A recent study conducted by the Ministry of Health on the novel Middle East Respiratory Syndrome Coronavirus (MERS-CoV) revealed that the virus is more complex than previously conceived and indicates the presence of additional sources of the virus.
MERS-CoV has affected 107 people in the Kingdom, of which 49 have died. Researchers from the Saudi Ministry of Health (MOH) have been working to sequence the virus to discover how it is spreading. The initiative was made in collaboration with the Wellcome Trust Sanger Institute, the University of Edinburgh and the University College London (UCL).
The study’s findings aim to help researchers develop interventions and infection-control measures.
The study has produced the largest number of MERS-CoV genomes identified to date and provides evidence that MERS-CoV has complicated transmission patterns.
The genetic sequence of the virus samples, which were taken from 21 patients located in different parts of the Kingdom, has been studied and analyzed.
Researchers have linked the geographical location of patients and time of injury with the rate of genetic differences that were observed between the genomes of the virus. Accordingly, this finding gave a clearer image of how the genome of the virus spreads over time.
“We deep-sequenced the genomes of MERS-CoV taken from 21 infected people to accurately calculate the rate of evolution of the virus,” said Dr. Matthew Cotten of the Sanger Institute who is also the study’s first author. “We could define genetically plausible transmission pairs using this evolution rate. However, the genetic evidence we gathered could only support eight of the 13 transmission events that were predicted from the epidemiology.”
The findings suggest that human-to-human transmission is more complicated and indicates that additional sources of the virus, either human or animal, are involved. One possibility is that there may be undetected cases and possibly asymptomatic individuals who could be carrying and spreading the virus.
“The genome differences we discovered in some infected individuals were too great to be explained by replication errors occurring in the virus, as it is passed from human to human in a single chain of infection,” explained Professor Paul Kellam, senior author of the Sanger Institute.
“Instead, our findings suggest that different lineages of the virus have originated from the virus jumping across to humans from an animal source numerous times.”
As of yet, no animal with MERS-CoV has been identified in the Middle East or elsewhere and studies based on small sequence fragments suggest that a common ancestor of the virus may have existed in bats many years ago.
Field studies of likely reservoir species, including camels, bats, goats, sheep, dogs, cats and rodents in the Kingdom and other Middle-Eastern countries are still ongoing.
“Further MERS-CoV genomic studies need to be carried out in conjunction with investigations into the recent exposures and activities of infected people,” said corresponding author Dr. Ziad Al-Memish, undersecretary to the Ministry of Health on behalf of Saudi co-authors who are members of the National Infectious Diseases committee overseeing the response strategy for MERS-COV.
“The animal source of MERS-CoV and the way it is transmitted to humans is not yet known. This information is critical for developing intervention for reducing the risk of transmission, defining the epidemiology and developing effective control measures,” Al-Memish said.
Around 130 people have been diagnosed with MERS-CoV globally since 2012, including 52 deaths.
MD Rasooldeen - Arab News
