Immunologic responsiveness and safety associated with the Coccidioides immitis spherule vaccine in volunteers of white, black, and Filipino ancestry

Challenges to Implementing a Vaccine for Coccidioidomycosis

A vaccine for coccidioidomycosis is likely to undergo trials in the near future. In this paper, we raise 4 questions that should be answered before its use and offer our solutions to these questions. These include defining the goals of vaccination, determining who should be vaccinated, how to measure vaccine immunity and protection, and how to address vaccine hesitancy and denial.

Fungal Vaccine Development: State of the Art and Perspectives Using Immunoinformatics

Fungal infections represent a serious global health problem, causing damage to health and the economy on the scale of millions. Although vaccines are the most effective therapeutic approach used to combat infectious agents, at the moment, no fungal vaccine has been approved for use in humans. However, the scientific community has been working hard to overcome this challenge. In this sense, we aim to describe here an update on the development of fungal vaccines and the progress of methodological and experimental immunotherapies against fungal infections. In addition, advances in immunoinformatic tools are described as an important aid by which to overcome the difficulty of achieving success in fungal vaccine development. In silico approaches are great options for the most important and difficult questions regarding the attainment of an efficient fungal vaccine. Here, we suggest how bioinformatic tools could contribute, considering the main challenges, to an effective fungal vaccine.

Coccidioides Species: A Review of Basic Research: 2022

Coccidioides immitis and posadasii are closely related fungal species that cause coccidioidomycosis. These dimorphic organisms cause disease in immunocompetent as well as immunocompromised individuals and as much as 40% of the population is infected in the endemic area. Although most infections resolve spontaneously, the infection can be prolonged and, in some instances, fatal. Coccidioides has been studied for more than 100 years and many aspects of the organism and the disease it causes have been investigated. There are over 500 manuscripts concerning Coccidioides (excluding clinical articles) referenced in PubMed over the past 50 years, so there is a large body of evidence to review. We reviewed the most accurate and informative basic research studies of these fungi including some seminal older studies as well as an extensive review of current research. This is an attempt to gather the most important basic research studies about this fungus into one publication. To focus this review, we will discuss the mycology of the organism exclusively rather than the studies of the host response or clinical studies. We hope that this review will be a useful resource to those interested in Coccidioides and coccidioidomycosis.

Vaccines to Prevent Coccidioidomycosis: A Gene-Deletion Mutant of Coccidioides Posadasii as a Viable Candidate for Human Trials

Coccidioidomycosis is an endemic fungal infection that is reported in up to 20,000 persons per year and has an economic impact close to $1.5 billion. Natural infection virtually always confers protection from future exposure, and this suggests that a preventative vaccine strategy is likely to succeed. We here review progress toward that objective. There has been ongoing research to discover a coccidioidal vaccine over the past seven decades, including one phase III clinical trial, but for reasons of either efficacy or feasibility, a safe and effective vaccine has not yet been developed. This review first summarizes the past research to develop a coccidioidal vaccine. It then details the evidence that supports a live, gene-deletion vaccine candidate as suitable for further development as both a veterinary and a human clinical product. Finally, a plausible vaccine development plan is described which would be applicable to this vaccine candidate and also useful to other future candidates. The public health and economic impact of coccidioidomycosis fully justifies a public private partnership for vaccine development, and the development of a vaccine for this orphan disease will likely require some degree of public funding.

Advances in Fungal Peptide Vaccines

Vaccination is one of the greatest public health achievements in the past century, protecting and improving the quality of life of the population worldwide. However, a safe and effective vaccine for therapeutic or prophylactic treatment of fungal infections is not yet available. The lack of a vaccine for fungi is a problem of increasing importance as the incidence of diverse species, including Paracoccidioides, Aspergillus, Candida, Sporothrix, and Coccidioides, has increased in recent decades and new drug-resistant pathogenic fungi are emerging. In fact, our antifungal armamentarium too frequently fails to effectively control or cure mycoses, leading to high rates of mortality and morbidity. With this in mind, many groups are working towards identifying effective and safe vaccines for fungal pathogens, with a particular focus of generating vaccines that will work in individuals with compromised immunity who bear the major burden of infections from these microbes. In this review, we detail advances in the development of vaccines for pathogenic fungi, and highlight new methodologies using immunoproteomic techniques and bioinformatic tools that have led to new vaccine formulations, like peptide-based vaccines.

A Coccidioides posadasii CPS1 Deletion Mutant Is Avirulent and Protects Mice from Lethal Infection

The CPS1 gene was identified as a virulence factor in the maize pathogen Cochliobolus heterostrophus Hypothesizing that the homologous gene in Coccidioides posadasii could be important for virulence, we created a Δcps1 deletion mutant which was unable to cause disease in three strains of mice (C57BL/6, BALB/c, or the severely immunodeficient NOD-scid,γc(null) [NSG]). Only a single colony was recovered from 1 of 60 C57BL/6 mice following intranasal infections of up to 4,400 spores. Following administration of very high doses (10,000 to 2.5 × 10(7) spores) to NSG and BALB/c mice, spherules were observed in lung sections at time points from day 3 to day 10 postinfection, but nearly all appeared degraded with infrequent endosporulation. Although the role of CPS1 in virulence is not understood, phenotypic alterations and transcription differences of at least 33 genes in the Δcps1 strain versus C. posadasii is consistent with both metabolic and regulatory functions for the gene. The in vitro phenotype of the Δcps1 strain showed slower growth of mycelia with delayed and lower spore production than C. posadasii, and in vitro spherules were smaller. Vaccination of C57BL/6 or BALB/c mice with live Δcps1 spores either intranasally, intraperitoneally, or subcutaneously resulted in over 95% survival with mean residual lung fungal burdens of <1,000 CFU from an otherwise lethal C. posadasii intranasal infection. Considering its apparently complete attenuation of virulence and the high degree of resistance to C. posadasii infection when used as a vaccine, the Δcps1 strain is a promising vaccine candidate for preventing coccidioidomycosis in humans or other animals.

Coccidioidomycosis in African Americans

Coccidioidomycosis is caused by Coccidioides species, a fungus endemic to the desert regions of the southwestern United States, and is of particular concern for African Americans. We performed a PubMed search of the English-language medical literature on coccidioidomycosis in African Americans and summarized the pertinent literature. Search terms were coccidioidomycosis, Coccidioides, race, ethnicity, African, black, and Negro. The proceedings of the national and international coccidioidomycosis symposia were searched. All relevant articles and their cited references were reviewed; those with epidemiological, immunologic, clinical, and therapeutic data pertaining to coccidioidomycosis in African Americans were included in the review. Numerous studies documented an increased predilection for severe coccidioidal infections, coccidioidomycosis-related hospitalizations, and extrapulmonary dissemination in persons of African descent; however, most of the published studies are variably problematic. The immunologic mechanism for this predilection is unclear. The clinical features and treatment recommendations are summarized. Medical practitioners need to be alert to the possibility of coccidioidomycosis in persons with recent travel to or residence in an area where the disease is endemic.

An insight into the antifungal pipeline: selected new molecules and beyond

Invasive fungal infections are increasing in incidence and are associated with substantial mortality. Improved diagnostics and the availability of new antifungals have revolutionized the field of medical mycology in the past decades. This Review focuses on recent developments in the antifungal pipeline, concentrating on promising candidates such as new azoles, polyenes and echinocandins, as well as agents such as nikkomycin Z and the sordarins. Developments in vaccines and antibody-based immunotherapy are also discussed. Few therapeutic products are currently in active development, and progression of therapeutic agents with fungus-specific mechanisms of action is of key importance.

Improved protection of mice against lethal respiratory infection with Coccidioides posadasii using two recombinant antigens expressed as a single protein

Two recombinant antigens which individually protect mice from lethal intranasal infection were studied in combination, either as a mixture of two separately expressed proteins or as a single chimeric expression product. Mice vaccinated with either combination survived longer than mice given single antigens. Immunized mice also exhibited specific IgG immunoglobulins and yielded splenocytes which produced interferon-gamma in response to either antigen. The chimeric antigen has the practical advantage of offering enhanced protection from multiple components without increasing production costs.

Coccidioidomycosis: host response and vaccine development

Coccidioidomycosis is caused by the dimorphic fungi in the genus Coccidioides. These fungi live as mycelia in the soil of desert areas of the American Southwest, and when the infectious spores, the arthroconidia, are inhaled, they convert into the parasitic spherule/endospore phase. Most infections are mild, but these organisms are frank pathogens and can cause severe lethal disease in fully immunocompetent individuals. While there is increased risk of disseminated disease in certain racial groups and immunocompromised persons, the fact that there are hosts who contain the initial infection and exhibit long-term immunity to reinfection supports the hypothesis that a vaccine against these pathogens is feasible. Multiple studies have shown that protective immunity against primary disease is associated with T-helper 1 (Th-1)-associated immune responses. The single best vaccine in animal models, formalin-killed spherules (FKS), was tested in a human trial but was not found to be significantly protective. This result has prompted studies to better define immunodominant Coccidioides antigen with the thought that a subunit vaccine would be protective. These efforts have defined multiple candidates, but the single best individual immunogen is the protein termed antigen 2/proline-rich antigen (Ag2/PRA). Studies in multiple laboratories have shown that Ag2/PRA as both protein and genetic vaccines provides significant protection against mice challenged systemically with Coccidioides. Unfortunately, compared to the FKS vaccine, it is significantly less protective as measured by both assays of reduction in fungal CFU and assays of survival. The capacity of Ag2/PRA to induce only partial protection was emphasized when animals were challenged intranasally. Thus, there is a need to define new candidates to create a multivalent vaccine to increase the effectiveness of Ag2/PRA. Efforts of genomic screening using expression library immunization or bioinformatic approaches to identify new candidates have revealed at least two new protective proteins, expression library immunization antigen 1 (ELI-Ag1) and a beta-1,3-glucanosyltransferase (GEL-1). In addition, previously discovered antigens such as Coccidioides-specific antigen (CSA) should be evaluated in assays of protection. While studies have yet to be completed with combinations of the current candidates, the hypothesis is that with increased numbers of candidates in a multivalent vaccine, there will be increased protection. As the genome sequences of the two Coccidioides strains which are under way are completed and annotated, the effort to find new candidates can increase to provide a complete genomic scan for immunodominant proteins. Thus, much progress has been made in the discovery of subunit vaccine candidates against Coccidioides and there are several candidates showing modest levels of protection, but for complete protection against pulmonary challenge we need to continue the search for additional candidates.

Surgical treatment of multiple skull abscesses associated with coccidioidomycosis. Fallbericht. Chirurgische Behandlung multipler Schadelabszesse bei Coccidioidomykose

This case emphasizes that aggressive neurosurgical management may benefit patients with disseminated coccidioidomycosis and skull abscesses. Disseminated infection due to Coccidioides immitis, the causative agent of coccidioidomycosis, is difficult to treat and often requires prolonged antifungal therapy in addition to surgical debridement. We present a case of a young woman with disseminated coccidioidomycosis who had multiple skull lesions, two of which penetrated the skull and invaded the subgaleal and epidural spaces. Despite prolonged aggressive medical management, these lesions failed to resolve until they were surgically drained.

Evaluation of the protective efficacy of the killed Coccidioides immitis spherule vaccine in humans. The Valley Fever Vaccine Study Group

A vaccine consisting of formaldehyde-killed spherules of Coccidioides immitis, previously shown to provide protection against development of lethal coccidioidomycosis in laboratory animals, was evaluated in humans. This double blind "Phase 3" study, conducted during the period 1980 to 1985, involved 2,867 healthy subjects with no history of coccidioidomycosis and negative skin tests. Randomized into vaccine (n = 1,436) or placebo (n = 1,431) groups, the former received three intramuscular injections of 1.75 mg (dry weight) of spherules, the latter received three injections of sterile 0.85% NaCl solution. Compatible clinical presentation with cultural or serologic findings permitted detection of coccidioidomycosis. Of those receiving vaccine, nine developed coccidioidomycosis and nine additional were suspected of having the disease. Of the group receiving placebo, 12 developed coccidioidomycosis, and 13 additional were suspected of having the disease. All cases and suspected cases were mild. Under the conditions of this study, a slight but statistically insignificant reduction in the incidence of coccidioidomycosis was noted in the vaccinated group compared with that in the placebo group, and there was no discernible difference in severity of disease between these groups.

Induction and expression of cell-mediated immune responses in inbred mice infected with Coccidioides immitis

Comparisons of the course of coccidioidomycosis in two strains of inbred mice established that BALB/c mice are significantly more susceptible to pulmonary infection with Coccidioides immitis than are DBA/2 mice. The susceptibility of BALB/c mice does not reside in their inability to mount a delayed-type hypersensitivity response to C. immitis antigen. That is, BALB/c mice manifested footpad hypersensitivity to coccidioidin early during the course of disease, to a level comparable to that of DBA/2 mice. In contrast to the more resistant DBA/2 mouse strain, however, BALB/c mice developed anergy by day 15 postinfection. Suppression of the delayed-type hypersensitivity response was not specific for C. immitis antigen, as evidenced by the finding that BALB/c mice immunized with mycobacterial purified protein derivative prior to infection with C. immitis were suppressed in their footpad response to mycobacterial antigen at day 15 postinfection. Taken together, these results establish that genetically determined susceptibility to this fungus is associated with an acquired suppression of cell-mediated immune reactivity.

Vaccines against fungal infections

The state-of-the-art reached in developing protective immunity against fungal infections through vaccination makes a survey of methodologies and results timely. This review describes experimental vaccinations against dermatophytes, pathogenic yeasts, and dimorphic fungi with special attention to the anti-Coccidioides immitis vaccine, which has reached clinical trials, and to the anti-Candida albicans and anti-Histoplasma capsulatum ribosomal vaccines. Also covered are vaccination experiments in compromised hosts aimed at eliciting acquired resistance to opportunistic fungal infections which constitute risk factors for these hosts. Immunization procedures include live, killed, and attenuated organisms, as well as different subcellular fractions such as cytoplasmic extracts, fungal culture filtrates, cell walls, or ribosomal fractions. A variety of experimental animal models and isolated human trials constitute the subjects in these studies. Acquired immunity has been evaluated through assessment of resistance to infection and determination of specific immune responses. It has been demonstrated that fungal vaccines do elicit both humoral and cell-mediated immunity in the immunized host. For some vaccines (e.g., H. capsulatum), a correlation between the induced immunity and protection was observed and the immunity could be adoptively transferred. In view of the potential of vaccines against fungal infections, a perspective on their applicability, significance, and value for human use is discussed.