Fourth victim raises fears of SARS return

News of this latest outbreak brings greater urgency to finding effective forms of treatment aimed at halting the virus's progress. The SARS coronavirus swept Asia and other areas of the world in early 2003, with China the country worst affected by the epidemic. Some 5,327 people were infected and 349 deaths were attributed to the virus. In total, 774 people died around the world from the disease.

Now the Chinese authorities have reported a clinically confirmed SARS coronavirus (SARS-CoV) infection in two of people - a 26-year-old female laboratory researcher who had worked at an institute known to engage in SARS research and a 20-year-old nurse who was caring for her while she was being treated.

The dead victim was the mother of the 26-year-old. Her clinical symptoms were compatible with SARS, and health authorities have diagnosed her as a suspected SARS case.

The fourth person is a 31-year-old male laboratory researcher who also worked at the institute. He developed symptoms and was hospitalised in isolation. Health authorities have diagnosed him as a suspected SARS case.

Laboratory testing for SARS-CoV is now available at many Chinese state public health laboratories. Available tests include antibody testing using an enzyme immunoassay (EIA) and reverse transcription polymerase chain reaction (RT-PCR) tests for respiratory, blood, and stool specimens.

Since the 2003 epidemic, researchers around the world have been trying to identify ways to treat the virus, especially as existing drugs used to treat the disease, such as ribavirin, have not been as effective as originally thought.

Earlier this year, scientists identified one particularly promising new drug target, a viral protein called coronavirus main protease.

A drug developed by Pfizer subsidiary Agouron Pharmaceuticals for rhinovirus infections, which are often behind the common cold, is already in clinical trials and has shown some activity against the coronavirus protease. It could form a useful starting point for drugs specifically designed to treat SARS.

Another company, AVI BioPharma, presented confirmatory positive results on the inhibition of the SARS coronavirus using its NeuGene antisense drugs at the start of this year. The drug targeted AVI's proprietary NeuGene antisense technology for inhibition of the SARS coronavirus.

The technology interferes with an RNA processing site unique to the SARS class of coronaviruses and resulted in a greater than hundredfold reduction in viral expression. This antisense agent was found to be more than 10 times more potent than any other SARS inhibitor previously reported.

Yet another firm, Sinovac Biotech​, is conducting preclinical tests of a SARS antibody developed jointly with Medarex. Sinovac plans to conduct preclinical tests to determine the antibody's effectiveness in neutralising the strains of the virus.

Researchers believe this advance may lead to treatments to prevent infection with SARS after individuals have been exposed to the virus, and potentially to therapeutic products to treat those already infected.

Using fully human monoclonal antibody technology is more likely to have favourable safety and toxicity profiles and be eliminated less rapidly from the human body, because human monoclonal antibodies are natural proteins. This can potentially reduce the frequency and amount of dosing required to affect disease targets.

Additionally, it is possible to reduce the time and cost of drug development. New pharmaceutical products traditionally take nearly six years of preclinical development compared to two years using fully human monoclonal antibody technology.