Diagnosis and Monitoring of Murine Histoplasmosis by a Nested PCR Assay

A newly developed nested PCR assay was applied to murine models of histoplasmosis. ICR and BALB/c mice were intravenously infected with Histoplasma capsulatum and sacrificed up to 29 days later. Samples of blood, spleen, and lung homogenates were cultured and examined by the PCR assay. In the ICR mouse model, 265 of 319 organ samples showed concordant results. With 7 samples, the culture was positive and the PCR assay was negative whereas a positive PCR but a negative culture were obtained with 47 samples (P < 0.0001 according to McNemar’s test). Organ homogenates and blood samples of either spontaneously cured or treated BALB/c mice were PCR negative. The nested PCR assay performs excellently in the monitoring of spontaneously and treatment-cured murine histoplasmosis. It limits the infection risks of the laboratory staff and might be of diagnostic value for humans. Histoplasmosis is mainly diagnosed by culture and antigen detection in clinical specimens. Since the culture of the etio-logical agent, Histoplasma capsulatum, requires a biosafety level III laboratory and the antigen assay is currently per-formed in only one laboratory (9), diagnosis is restricted. Stud-ies of potentially effective new drugs with animal models ar