By Feng Zengkun, The Straits Times

Researchers in Singapore have identified a super-potent antibody that they say can kill one of the four dengue virus serotypes.

Just a very small amount - 0.000000005g of the antibody, called 5J7 - is needed to kill the serotype 3 virus. That means its use in drugs is likely to be cheaper.

Although serotypes 1 and 2 are more common in Singapore, the discovery brings the scientists one step closer to developing a cocktail drug that could be effective against all four serotypes.

The 5J7 antibody binds to and is effective only against serotype 3, but according to Associate Professor Lok Shee Mei from the Duke-NUS Graduate Medical School, this is ideal.

She said the cocktail drug should consist of four antibodies that are each effective against only one serotype.

When a person is infected with one serotype, his body can generate protection against that serotype, but not the others.

If he is later infected with a different serotype, he has a higher chance of developing more severe and potentially fatal symptoms such as dengue hemorrhagic fever.

Prof Lok said: "Some antibodies can bind to multiple serotypes, but they may be able to kill one serotype and only slightly weaken the others.

"Such antibodies are not suitable to be used as drugs as there is a chance they may enhance the infection of the slightly weakened serotypes."

The researchers identified the 5J7 antibody by examining blood samples from a patient who had recovered from dengue.

They found more than 200 antibodies, and tested their effectiveness against all four dengue serotypes, a process that took about two years.

Prof Lok, from Duke-NUS' Emerging Infectious Diseases Programme, said the school had already found an antibody against serotype 1. It is working on antibodies for serotypes 2 and 4.

"We are optimistic that we will make a treatment breakthrough within these few years, but antibodies against all the other serotypes have to be identified first," she added.

The researchers in the study were from Duke-NUS, the University of North Carolina and Vanderbilt University in the United States. Their work was supported by the National Research Foundation, and the Ministry of Education's Academic Research Fund.

The research was published in the scientific journal Nature Communications yesterday.

Source: The Straits Times, Singapore Press Holdings Limited. Reproduced with permission.