Increase in Middle East Respiratory Syndrome-Coronavirus Cases in Saudi Arabia Linked to Hospital Outbreak With Continued Circulation of Recombinant Virus, July 1–August 31, 2015

Assiri, Abdullah M.; Biggs, Holly M.; Abedi, Glen R.; Lu, Xiaoyan; Bin Saeed, Abdulaziz; Abdalla, Osman; Mohammed, Mutaz; Al-Abdely, Hail M.; Algarni, Homoud S.; Alhakeem, Raafat F.; Almasri, Malak M.; Alsharef, Ali A.; Nooh, Randa; Erdman, Dean D.; Gerber, Susan I.; Watson, John T.

Our finding of a single unique deletion in ORF5 of the sequence from 1 patient mirrors a recent report by Lamers et al [11] that identified deletion mutations in ORF3 and ORF4a among MERS-CoVs obtained from an outbreak cluster in Jordan, 2015. Middle East respiratory syndrome-CoV possesses 5 group-specific ORFs (3, 4a, 4b, 5 , and 8b) that encode putative accessory proteins whose functions have not yet been fully characterized [12] . Deletion analysis by reverse genetics has shown that several of these ORFs, including ORF5, are not essential for virus replication in vitro [13] . The ORF5 frameshift mutation described here would most likely result in diminished or lost protein function, suggesting that it was not essential for efficient virus propagation in this particular patient. The possible effect of the ORF5 frameshift mutation on the clinical course of infection in this patient is unknown; we have no evidence that the deletion resulted in altered virulence or transmissibility of the virus, nor do we know whether the MERS-CoV ORF5 deletion was successfully transmitted to a new host.