A marmoset model for Mycobacterium avium complex pulmonary disease

Area of Science:

• Pulmonary Medicine
• Infectious Diseases
• Veterinary Pathology

Background:

• Mycobacterium avium complex (MAC) is a leading cause of nontuberculous mycobacterial lung disease.
• Understanding MAC pathogenesis is hindered by the lack of a suitable animal model.

Purpose of the Study:

• To evaluate the common marmoset (Callithrix jacchus) as an animal model for MAC pulmonary disease.
• To assess marmoset susceptibility, immune, and histopathologic responses to M. intracellulare infection.

Main Methods:

• Seven marmosets were inoculated endobronchially with M. intracellulare and monitored for 30 or 60 days.
• Evaluations included radiography, bronchoalveolar lavage cytokine analysis, histopathology, and cultures of various tissues.
• Serum cytokines were measured longitudinally, and statistical models analyzed group differences.

Main Results:

• Pulmonary M. intracellulare infection was confirmed in 5/7 marmosets, with extra-pulmonary spread in 3.
• Radiographic and histopathologic changes (pneumonitis, granulomatous inflammation, bronchiectasis) were observed.
• Elevated cytokine levels in bronchoalveolar lavage fluid and serum correlated with productive infection.

Conclusions:

• M. intracellulare endobronchial inoculation successfully established pulmonary infection in marmosets.
• The observed immune, radiographic, and histopathologic responses mimic human MAC lung disease.
• The marmoset serves as a viable animal model for studying M. avium complex pulmonary infections.