why usually impossible to make a successful vaccine against helminths or protozoa and don't quite understand why.
It's hard to vaccinate against parasites because they're so much more complicated genetically than most bacteria and viruses. However, Malaria vaccines are being tested now; they are not spectacularly effective, but they do seem to work. What's more, there are actually highly effective malaria vaccines that have been known for decades, but that are impossible to produce in large scale; effective, but impractical.
https://www.ncbi.nlm.nih.gov › NCBI › Literature › PubMed Central (PMC)
by F Mutapi - 2013 - Cited by 20 - Related articles
DNA Vaccines against Protozoan Parasites: Advances and Challenges
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1940056/
he difficulties in developing a vaccine against parasitic disease are complicated not only by the necessity to identify (and produce) appropriate, protective antigens but also a lack of complete understanding of the types of immune responses needed for protection
you can see this link
https://www.quora.com/Why-havent-we-developed-any-vaccines-for-parasites
he difficulties in developing a vaccine against parasitic disease are complicated not only by the necessity to identify (and produce) appropriate, protective antigens but also a lack of complete understanding of the types of immune responses needed for protection
It's hard to vaccinate against parasites ?. Available from: https://www.researchgate.net/post/Its_hard_to_vaccinate_against_parasites/1 [accessed Apr 24, 2017].
Hello,this link so important for answer your question
https://www.researchgate.net/.../Its_hard_to_vaccinate_against_parasit...
Dear Dr. Mansoor
It's hard to vaccinate against parasites because they're so much more complicated genetically than most bacteria and viruses. However, it's not true that there are no vaccines against them. Malaria vaccines are being tested now; they are not spectacularly effective, but they do seem to work. What's more, there are actually highly effective malaria vaccines that have been known for decades, but that are impossible to produce in large scale; effective, but impractical.
There are Giardia vaccines in dogs (Giardia vaccination), experimental hookworm vaccines (The Human Hookworm Vaccine) -- though I don't think they're very effective yet -- and a tapeworm vaccine in pigs (Vaccine against tapeworm - First field study is positive). There are even vaccines against external parasites, such as one that protects cattle against ticks: Vaccines to protect Hereford cattle against the cattle tick, Boophilus micro plus)
So it's not an absolute truth, even though it's in general much harder to develop anti-parasite vaccines.
The long-term survival of helminth parasites within mammalian hosts indicates that they have developed sophisticated mechanisms to evade the cytotoxic effects of the immune response.
For example, antibodies in the sera of schistosome-infected hosts fail to bind to the surface of the living parasites and yet bind strongly to dead parasites or parasites extracts, indicating that living parasites are able to modulate their surface structure in a way that prevents recognition .
Recent studies have begun to provide mechanistic explanations for evasion .
For example, serpins made by the microfilariae of B. malayi are able to inhibit neutrophil serine preoteases , and a cystatin homologue from the same parasite can inhibit class II major histocompatibility complex-restricted Ag processing.
Deeper understanding of the basic requirements of metazoan life have revealed areas in which interactions between helminths and their hosts that could influence immune effector functions are likely to occur
Prominent among these is the expression of transforming growth factor β receptor family members by helminths , and, in the case of nematodes at least, a homologue of transforming growth factor β itself .
Recent advances in vaccination with recombinant helminth antigens have been successful against cestode infections of livestock and new vaccines are being tested against nematode parasites of animals.
YOUR QUESTION: why usually impossible to make a successful vaccine against helminths or protozoa?
Well I disagreed with you about protozoa because we have a good response of protection against commercial vaccine for coccidia, which is one of protozoa
best regards
this link may help you
https://www.researchgate.net/.../Its_hard_to_vaccinate_against_parasit
https://www.researchgate.net/post/Its_hard_to_vaccinate_against_parasites/1
Dear Dr. M. Jadaan
It's hard to vaccinate against parasites because they're so much more complicated genetically than most bacteria and viruses. However, it's not true that there are no vaccines against them. Malaria vaccines are being tested now; they are not spectacularly effective, but they do seem to work. What's more, there are actually highly effective malaria vaccines that have been known for decades, but that are impossible to produce in large scale; effective, but impractical.
There are Giardia vaccines in dogs (Giardia vaccination), experimental hookworm vaccines (The Human Hookworm Vaccine) -- though I don't think they're very effective yet -- and a tapeworm vaccine in pigs (Vaccine against tapeworm - First field study is positive). There are even vaccines against external parasites, such as one that protects cattle against ticks: Vaccines to protect Hereford cattle against the cattle tick, Boophilus micro plus)
So it's not an absolute truth, even though it's in general much harder to develop anti-parasite vaccines.
hello doctor ,see this link
https://www.researchgate.net/post/Its_hard_to_vaccinate_against_parasites/1
Significant effort and progress has occurred over the last several years in the development of vaccines against three main tropical parasitic diseases (malaria, leishmaniases and schistosomiasis). However, an effective vaccine is not yet available. The difficulties in developing a vaccine against parasitic disease are complicated not only by the necessity to identify (and produce) appropriate, protective antigens but also a lack of complete understanding of the types of immune responses needed for protection. Despite these hurdles, several candidate vaccines are under development for each disease; at least one promising vaccine candidate exists that is in late stage clinical testing.
There are several reasons why vaccines against these pathogens have not been developed. Viruses and bacteria have many antigens that we do not have and therefore we can use them as vaccines without triggering an attack on our body. But protozoa and helminths are eukaryotic organisms like us, so it is more complicated to select a antigen that is different from the ones we already have.
Developing vaccines against parasites is undoubtedly a great challenge. Strategies are now being considered to find new adjuvants that favor the appropriate targeting of the immune response and to select more effective antigens. Recent advances in the knowledge of the human genome and parasites allow accurate predictions of the immunogenicity of antigens to be carried out using bioinformatic analysis, which is expected to reduce the times and experiments required to select the best antigens for the development of vaccines.
It's hard to vaccinate against parasites because they're so much more complicated genetically than most bacteria and viruses. However, it's not true that there are no vaccines against them. Malaria vaccines are being tested now; they are not spectacularly effective, but they do seem to work. What's more, there are actually highly effective malaria vaccines that have been known for decades, but that are impossible to produce in large scale; effective, but impractical.
There are Giardia vaccines in dogs (Giardia vaccination), experimental hookworm vaccines (The Human Hookworm Vaccine) -- though I don't think they're very effective yet -- and a tapeworm vaccine in pigs (Vaccine against tapeworm - First field study is positive). There are even vaccines against external parasites, such as one that protects cattle against ticks: Vaccines to protect Hereford cattle against the cattle tick, Boophilus micro plus)
Thanks for raising an important issue which is the concern of many researchers these days. In addition to the genetic supercomplexity, parasites are the most manipulative and talented organisms ever in a sense that they develop unique code and strategy to modulate the the host immune response for the their own advantage.Such tactic is still elusive. As a result, despite the dramatic progress in developing trials against some important tropical parasitic diseases, no effective vaccine is not yet in the market for such important parasites. The involvement of multiple hosts to complete the life cycle also makes it hard to target and design a magic bullet. However, Thanks to the hard work of world class scientists, there is hope that a ground breaking finding will come soon. :)
hi
Since the advent of techniques for the expression of recombinant peptide antigens, the availability of human vaccines for parasitic diseases has been ‘imminent’. Yet vaccines based on recombinant proteins are still largely aspirations, not realities. It is now apparent that vaccine development needs additional knowledge about host protective immune response(s), antigen characteristics, and the delivery required to induce those responses. The most successful immune protection against parasites has been generated by infection and treatment, the induction of protective immunity by truncating the course of an infection with drug treatment. Here, we consider the characteristics of an effective, protective anti-parasite vaccine and propose a conceptual framework to aid parasite vaccine development using malaria and schistosomiasis as examples.
Hi
The successful immune protection against parasites may be generated by infection and treatment, the result will protective immunity by truncating the course of an infection with drug treatment.
This link may help you
Article DNA Vaccines against Protozoan Parasites: Advances and Challenges
regards
Developing vaccines against parasites is undoubtedly a great challenge. Strategies are now being considered to find new adjuvants that favor the appropriate targeting of the immune response and to select more effective antigens. Recent advances in the knowledge of the human genome and parasites allow accurate predictions of the immunogenicity of antigens to be carried out using bioinformatic analysis, which is expected to reduce the times and experiments required to select the best antigens for the development of vaccines.
May be due to:
Complexity of the life cycle of the parasite
Difficulty of identification and isolation of an effective antigen to be used as vaccine.
Immune-pathological lesions may be developed in response to the vaccine.
Possibilities of parasitic evasion to the immunity produced by the vaccine.
Vaccine preparation may not be equally effective.
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The difficulties in developing a vaccine against parasitic disease are complicated not only by the necessity to identify (and produce) appropriate, protective antigens but also a lack of complete understanding of the types of immune responses needed for protection. Despite these hurdles, several candidate vaccines are under development for each disease; at least one promising vaccine candidate exists that is in late stage clinical testing.
Because most parasities have immunoelucidation, some of them have the phenomenon of antigenic variations and antigenic shedding
May 1
Because most parasities have immunoelucidation, some of them have the phenomenon of antigenic variations and antigenic shedding
Dear Dr. Alkhaled M. J.A
Parasites go through a series of life stages and occupy several different niches in the body. They’ve also developed clever mechanisms to evade the immune system. So parasitic infections are the ultimate challenge.
best regards
Parasites have complex life cycle. Like larva, pupae, adult etc at all stages they change surface proteins. Having complex life cycle p parasites have complex protective mechanism to evade host immune system.
However, an effective vaccine is not yet available. The difficulties in developing a vaccine against parasitic disease are complicated not only by the necessity to identify (and produce) appropriate, protective antigens but also a lack of complete understanding of the types of immune responses needed for protection.
Article Vaccines for Parasitic Diseases
Only vaccines can eradicate parasitic worms
https://www.nature.com/articles/d41586-019-03643-9
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