Why should the virus responsible for swine flu bother us so much? Why can’t we have a vaccine for flu like vaccines for measles and polio? We don't change the measles-mumps-rubella vaccine every year, then why do we change flu vaccine every year?

It is because the influenza virus is ‘smarter than death’. It continuously changes the appearance of its chess pawns—the proteins on its coat—so that immune systems do not recognise the new disguise.

This change in the virus coat is quite bothersome. According to one estimate, seasonal flu contributes to an average of 500,000 deaths worldwide each year.

The problem is that due to rapid mutation of the influenza virus, a person immune to one strain is not protected from another strain. We thus depend upon ‘seasonal vaccines’ for our protection. One major goal of researchers is to shorten the time of identification of target flu strains. Developing seasonal vaccines has obvious disadvantages. What we want is universal vaccine for life-long immunity. We want that the universal vaccine should work against all types of flu viruses, thereby sparing us from the worries of the next epidemic.

Ideally, a universal vaccine should work as effectively against all kinds of flu viral strains as the strain-specific vaccines are effective against specific strains. So far we have not developed an ‘ideal’ flu vaccine. The flu vaccines which are at various developmental stages, however, have shown promise to limit the severity and spread of the disease.

The proteins on its coat, hemagglutinin (which allows the virus to attach and enter a cell) and neuraminidase (which boosts the virus’s ability to pass to other cells), are the fastest changing parts of the virus. When someone gets infected by the virus, the immune system recognises these proteins and makes antibodies to destroy these proteins.

The antibodies to one strain might not recognise another. A universal vaccine is expected to attack all influenza viruses, that is, while attacking it should not make a distinction between various strains.

The difficulty is that most non-varying viral proteins reside inside the virus where the accessibility of the antibodies is limited. The good news is that researchers have identified one internal protein (M2) that protrudes a bit from the virus.

The aim of the researchers thus is to have a system that will raise a robust immune response against this puny little protein that’s not present in any abundance.

Since M2 protein in animal influenza virus can be different from that in human viruses, the important question for the researchers to resolve is: How well an M2 vaccine might work, say, against the new swine flu?

Researchers have indicated the possibility of another non-varying region on the outside of the virus. But experts say it will be very difficult to isolate this part of the protein from the virus to use in a vaccine, or to manufacture it using genetic engineering.

The work on the development of DNA-based universal flu vaccine is also progressing.

This approach asks the cells to produce antibodies against different strains of viral invaders in order to marshal the appropriate immune response. The outcome of research on the development of universal flu vaccine is satisfying. The realistic expectation is not intended to totally block infection, but it can greatly reduce disease and spread, and the symptoms.

The writer is a biotechnologist and ED, Birla Institute of Scientific Research, Jaipur