U.S. researchers have developed a prototype vaccine that protects monkeys and mice against the emerging chikungunya virus, a major step toward the production of a vaccine for humans. Human trials could begin later this year.
Chikungunya is a mosquito-borne virus whose newest strain first appeared on Reunion Island off eastern Africa in 2005 and has since spread to more than 18 countries, infecting millions. It is characterized by rash, a high fever and its most distinctive trait, a severe arthritis that can persist for years. There are currently no effective treatments and no preventive measures for the virus.
Public health authorities fear that the virus could cause a pandemic because it has adapted to the Asian tiger mosquito, which survives in temperate climates and is widespread.
Increases in global travel and climate change may also encourage its spread, said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases.
To attack the problem, virologist Gary J. Nabel of NIAID and his colleagues adapted technology that is used in vaccines against hepatitis B and human papillomavirus.
They produced a virus-like particle that contains the outer protein shell of the virus -- which allows it to be recognized by the immune system -- but not the viral genetic information, preventing it from replicating.
The team reported Thursday in the online version of the journal Nature Medicine that immunization of rhesus macaque monkeys with the particles provided full immunity when the animals were subsequently exposed to the live virus.
Antibodies against the virus were then isolated from the monkeys and injected into immunodeficient mice. The antibodies protected the mice from a subsequent exposure to a normally lethal dose of the virus.
In addition to human trials of the new vaccine, Nabel and his team plan to study whether a similar approach could be used to protect against the related Western and Eastern equine encephalitis viruses found in the United States and the o'nyong-nyong virus found in Africa.