Interferon Treatment Eradicates a New Human Coronavirus in a Culture Model

A recently recognized human coronavirus was treated successfully in an in vitro model based on human bronchial epithelial tissue, which reduces fears that the virus might be capable of setting off a worldwide respiratory disease pandemic.

The recent emergence of a novel human coronavirus (HCoV-EMC) in the Middle East raised considerable concerns, as it was found to be associated with severe acute pneumonia, renal failure, and fatal outcome and thus resembled the clinical presentation of severe acute respiratory syndrome (SARS) observed in 2002 and 2003. Like SARS-CoV, HCoV-EMC is of zoonotic origin and closely related to bat coronaviruses.

To get a handle on this potentially fatal pathogen, investigators at Kantonal Hospital (St. Gallen, Switzerland) developed an in vitro model based on human bronchial epithelial cells, which are highly susceptible to HCoV-EMC infection and in which the virus is able to multiply at a faster initial rate than the SARS virus. The investigators employed advanced genomic research tools such as reverse transcription (RT)-PCR and RNAseq data to experimentally determine the identity of seven HCoV-EMC subgenomic mRNAs.

Results published in the February 19, 2013, online edition of the journal mBio revealed that while the human bronchial epithelial cells were readily responsive to type I and type III interferon (IFN), neither a pronounced inflammatory cytokine nor any detectable IFN responses were found following HCoV-EMC infection, suggesting that innate immune evasion mechanisms and possible IFN antagonists of the virus were operational in the human host. On the other hand, type I and type III IFN were found to efficiently reduce HCoV-EMC replication in the human cell cultures, providing a possible treatment option in cases of suspected HCoV-EMC infection.

"Surprisingly, this coronavirus grows very efficiently on human epithelial cells," said senior author Dr. Volker Thiel, a senior research fellow at Kantonal Hospital. "The other thing we found is that the viruses (HCoV-EMC, SARS, and the common cold virus) are all similar in terms of host responses: they do not provoke a huge innate immune response. We do not know whether the cases we observe are the tip of the iceberg, or whether many more people are infected without showing severe symptoms."

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