Leo Pine

Comparative fluorescent antibody staining of histoplasma capsulatum and histoplasma duboisii with a specific anti-yeast phase H. Capsulatum conjugate

The specific anti-yeast phaseHistoplasma capsulatum conjugate has been tested against 13 yeast phase strains ofH. capsulatum and 9 ofH. duboisii. The conjugate was specific forH. capsulatum, no yeast phase form ofH. duboisii obtained in vitro or in vivo reacted with it. The taxonomic implications of these results are discussed.

Effect of periodate oxidation on the detection of antibodies against the M-antigen of histoplasmin by enzyme immunoassay (EIA) inhibition

An enzyme immunoassay (EIA) inhibition method was devised that detects antibodies against the M-factor, a major protein antigen in histoplasmin. Purified M-factor still contains a large amount of a carbohydrate antigen impurity, but this can be inactivated by periodate oxidation. The resulting product improves the performance of the EIA to detect anti-M by (a) giving a more specific measurement, (b) increasing the percent inhibition in sera that contain antibodies to M-factor, and (c) increasing the precision in measuring negative reactions. An inhibition of 20% or greater is recommended for recording a result as positive.

Effect of thimerosal on the whole yeast phase antigen of Histoplasma capsulatum

Thimerosal (merthiolate) and formalin treated whole-cell yeast phase antigens ofHistoplasma capsulatum were prepared and their reactivities with sera from cases of histoplasmosis, blastomycosis and coccidioidomycosis were compared. Thimerosal treated antigens often gave complement fixation titers with heterologous sera 2 to 8 fold lower than the titers obtained with formalin treated antigens. However, with certain anti-histoplasmosis sera, thimerosal killed antigens had less reactivity with homologous antisera also. In virtually all cases an equal or higher specificity ratio was obtained with thimerosal killed antigens. The effects of thimerosal and formalin were independent, indicating different sites of reactivity of these reagents. Uptake of thimerosal at several concentrations suggested two types of reactions with live yeast phase cells. Analyses of the cellular fractions for thimerosal showed it was present only in the soluble fractions from which it was readily removed by dialysis. Cellular fractions killed with thimerosal retained several of the same physical and antigenic characteristics of those fractions isolated from frozen and thawed cells.