HIV And SARS reveal their secrets to drug researchers
SARS virus operates, which if exploited could be the starting point
for a host of effective antiviral drugs that combat the virus'
mechanism of action.
"The images we obtained give us an insight into how a virus-encoded RNA pseudoknot can induce frameshifting and may be useful in designing new ways to combat virus pathogens that use this process," said Ian Brierley, the project leader at the University of Cambridge.
The scientists have revealed that a process known as 'ribosomal frameshifting' plays a core part in the process, forcing a mis-reading of the genetic code during protein synthesis.
The correct expression of most genes depends upon accurate translation of the 'frame' of the genetic code, which has a three nucleotide periodicity.
Viruses such as HIV and SARS bring into the cell a special signal that forces the ribosome to back up by one nucleotide, pushing it into another 'frame' and allowing synthesis of different viral proteins. These are exploited by viruses and help them to survive and multiply.
The British researchers successfully imaged frameshifting in action and for the first time observed how a virus encoded element called an RNA pseudoknot interferes with the translation of the genetic code to allow viruses like HIV and SARS to express their own enzymes of replication.
"This is valuable research and demonstrates clearly why investment in fundamental science is so important. The treatments and therapies that we now take for granted are based on decades of work by scientists furthering our understanding of natural processes," said Professor Julia Goodfellow, Chief Executive of the Biotechnology and Biological Sciences Research Council.
"The work to explore fundamental biology today is laying the foundation for potential medical applications over the next twenty years."
A ring-shaped virus, known as a coronavirus, causes SARS. The SARS coronavirus is suspected of originating in animal populations before migrating to humans.
Hardest-hit were six Asian nations. By the time the epidemic had been controlled in 2003, the disease infected more than 8,000 people, causing 800 deaths. There is no current effective treatment or vaccine.
Like most viruses, HIV is not a cell but rather strands of genetic material encased in protein. The virus invades a cell and dominates it by swamping the cell's genetic code with its own.
However, most existing HIV drugs working inside the body's immune cells, after the virus has infected. This discovery is therefore sure to provide some much needed insight as to how primary infection can be halted.
Existing HIV drugs' mechanism of action also causes terrible side effects including anaemia, nerve pain, diarrhoea, fat wasting and organ damage - leading researchers to study other approaches.
The study appears in the May 11 edition of the journal >Nature tomorrow.
