A virus similar to the one responsible for severe acute respiratory syndrome (SARS) has been found in Chinese horseshoe bats and may be poised to infect humans without the need for adaptation, potentially setting the stage for a widespread outbreak, according to a study from the University of North Carolina at Chapel Hill.
The work, published online in the Proceedings of the National Academy of Sciences, comes on the heels of two recent high-profile outbreaks––Ebola and Zika––for which there are no vaccines. The two outbreaks combined have claimed thousands of lives and cost billions of dollars in economic growth, according to the investigators.
“The capacity of this group of viruses to jump into humans is greater than we originally thought,” said lead author Vineet Menachery, PhD. “While other adaptations may be required to produce an epidemic, several viral strains circulating in bat populations have already overcome the barrier of replication in human cells and suggest re-emergence as a distinct possibility.”
The researchers worked with SARS-like coronavirus sequences isolated from horseshoe bats from China, where SARS originated. Based on the sequences, they reconstructed the viruses to evaluate their potential to infect human cells and mice. They found that the newly identified virus, known as WIV1-CoV, could bind to the same receptors as SARS-CoV. They also found that the virus readily and efficiently replicated in cultured human airway tissues, suggesting an ability to infect humans.
“To be clear, this virus may never jump to humans, but if it does, WIV1-CoV has the potential to seed a new outbreak with significant consequences for both public health and the global economy,” Menachery said.
The researchers also found that antibodies developed to treat SARS were effective against WIV1-CoV in both human and animal tissue samples, providing a potential treatment option if there were an outbreak. However, the limitation to treatment with antibodies is the same as that to treatment with ZMapp, the antibody approach used for Ebola: It is difficult to produce enough antibodies to treat large populations. Moreover, in terms of prevention, existing vaccines against SARS would not provide protection for the new virus because of slight differences in the viral sequence, Menachery said.
SARS first appeared in 2002, resulting in 8,000 cases and nearly 800 deaths. Spread through airborne contact, its onset presents symptoms similar to those of influenza, with a dry cough, but the infection can accelerate rapidly to pneumonia, putting extreme stress on the body’s immune system. According to the Centers for Disease Control and Prevention, the mortality rate for SARS ranges from less than 1% in patients younger than 24 years of age to more than 50% in patients aged 60 years and older. Menachery and his team believe that WIV1-CoV has the potential to produce similar results in humans.
Source: Medical Xpress; March 14, 2016.
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