14th ICID - Poster Abstracts - International Society for Infectious ...

When citing these abstracts please use the following reference:
Author(s) of abstract. Title of abstract [abstract]. Int J Infect Dis 2010;14S1: Abstract number.
Please note that the official publication of the International Journal of Infectious Diseases 2010, Volume 14, Supplement 1
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Final Abstract Number: 83.027
Session: Vaccines and Vaccine Development
Date: Thursday, March 11, 2010
Time: 12:30-13:30
Room: Poster & Exhibition Area/Ground Level
Type: Poster Presentation
Genetic characterization of Mycobacterium bovis BCG Mexico 1931
P. Orduña 1 , Y. López 1 , M. A. Cevallos 2 , S. Ponce de León 3
1 Universidad Nacional Autonoma de Mexico, D.F., Mexico, 2 Universidad Nacional Autonoma de
Mexico, Cuernavaca, Mexico, 3 BIRMEX, D.F., Mexico
Background: BCG vaccine is the only preventive measure against tuberculosis. At least two
genomes from BCG, Pasteur and Japan, have been described. Evolutionary schemes establish
by DU2 and other markers situated BCG Japan and Pasteur into group I and IV from genealogy
of BCG vaccines, respectively, classified as early and late strains. Some BCG such as Mexico
1931 is not included in any comparative studies based on phenotypic, genotyping, immune
response and drug resistance. Our aim was to characterize by full sequence BCG Mexico 1931
for using in the new develop vaccine.
Methods: The sequence of BCG Mexico 1931 was performed with 2X pyrosequencing method.
BCG Mexico 1931 genetic profile was performed by multiplex PCR and PFGE. The multiplex
PCR was performed to detect RD and DU regions in strains. The reference BCG strains used in
this study were Pasteur 1173P2, Phipps, Tice and Danish 1331.
Results: The circular chromosome at 99.8% coverage of BCG Mexico 1931 was 4 350 386-bp,
its analyses confirm the RD1, RD2, nRD18 absence and the presence of duplication DU2 group
IV described by multiplex PCR. The comparison of BCG Pasteur1173P2 genome sequence with
BCG Mexico 1931 showed differences between strains, including the presence of RD14, SNPs
and the absence of DU1. In addition, three new RD regions of 53, 655 and 2847 bp were
uncovered.
The comparison of profiles obtained by PCR multiplex showed that BCG Mexico 1931 profile was
identical to BCG Phipps and Tice, with the lost of RD1, RD2, nRD18 and presence of DU2 group
IV. PFGE was performed with AsnI/DraI enzymes, the analyses detected 18/12 fragments in BCG
Danish 1331 and Mexico 1931, 17/12 in Pasteur 1173P2, 15/10 in Phipps and 14/10 in Tice,
respectively. Interesting, the restriction pattern with AsnI showed the presence of 220kb fragment
only in BCG Mexico, Tice and Phipps.
Conclusion: The BCG Mexico 1931 showed a close relation with BCG Phipps and Tice, strains
situated into group IV from genealogy of BCG vaccines. However, in diverse studies these strains
shown differences on the induction of immune response.