The genome of the novel coronavirus believed to be responsible for one death and one critical illness indicates, as suspected, that it may have originated in bats, researchers reported.
The virus, obtained from sputum samples of a 60-year-old Saudi Arabian man who died from progressive respiratory and renal failure in June, is distinct from the five other coronaviruses known to infect humans, including the virus behind the severe acute respiratory syndrome (SARS) outbreak that killed about 800 people in 2003, according to Ron Fouchier, PhD, of Erasmus Medical Center in Rotterdam, and colleagues.
It is most closely related to two coronaviruses found in bats, the researchers reported online in the New England Journal of Medicine.
"We hypothesize that one or more species of animals, possibly bats, were the reservoir host of this new coronavirus," they wrote, noting that Saudi Arabia - home to the patient who died and visited by a critically ill 49-year-old Qatari man - has numerous bat species. Coronaviruses can also been found in birds, cats, dogs, pigs, mice, horses, and whales.
Fouchier and colleagues isolated the new virus - dubbed HCoV-EMC (human coronavirus-Erasmus Medical Center) - from the 60-year-old man living in Saudi Arabia, who presented with acute pneumonia on June 13. He had had fever, cough, expectoration, and shortness of breath for 7 days before presentation.
Chest radiography, combined with the clinical symptoms, indicated acute respiratory distress syndrome with multi-organ distress syndrome.
The day after admission, the man was transferred to the intensive care unit, where he was intubated for mechanical ventilation. His levels of blood urea nitrogen and creatinine began to increase on the third day and his liver enzymes became elevated on the seventh day. On the eighth day, his white-cell count began to rise, leading to neutrophilia, persistent lymphopenia, and progressive thrombocytopenia.
A deterioration of renal function began on the ninth day of symptoms, and the man ultimately died from progressive respiratory and renal failure on the eleventh day after admission.
The new coronavirus was isolated from sputum samples obtained on the first day of the hospitalization. The researchers found that the virus replicated easily in cultures of monkey cells, with cytopathic effects.
Genome sequencing revealed that the virus belongs to the genus betacoronavirus and is most closely related to the bat coronaviruses HKU4 and HKU5.
It is distinct from the four coronaviruses that are endemic in humans - 229E, OC43, NL63, and HKU1 - and the SARS coronavirus.
"The diversity of coronaviruses is facilitated by the infidelity of the RNA-dependent RNA polymerase, the high frequency of RNA recombination, and the unusually large genomes for RNA viruses," Fouchier and colleagues wrote. "These factors not only have led to the diversity of known coronaviruses but also have facilitated the emergence of viruses with new traits that allow the organism to adapt to new hosts and ecologic niches, sometimes causing zoonotic events."
They added that the clinical situation of the new virus appears similar to that of the SARS virus outbreak in 2003, although the newer virus has not been shown to be easily transmitted from person to person. The two men infected with the virus had no known connection, aside from being in Saudi Arabia.
"This case is a reminder that although most infections with human coronaviruses are mild and associated with common colds, certain animal and human coronaviruses may cause severe and sometimes fatal infections in humans," Fouchier and colleagues wrote. "Although HCoV-EMC does not have many of the worrisome characteristics of SARS-coronavirus, we should take notice of the valuable lessons learned during the 2003 SARS outbreak with respect to outbreak investigations and management."
In an accompanying editorial, Larry Anderson, MD, of Emory-Children's Center in Atlanta, and Ralph Baric, PhD, of the University of North Carolina at Chapel Hill, said that the new coronavirus is not considered a public health risk right now because of the lack of evidence that it can transmit between humans.
Source: Med Page Today-Oct. 17, 2012 at http://www.medpagetoday.com/InfectiousDisease/Surveillance/35388?utm_source=share&utm_medium=mobile&utm_campaign=medpage%2Biphone%2