Critically weakened

What happens when a vampire does not feed on human blood?

If you believe the tales spun in Vampire Diaries, then the once-deadly creature becomes significantly weakened, looses the ability to affect the human brain, and is generally much less threatening than his human blood consuming counterpart. The same is true for the variety of parasite that Dr Andrea Crisanti is studying in an attempt to find a malaria vaccine.

Malaria, a mosquito-borne disease that affects 300-500 million people each year, is caused by infection with Plasmodium parasites. The deadly disease kills approximately one million people every year, most of whom are children and pregnant women, is treatable and preventable. The search for a malaria vaccine is well under way, but the "number of life cycle changes" that the parasites undergo increase "the challenges of malarial vaccine development." In other words, because the malaria parasites change and adapt rapidly, a workable vaccine is difficult to develop.

However, recent research by Crisanti and her colleagues "have found that weakened Plasmodium elicits a protective immune response." This means that clinically and genetically weakened parasites may be used for vaccine development. Crisanti's team targeted Plasmepsin 4, "a digestive enzyme that is critical for Plasmodium growth and survival within the host red blood cells." Research showed that parasites without the critical digestive enzyme "were significantly less virulent than their wild-type [define: normal] counterparts."

Furthermore, "infection with plasmepsin 4-deficient parasites, in contrast to infection with wild-type Plasmodium, did not induce cerebral complications", which means that infection with the weaker parasite produces a less severe illness than an ordinary malaria infection. Also, parasites without the digestive enzyme "induced strong protective immune responses against secondary immunization with wild-type Plasmodium." This weakened parasite may provide a model for comparing genetically-weakened malarial vaccines.

Dr. Crisanti and colleagues conclude that "it is possible, by engineered inactivation of parasite proteins, to generate attenuated blood stage parasites that are capable of inducing protective immunity against blood-stage infection. Such parasites should be powerful tools in elucidating parasite-derived factors that cause severe disease and should provide additional insight into factors that are required to induce protective immunity."

Source:
American Journal of Pathology (2009, December 31). Weakened Plasmodium generates protective immunity. ScienceDaily. Retrieved January 3, 2010, from http://www.sciencedaily.com¬ /releases/2009/12/091230193211.htm