IMMUNOCHEMICAL STUDIES OF HEAT-SHOCK PROTEIN-80 OF HISTOPLASMA-CAPSULATUM

A monoclonal antibody (MAb) of the IgG1 subclass, with greater activit y to the yeast than the mycelial phase of Histoplasma capsulatum was r aised and was found to predominently recognize a molecule of 80kDa by immunoblot. Enzymatic deglycosylation and chemical degradation, follow ed by reaction with MAb 69F on Western blots showed the molecule to be O-glycosylated, and immunofluorescence studies showed it to be heat-i nducible and its distribution to be cytoplasmic and possibly cell memb raneous. There was no apparent staining of the cell wall. Culture filt rate was positive by ELISA and Western blot when reacted with MAb 69F. In addition, ELISA and Western blot demonstrated that a similar epito pe was present in other fungal species. The glycoprotein had a pI of a pproximately 4.7. N-terminal amino acid sequencing revealed this molec ule to be homologous to members of the heat-shock protein 70 family an d to a recently described antigen from H. capsulatum.