Scientists have discovered a SARS-like coronavirus in Chinese horseshoe bats, according to a new study published Wednesday in the journal Nature by a team of international researchers, including a wildlife epidemiologist from UC Davis.
The research team isolated and cultured the live virus that binds to the human SARS ACE2 receptor, proving that it can be transmitted directly from bats to people.
The study describes how the team uncovered genome sequences of a new virus closely related to the SARS coronavirus, which erupted in Asia in 2002 and 2003 and caused a global pandemic crisis.
The research is the first time that scientists have been able to isolate a live SARS-like virus from bats. It will allow them to conduct detailed studies to create control measures to thwart outbreaks and provide opportunities for vaccine development.
"This work shows that these viruses can directly infect humans and validates our assumption that we should be searching for viruses of pandemic potential before they spill over to people," said co-author and UC Davis professor Jonna Mazet, co-director of PREDICT, a project of USAID's Emerging Pandemic Threats program.
PREDICT, which partially supported the study, is designed to target surveillance of wildlife populations and identify potential pandemic viruses before they emerge.
Coronaviruses are common viruses that usually cause mild to moderate upper-respiratory tract illnesses. The SARS coronavirus causes severe acute respiratory illness and can infect people and animals.
During the original SARS outbreak in the wet markets of Guangdong province in China, it was thought that bat viruses first infected civets -- small mammals native to tropical Asia and Africa -- and then evolved to infect people through this intermediate host. The current breakthrough suggests that SARS may have originated from one of these bat viruses, precluding civets from playing a part in the human infection process.
"We have been searching for this missing link for 10 years, and finally we've found it," said co-senior author Zhengli Shi from the Wuhan Institute of Virology in China.
Generally speaking bats are very beneficial to humans, despite myths to the contrary. With the exception of rabies, bats can eat more than their weight insects each night, which is also a benefit to farmers.
"The discovery that bats may directly infect humans has enormous implications for public health control measures," said co-senior author Peter Daszak, president of EcoHealth Alliance, which led the international effort, including scientists in China, Australia, Singapore and the United States. "Our research here uncovered a wide diversity of potentially pandemic viruses present, right now, in bats in China that could spill over into people and cause another SARS-like outbreak. Even worse, we don't know how lethal these viruses would be if such an outbreak erupted."
Daszak said the study carries lessons for the recent outbreak of Middle East Respiratory Syndrome coronavirus, which likely originated in Saudi Arabian bats. He said bat habitats need to be protected from severe human-induced changes to the environment, and that public health measures need to be created to reduce the risk of transmission.
It is not uncommon for bats to be a food source for many people in China and other parts of Asia.