Virulence-attenuating genetic deletions deleted from mycobacterium BCG

An isolated marker for an avirulent mycobacterium, said marker comprising a first nucleic acid that specifically hybridizes under stringent conditions with a second nucleic acid or a complement of said second nucleic acid where said second nucleic acid or complement of said second nucleic acid is selected from the group consisting of BCG.DELTA.1a (SEQ ID NO:

• 1), BCG.DELTA.1b (SEQ ID NO:
• 2), BCG.DELTA.2a (SEQ ID NO:
• 3), BCG.DELTA.2b (SEQ ID NO:
• 4), BCG.DELTA.3a (SEQ ID NO:
• 5), BCG.DELTA.3b (SEQ ID NO:
• 6), BCG.DELTA.1ab (SEQ ID NO:
• 7), BCG.DELTA.2ab (SEQ ID NO:
• 8), BCG.DELTA.3ab (SEQ ID NO:
• 9), BCG.DELTA.1 (between nucleotide 2327 and nucleotide 11126 of SEQ ID NO:
• 16), BCG.DELTA.3 (between nucleotide 1406 and nucleotide 10673 of SEQ ID NO:
• 18), ORF 2B2 (nucleotides 3003-3590 of SEQ ID NO:
• 17), ORF 2C (nucleotides 5187-6134 of SEQ ID NO:
• 17), ORF 2D (nucleotides 6561-7217 of SEQ ID NO:
• 17), ORF 2E (nucleotides 8036-8560 of SEQ ID NO:
• 17), ORF 2F (nucleotide 9941-10909 of SEQ ID NO:
• 17), ORF 2H (nucleotides 11965-13407 of SEQ ID NO:
• 17), ORF 2I (nucleotides 13376-14221 of SEQ ID NO:
• 17), ORF 2J (nucleotides 7211-8259 of SEQ ID NO:
• 17), ORF 2K (nucleotides 4327-4992 of SEQ ID NO:
• 17), and ORF 2L (nucleotides 4521-5117 of SEQ ID NO:
• 17);
• wherein said marker specifically hybridizes under stringent conditions to a nucleic acid from BCG, but not to a nucleic acid from Mycobacterium tuberculosis or Mycobacterium bovis, or where said marker specifically hybridizes under stringent conditions to a nucleic acid from Mycobacterium tuberculosis or Mycobacterium bovis, but not to a nucleic acid from BCG.