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Trends in Parasitology Jan 2014The intestinal disease coccidiosis, caused by protozoan parasites of the genus Eimeria, is one of the most important livestock diseases in the world. It has a high... (Review)
Review
The intestinal disease coccidiosis, caused by protozoan parasites of the genus Eimeria, is one of the most important livestock diseases in the world. It has a high impact in the poultry industry where parasite transmission is favoured by high-density housing of large numbers of susceptible birds. Coccidiosis control in poultry is achieved by careful husbandry combined with in-feed anticoccidial drugs or vaccination with live parasites. However, outbreaks of coccidiosis still occur and subclinical infections, which significantly impact on productivity and food security, are common due to widespread drug resistance, high parasite prevalence, and environmental persistence. Herein, we review some recent approaches for the production of cheaper third generation vaccines, based on robust methods for identification of immunoprotective antigens and the use of transgenic Eimeria.
Topics: Animal Husbandry; Animals; Coccidiosis; Eimeria; Poultry; Poultry Diseases; Protozoan Vaccines
PubMed: 24238797
DOI: 10.1016/j.pt.2013.10.003 -
Frontiers in Immunology 2021Despite mass drug administration programmes with praziquantel, the prevalence of schistosomiasis remains high. A vaccine is urgently needed to control transmission of... (Review)
Review
Despite mass drug administration programmes with praziquantel, the prevalence of schistosomiasis remains high. A vaccine is urgently needed to control transmission of this debilitating disease. As some promising schistosomiasis vaccine candidates are moving through pre-clinical and clinical testing, we review the immunological challenges that these vaccine candidates may encounter in transitioning through the clinical trial phases in endemic settings. Prior exposure of the target population to schistosomes and other infections may impact vaccine response and efficacy and therefore requires considerable attention. Schistosomes are known for their potential to induce T-reg/IL-10 mediated immune suppression in populations which are chronically infected. Moreover, endemicity of schistosomiasis is focal whereby target and trial populations may exhibit several degrees of prior exposure as well as exposure which may increase heterogeneity of vaccine responses. The age dependent distribution of exposure and development of acquired immunity, and general differences in the baseline immunological profile, adds to the complexity of selecting suitable trial populations. Similarly, prior or concurrent infections with other parasitic helminths, viral and bacterial infections, may alter immunological responses. Consequently, treatment of co-infections may benefit the immunogenicity of vaccines and may be considered despite logistical challenges. On the other hand, viral infections leave a life-long immunological imprint on the human host. Screening for serostatus may be needed to facilitate interpretation of vaccine responses. Co-delivery of schistosome vaccines with PZQ is attractive from a perspective of implementation but may complicate the immunogenicity of schistosomiasis vaccines. Several studies have reported PZQ treatment to induce both transient and long-term immuno-modulatory effects as a result of tegument destruction, worm killing and subsequent exposure of worm antigens to the host immune system. These in turn may augment or antagonize vaccine immunogenicity. Understanding the complex immunological interactions between vaccine, co-infections or prior exposure is essential in early stages of clinical development to facilitate phase 3 clinical trial design and implementation policies. Besides well-designed studies in different target populations using schistosome candidate vaccines or other vaccines as models, controlled human infections could also help identify markers of immune protection in populations with different disease and immunological backgrounds.
Topics: Animals; Coinfection; Drug Design; Drug Development; Endemic Diseases; Host-Parasite Interactions; Humans; Immunogenicity, Vaccine; Praziquantel; Protozoan Vaccines; Schistosoma; Schistosomiasis; Schistosomicides
PubMed: 33746974
DOI: 10.3389/fimmu.2021.635985 -
Archives of Medical Research Feb 2006The persistence of amebiasis as a global health problem, despite the availability of effective treatment, has led to the search for vaccines to prevent this deadly... (Review)
Review
The persistence of amebiasis as a global health problem, despite the availability of effective treatment, has led to the search for vaccines to prevent this deadly disease. Recent clinical studies suggest that mucosal immunity could provide some protection against recurrent intestinal infection with E. histolytica, but there is contradictory evidence about protective immunity after amebic liver abscess. Progress in vaccine development has been facilitated by new animal models that allow better testing of potential vaccine candidates and by the application of recombinant technology to vaccine design. Oral vaccines utilizing amebic antigens either co-administered with some form of cholera toxin or expressed in attenuated strains of Salmonella or Vibrio cholera have been developed and tested in animals for mucosal immunogenicity. Although there has been significant progress on a number of fronts, there are unanswered questions regarding the effectiveness of immune responses in preventing disease in man and, as yet, no testing of any of these vaccines in humans has been performed.
Topics: Entamoebiasis; Feasibility Studies; Humans; Protozoan Vaccines
PubMed: 16380333
DOI: 10.1016/j.arcmed.2005.09.006 -
Current Medicinal Chemistry 2009Leishmaniasis is a disease that ranges in severity from skin lesions to serious disfigurement and fatal systemic infection. WHO estimates that the disease results in 2... (Review)
Review
Leishmaniasis is a disease that ranges in severity from skin lesions to serious disfigurement and fatal systemic infection. WHO estimates that the disease results in 2 million new cases a year, threatens 350 million people in 88 countries and that there are 12 million people currently infected worldwide. Current treatment is based on chemotherapy, which relies on a handful of drugs with serious limitations such as high cost, toxicity, difficult route of administration and lack of efficacy in endemic areas. Pentavalent antimonials have been the mainstay of antileishmanial therapy for over 70 years with second line drugs, Amphotericin B and Pentamidine, used in case of antimonial failure. Since the introduction of miltefosine at the beginning of this century, no new antileishmanial compounds have been approved for human treatment. Leishmaniasis is considered one of a few parasitic diseases likely to be controllable by vaccination. However, to date no such vaccine is available despite substantial efforts by many laboratories. The development of a safe, effective and affordable antileishmanial vaccine is a critical global public-health priority. This review outlines the current status of vaccine development and looks at the currently available chemotherapy as well as examples of drugs in development and different approaches to antileishmanial drug discovery and identification of novel antiparasitic compounds.
Topics: Antiprotozoal Agents; Humans; Leishmaniasis; Protozoan Vaccines
PubMed: 19199925
DOI: 10.2174/092986709787458489 -
Human Vaccines & Immunotherapeutics 2014Entamoeba histolytica is the causative agent of amebiasis, one of the top three parasitic causes of mortality worldwide. In the majority of infected individuals, E.... (Review)
Review
Entamoeba histolytica is the causative agent of amebiasis, one of the top three parasitic causes of mortality worldwide. In the majority of infected individuals, E. histolytica asymptomatically colonizes the large intestine, while in others, the parasite breaches the mucosal epithelial barrier to cause amebic colitis and can disseminate to soft organs to cause abscesses. Vaccinations using native and recombinant forms of the parasite Gal-lectin have been successful in protecting animals against intestinal amebiasis and amebic liver abscess. Protection against amebic liver abscesses has also been reported by targeting other E. histolytica components including the serine-rich protein and the 29-kDa-reductase antigen. To date, vaccines against the Gal-lectin hold the most promise but clinical trials will be required to validate its efficacy in humans. Here, we review the current strategies and future perspectives involved in the development of a vaccine against E. histolytica.
Topics: Animals; Disease Models, Animal; Drug Discovery; Entamoeba histolytica; Entamoebiasis; Humans; Protozoan Vaccines
PubMed: 24504133
DOI: 10.4161/hv.27796 -
The Journal of Parasitology Nov 2021Toxoplasma gondii is an apicomplexan parasite that affects both humans and livestock. Transmitted to humans through ingestion, it is the second-leading cause of... (Review)
Review
Toxoplasma gondii is an apicomplexan parasite that affects both humans and livestock. Transmitted to humans through ingestion, it is the second-leading cause of foodborne illness-related death. Currently, there exists no approved vaccine for humans or most livestock against the parasite. DNA vaccines, a type of subunit vaccine which uses segments of the pathogen's DNA to generate immunity, have shown varying degrees of experimental efficacy against infection caused by the parasite. This review compiles DNA vaccine efforts against Toxoplasma gondii, segmenting the analysis by parasite antigen, as well as a review of concomitant adjuvant usage. No single antigenic group was consistently more effective within in vivo trials relative to others.
Topics: Adjuvants, Immunologic; Animals; Antigens, Protozoan; Humans; Microneme; Protozoan Vaccines; Toxoplasma; Toxoplasmosis; Vaccines, DNA
PubMed: 34852176
DOI: 10.1645/20-157 -
Expert Review of Vaccines Oct 2003The leishmaniases are a group of diseases caused by protozoa of the genus Leishmania which affects millions of people worldwide. The leishmaniases are transmitted to the... (Review)
Review
The leishmaniases are a group of diseases caused by protozoa of the genus Leishmania which affects millions of people worldwide. The leishmaniases are transmitted to the vertebrate hosts by phlebotomine sand flies. In this review, we focus on clinical aspects of the leishmaniases and on the immune response against the parasite, both in animal models and humans. These aspects are of key importance to understand the many attempts to obtain an effective vaccine against Leishmania. We considered the last advances in new generation vaccines, including the use of new adjuvants to improve the protective response against the parasite. Finally, the possibility to use components of the sand fly saliva as part of vaccines against the infection by Leishmania is mentioned.
Topics: Animals; Antiprotozoal Agents; Humans; Leishmania; Leishmaniasis, Cutaneous; Leishmaniasis, Visceral; Protozoan Vaccines
PubMed: 14711330
DOI: 10.1586/14760584.2.5.705 -
The Journal of Experimental Medicine Aug 2001
Review
Topics: Animals; Humans; Leishmania; Leishmaniasis; Protozoan Vaccines; Vaccination
PubMed: 11489957
DOI: 10.1084/jem.194.3.f7 -
Expert Review of Vaccines Nov 2021Pathogenesis of Chagas disease (CD) caused by involves chronic oxidative and inflammatory stress. In this review, we discuss the research efforts in therapeutic vaccine... (Review)
Review
INTRODUCTION
Pathogenesis of Chagas disease (CD) caused by involves chronic oxidative and inflammatory stress. In this review, we discuss the research efforts in therapeutic vaccine development to date and the potential challenges imposed by oxidative stress in achieving an efficient therapeutic vaccine against CD.
AREAS COVERED
This review covers the immune and nonimmune mechanisms of reactive oxygen species production and immune response patterns during in CD. A discussion on immunotherapy development efforts, the efficacy of antigen-based immune therapies against , and the role of antioxidants as adjuvants is discussed to provide promising insights to developing future treatment strategies against CD.
EXPERT OPINION
Administration of therapeutic vaccines can be a good option to confront persistent parasitemia in CD by achieving a rapid, short-lived stimulation of type 1 cell-mediated immunity. At the same time, adjunct therapies could play a critical role in the preservation of mitochondrial metabolism and cardiac muscle contractility in CD. We propose combined therapy with antigen-based vaccine and small molecules to control the pathological oxidative insult would be effective in the conservation of cardiac structure and function in CD.
Topics: Chagas Disease; Humans; Oxidative Stress; Protozoan Vaccines; Trypanosoma cruzi; Vaccine Development
PubMed: 34406892
DOI: 10.1080/14760584.2021.1969230 -
Future Microbiology Mar 2010
Topics: Animals; Cryptosporidiosis; Cryptosporidium; Humans; Protozoan Vaccines
PubMed: 20210541
DOI: 10.2217/fmb.09.115