Protective efficacy of a 62-kilodalton antigen, HIS-62, from the cell wall and cell membrane of Histoplasma capsulatum yeast cells

Abstract

We reported previously that a detergent extract of the cell wall and cell membrane of Histoplasma capsulatum yeast cells contains antigens recognized by T cells. In T-cell immunoblot analysis, a region encompassing 62 kDa was stimulatory for an H. capsulatum-reactive T-cell line and T-cell clones derived from C57BL/6 mice. In this study, we isolated a 62-kDa band, termed HIS-62, from electrophoresed cell wall and cell membrane of H. capsulatum yeast cells and examined its antigenicity and immunogenicity. C57BL/6, BALB/c, and CBA/J mice that were immunized with viable H. capsulatum yeast cells mounted a delayed-type hypersensitivity response to HIS-62 that was stronger than that of normal controls. Spleen cells from each strain of mouse immunized with viable yeast cells proliferated vigorously in response to HIS-62; conversely, splenocytes from control animals did not recognize this antigen. A T-celH line and 5 of 5 T-cell clones from C57BL/6 mice, 10 of 15 BALB/c T-cell hybridomas, and 8 of 12 CBA/J T-cell hybridomas recognized HIS-62. A cutaneous delayed-type hypersensitivity response to the antigen was apparent in each strain of mouse that was injected with 80 ,ug of HIS-62 mixed with Freund adjuvant. In addition, spleen cells from HIS-62-immunized mice proliferated in vitro in response to this antigen. Vaccination of each strain of mouse with 80 ,Ig of HIS-62 conferred protection against a lethal intravenous challenge with H. capsulatum yeast cells. Thus, HIS-62 appears to be an important target of the cellular immune response to H. capsulatum and induces a protective immune response in mice.

An 80-kilodalton antigen from Histoplasma capsulatum that has homology to heat shock protein 70 induces cell-mediated immune responses and protection in mice

“…This study extends the reported number of protective antigens in CW/M to two. There is the 80-kDa antigen and a previously isolated 62-kDa antigen (14). The latter, however, was able to confer protection in mice against a lethal challenge that was identical to the challenge employed in this study (14).…”

The arbuscular mycorrhizal fungal protein glomalin is a putative homolog of heat shock protein 60

“…However, Hsp 60 proteins are known to indirectly modulate free Fe pools to prevent cell damage (Cabiscol et al, 2002) Production increased with limited hyphal growth (Rillig & Steinberg, 2002;Lovelock et al, 2004) Stress-protein homology Conserved/ cross-reactive among glomeromycotan fungi Hsp 60 genes are highly conserved and are used for molecular taxonomy of microorganisms (Hill et al, 2005;Zhu & Dong, 2001) Tightly mycelium or hyphal wall-bound (Driver et al, 2005) Mitochondrial target sequence, but 'moonlighting' commonly observed resulting in cell wall localization of mature protein Heat stable (extraction by autoclaving) Can survive boiling (Lewthwaite et al, 2001) GRSP, including lectin-binding and capillary electrophoresis, arrived at the conclusion that N-terminal glycosylation may be present ; this is corroborated by our findings here. Other researchers have also found that the mature Hsp 60 protein can be both glycolsylated and present in the cell wall (Gomez et al, 1991(Gomez et al, , 1995Thomas et al, 1997). It is currently not known whether glycosylation is essential to the functionality of glomalin.…”

Heat shock protein 60: Identification of specific epitopes for binding to primary macrophages

“…Recombinant H. capsulatum HSP60 corresponding to the sequence of the unprocessed precursor of H. capsulatum HSP60 (Swiss‐Prot. P50142) from aa40–590 [18] and recombinant H. capsulatum HSP60‐derived fragment 1 (aa40–328), fragment 2 (aa131–394), fragment 3 (aa214–484) and fragment 4 (aa373–590) have been synthesized as previously described [19,20].…”