Kim C. Williamson
Ph.D. 1987, Boston University
Physiology and Immunology
Malaria continues to be a critical world health problem resulting in 100-200 million clinical cases a year with over 0.5 million deaths, mainly children under the age of five. In the past decade the introduction of insecticide-treated bed nets and Artemisinin combination therapy have reversed the increase in mortality caused by the spread of chloroquine-resistant parasites and led to renewed hope for malaria eradication. Key to eradication efforts is the development of new strategies to control parasite transmission, which is the focus of Dr. Williamson’s research.
The Plasmodium parasite that causes malaria is transmitted from person to person by a mosquito (Fig. 1). Parasites are introduced into the blood stream by the bite of an infected mosquito and then travel to the liver. After development in liver cells, parasites are re-released to the blood stream where they now invade red blood cells and replicate, producing 16-32 new parasites every two days. Instead of continuing to replicate, some parasites differentiate into either male or female gametocytes. Gametocytes, after being taken up in a blood meal by a mosquito, are stimulated to fertilize and begin a developmental cascade in the mosquito that leads to the production of sporozoites, which are infectious to humans. Sporozoites are stored in the salivary gland of a mosquito until release during another blood meal, initiating a new infection.
The complex life cycle allows the parasite to avoid many standard defenses used by the human immune system, but also provides multiple points for interventions. Ongoing projects in the Williamson lab are directed toward: 1) Identifying new anti-malaria drug and vaccine candidates and defining their mechanisms of action. 2) Determining the factors and molecular mechanisms that contribute to the transition from asexual replication to sexual differentiation in vitro and in vivo.