Several bat species are natural hosts of coronaviruses closely related to the SARS virus, an international research group reported on Thursday.

In this latest study, researchers from China, Australia, and the United States tested a variety of wild bats from four locations in China for coronaviruses.

They found in wild bats several genetically diverse coronaviruses, one of which very closely resembles the SARS virus. They noted that bats are the original source of the killer virus.

The SARS virus itself is a member of this coronavirus group, researchers said.

The new findings will appear in the Sept. 30 online issue of the journal Science.

Since the SARS outbreak in year 2002-03 that killed about 800people, scientists have been hunting for the natural reservoir of the SARS virus.

Previous studies have found that palm civets sold at the liveanimal markets were infected with the SARS virus, but further evidence suggested that these animals were not themselves the original hosts, the researchers said.

Bats are hosts of several other known viruses, including Hendraand Nipah viruses, and they can be infected with many viruses but rarely display clinical symptoms. They're also increasingly present in food and traditional medicine markets in southern China and elsewhere in Asia.

In this study conducted in 2004, the researchers trapped408 bats from their native habitat in the Chinese provinces of Guangdong, Guangxi, Hubei, and Tianjin. Nine bat species, 6 generaand 3 families were included in the samples.

The researchers collected those bats' blood, fecal and throat swabs, and analyzed their serum samples along with DNA from fecal or throat samples using different methods independently in laboratories in Wuhan, China and Geelong, Australia.

They found that three communal, cave-dwelling bat species from the horseshoe bat family demonstrated a high SARS-coronavirusantibody prevalence. Among them, 71 percent samples of the Rhinolophuspussilus species trapped in Guangxi showed positive.

"The high seroprevalence and wide distribution of seropositive

bats is expected for a wildlife reservoir host for a pathogen," wrote the researchers.

The coronaviruses found in bat samples were genetically diverse, but they all show some similarity to the SARS coronavirus that aroused the pandemic, the researchers noted. Genetical identity between a bat virus strain and the SARS coronavirus even reached 94 percent.

Earlier this month, a team led by Professor Kwok-yung Yuen of the Hong Kong University also reported a coronavirus in wild bats to be close relative of the SARS virus.

But compared with these newly found SARS-like bat viruses, the bat SARS coronavirus identified by Hong Kong researchers are genetically more distant to the human SARS virus, according to the researchers.

The SARS-coronavirus found in humans and the SARS like coronavirus found in bats will be collectively called the SARS cluster of coronaviruses, the researchers suggested, noting that SARS-coronavirus may phylogenetically belong to the family of those bat viruses.

Editor: Yan