Relatedness analyses of Histoplasma capsulatum isolates from Mexican patients with AIDS-associated histoplasmosis by using histoplasmin electrophoretic profiles and randomly amplified polymorphic DNA patterns

Abstract

The present paper analyzes the histoplasmin electrophoretic profiles and the randomly amplified polymorphic DNA (RAPD) patterns of the fungus Histoplasma capsulatum isolated from Mexican patients with AIDS-associated histoplasmosis. Clinical isolates from Guatemala, Colombia, and Panama, as well as H. capsulatum isolates from different sources in nature, were also processed. All histoplasmin samples shared four antigenic fractions of 200, 49, 10.5, and 8.5 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). According to their percentage of relatedness, based on SDS-PAGE histoplasmin electrophoretic image analysis, H. capsulatum isolates were divided in two groups: group A contained all AIDS-associated isolates studied and two human reference strains from Mexican histoplasmosis patients without AIDS; group B included bat guano, infected bat, and cock excreta isolates from the State of Guerrero, Mexico, plus three human histoplasmosis strains from Guatemala, Panama, and Colombia. Polymorphic DNA patterns evaluated by RAPD-PCR showed three major bands of 4.4, 3.2, and 2.3 kb in most H. capsulatum isolates studied. Four groups were related by DNA polymorphisms: group I was formed by most of the AIDS-associated H. capsulatum isolates studied, one human histoplasmosis strain from Colombia, two human reference strains from Mexican patients without AIDS, and one human histoplasmosis strain from Guatemala. Group II consisted of only a single strain from Panama. Group III included three strains: one from a Mexican patient with AIDS and two isolated from nature in Guerrero (cock excreta and bat guano). The last, group IV, consisted of only one strain isolated from an infected bat, captured in Guerrero. A tight relationship between phenotypic and genotypic characterization was observed, and both analyses could be useful tools for typing H. capsulatum from different sources and geographic origins.

FIG. 1

Exoantigens of H. capsulatum strains. Center well, positive human histoplasmosis immune serum; EH-53, human reference strain; EH-313, H. capsulatum isolated from bat guano; EH-314, H. capsulatum isolated from cock excreta; EH-315, H. capsulatum isolated from an infected bat; EH-323, H. capsulatum isolated from Mexican histoplasmosis patient with AIDS.

FIG. 2

SDS-PAGE of histoplasmin from H. capsulatum isolates from different sources and geographic origins. Lanes 1 and 8, molecular weight markers. The gel was silver stained as described elsewhere (10). Image analysis was performed as described in Materials and Methods.

FIG. 3

Dendrogram showing relatedness among H. capsulatum isolates from different sources and geographic origins (Table 1) according to their histoplasmin electrophoretic profiles. The SPSS/PC+ computer program was used to elaborate the dendrogram.

FIG. 4

RAPD-PCR patterns obtained for H. capsulatum isolates from different sources and geographic origins, generated by primer 1281. Lanes 1, 8, and 17 size markers; lane 18, negative control. The gel was ethidium bromide stained. Image analysis was performed as described in Materials and Methods.

FIG. 5

Dendrogram showing relatedness among H. capsulatum isolates from different sources and geographic origins (Table 1) according to their polymorphic DNA patterns. The SPSS/PC+ computer program was used to elaborate the dendrogram.