Lisa F. Shubitz

Protection of Mice against Coccidioides immitis Intranasal Infection by Vaccination with Recombinant Antigen 2/PRA

ABSTRACT Subcutaneous vaccination with recombinant antigen 2/PRA (rAg2/PRA) protected BALB/c mice against intranasal infection with Coccidioides immitis. Subcutaneously vaccinated C57BL/6 mice and intranasally vaccinated BALB/c mice were protected against larger numbers of infecting spores. Weight loss correlated with lethality, but histologic appearance did not. These studies support rAg2/PRA vaccination to prevent coccidioidomycosis.

Coccidioidomycosis in dogs and cats: A review

The dimorphic fungi Coccidioides immitis and Coccidioides posadasii are the causative agents of coccidioidomycosis. Dogs and cats residing in and visiting endemic areas are at risk of exposure to infectious arthrospores. The primary infection is pulmonary and frequently results in chronic cough. Disseminated disease is common and causes cutaneous, osseous, cardiac, ocular, nervous system, or other organ disease. Radiographic changes include a variable degree of interstitial pulmonary infiltration, hilar lymphadenopathy, and osseous lesions. Serological titers support the diagnosis, but definitive diagnosis relies on identification of Coccidioides in cytological or tissue samples. Coccidioidomycosis should be considered in any dog or cat that has been potentially exposed during the previous 3 years and is presented with chronic illness, respiratory signs, lameness, lymphadenopathy, nonhealing cutaneous lesions, or neurological, ocular, or cardiac abnormalities.

Comparative aspects of coccidioidomycosis in animals and humans

Abstract:  Coccidioides spp. appear capable of infecting all mammals and at least some reptiles. Development of disease as a result of infection is species‐dependent. Dogs seem to have a susceptibility similar to that of humans, with subclinical infections, mild‐to‐severe primary pulmonary disease, and disseminated disease. Whereas central nervous system disease in humans is typically meningitis, brain disease in dogs and cats takes the form of granulomatous parenchymal masses. Osteomyelitis is the most common form of disseminated disease in the dog, while skin lesions predominate in the cat. Orally administered azole antifungal agents are the backbone of therapy in animals as they are in humans.

Localization within a proline-rich antigen (Ag2/PRA) of protective antigenicity against infection with Coccidioides immitis in mice.

ABSTRACT Subunits of a proline-rich coccidioidal antigen (Ag2/PRA) of Coccidioides immitis were analyzed by comparison as vaccines in mice. The optimal dose of plasmid vaccine encoding full-length Ag2/PRA was determined to be between 10 and 100 μg. Mice vaccinated with plasmids encoding amino acids (aa) 1 to 106 were as protective as full-length Ag2/PRA (aa 1 to 194). The subunit from aa 27 to 106 was significantly but less protective. Plasmids encoding aa 90 to 151 or aa 90 to 194 were not protective. Analogous results were obtained with recombinant vaccines of the same amino acid sequences. In addition, mixtures of aa 90 to 194 with either aa 1 to 106 or aa 27 to 106 did not enhance protection compared to the active single-recombinant subunits alone. Humoral response of total immunoglobulin G (IgG) and subclasses IgG1 and IgG2a were detectable in subunit vaccinations but at significantly (100-fold) lower concentrations than after vaccination with plasmids encoding full-length Ag2/PRA. Since virtually all protection by vaccination with full-length Ag2/PRA can be accounted for in the first half of the protein (aa 1 to 106), this subunit could make a multicomponent vaccine more feasible by reducing the quantity of protein per dose and the possibility of an untoward reactions to a foreign protein.

Protein Expression Profiling of Coccidioides posadasii by Two-Dimensional Differential In-Gel Electrophoresis and Evaluation of a Newly Recognized Peroxisomal Matrix Protein as a Recombinant Vaccine Candidate

ABSTRACT Coccidioides posadasii and Coccidioides immitis are dimorphic, soil-dwelling pathogenic ascomycetes endemic to the southwestern United States. Infection can result from inhalation of a very few arthroconidia, but following natural infection, long-lived immunity is the norm. Previous work in the field has shown that spherule-derived vaccines afford more protection than those from mycelia. We have used two-dimensional differential in-gel electrophoresis coupled with nano-high-performance liquid chromatography-tandem mass spectrometry to directly assess both absolute abundance and differential expression of proteins in the spherule and the mycelial phases of C. posadasii with the intent to identify potential vaccine candidates. Peptides derived from 40 protein spots were analyzed and a probable identity was assigned to each. One spherule-abundant protein, identified as Pmp1, showed homology to allergens from Aspergillus fumigatus and other fungi, all of which exhibit similarity to yeast thiol peroxidases. Recombinant Pmp1 was reactive with serum from individuals with both acute and protracted disease, and evoked protection in two murine models of infection with C. posadasii. These results demonstrate the utility of proteomic analysis as a point of discovery for protective antigens for possible inclusion in a vaccine candidate to prevent coccidioidomycosis.

Vaccine-Induced Cellular Immune Responses Differ from Innate Responses in Susceptible and Resistant Strains of Mice Infected with Coccidioides posadasii†

ABSTRACT Susceptibility to Coccidioides spp. varies widely in humans and other mammals and also among individuals within a species. Among strains of mice with various susceptibilities, immunohistopathology revealed that C57BL/6 mice were highly susceptible to the disease following intranasal infection, DBA/2n mice were intermediate, and Swiss-Webster mice were innately resistant. Resistant Swiss-Webster mice developed prominent perivascular/peribronchiolar lymphocytic cuffing and well-formed granulomas with few fungal elements and debris in the necrotic center, surrounded by a mantle of macrophages, lymphocytes, and fibrocytes. Susceptible C57BL/6 mice became moribund between 14 and 18 days postinfection, with overwhelming numbers of neutrophils and spherules and very few T cells, the drastic reduction of which was associated with failure and death, while intermediate DBA/2n mice controlled the fungal burden but demonstrated progressive lung inflammation with prominent suppuration, and they deteriorated clinically. Vaccinated C57BL/6 mice had an early and robust lymphocyte response, which included significantly higher Mac2+, CD3+, and CD4+ cell scores on day 18 than those of innately resistant SW mice and DBA/2n mice; they also had prominent perivascular/peribronchiolar lymphocytic infiltrates not present in their unvaccinated counterparts, and they appeared to be resolving lesions by day 56 compared to the other two strains, based on significantly lower disease scores and observably smaller and fewer lesions with few spherules and neutrophils.

Evaluation of VT-1161 for Treatment of Coccidioidomycosis in Murine Infection Models

ABSTRACT Coccidioidomycosis, or valley fever, is a growing health concern endemic to the southwestern United States. Safer, more effective, and more easily administered drugs are needed especially for severe, chronic, or unresponsive infections. The novel fungal CYP51 inhibitor VT-1161 demonstrated in vitro antifungal activity, with MIC50 and MIC90 values of 1 and 2 μg/ml, respectively, against 52 Coccidioides clinical isolates. In the initial animal study, oral doses of 10 and 50 mg/kg VT-1161 significantly reduced fungal burdens and increased survival time in a lethal respiratory model in comparison with treatment with a placebo (P < 0.001). Oral doses of 25 and 50 mg/kg VT-1161 were similarly efficacious in the murine central nervous system (CNS) model compared to placebo treatment (P < 0.001). All comparisons with the positive-control drug, fluconazole at 50 mg/kg per day, demonstrated either statistical equivalence or superiority of VT-1161. VT-1161 treatment also prevented dissemination of infection from the original inoculation site to a greater extent than fluconazole. Many of these in vivo results can be explained by the long half-life of VT-1161 leading to sustained high plasma levels. Thus, the efficacy and pharmacokinetics of VT-1161 are attractive characteristics for long-term treatment of this serious fungal infection.

Modeling Nikkomycin Z Dosing and Pharmacology in Murine Pulmonary Coccidioidomycosis Preparatory to Phase 2 Clinical Trials

Nikkomycin Z (NikZ) is a chitin synthase inhibitor with activity against Coccidioides species that is being developed as a first-in-class orphan product for treatment of coccidioidomycosis. It has previously been shown to reduce lethal respiratory infections in mice to undetectable levels when treatment is begun 48 hours after infection. The studies described here focus on bracketing NikZ doses for phase 2 and 3 clinical trials, using an established mouse respiratory infection as a model and starting treatment 120 hours after infection. A dose of 80 mg/kg/day, divided into 2 doses, nearly eradicated infection, and larger doses did not improve fungal clearance. Increasing the duration of treatment from 1 week to 3 weeks resulted in a greater percentage of culture-negative mice. Comparative data show that plasma levels of NikZ that nearly eradicate Coccidioides in mice are achievable in patients and provide a plausibly effective dose range for initial phase 2 clinical studies.

Efficacy of Ambruticin Analogs in a Murine Model of Coccidioidomycosis

ABSTRACT Ambruticin S, an antifungal cyclopropyl-pyran acid, showed curative effects against murine coccidioidal infection. Two analogs of this compound with greater in vitro potency were tested against lethal murine Coccidioides infection. Both improved the survival of mice over that of controls; one resulted in near-sterilization of infection.

Efficacy of Nikkomycin Z for respiratory coccidioidomycosis in naturally infected dogs.

Nikkomycin Z (NikZ) is a chitin synthase inhibitor with antifungal efficacy against Coccidioides spp. and other endemic fungi. Dogs suffer a rate and range of natural coccidioidomycosis similar to humans and were considered an excellent model for initially testing NikZ against naturally acquired disease. Twelve dogs with coccidioidal pneumonia that had been present for an average of three months were treated with 250 mg (5-15 kg) or 500 mg (> 15-30 kg) twice daily for 60 days. Nine dogs completed the course of treatment and seven dogs had improvement in disease based on radiographs, clinicopathological parameters, physical examination findings, and subjective assessment by owners; three dogs had resolution or near resolution of disease. Based on this small study, NikZ shows efficacy to treat naturally acquired coccidioidomycosis and merits further development for trials in humans.