Chikungunya vaccine on the anvil

Chikungunya MosquitoWashington (ISJ) - US scientists have developed an experimental vaccine to prevent the mosquito-borne viral illness Chikungunya. Researchers at the National Institute of Allergy and Infectious Diseases (NIAID), Maryland have successfully developed neutralising antibodies in a recent early-stage clinical trial. The results are reported in the current issue of The Lancet.

During the trial, 23 healthy volunteers received three injections, while two others received two injections of vaccine at one of three different dosages (10, 20 or 40 micrograms) over a 20-week span. Investigators detected chikungunya neutralizing antibodies in all volunteers following the second injection, with a significant boost of neutralizing antibodies seen following the third injection. Vaccine-induced antibodies persisted in all volunteers, even those who received the lowest dosage, for at least 11 months after the final vaccination, suggesting that the vaccine could provide durable protection against disease.

"The candidate vaccine prompted a robust immunological response in recipients and was very well tolerated," noted Julie E. Ledgerwood, principal investigator of the trial. "Notably, the levels of neutralizing antibody produced in response to the experimental vaccine were comparable to those seen in two patients who had recovered from a chikungunya virus infection acquired elsewhere."

Traditional vaccines are typically made from either killed viruses or from weakened live viruses, whereas the experimental vaccine used in the trial is a different type - a virus-like particle (VLP) vaccine. VLP vaccines contain the outer shell proteins of a virus without any of the material the virus needs to replicate inside cells. VLP vaccines often prompt an immune reaction similar to that of natural, whole virus and have a number of potential advantages over traditional vaccines, said Dr. Ledgerwood. Notably, because no live viruses are used in their manufacture, VLP vaccines do not need to be produced under high-level biocontainment conditions.

The most distinctive symptom of chikungunya infection is severe joint pain accompanied by headache and fever. There are currently no vaccines or specific drug treatments for chikungunya. Chikungunya was first identified in Tanzania in the early 1952 and has caused periodic outbreaks in Asia and Africa since the 1960s. Outbreaks are often separated by periods of more than 10 years. Between 2001 and 2011, a number of countries reported on chikungunya outbreaks.

In 2006, more than 1,500,000 cases of Chikungunya were reported in India, with no attributable deaths.

Source: US National Institute of Health/WHO

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