Genotipificacion de cepas de Histoplasma capsulatum aisladas de pacientes con histoplasmosis asociada al SIDA, mediante el polimorfismo en la longitud de los fragmentos de restriccion

Introduction: Histoplasmosis is one of the most important AIDS- associated mycoses in Mexico. In this work, genotypic characterization of 31 Histoplasma capsulatum isolates from AIDS-associated histoplasmosis patients was achieved, using RFLP analysis of total DNA. The RFLP profiles were compared to those of reference strains from Mexico, the United States of America (USA), and Panama. Material and methods: Strains were isolated and identified as H. capsulatum by colony and microscopic morphology, mycelium- to-yeast conversion, and exoantigen production tested by immunodiffusion with specific sera. Total DNA from the strains was isolated from mycelium ground in liquid nitrogen and incubated with proteinase K and dodecyl sodium sulfate. The DNA was digested with HaeIII and the products separated in agarose gel electrophoresis and stained with ethidium bromide. In order to establish the relationship between strains, a dendrogram was done with the SPSS/PC⁺ program. Results and discussion: Strains were separated in 10 groups according to their RFLP profiles, yielding two main profiles, A and C, with 33.3 and 29.1% of the strains, respectively. Other patterns were represented by single strains, except for the J profile with two strains that showed an identical profile to those of the Downs strain (class 1, from USA). No strain showed a similar profile to those of the most prevalent strains in USA or Panama. The dendrogram showed a relation at 85% between the most prevalent A and C profiles, as well as the J profile, and the Downs and FLs1 strains from USA. All isolates with unique profiles were at least 75% similar to the other strains.