title: Purification of an IgA Monoclonal Antibody Specific for the Acr Protein of Mycobacterium tuberculosis by Immunoaffinity Chromatography.
abstract: BACKGROUND
  A monoclonal antibody (mAb) of the IgA isotype, designated TBA61, is specific for the Acr protein of Mycobacterium tuberculosis (MTB). TBA61 has been used in studies exploring protection against tuberculosis (TB), and its efficacy has been proven using different challenge models. To purify the mouse IgA isotype, a combination of methods, such as globulin precipitation, ion exchange, and gel filtration, is usually required to achieve a satisfactory degree of purity.
  
  
  METHODS
  To minimise the number of chromatographic steps, we proposed to employ immunoaffinity chromatography using the Acr protein of MTB as a specific ligand for this mAb. For this purpose, the HspX gene was cloned and expressed in Escherichia coli, and recombinant Acr (rAcr) was coupled to a cyanogen bromide-activated Sepharose 4B matrix, which was used to purify TBA61 mAb from ascites produced in mice in a single step.
  
  
  RESULTS
  The recovery from the purification procedure was 1.46 mg per mL of ascites. Analysis by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and western blot showed a high purity. The purified mAb retained its reactivity against the Acr protein based on enzyme-linked immunosorbent assay (ELISA) and western blot.
  
  
  CONCLUSIONS
  The purification method used is rapid, simple, and specific and can be easily scaled up.
authors.affiliation: Finlay Institute, Calle 27, No 19805, La Lisa, AP 16017, Cod 11600 Havana, Cuba.
authors.forename: Fátima
authors.initials: F
authors.lastname: Reyes
authors.affiliation: Finlay Institute, Calle 27, No 19805, La Lisa, AP 16017, Cod 11600 Havana, Cuba.
authors.forename: Oscar
authors.initials: O
authors.lastname: Otero
authors.affiliation: Finlay Institute, Calle 27, No 19805, La Lisa, AP 16017, Cod 11600 Havana, Cuba.
authors.forename: Frank
authors.initials: F
authors.lastname: Camacho
authors.affiliation: Finlay Institute, Calle 27, No 19805, La Lisa, AP 16017, Cod 11600 Havana, Cuba.
authors.forename: María Elena
authors.initials: ME
authors.lastname: Sarmiento
authors.affiliation: Finlay Institute, Calle 27, No 19805, La Lisa, AP 16017, Cod 11600 Havana, Cuba.
authors.forename: Armando
authors.initials: A
authors.lastname: Acosta
keywords: Acr protein; IgA; Mycobacterium tuberculosis; affinity; chromatography; monoclonal antibody