Deadly MERS Virus Genome Suggests Complex Transmission

Deadly MERS virus has genome probed to show transmission

A recent study has sought to perform genomic sequencing of the virus responsible for the deadly Middle East Respiratory Syndrome (MERS). Preliminary data suggests transmission of the pathogen is more advanced than scientists initially suspected.

What is the MERS Virus?

The MERS virus is caused by a coronavirus (MERS-CoV), and was initially reported back in 2012. Unfortunately, information concerning the MERS is relatively limited, although a number of high-profile research endeavors are currently ongoing.

The virus has, however, been taxonomically verified, and belongs to the same family of viruses as that responsible for severe acute respiratory syndrome (SARS), which spread throughout Asia between 2002 and 2003.

MERS incidence and death for Sep 20
CDC data, showing the death toll, and number of people infected, following the MERS outbreak

As of Sep. 20, the Centers for Disease Control and Prevention (CDC) report a total of 130 cases of infections, with 58 deaths, principally within Saudi Arabia.

MERS-CoV causes severe acute respiratory illness, alongside the following characteristic signs and symptoms:

  • Pneumonia
  • Fever
  • Shortness of breath (SOB)
  • Cough
  • Diarrhea and other gastrointestinal issues
  • Renal failure

The Study

The research group published the findings of their study in the journal Lancet, providing the most comprehensive number of MERS-CoV genomes, thus far, and suggests a number of human “transmission chains” to be associated with the elusive virus.

Researchers working for the Wellcome Trust Sanger Institute wanted to acquire an accurate interpretation of how the virus had potentially mutated over time. Samples were extracted from a total of 21 infected patients from across the Saudi Arabian Peninsula. The team explored variations in the genetic sequences of the MERS-CoV viruses, between each of the patient samples, and matched them to the geographic location and time of infection; essentially, this provided the scientists with a timeline, showing the progressive changes in the genomic sequence of MERS-CoV.

Dr. Matthew Cotton, of the Sanger Institute, who was the study’s lead author, explained how he and his colleagues deep-sequenced the collected viral samples to determine its “rate of evolution.”

Based upon their findings, the scientists suggest that disease spread cannot involve simple human to human transmission in isolation. Rather, they posit that human beings may be a part of dynamic infection chain, with the virus jumping from one species of animal to another, mutating as it does so. The team base this assumption on the highly divergent genomic sequences of the MERS viruses investigated in their 21 patient samples.

Cotton explains why the virus cannot be restricted to human beings:

“The genome differences we discovered in some infected people were too great to be explained by replication errors occurring in the virus as it is passed from human to human during a single chain of infection.”

Other Potential MERS-CoV Reservoirs

Previous studies have correlated the spread of MERS-CoV to a number of different animals. Ziad Memish and colleagues published a paper in the journal Emerging Infectious Disease, entitled Middle East Respiratory Syndrome Coronavirus in Bats, Saudi Arabia.

The team traced the first MERS case back to Bisha, in the southwest province of ‘Asir in Saudi Arabia, and began combing the area for bats. The team used polymerase chain reaction to confirm the presence of MERS-CoV in their collected samples, and formed a tentative relationship between bat and human transmission.

Camels could be involved in MERS virus spreadMeanwhile, camels have also be highlighted as a potential reservoir of the virus. In the Eurosurveillance, researchers published their findings on the seroepidemiological studies of dromedary camels. Interestingly, they identified antibodies that showed high affinity for MERS-CoV, showing the beasts’ immune systems were primed against the deadly virus and, therefore, had encountered it beforehand.

Thus far, no single treatment has been identified or developed, although one research group has demonstrated limited success using a cocktail of anti-viral drugs, including ribavirin and interferon alpha 2b. Around 50% of those infected, who have not undergone any experimental treatment, have died.

With regards to the future, Cotton identifies the need to carry out further genomic studies, into the deadly MERS virus, in those patients most recently affected. Professor Ziad Memish, the Deputy Minister of Health in Riyadh, suggests that uncovering the complexities of disease transmission is key to “… reducing the risk of transmission, defining the epidemiology and developing effective control measures.

By: James Fenner

LV Guardian Express Link1

LV Guardian Express Link2

CDC Link

Press Release Link

Lancet Journal Link

Eurosurveillance Journal Link

Emerging Infectious Disease Journal Link

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