Biomedical subjects

José Cremata

Publications and source records attributed to José Cremata.

4 recordsLinked to original sources

PubMed2006

High-performance reverse phase chromatography with fluorescence detection assay for characterization and quantification of pneumococcal polysaccharides.

A methods using high-performance reverse phase (RP) chromatography with fluorescence detection, has been developed to determine the composition and identity of Streptococcus pneumoniae capsular polysaccharide used in formulating conjugate vaccine for prevention of pneumococcal infection. For the monosaccharide composition, the polysaccharides were subjected to hydrofluoric acid (HF) hydrolysis followed by trifluoroacetic acid (TFA). After acid hydrolysis, the released monosaccharides were re-N-acetylated and labeled with 2-aminobenzamide (2AB) by reductive amination reaction. High-performance RP chromatography was performed on C18 TSKODS 120T column. Nuclear magnetic resonance was used to confirm chemical structure and purity of pneumococcal capsular polysaccharides.

Chromatography↗

PubMed2006

Enzyme-linked immunosorbent assay for quantitative determination of capsular polysaccharide production in Streptococcus pneumoniae clinical isolates.

A simple, specific, sensitive and reproducible ELISA has been developed to quantify the level of CPS (capsular polysaccharide) production in supernatants of Streptococcus pneumoniae cell cultures. CPSs from Strep. pneumoniae have been widely used as vaccine antigens. The quantification method is based on two type-23F serotype-specific polyclonal antibodies: IgG, purified from sera of mice immunized with a pneumococcal type-23F CPS conjugate, used in the coating step, and a serotype-specific rabbit serum as the second antibody. Solutions of purified type-23F CPS were used as standards. The relationship between A(492) and type-23F CPS concentration was linear over the range 1-310 ng/ml (r=0.989), with 1 ng/ml as the lower limit of sensitivity. The specificity of ELISA was assessed because purified type-19F CPS and cell-wall polysaccharide samples were not detected after their evaluation by the ELISA described in the present study. Repeatability and intermediate precision of the assay were good, the coefficients of variation being 3 and 10% respectively. This ELISA allowed selection of an appropriate vaccine strain, for a natural polysaccharide vaccine, among several 23F pneumococcal clinical isolates and constituted a valuable analytical tool for Strep. pneumoniae fermentation and CPS purification follow-up.

Animals↗

PubMed2003

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.

Animals↗

PubMed2002

Cellobiose quinone oxidoreductase from the white rot fungus Phanerochaete chrysosporium is produced by intracellular proteolysis of cellobiose dehydrogenase.

The fungus Phanerochaete chrysosporium was grown in a 10-l automatic fermenter using cellobiose as carbon source to monitor the induction of cellobiose dehydrogenase (CDH) and cellobiose quinone oxidoreductase (CBQ) enzymes, and to search for tentative cbq and cdh genes and their transcriptional products. After 24 h of induction, CDH was detected in the culture supernatant and a protein was recognized by a specific anti-CDH polyclonal antibody in the sonicated biomass. Northern blot experiments performed with several fungal RNA samples showed, after 24 h of induction, only one single species of an mRNA transcript corresponding in size to the cdh gene (2.5 kb) The relative amount of this transcript decreased as a function of time. Southern blot experiments done with genomic DNA and database search in the recently available genome information also ruled out the presence in this strain of a separate cbq gene distinct from the cdh gene. Taken together, these results demonstrated that CBQ originates from the cdh gene. Furthermore, it is not produced by differential splicing but by a posttranslational, predominantly intracellular, proteolytic cleavage.

Alleles↗