patients completed the treatment with CIGB-230. Adverse events were only slight (83.6%) or moderate (16.4%). No significant differences in hematological and biochemical parameters, including serum aminotransferases, were detected between the baseline and post-treatment state. Induction of a CD4+ T lymphocyte response against a particular region in HCV E1, spanning amino acids 230-312 in HCV polyprotein, was detected in 42.8% of patients during treatment with CIGB-230. The ability of T cells to proliferate in response to mitogenic stimulation was not weakened. Most individuals (78.6%) were seroprotected after anti-hepatitis B vaccination and 42.8% were hyper-responders (antibody titers > 100 UI/ml). No anti-mitochondrial, anti-nuclear and anti-extractable nuclear antigen antibodies were generated during immunization with CIGB-230. CONCLUSIONS: Vaccination with CIGB-230 in HCV chronically-infected individuals was safe, well tolerated and did not impair the ability to respond to non-HCV antigens.

Recombinant in vitro assembled hepatitis C virus core particles induce strong specific immunity enhanced by formulation with an oil-based adjuvant.

In the present work, immunogenicity of recombinant in vitro assembled hepatitis C virus core particles, HCcAg.120-VLPs, either alone or in combination with different adjuvants was evaluated in BALB/c mice. HCcAg.120-VLPs induced high titers of anti-HCcAg.120 antibodies and virus-specific cellular immune responses. Particularly, HCcAg.120-VLPs induced specific delayed type hypersensitivity, and generated a predominant T helper 1 cytokine pro file in immunized mice. In addition, HCcAg.120-VLPs prime splenocytes proliferate in vitro against different HCcAg.120-specific peptides, depending on either the immunization route or the adjuvant used. Remarkably, immunization with HCcAg.120-VLPs/Montanide ISA888 formulation resulted in a significant control of vaccinia virus titer in mice after challenge with a recombinant vaccinia virus expressing HCV core protein, vvCore. Animals immunized with this formulation had a marked increase in the number of IFN-gamma producing spleen cells, after stimulation with P815 cells infected with vvCore. These results suggest the use of recombinant HCV core particles as components of therapeutic or preventive vaccine candidates against HCV.

Recombinant in vitro assembled hepatitis C virus core particles induce strong specific immunity enhanced by formulation with an oil-based adjuvant

In the present work, immunogenicity of recombinant in vitro assembled hepatitis C virus core particles, HCcAg.120-VLPs, either alone or in combination with different adjuvants was evaluated in BALB/c mice. HCcAg.120-VLPs induced high titers of anti-HCcAg.120 antibodies and virus-specific cellular immune responses. Particularly, HCcAg.120-VLPs induced specific delayed type hypersensitivity, and generated a predominant T helper 1 cytokine pro file in immunized mice. In addition, HCcAg.120-VLPs prime splenocytes proliferate in vitro against different HCcAg.120-specific peptides, depending on either the immunization route or the adjuvant used. Remarkably, immunization with HCcAg.120-VLPs/Montanide ISA888 formulation resulted in a significant control of vaccinia virus titer in mice after challenge with a recombinant vaccinia virus expressing HCV core protein, vvCore. Animals immunized with this formulation had a marked increase in the number of IFN-γ producing spleen cells, after stimulation with P815 cells infected with vvCore. These results suggest the use of recombinant HCV core particles as components of therapeutic or preventive vaccine candidates against HCV.

A C-terminal truncated hepatitis C virus core protein variant assembles in vitro into virus-like particles in the absence of structured nucleic acids.

Little is known about the assembly pathway or structure of the hepatitis C virus (HCV). In this work a truncated HCcAg variant covering the first 120 aa (HCcAg.120) with a 32 aa N-terminal fusion peptide (6x Histag-Xpress epitope) was purified as a monomer under strong denaturing conditions. In addition, minor HCcAg.120 peaks exhibiting little different molecular mass by SDS-PAGE which possibly represents alternative forms harboring the N-termini of HCcAg.120 were detected. Analysis using gel filtration chromatography showed that HCcAg.120 assembled into high molecular weight structures in vitro in the absence of structured nucleic acids. The negative-stain electron microscopy analysis revealed that these structures correspond with spherical VLPs of uniform morphology and size distribution. The diameters of these particles ranged from 20 to 43nm with an average diameter of approximately 30 nm and were specifically immunolabelled with a mouse monoclonal antibody against the residues 5-35 of HCcAg. Results presented in this work showed that HCcAg.120 assembled in vitro into VLPs in the absence of structured nucleic acids with similar morphology and size distribution to those found in sera and hepatocytes from HCV-infected patients. Therefore, these VLPs would be important to elucidate the mechanisms behind the ability of HCcAg to assemble into a nucleocapsid structure.

Large-scale purification of an antibody directed against hepatitis B surface antigen from transgenic tobacco plants.

The application of bioengineering to plants for production of biological products for human and animal use has expanded in recent years. The reasons for this expansion are several and include advances in the technology for novel production systems and the need for very large quantities of therapeutic proteins. The process of growing pharmaceutical proteins in plants, extracting, and purifying is a hard task considering the lack of available information concerning these topics. In this work, a recombinant murine monoclonal antibody specific for the hepatitis B surface antigen, expressed in stably transformed transgenic Nicotiana tabacum plants, was purified by means of a recombinant protein A Streamline chromatography as the main purification step. The antibody expression level varied with the age of the plants and the number of harvests from 40 to 15microg/ml and the maximum process yield was about 25mg of plantibody/kg of biomass. Protein A Streamline chromatography was successfully used in the purification process yielding a recovery of about 60% and a plantibody SDS-PAGE purity of over 90% but unexpectedly, previous clarification steps could not be totally avoided. The amino acid sequence recognized by this affinity purified plantibody was similar to its murine counterpart verifying the potentiality of plants to replace animals or bioreactors for large-scale production of this monoclonal antibody.

Expression and characterization of an anti-(hepatitis B surface antigen) glycosylated mouse antibody in transgenic tobacco (Nicotiana tabacum) plants and its use in the immunopurification of its target antigen.

Transgenic plants expressing recombinant immunoglobulins have arisen as an alternative technology for the large-scale production of antibodies useful in therapeutics and in industrial processes. In the present paper we report the expression in transgenic tobacco ( Nicotiana tabacum ) of an anti-HBsAg [anti-(hepatitis B virus surface antigen)] mouse IgG1 mAb (monoclonal antibody), currently used for the industrial purification of the recombinant vaccine antigen. Using the sweet potato sporamin signal peptide, a KDEL (Lys-Asp-Glu-Leu) ER (endoplasmic reticulum) anchorage domain, and a heavy- and light-chain gene tandem construction, we generated F1 plants in which the expression of the antibody accounted for 0.5% of the total soluble proteins. The 'plantibody' (functional IgG antibody produced in plants) was easily purified by Protein A-Sepharose chromatography with a yield of approximately 35 microg/g of fresh leaf material, and its glycosylation indicated that, irrespective of the KDEL signal, the molecule is modified in both the ER and Golgi. Finally, a successful comparison of the plantibody with the ascites-derived mAb in the immunoaffinity purification of the vaccine recombinant HBsAg was performed. Taken as a whole, our results show that the large-scale production of this antibody of industrial relevance in transgenic tobacco is feasible.