Which of the following is required for M. tuberculosis to be virulent?

• A. Ghon complexes.
• B. Presence of neuraminidase enzyme.
• C. Infection by a phage.
• D. Presence of cord factor.

Answer: (D)

Verified step by step guidance

1. Understand the concept of virulence in microbiology, which refers to the degree of pathogenicity or the ability of a microorganism to cause disease.
2. Identify the specific virulence factors associated with Mycobacterium tuberculosis, the bacterium that causes tuberculosis.
3. Recognize that Ghon complexes are not virulence factors but rather lesions formed in the lungs as a result of infection.
4. Know that neuraminidase enzyme is typically associated with viruses like influenza, not M. tuberculosis.
5. Focus on the presence of the cord factor, a glycolipid molecule on the surface of M. tuberculosis, which is essential for its virulence by inhibiting immune responses and promoting granuloma formation.