"Yellow fever research was neglected because the vaccine was so effective," ter Meulen said. "Medical science works in cycles. As soon as the problem is solved, the caravan moves on. Once the disease comes back, people realize they are lacking certain information."
To learn more about the immune response and to identify the necessary components of an improved vaccine, ter Meulen turned to survivors of acute yellow fever in the Republic of Guinea in West Africa. Along the war-torn border with Sierra Leone, disruptions in vaccination and medical services led to a large epidemic in 2000. In collaboration with local health authorities, ter Meulen set up a viral hemorrhagic fever laboratory in Conakry to collect and evaluate blood samples from patients.
In people, the mosquito-borne virus incubates for three to six days. Initial flu-like symptoms are followed by a brief remission of up to a day. Then, about 15 percent of people suffer more dangerous complications--, jaundice, liver, kidney, and heart damage, and bleeding from the mouth, nose, eyes or stomach. At that stage, ter Meulen and colleagues reported last year in the Journal of Infectious Diseases, a person's own immune system, disrupted by its reaction to yellow fever virus infection, may lead to death rather than recovery.
The most recent study was led by Stephane Daffis, a graduate student at Philipps-Universitat in Marburg, Germany. Using blood samples from two yellow fever patients who had recovered, and sophisticated molecular techniques, the researchers generated a library of the millions of specialized antibodies that made up their immune repertoires.
Then they screened the libraries with a vaccine strain of yellow fever. Four of the antibodies neutralized yellow fever. Genetic analysis showed they all homed in on one particular part of the protein coating the virus. The epitope is called E-71, signifying its ad
Source:Howard Hughes Medical Institute