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Middle East Respiratory Syndrome Coronavirus Gene 5 Modulates Pathogenesis in Mice
Journal article   Open access   Peer reviewed

Middle East Respiratory Syndrome Coronavirus Gene 5 Modulates Pathogenesis in Mice

Javier Gutierrez-Alvarez, Kun Li, Paul B McCray Jr, Li Wang, Stanley Perlman, Raul Fernandez-Delgado, Isabel Sola, Sonia Zuñiga and Luis Enjuanes
Journal of virology, Vol.95(3), e01172-20
01/13/2021
DOI: 10.1128/JVI.01172-20
PMCID: PMC7925085
PMID: 33144319
url
https://doi.org/10.1128/JVI.01172-20View
Published (Version of record) Open Access

Abstract

Middle East respiratory syndrome coronavirus (MERS-CoV) causes a highly lethal pneumonia that emerged in 2012. There is limited information on MERS-CoV pathogenesis, as data from patients are scarce and the generation of animal models reproducing MERS clinical manifestations has been challenging. Human dipeptidyl peptidase 4 knock-in (hDPP4-KI) mice and a mouse-adapted MERS-CoV strain (MERS -6-1-2) were recently described. hDPP4-KI mice infected with MERS -6-1-2 show pathological signs of respiratory disease, high viral titers in the lung, and death. In this work, a mouse-adapted MERS-CoV infectious cDNA was engineered by introducing nonsynonymous mutations contained in the MERS -6-1-2 genome into a MERS-CoV infectious cDNA, leading to a recombinant mouse-adapted virus (rMERS-MA) that was virulent in hDDP4-KI mice. MERS-CoV adaptation to cell culture or mouse lungs led to mutations and deletions in genus-specific gene 5 that prevented full-length protein expression. In contrast, analysis of 476 MERS-CoV field isolates showed that gene 5 is highly stable in both humans and camels. To study the role of protein 5, two additional viruses were engineered expressing a full-length gene 5 (rMERS-MA-5FL) or containing a complete gene 5 deletion (rMERS-MA-Δ5). rMERS-MA-5FL virus was unstable, as deletions appeared during passage in different tissue culture cells, highlighting MERS-CoV instability. The virulence of rMERS-MA-Δ5 was analyzed in a sublethal hDPP4-KI mouse model. Unexpectedly, all mice died after infection with rMERS-MA-Δ5, in contrast to those infected with the parental virus, which contains a 17-nucleotide (nt) deletion and a stop codon in protein 5 at position 108. Expression of interferon and proinflammatory cytokines was delayed and dysregulated in the lungs of rMERS-MA-Δ5-infected mice. Overall, these data indicated that the rMERS-MA-Δ5 virus was more virulent than the parental one and suggest that the residual gene 5 sequence present in the mouse-adapted parental virus had a function in ameliorating severe MERS-CoV pathogenesis. Middle East respiratory syndrome coronavirus (MERS-CoV) is a zoonotic virus causing human infections with high mortality rate (∼35%). Animal models together with reverse-genetics systems are essential to understand MERS-CoV pathogenesis. We developed a reverse-genetics system for a mouse-adapted MERS-CoV that reproduces the virus behavior observed in humans. This system is highly useful to investigate the role of specific viral genes in pathogenesis. In addition, we described a virus lacking gene 5 expression that is more virulent than the parental one. The data provide novel functions in IFN modulation for gene 5 in the context of viral infection and will help to develop novel antiviral strategies.
 Mutation Cell Line Lung - pathology Cytokines - metabolism Genome, Viral - genetics Humans DNA, Complementary - genetics Viral Nonstructural Proteins - genetics Dipeptidyl Peptidase 4 - genetics Mice, Transgenic Immunity, Innate Coronavirus Infections - immunology Viral Load Lung - virology Middle East Respiratory Syndrome Coronavirus - pathogenicity Animals Coronavirus Infections - virology Virulence - genetics Middle East Respiratory Syndrome Coronavirus - genetics Coronavirus Infections - pathology Viral Nonstructural Proteins - metabolism Mice Lung - immunology Disease Models, Animal

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