Reply to Leow

TL;DR: It is supported by the findings in subsequent ex vivo culture systems that showed that MERS-CoV productively replicates in both human bronchial and lung tissues, as compared with severe acute respiratory syndrome (SARS)-CoV, which only replicate in lung tissues.

Abstract: TO THE EDITOR—We thank Leow for his correspondence [1] in which he recognized the significance of our recent work [2]. We also welcome the constructive comments he provided concerning the limitations of our study. In our study, we focused on the in vitro cell line susceptibility of the novel coronavirus, now renamed “Middle East respiratory syndrome coronavirus” (MERS-CoV) [3]. We agree with Leow that the results from studies of in vitro cell line tropism may not directly correlate with the in vivo behavior of the virus. Our observation that MERS-CoV replicates more efficiently than does SARSCoV within in vitro human tissues is supported by the findings in subsequent ex vivo culture systems that showed that MERS-CoV productively replicates in both human bronchial and lung tissues, as compared with severe acute respiratory syndrome (SARS)-CoV, which only replicates in lung tissues [4]. Furthermore, an animal model using rhesus macaques for MERSCoV infection was recently developed and showed histopathological evidence of acute localized to widespread lung consolidation in all infected animals, resulting in clinical disease [5]. Detailed histopathological examination of patients with MERS-CoV infection would be important for the confirmation of these changes in humans. Although dysfunction of the hypothalamus–pituitary–adrenal axis has not been well described in patients with MERS-CoV, some patients did develop hyponatremia, which was possibly related to a syndrome of inappropriate antidiuretic hormone secretion [3]. We agree that further studies on the predilection of