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Wednesday, 18 December 2002, 19.00 hours

Leap forward in war on infectious disease

The post-genomic era has delivered its first major breakthrough in the war against infectious disease.

Just a year after the publication of the complete genome sequence of Salmonella, a group of scientists led by Dr Jay Hinton at the Institute of Food Research (IFR) in Norwich has unlocked the secrets of this bacteria's power to cause disease.

Salmonella typhimurium

In a collaboration between the IFR and the Karolinska Institute in Sweden, the scientists have identified all the genes activated during Salmonella infection - a major breakthrough in understanding how it makes people ill. The bacteria's resistance to antibiotics has increased at an alarming pace and Salmonella now kills more people in the west than any other foodborne pathogen. It costs the British economy about £1 billion a year and the US economy almost £4 billion.

The work is published in the Molecular Microbiology Journal this month. It provides a new resource for the Salmonella research community worldwide, and leads the way for scientists working on other infectious diseases, such as malaria, HIV and tuberculosis. Disease-causing genes can now be targeted in the development of new vaccines and antibiotics.

"The sequencing of Salmonella last year was humbling. It made us realise how little we knew after a century of worldwide research. Until then, our understanding of infectious disease was based on the analysis of less than 100 Salmonella genes. With the sequencing of the entire genome, we suddenly had all 4,644 genes to study, but realised we didn't understand the function of a third of them", said Dr Hinton. "This is the first time anyone has created a complete picture of gene expression for any organism during infection. It exposes which genes are the real killers. This new technique can be applied to any infectious disease", he said.

"Genome-based microbiology will provide a new age in understanding the problems of infectious diseases equally as important as those initial studies of Edward Jenner, Louis Pasteur and Robert Koch of the 18th and 19th centuries", said Professor Phil Butcher, international tuberculosis expert at St George's Hospital Medical School, London.

Professor Gordon Dougan, specialist in bacterial pathogens at Imperial College London, said, "this research allows us to generate a detailed snapshot of what the bacteria is actually doing during infection rather than in the laboratory, opening up new routes to exciting therapies".

Salmonella is one of the few bacteria able to grow in human cells. "The immune system tries to stop this happening", said Dr Hinton. "But the salmonella bacterium waits until it reaches the inside of the animal cell to unleash its weapons. Now that we have identified those weapons we can begin to disarm it. It is particularly important that we regain control of this disease as many antibiotics are no longer able to defeat it ", said Dr Hinton.

Dr Jay Hinton will launch the findings at the Science Museum on Friday 20 December, where he will be available to answer questions from the public.

Salmonella facts

• Since 1885, a total of 2213 strains of salmonella have been identified. They vary in the severity of illness they cause. The new technique developed by Dr Hinton can be used to understand all of them, as well as other disease-causing bacteria.
• Salmonella typhimurium can be found in a broad range of animals, birds and reptiles as well as the environment. It causes food poisoning in humans mainly through the consumption of raw or undercooked contaminated food of animal origin - especially meat, poultry, eggs and milk.
• Salmonella typhimurium and Salmonella enteriditis cause the overwhelming majority of cases of foodborne illness in many countries worldwide. In 2000, 2.1 million people died from foodborne illnesses.
• An estimated 1.4 million cases occur annually in the United States; of these, approximately 40,000 are culture-confirmed cases reported to the Centre for Disease Control: http://www.cdc.gov/ncidod/dbmd/diseaseinfo/salmonellosis_t.htm
• Symptoms of salmonellosis (food poisoning caused by Salmonella) are fever, headache, abdominal pain, diarrhoea, nausea and vomiting. In some cases, particularly in the young and very elderly, dehydration can become severe and life threatening.
• The annual cost of salmonellosis in the US is estimated to total almost US$ 4,000 million.
• The UK Food and Drink Federation calculated in its 1994 report that foodborne illness, principally salmonellosis, costs the British economy about £ 1,000 million a year.
• Since the beginning of the 1990s, strains of S. typhimurium resistant to a range of antibiotics have emerged and are threatening to become a serious public health problem.
• To keep turkey salmonella-free this Christmas, make sure that the centre of the turkey has been cooked at 65°C or above for at least 10 minutes. This will also kill other bacteria that may be lurking, such as Campylobacter and E Coli. Ideally use a plastic surface rather than wood while preparing the turkey.

For further information contact:

Jo Belsten Communications Institute of Food Research Norwich Research Park Colney Norwich NR4 7UA

Tel: +44 (0) 1603 255 218 Fax: +44 (0)1603 255 168 Out-of-hours Tel/Fax: +44 (0)1692 583 024 e-mail jo.belsten@ifr.ac.uk www.ifr.ac.uk

Notes for editors:

• Please contact Jo Belsten, IFR Communications, for further details, images and to arrange an interview with Dr Jay Hinton: 01603 255111 / jo.belsten@ifr.ac.uk
• The paper is published in Molecular Microbiology (2003) 47(1), 103-118. The authors are Jay Hinton, Sacha Lucchini and Arthur Thompson from the Institute of Food Research, Norwich, England and Sofia Eriksson and Mikael Rhen from the Karolinska Institute, Stockholm, Sweden.
• The research was funded by the Biotechnology and Biological Sciences Research Council and the EU.
• Prof Gordon Dougan is Director of the Centre for Molecular Microbiology and Infection at Imperial College London.
• Dr Phil Butcher is Professor of Molecular Medical Microbiology at St George's Hospital Medical School, London.
• Background information on salmonella and its impact was taken from the World Health Organisation (WHO) website: http://www.who.int/inf-fs/en/fact139.html

 

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