Magazine article Science News

Recombinant Vaccine Shows Promise against Dengue Fever

Magazine article Science News

Recombinant Vaccine Shows Promise against Dengue Fever

Article excerpt

Recombinant vaccine shows promise against dengue fever

Scientists this week reported progress in genetically engineering a 'vaccine for dengue fever, a severe viral disease of global significance that is beginning to spread to North America. Public health officials in the United States and abroad have expressed increasing concern about the mosquito-borne disease, which is endemic to much of Asia, Africa and South and Central America. Development of a vaccine has been hampered, however, by a peculiar characteristic of the dengue virus: Antibodies against dengue tend to promote rather then prevent reinfection with closely related strains of the dengue virus.

Ching-Juh Lai, a researcher with the National Institute of Allergy and Infectious Diseases in Bethesda, Md., reported at a National Institutes of Health seminar that a novel approach to vaccine development has so far conferred complete protection against dengue in mice. The vaccine is now being tested on rhesus monkeys.

Most viral antibodies -- whether naturally occurring or vaccine induced recognize and bind to the outer envelope of a target virus. But strains of the dengue virus can bind to such antibodies and subvert them to enhance the virus's ability to infect human monocytes, a kind of white blood cell. Moreover, such antibody-enhanced infections tend to be much more severe than the original infection, which is characterized by fever, headache and joint pain. Antibody-enhanced infection can lead to a potentially fatal syndrome involving internal bleeding, severe dehydration and shock.

Lai's approach is based on work by scientists at the University of Rochester (N.Y.), who found that antibodies against a so-called nonstructural protein, produced inside the monocytes to help assemble new viruses, can protect against dengue without enhancing re-infection later. The nonstructural protein, dubbed NS-1, is produced in monocytes after a dengue virus "hijacks" the cells' genetic machinery. …

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