WASHINGTON, Nov. 25 (Xinhua) -- Researchers at University of North Carolina and Vanderbilt University have synthetically reconstructed the bat variant of the SARS coronavirus (CoV) that caused the SARS epidemic in 2003.

    The scientists say designing and synthesizing the virus is a major step forward in their ability to find effective vaccines and treatments for any strain of SARS virus that might affect humans in the future.

    A report of the work was published Tuesday in the Proceedings of the National Academy of Sciences.

    "Only three other teams of researchers have synthetically reconstructed a virus. In this case we reconstructed the likely progenitor of the SARS-CoV epidemic," said Ralph Baric, one of the leaders on the project. "The bat SARS virus is about four times larger than any other virus that has been synthesized to date. It will allow us to test the pathways in which the virus emerges and understand the ways that animal coronaviruses move from one species to another."

    SARS is believed to have first emerged humans in Asia in late 2002. Over the next several months, the illness spread to more than two dozen countries before the global outbreak was contained.Of the more than 8,000 people worldwide who were diagnosed with SARS in 2003, 774 died.

    Baric said SARS is believed to have originated in bats, and "jumped" to humans either directly or through raccoon dogs and palm civets.

    "Although the strains associated with the 2002-2003 epidemic no longer circulate in humans, the animal precursor strains are common and will likely re-emerge in the future," he said. "The key problem is that many of the vaccines and therapeutics targeting the 2002-2003 epidemic strains may not work against future emergent strains."

    Baric said synthesizing the SARS co-variant that infects bats and then modifying it so that it can grow well in laboratory animals will allow researchers to search for vaccines and treatments that would be effective against any strain of SARS that might infect humans in the future.

    Viruses that start in animals and mutate to infect humans tend to be slightly different each year. An example is the influenza virus, which is different each year and requires a different vaccine each year to provide immunity.

    The value of the research goes beyond SARS, he added. "Potentially, we can apply this technology to many other emerging viruses," he said.