Brazilian scientists have identified a new strain of the H1N1 virus after examining samples from a patient in Sao Paulo, their institute said Tuesday.
The variant has been called A/Sao Paulo/1454/H1N1 by the Adolfo Lutz Bacteriological Institute, which compared it with samples of the A(H1N1) swine flu from California.

The genetic sequence of the new sub-type of the H1N1 virus was isolated by a virology team lead by one of its researchers, Terezinha Maria de Paiva, the institute said in a statement.

The mutation comprised of alterations in the Hemagglutinin protein which allows the virus to infect new hosts, it said.

It was not yet known whether the new strain was more aggressive than the current A(H1N1) virus which has been declared pandemic by the World Health Organization.

The genetic make-up of the H1N1 virus and its subvariants are important for scientists.

Pharmaceutical companies are working to mass produce a vaccine against the current A(H1N1) flu.

There are fears though that it could mutate into a deadly strain, much in the same way as the 1918 Spanish flu -- also an A(H1N1) virus type -- did when it killed tens of millions around the planet.

According to the WHO, 36,000 people in 76 countries have been infected with the H1N1 virus, causing 163 deaths.