Malaria is a parasite-induced disease that is a significant medical and economical burden due to the fact that it causes both distress and death (Springer-Verlag Heidelberg, 2010). Roughly forty percent of world population, or three hundred million people, are affected by malaria, and over two million people die from it every year. (MicrobiologyBytes, 2009). Every day, there are approximately six thousand deaths that occur due to the protozoans within the genus Plasmodium (Amexo, Barnish, Bates, & Tolhurst, 2004). Unfortunately, 90 percent of the casualties due to parasite Plasmodium falciparum are children, making it the number one killer of children in the world (Amexo, Barnish, Bates, & Tolhurst, 2004). It is apparent that an affordable and easily transported vaccination for the disease is in dire need.

The focus of this research is to create a vaccine for malaria utilizing a three-pronged protein approach. Malaria is caused by four species of the genus Plasmodium: Plasmodium (P.) falciparum, P. vivax, P. ovale, or P. malaria. Due to the fact P. falciparum causes most malaria deaths, this is the parasite that research is focusing on specifically. This protozoan has a very complicated three-stage lifecycle. Therefore, the method for creating a vaccine involves isolating genes from every stage of the protozoan’s lifecycle. The three stages of P. falciparum, all of which have to be targeted, are: the liver stage (also known as the pre-erythrocyte stage), the blood stage (also known as the erythrocyte stage), and the sexual stage (also known as the transmission stage) (Figure 2). An infected female anopheles mosquito spreads P. falciparum by injecting sporozoites into a host (Webster & Hill, 2003). Within just an hour, the sporozoites infect the hepatocytes in the liver, which starts the liver stage. After a period of seven to ten days, an estimated 20,000-40,000 merozoites start to circulate throughout the circulatory system within the body (Webster & Hill, 2003). Once the merozoites leave the pre-erythrocyte stage and enter the blood stage, they are in systemic circulation and travel throughout the host (Webster & Hill, 2003). During the blood stage, the merozoites have a cyclic pattern of invading the erythrocytes and reproducing (Webster & Hill, 2003). It is within the blood stage where the first and only symptoms appear. Common symptons include: fever, chills, headache, sweats, fatigue, nausea and vomiting (WebMD, 2010). After the blood stage is the sexual stage, in which some merozoites differentiate into gametocytes (Webster & Hill, 2003). These gametocytes are taken up by a feeding mosquito (Webster & Hill, 2003). The male gametocytes experience exflagellation, which is the development of flagellum for navigation, and mature into ookinetes (Webster & Hill, 2003). The ookinete then migrates into the mosquito midgut where differentiation into an oocyst occurs (Webster & Hill, 2003). The oocyst lyses and releases sporozoites (Webster & Hill, 2003). The cycles then begins again from the liver stage after another host is infected (Webster & Hill, 2003). The three-stage cycle continues to repeat until the infection is under control or death of the host occurs.

As you can concur, in each stage of P. falciparum’s life cycle, different proteins and antigens are expressed. This means that a vaccine that works in only one stage of the life cycle will probably only confer immunity to that one stage, not all three. Thus, the parasite can overcome the stage, making this type of vaccine ineffective (Webster & Hill, 2003). Therefore, a subunit protein vaccine has the biggest probability of being effective—thus the reasoning for a three-pronged approach. For this three-pronged approach to be successful, proteins that play a significant role in each stage must be isolated. Proteins of particular lifecycle stages that the team is currently targeting include MSP1_19 (Merozoite surface protein 1_19), AMA1 (Apical membrane antigen 1), and MSP2 (Merozoite surface protein 2) all from the blood stage, Pfs48_45 (Plasmodium falciparum surface protein 48_45) from the sexual stage, and SSP2 (Sporozoite surface protein 2) from the liver stage. All of the proteins mentioned above are surface proteins which is important for the success of the vaccine. Without surface proteins, the body would not be able to identify foreign proteins when a parasite enters the body. Surface proteins have been extremely useful in the research of malaria.

Once all proteins have been isolated, a protein from each stage will be chosen to genetically engineer carrots thus creating transgenic carrots. These transgenic carrots will produce antigens of all three target genes, which will then create antibodies when ingested. This edible vaccine will be inexpensive and easily transported, making traditional vaccines a thing of the past. Eating three to four servings of these carrots will be the equivalent to being vaccinated by a shot or the like.

There are several reasons for integrating the vaccine into the carrot. First of all, making the vaccine edible you can avoid the costs of mass production that would be required for a traditional vaccine. It would be a far less hassle to grow up several thousands of acres of these transgenic carrots than it would to mass produce all the needed parts, such as the plastics, glass, and vaccination itself. Second, carrots can easily be eaten raw. Cooking the carrot in any way could pose a threat to ultimately de-naturing the proteins within the carrot, which would make the vaccine ineffective. Third, it is easier to ship and transport carrots than it is to ship and transport the utensils needed for a traditional vaccine due to the sheer magnitude reduction of materials needed. In addition carrots do not have to be kept cool like a traditional vaccine does. Obviously integrating the vaccine into a carrot is a win-win situation—traditional vaccines and the products used to distribute them will become a thing of the past.