Selective expression of Pneumocystis antigens in different patients during a suspected outbreak of Pneumocystis pneumonia
https://journals.asm.org/doi/10.1128/mbio.00692-25
This study sequenced Pneumocystis jirovecii msg-I genes in Swiss patients with PCP, identifying identical repertoires in three renal transplant recipients, consistent with an outbreak and interhuman transmission. Despite shared repertoires, distinct antigen expression patterns were observed, suggesting selective Msg expression as a novel mechanism for immune evasion and pathogenesis in immunosuppressed hosts.
The fungus Pneumocystis causes severe pneumonia in patients with weakened immune systems. It possesses a genetic system to vary the antigens at the surface of its cells that are presented to the immune system of the patient. We report for the first time that this system may have been implicated in the infections of renal transplant recipients involved in a suspected outbreak. Our observations suggest that the antigens presented might be selected to avoid the elimination of the fungus by the immune response specific to each patient. The resistance of the fungus to the immunosuppressant mycophenolate administered to these patients to prevent organ rejection probably also played a role in the infections during the suspected outbreak.
