Polyphyletic origin of MERS coronaviruses and isolation of a novel clade A strain from dromedary camels in the United Arab Emirates

Emerg Microbes Infect. 2016 Dec 21;5(12):e128. doi: 10.1038/emi.2016.129.

Abstract

Little is known regarding the molecular epidemiology of Middle East respiratory syndrome coronavirus (MERS-CoV) circulating in dromedaries outside Saudi Arabia. To address this knowledge gap, we sequenced 10 complete genomes of MERS-CoVs isolated from 2 live and 8 dead dromedaries from different regions in the United Arab Emirates (UAE). Phylogenetic analysis revealed one novel clade A strain, the first detected in the UAE, and nine clade B strains. Strain D998/15 had a distinct phylogenetic position within clade A, being more closely related to the dromedary isolate NRCE-HKU205 from Egypt than to the human isolates EMC/2012 and Jordan-N3/2012. A comparison of predicted protein sequences also demonstrated the existence of two clade A lineages with unique amino acid substitutions, A1 (EMC/2012 and Jordan-N3/2012) and A2 (D998/15 and NRCE-HKU205), circulating in humans and camels, respectively. The nine clade B isolates belong to three distinct lineages: B1, B3 and B5. Two B3 strains, D1271/15 and D1189.1/15, showed evidence of recombination between lineages B4 and B5 in ORF1ab. Molecular clock analysis dated the time of the most recent common ancestor (tMRCA) of clade A to March 2011 and that of clade B to November 2011. Our data support a polyphyletic origin of MERS-CoV in dromedaries and the co-circulation of diverse MERS-CoVs including recombinant strains in the UAE.

MeSH terms

  • Animals
  • Camelus / virology*
  • Cluster Analysis
  • Coronavirus Infections / epidemiology
  • Coronavirus Infections / veterinary*
  • Coronavirus Infections / virology
  • Evolution, Molecular
  • Genetic Variation*
  • Genome, Viral
  • Middle East Respiratory Syndrome Coronavirus / classification*
  • Middle East Respiratory Syndrome Coronavirus / genetics
  • Middle East Respiratory Syndrome Coronavirus / isolation & purification*
  • Molecular Epidemiology
  • Phylogeny*
  • Recombination, Genetic
  • Sequence Analysis, DNA
  • Sequence Homology
  • United Arab Emirates / epidemiology