An Appropriate Lower Respiratory Tract Specimen Is Essential for Diagnosis of Middle East Respiratory Syndrome (MERS)

Lee, Jae Hoon; Lee, Chang-Seop; Lee, Heung-Bum

Dipeptidyl peptidase 4 (DPP4) has been identified as the receptor for MERS-CoV (5). DPP4 is expressed in type I and II alveolar cells, ciliated or non-ciliated bronchial epithelium, and bronchial submucosal glands (5, 6) . This corresponds with viral tropism in ex vivo human lung cultures (5) (6) (7) . In studies with rhesus macaques, intra-tracheally inoculated virus was present in the lungs but neither in the upper respiratory tracts, trachea, nor other organs (8, 9) . All of marmosets infected with a high dose of MERS-CoV via various routes showed multifocal to coalescing, moderate to marked acute broncho-interstitial pneumonia centered on small calibre and terminal bronchioles which further extended into the adjacent pulmonary parenchyma. In summary, in vitro and in vivo studies concluded that MERS-CoV had adherence to the lower respiratory tract and high viral loads were mainly detected in distal respiratory tissues. Therefore, lower respiratory tract specimens such as bronchoalveolar lavage fluid, deep tracheal aspirates, and induced sputum contain the highest viral loads which are optimal for increasing di- agnostic accuracy (10) (11) (12) (13) .