Following on the heels of Ebola and Zika, a new SARS-like virus found in Chinese horseshoe bats has been identified that could cross the barrier species without need for adaptation and lead to an outbreak. Eventually, with adaptations the virus could lead to an epidemic, according to a study from the University of North Carolina at Chapel Hill.
"The capacity of this group of viruses to jump into humans is greater than we originally thought," said Vineet Menachery, Ph.D., the study's first author. "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 reemergence as a distinct possibility."
Usually, for a virus to cross species, many genetic adaptations in its DNA are required. The steps begin with interactions between the two species enabling transfer of the virus, specific receptor molecules on host cell membranes that allow or prevent the virus entry, and ability of the virus to take over the host cell machinery. Finally, the virus must overcome the barrier of transfer within the new species.
Ralph Baric, Ph.D., professor of epidemiology at UNC's Gillings School of Global Public Health, and Menachery were working with SARS-like coronavirus sequences isolated from Chinese horseshoe bats. They found that the new virus, known as WIV1-CoV, could bind to the same receptors as SARS-CoV. They also saw that the virus readily and efficiently replicated in cultured human airway tissues, suggesting an ability to jump directly to 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," said Vineet, whose work is reported in the Mar. 13 online version of the Proceedings of the National Academy of Sciences.
Treatment is possible with antibodies developed to treat SARS but as with Ebola, producing required amounts at a large enough scale during an epidemic may be tough. Also, existing vaccines against SARS will not provide protection due to the variation in the viral sequence of the new virus.
The news comes even as the medical fraternity struggles to treat Zika which has no treatment or vaccines just like Ebola. More than 11,000 people died during the Ebola epidemic which struck parts of West Africa towards the end of 2014. Just when WHO had declared West Africa Ebola free this January, two deaths in Sierra Leone have raised fears all over again.
The spread of mosquito-borne Zika virus to 24 nations and 1.5 million cases in Brazil alone has led WHO to declare a global emergency.
SARS (severe acute respiratory syndrome) first struck in an outbreak in 2002 and resulted in nearly 800 deaths. According to the Centers for Disease Control and Prevention, SARS' mortality rate can range from less than one percent in patients below 24 years old to more than 50 percent in patients aged 60 and older. The new virus WIV1-CoV is believed to have the potential to induce similar results after adaptation to humans.