Experimental vaccine works against Chikungunya

An experimental vaccine works against the newly spreading Chikungunya virus, at least in monkeys, and the approach may also work against other exotic viruses, US government researchers reported on Thursday.

They used virus-like particles, which are mock versions of the virus that resemble an empty shell, to vaccinate monkeys against the rarely fatal but painful mosquito-borne infection.

"At a time when there are no commercially available vaccines ... a virus-like particle vaccine has the potential to have a considerable impact on the spread of this disease," Dr Gary Nabel of the National Institute of Allergy and Infectious Diseases and colleagues wrote in the journal Nature Medicine.

They said the same approach may be useful similar mosquito-borne viruses, known as alphaviruses.

Chikungunya, first seen in the 1950s, came back in 2004 and 2005 and has since spread to nearly 20 countries to infect millions.

It is rarely fatal but it causes debilitating pain and exhaustion and can have long-term or even permanent effects.

"Changes in trade, travel and global climate have aided the spread of mosquito species worldwide, which may potentially cause other alphavirus outbreaks," they wrote.

"Our approach may prove useful for vaccine development against other pathogenic alphaviruses, including Western, Eastern and Venezuelan equine encephalitis viruses, O'nyong-nyong virus and Ross River virus."

O'nyong-nyong virus is similar to Chikungunya and is found in Uganda, while Ross River virus affects Australia, Papua New Guinea and other Pacific islands.

People have tried to make a Chikungunya vaccine but one attempt caused similar symptoms to infection and others did not do well in testing.

Nabel's team tried making virus-like particles, an approach that Merck and Co uses in a vaccine against the human papillomavirus that causes cervical cancer.

These particles resemble hollowed-out viruses, which the body can recognize and attack. They cannot cause infection on their own.

Vaccinated monkeys fought off infection and the antibodies their bodies made against Chikungunya also protected mice, Nabel's team reported.

"Because virus-like-protein-based vaccines are currently safely used in people for protection against hepatitis B and human papillomavirus infections, they may prove to be a practical candidate for Chikungunya vaccine efforts," the researchers wrote.

Nabel said the next step is human testing.

Maryland-based vaccine maker Novavax has been using virus-like particles to make vaccines against influenza and has teamed up with Cadila Pharmaceuticals in India to make vaccines they hope will work against influenza and perhaps dengue fever and Chikungunya.