Isolation of Middle East Respiratory Syndrome Coronavirus from a Patient of the 2015 Korean Outbreak

Abstract

During the 2015 outbreak of Middle East respiratory syndrome coronavirus (MERS-CoV) in Korea, 186 persons were infected, resulting in 38 fatalities. We isolated MERS-CoV from the oropharyngeal sample obtained from a patient of the outbreak. Cytopathic effects showing detachment and rounding of cells were observed in Vero cell cultures 3 days after inoculation of the sample. Spherical virus particles were observed by transmission electron microscopy. Full-length genome sequence of the virus isolate was obtained and phylogenetic analyses showed that it clustered with clade B of MERS-CoV.

Keywords: Korea; Microscopy, Electron; Middle East Respiratory Syndrome; Middle East Respiratory Syndrome Coronavirus; Phylogeny.

Fig. 1. Cytopathic effects of MERS-CoV in Vero cell cultures and Electron microscopy image of MERS-CoV. Vero cells were inoculated with oropharyngeal swab sample. (A) Vero cell cultures in negative control. (B) Cytopathic effects (rounding and detachment of cells) in Vero cell cultures 3 days after inoculation of the sample. (C, D) Transmission electron microscopy image of Vero cells infected with MERS-CoV. White arrow denotes nuclear membrane. Brown scale bar indicates 100 μm (A and B). Black scale bar indicates 500 nm (C) and white scale bar does 200 nm (D).

Fig. 2. Molecular phylogenetic analysis. Phylogenetic tree on complete genome (A), S genes (B), and ORF1ab genes (C) for the 101 gene sequences of MERS-CoV. The evolutionary history was inferred by using the maximum likelihood method based on the Tamura-Nei model (16). Evolutionary analyses were conducted in MEGA6 (17). Red box indicates our virus isolate.