Recombinant urease and urease DNA of Coccidioides immitis elicit an immunoprotective response against coccidioidomycosis in mice.
Coccidioides immitis antigens which stimulate a T helper cell 1 (Th1) pathway of host immune response are considered to be essential components of a vaccine against coccidioidomycosis. Recombinant urease (rURE) and recombinant heat shock protein 60 (rHSP60) of C. immitis were expressed in Escherichia coli and tested as vaccine candidates in BALB/c mice. A synthetic oligodeoxynucleotide which contained unmethylated CpG dinucleotides and was previously shown to enhance a murine Th1 response was used as an immunoadjuvant. T cells isolated from the spleens and lymph nodes of the rURE- and rHSP60-immune mice showed in vitro proliferative responses to the respective recombinant protein, but only those T lymphocytes from rURE-immunized mice revealed markedly elevated levels of expression of selected Th1-type cytokine genes. BALB/c mice immunized subcutaneously with rURE and subsequently challenged by the intraperitoneal (i.p.) route with a lethal inoculum of C. immitis arthroconidia demonstrated a significant reduction in the level of C. immitis infection compared to control animals. rHSP60 was much less effective as a protective antigen. Evaluation of cytokine gene expression in lung tissue and levels of recombinant urease-specific immunoglobulins (immunoglobulin G1 [IgG1] versus IgG2a) in murine sera at 12 days after challenge provided additional evidence that immunization with rURE stimulated a Th1 response to the pathogen. Urease was further evaluated by expression of the URE gene in a mammalian plasmid vector (pSecTag2A.URE) which was used to immunize mice by the intradermal route. In this case, 82% of the vector construct-immunized animals survived more than 40 days after i.p. infection, compared to only 10% of the mice immunized with the vector alone. In addition, 87% of the pSecTag2A.URE-immunized survivors had sterile lungs and spleens. These data support the need for further evaluation of the C. immitis urease as a candidate vaccine against coccidioidomycosis.
Li
K
K
Department of Microbiology and Immunology, Medical College of Ohio, Toledo, Ohio 43614-5806, USA.
Yu
J J
JJ
Hung
C Y
CY
Lehmann
P F
PF
Cole
G T
GT
D000818:Animals; D000908:Antibodies, Fungal / Q000097:blood; D018834:Chaperonin 60 / Q000276:immunology; D003045:Coccidioides / Q000276:immunology*; D003047:Coccidioidomycosis / Q000517:prevention & control*; D016207:Cytokines / Q000235:genetics; D005260:Female; D005657:Fungal Vaccines / Q000276:immunology*; D007114:Immunization; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D011994:Recombinant Proteins / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology; D014510:Urease / Q000235:genetics / Q000276:immunology*; D019444:Vaccines, DNA / Q000276:immunology*; D014614:Vaccines, Synthetic / Q000276:immunology*
D000908:Antibodies, Fungal; D018834:Chaperonin 60; D016207:Cytokines; D005657:Fungal Vaccines; D011994:Recombinant Proteins; D019444:Vaccines, DNA; D014614:Vaccines, Synthetic; D014510:Urease