Importance of Malaria Vaccine. Challenges of Malaria Vaccine - Essay Example

Introduction Malaria, is a mosquito-borne, protozoal illness, identified as a parasite disease with the vector been a mosquito in early 19th century. It is infection manifest in human beings as a result of infection by Plasmodium falciparum, Plasmodium ovale, and Plasmodium vivax. In essence, the female anopheles mosquito transmits the plasmodium parasite. According to Coleman and Tsongalis 2009, it leaves the parasite in the human blood in the process of feeding on the blood meal. However, “Anopheles gambiae, Anopheles arabiensis and Anopheles funestus”are the maintransmitters of malaria in human beings. All the malaria manifest through common symptoms like fever, although some patients progress to severe malaria that is often caused by the P. falciparum species. Essentially, it takes one to three days after infection for the infecting parasites to release the infection depending on their species. Additionally, merozoites are released through the lysis of infected erythrocytes with the inclusion of waste substances such as red membrane products, hemozoin pigments and glycosylphosphatidylinositol (GPI). The infectivity of red cells by the parasite of malaria like, P. falciparum brings about progressive together with mechanical alternation of the red cells that can deteriorate over time into the life threatening complications of malaria Although, P.falciparum has devastatingly castigated as the major contribution to severe malaria all over the world. For instance, there have been severe infections and reports of death due to infections of P. vivax and P. knowlesi. Some pathophysilogical features like sponge biomass, reset and confiscation alter formality and restraint of parasitized erythrocyte. Endothelial activation, injury, dysfunction and altered thrombostasis have been found to entail the acquisition of severe malaria. This is common in cases of P. falciparum infection (Choffnes and Relman 2011). However, malaria’s chronicity is rare and if it happens it leads to induction of sterilizing immunity. Individuals who experience repeated exposures may be in dire need of re-exposure of the parasite if cured through drug treatment. Thus, there is a need into curbing the ease into which malaria parasite are capable of invading human hosts while at the same time minimizing the immune response arm (Coleman and Tsongalis 2009). Basically, two models of supporting the protection against the chances of infection of malaria through vaccination exist. The first type of vaccine entails immunization with irradiated sporozoites, which are meant to ensure maximum protection against possibility of malaria infection. The other type of vaccine entails the repeated exposure to malaria that induces immunity malaria infections and effective protection against any clinical manifestation of malaria. Importance of Malaria Vaccine Malaria has been rated among the fastest killer disease all over the world. Hence, much has to be done in order to curb the disease against causing deaths especially in infants, and the old people who have weak defence system toward diseases. In essence, malaria has not been controlled by the widespread deployment of existing control tools in most endemic areas. Moreover, there has been increased concern on the surfacing of insecticides and anti malarial drugs (Palmer and Reeder 2001). Vaccinations are been described as relative tools that are used to deliver and have played major roles toward the elimination of rinderpest, smallpox and other similar diseases. Never the less, the malaria vaccine is expected to provide direct individual protection against malaria infection and it clinical consequences. Additionally,, it is meant to decrease the rate of transmission of malaria infections better known as herd immunity. Immunization using Irradiated Sporozoites The possibility of giving safeguard against experimental sporozoite issues through the immunization by use of radiation attenuated sporozoites is evidenced in rodents, the natural rodents’ host, and the non-human primates. In essence, mosquitoes that are infectious are subjected to 12-15000 cGy of X radiation. Sporozoites enter the vasculature, and then penetrate the liver where they go through half done development. However, due to the radiation exposure, it becomes impossible for them to complete a full development stage inside the liver so as to enter the blood vessels as merozoites (Choffnes and Relman 2011). At this point, the parasite stimulates an immune safeguard that stimulates an excellent protection against challenge in compact sporozoites. CD8+ T cell arbitrate the protection a situation that is recognized as a case of unspecified antigens at play. Though the circumsporozoite protein is responsible for the coating of sporozoite, it is an important target of immunity. Host that are immunized with irradiated sporozoites stay vulnerable to blood level challenges illustrating that protective immunity targets pre-erythrocytic levels (Merson 2005). The presence of persistence of sporozoites in the host will aid the sustainability of immunity. Needless to mention, that continued presence of antigen will stimulate a continued regeneration of effectors memory that is conscripted from a centralized memory. Of importance to note is that, the limitation of human data put emphasis on the immunization that is derived from one strand of P.falciparum which is in a position to offer protection against other types of strains. Hence, this model hold the promise of holding a vaccine form one strain that is capable of giving immunity that is successful towards diverse strains. Nether the less, possibility of having cross –species protection has not yet being confirmed. Naturally Acquired Immunity Malaria immunity can also be open or better known as natural acquired immunity (NAI). Several research have indicated that people living in endemic areas, after several infections with the parasite are in positions to limit the density of parasitaemias and severity of clinical infection even though they stay vulnerable to infections. In essence, the immunoglobulins isolated from the clinically immune African adults are capable of decreasing the density of parasites and ameliorate clinical symptoms when provided to parasitaemic children (Palmer and Reeder 2001). . Although antibody –dependent cellular inhibition and the cell stimulated immunity when there is no presence of any response from antibody, those that are associated with protection against blood stage infections in human beings. Of importance to note about the existence of natural acquired immunity is that there is evidence of the fact that a blood-stage antigens vaccination can put restrictions or arrest the spread of disease, and the causes of death in recipients even if it is does not prevent infections. The presence of both the immunity by use of Irradiated Sporozoites and the natural acquired immunity investigator believe that in case the antigens and immune responses that are assigned to offer protection are automatically identified, then it would be more possible to involve the antigens in the multivalent sub-unit vaccine by way of a vaccine delivery system that is stimulated to act as protective responses to immune, a rationale that is used as cornerstone for the initiation of vaccine (Bloom and Lambert 2003). Subunit malaria vaccine: rational approach The crossing point between parasite and host entail composite molecular interactions that are linked with the identification and attack of the hosting cells, or acquiring nutrients from the cytoplasm or the plasma milieu. According to Merson 2005, numerous of the critical events are intervened by receptor –ligand interactions that entail the attack of hepatocytes by sporozoites or the erythrocytes by merozoites. Having a well clarified, obligatory interaction of the host and the malaria parasite supply good environment for approaching any development of vaccine. In essence, there is identification and selection of parasite antigens that are involved in molecular interfaces as potential candidates for stimulating response that is capable of disrupting receptor –ligand binding (Bloom and Lambert 2003). Preferably, a vaccine could bring together numerous key antigens that are responsible for the interruption of multiple pathways that are essential to the survival of the parasites. For instance, a multiple stage vaccine is capable of bringing together sporozoite/ or liver-stage antigens that are made to stimulate the immune response thus suppressing the multiplication in the blood of parasites, and breaking past the pre-erythrocytic defence. This rational approach is workable since it practically focuses on the antigens with a clear functional role in parasite biology and avoids the unidentified components that could possibly stimulate response that are deleterious. Current vaccines Optimistically, scientists have continued to look for more possible malaria vaccine in their continuous research. Some types of vaccines that are currently used include mosquito – stage malaria vaccine, and erythrocytic stage malaria vaccine. Erythrocytic stage malaria vaccine It entails working by utilizing of alpha –helical coiled coil domains consisting of proteins that are supposed to be present in the parasite during the erythrocytic stage those peptides are supposed to be the same in their structural nature to the native epitopes. Of importance to note is that, a large percentage of chemically synthesized peptides have been clearly identified through the sera of human although in various prevalence (Moxham and Souhami 2002). Every peptide make specific antibody in type reaction when they used as a trial in immunization, with on close reaction of the antibodies for other types of peptides. Thus, using bioinformatics and approach of chemical synthesis could lead to isolation of some molecules that aim at the biological active antibodies that finally formulate a novel vaccine against malaria in the erythrocytic stage. Mosquito – Stage Malaria Vaccine This is another viable vaccine that has been engineered to deal with malaria. It is widely known as the transmission-blocking vaccine. Basically, it is designed to produce an immune response in human hosts, as the growth of the parasite into mosquito vector and the ultimate transmission is bound to be fruitless. Proteins that are present in the surface of the gametes like Pfs48/45 and Pfs230 found in P.falciparum are expressed by parasites while within the vertebrate host and exposed on the free living gamete (Palmer and Reeder 2001). Hence, the mosquito-stage vaccine or transmission- blocking vaccine intends to bar the spread of infection from one person to another through prevention of infection in the mosquito vector. However, with the advancement in biotechnology and bioinformatics, as well as, the acknowledgment of the whole genome sequence of malaria, there are bigger chances of antigens and protein targets being initiated towards the development of a mosquito stage vaccine which would be handy in fighting this deadly disease together wit h the reduction of morbidity and mortality (Russell et al 1996). Challenges of Malaria Vaccine The generation of malaria vaccine has not been an easy task due to the nature of the parasite. In essence, it has a complicated life cycle that has rapid amplification once it has entered the human body posing a great predicament (Moxham and Souhami 2002). The idea of sophisticated protein –based method of vaccine development has not worked because various proteins are emitted by the malaria parasites in various stages. Moreover, the immunogenicity of antigen depends on particular stage in order to work. Never the less, there is sustained hope that continuous research on the DNA vaccinology will be able to overpower this and assist in the formulation of the deadly disease. Conclusion The malaria epidemic has caused about 500 million clinical cases and over 3 million deaths annually. The largest death toll of malaria is experienced in Africa and other parts the world. The continuous resistance of both the parasite and the anti malaria drugs has led to the development of an effective malaria vaccine a global priority. The ideal malaria vaccine is expected to stimulate natural acquired immunity in populations where malaria is endemic. The attempt by researchers to come up with long lasting vaccine has been fruitless making malaria to be one of the fastest killer diseases. Bibliography: Bloom, B. and Lambert, P., 2003. The vaccine book. Amsterdam; Boston: Academic Press. Choffnes, E. R. and Relman, D. A., 2011.The causes and impacts of neglected tropical and zoonotic diseases: opportunities for integrated intervention strategies: workshop summary. Washington, D.C.: National Academies Press. Coleman, W. B. and Tsongalis G.J.,2009. Molecular pathology: the molecular basis of human disease. Burlington, Mass.: Academic Press. Merson, H. M., 2005.International public health: diseases, programs, systems, and policies. Sudbury, Mass. [u.a.]: Jones and Bartlett Publ. Moxham, J. and Souhami, R., L.2002. Textbook of medicine. Edinburgh [u.a.]: Churchill Livingstone. Palmer, E. S. and Reeder, M., 2001. Imaging of tropical diseases: with epidemiological, pathological, and clinical correlation. Heidelberg, Germany; New York: Springer- Verlag. Russell, P et al., 1996.Vaccines against malaria: hope in a gathering storm. Washington, D.C.: National Academy Press. Read More