Dengue vaccine

At a local hospital in the Indian capital, Hiralal Pandey, a daily wage laborer, is being treated for dengue. Aside from the muscle aches, pains and fever, Pandey has gone through a phase of blood transfusions to kick up his dipping platelet count because of the crippling fever.

"I was having high fever and my health was deteriorating as well as my blood count," says Pandey. "I was helpless and brought to the hospital. I hope the doctors help me. I understand this fever is because of mosquitoes."

Like Pandey, millions are infected annually with dengue across the globe.

In India, over a million people are hit annually by the disease, which is considered a major factor in infant mortality.

Already this year, thousands have been admitted to hospital across Asia.

This rapid transmission of the virus has led experts to believe that there is a new carrier on the loose.

And so far there is no licensed vaccine to protect against dengue.

Early progress

Efforts to develop a dengue vaccine have been complicated by the fact that there are four different strains of the virus - all of which circulate in an outbreak zone.

But there could be hope as the International Centre for Genetic Engineering and Biotechnology (ICGEB) is currently developing a non-infectious dengue vaccine based on Hepatitis B vaccine technology.

Professor V. S. Chauhan is the director of the institute's New Delhi chapter.

"We looked at the structure of the virus and from that structural information we were able to remove what we call 'the business end' of the virus for immune protection. So we pulled out these small stretches from the outside structure of the virus - the business end - and stitched them together. So, when we stitched them together and put them in animals to look at the immune responses, and we were happy to see that we got a good response to all the four viruses and none of them was depressed. But you'll appreciate that working in animals is one thing, and working in humans is totally different," says Chauhan.

Vaccine development is a laborious and lengthy process.

But speedy development has been a characteristic of the new vaccine industry in India.

It has had recent successes in response to the Japanese Encephalitis virus and to the H1N1 flu virus. The H1N1 flu vaccine took just a few years to develop.

Dr S. Swaminathan, a key member working on the dengue vaccine says the clinical trials will be the true test.

"Giving protection to all four [strains] has been an elusive goal and it is being going on for 50 to 60 years," says Swaminathan. "And the challenge is all that more complex as we don't have a good animal model of dengue, where you are able to assess and predict the efficacy of a vaccine. You are essentially working on a blind environment and the ultimate test for a vaccine is going to be a human. So the clinical trials is going to tell you whether [the vaccine] is going to work or not."

Worldwide spread

The World Health Organization estimates that between 50 and 100 million dengue infections occur each year in more than 100 countries.

After malaria, dengue fever is the second most widespread mosquito-borne disease in the world.

Professor Chauhan admits the burden of dengue is enormous, but he remains optimistic.

"Making a vaccine against this kind of virus should not be difficult," says Chauhan. "But it becomes difficult because there are four strains and they each have to be addressed. With the approach we have taken, I think we are only one of two, or the only ones to have taken this approach."

The prevalent dengue scenario is so adverse that several big organizations such as Sanofi Pasteur, Pediatric Dengue Vaccine Initiative, and the Rockefeller Foundation have come together to find a cure for the disease.

"The sub-unit vaccine that we are trialing, we are still in a pre-clinical stage, so we are looking at something like 5 years and more before we have a lead candidate and proceed to a clinical trial. We actually have all the four serotypes of dengue viruses circulating in many parts of the world. So it is a global problem and there are no differences in terms of the disease from one part of the world to the other," Swaminathan says.

Scientists believe that the estimated total economic burden of dengue on the world is $587 million annually - and rising.

But the big question is whether a vaccine will be launched soon enough to stop dengue taking an even bigger toll on life.