BCG Gene Polymorphism Vaccine Strains

Background: The BacilleCalmette-Guérin (BCG) is the only vaccine available against tuberculosis.The BCG strain used in Iran as the vaccine is not specified. The purpose of the present study was to confirm and make a qualitative control for BCG vaccine in Iran and to determine the genetic polymorphism of the given strain. Methods: Twenty eight lyophilized BCG vaccines (Pasteur Institute, Iran) with different batch numbers were collected over a year (2011-12) and transferred under the temperature condition of 4°C to the laboratory. Three strains of vaccine were selected randomly out of each batch number. The DNA was extracted using CTAB method. DNA samples were kept at-20°C. Of four primers, RD14 and DU1 genes were used for PCR. The sequence of RD16 region in BCG strains was determined using DNA analyzer ABI3730XL using Chromas and Mega4software. VNTR typing was done for six genic positions. Results: All strains were positive in terms of their culture on the medium. In all BCG strains under study, DU1 duplication in the bacteria’s chromosome was observed. None of strains had RD14 gene. All RD16 regions had similar sequence with RD16 region in the genome of Pasture 1173p2 strain. The number and size of repeated units for six gene positions includingMIRU4, MIRU24, MIRU26, MIRU40, VNTR1895 and VNTR11b in 28 strains of different BCG in the vaccine samples were respectively (2x77)+122, (2x54)+393, (5x51)+285, (2x54)+354, (4x57)+281 and (3x69) + 67. Conclusion: BCG strain using in Iran is the very Pasteur 1173p2 and may be used as vaccine.

Keywords:

BCG Vaccine , Polymorphism , Genetic , Polymerase Chain Reaction , MIRU-VNTR Typing