A new strain of the deadly SARS virus has been closely related to a virus found in Asian bats, states study.
Scientists in the Netherlands said they had sequenced the genetic code of a viral sample taken from a 60-year-old man whose death in Jeddah, Saudi Arabia, in June triggered fears that Severe Acute Respiratory Syndrome (SARS) was returning in a new guise.
The new strain, called HCoV-EMC/2012, is part of a viral family called coronavirus, but in a specific category called betacoronavirus.
Its closest known cousins are a strain found in lesser bamboo bats (Tylonycteris pachypus) and another found in Japanese house bats, Pipistrellus abramus.
"The virus is most closely related to viruses in bats in Asia, and there are no human viruses closely related to it," said Ron Fouchier of the prestigious Erasmus Medical Centre in Rotterdam.
"Therefore we speculate that it comes from an animal source," he said, noting that Pipistrellus bats are present in Saudi Arabia and neighbouring countries.
An epidemic of SARS erupted in China in 2002, eventually claiming around 800 deaths in some 30 countries.
Bats were linked with a novel strain of SARS found in 2005. Hong Kong researchers found a natural "reservoir" of it in Chinese horseshoe bats.
Two other men have also fallen sick in the latest SARS episode.
One is a Qatari man who had been in Saudi Arabia and is being treated at a hospital in London.
There is 99.6-99.7 percent similarity between his strain and the virus sequenced in the Netherlands, said Fouchier in a press release.
"They are the same species," he said, adding that the difference was sufficient to suggest that the men had been infected by different sources.
The other is a Saudi man whose case was announced earlier this month by the Saudi health ministry, which on November 4 described him as cured.
The genomic sequence of that virus is not yet available, Fouchier said.
The WHO said that what set the new virus apart from SARS was that it causes rapid kidney failure.
Fears rose last month over the potential spread of the virus during the Muslim hajj pilgrimage in Saudi Arabia. But the kingdom's health ministry repeatedly reassured pilgrims that no epidemic outbreaks had been registered.
The new paper appears in mBio, an online journal of the American Society for Microbiology.