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  • Sequencing opens door for bacterial disease vaccine


[RIO DE JANEIRO] Brazilian researchers have sequenced the genome of a type of bacteria that causes leptospirosis — a disease that affects humans and animals. They say that their work is an important first step towards creating a vaccine against the disease, which can lead to kidney damage, liver failure and meningitis.

The team, which also included scientists from the Netherlands and the United States, analysed the 4.6-million-base-pair genome of the strain of bacteria mainly responsible for the disease in Brazil, known as Leptospira interrogans serovar Copenhageni.

"This research is directed towards the production of vaccines," says one of the researchers, Ana Lúcia Tabet Oller do Nascimento of the Instituto Butantan in Sao Paulo. "The results point to the identification of candidate proteins for this purpose."

The team identified 23 proteins — all of which have already been patented in the United States — that they consider are potentially important for the development of a vaccine against leptospirosis. They are also analysing a further 200 proteins that may have vaccine potential.

At the moment, there is no vaccine against the disease, which can be treated with antibiotics. The most common symptoms of leptospirosis are fever, headache, nausea, and vomiting. In untreated cases, the bacterium can affect the kidneys and the liver and in extreme cases, the disease leads to death. Between 1987 and 2001, more than 46,000 cases were reported in Brazil. Between 6 and 20 per cent of these people were killed by the disease.

The new research, which is part of a US$2.4 million project launched in 2001, is published in the April issue of the Brazilian Journal of Medical and Biological Research.

It is the second time that a variety of Leptospira interrogans has been sequenced. Last year, a team of Chinese scientists published the sequence of Leptospira interrogans serovar Lai, the main cause of the disease in that country.

The disease is spread through contact with floodwater or water contaminated with the urine of infected animals.

Link to research article in the Brazilian Journal of Medical and Biological Research

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