Development of a Mouse-Adapted MERS Coronavirus

Abstract

First identified in 2012, Middle East respiratory syndrome coronavirus (MERS-CoV) is a novel virus that can cause acute respiratory distress syndrome (ARDS), multiorgan failure, and death, with a case fatality rate of~35%. An animal model that supports MERS-CoV infection and causes severe lung disease is useful to study pathogenesis and evaluate therapies and vaccines. The murine dipeptidyl peptidase 4 (Dpp4) protein is not a functional receptor for MERS-CoV; thus, mice are resistant to MERS-CoV infection. We generated human DPP4 knock-in (hDPP4 KI) mice by replacing exons 10-12 at the mouse Dpp4 locus with exons 10-12 from the human DPP4 gene. The resultant human DPP4 KI mice are permissive to MERS-CoV (HCoV-EMC/2012 strain) infection but develop no disease. To generate a mouse model with associated morbidity and mortality from respiratory disease, we serially passaged HCoV-EMC/2012 strain in the lungs of young hDPP4 KI mice. After 30 in vivo passages, an adapted virus clone was isolated and designated MERS MA 6.1.2. This virus clone produced significantly higher titers than the parental clone in the lungs of hDPP4 KI mice and caused diffuse lung injury and a fatal respiratory infection. In this chapter, we will describe in detail the procedures used to mouse adapt MERS-CoV by serial passage of the virus in lungs. We also describe the methods used to isolate virus clones and characterize virus infection.

Adaptation of SARS-CoV-2 in BALB/c mice for testing vaccine efficacy

“…The development of a mouse-adapted strain-based challenge model has been well demonstrated in SARS-CoV and MERS-CoV studies ( 12 , 19 , 20 ). Serial passaging of virus in mouse lungs results in adaptive mutations that increase viral infectivity.…”

SARS-CoV-2 in animals: From potential hosts to animal models

“…This obstacle might be overcome by either virus adaptation to mice or by expression of human ACE2 in genetically modified mice. Both approaches were successful for the closely related MERS-CoV ( Kim et al, 2020a ; Li and McCray, 2020 ), in which the murine dipeptidyl peptidase 4 receptor failed to support MERS-CoV infection. For SARS-CoV-2, genetically modified mice were generated that express human ACE2, e.g., driven by the mouse ACE2 promotor (ACE2-hACE2 mice), by the human keratin 18 promoter (K18-hACE2 mice), by the human lung ciliated epithelial cell-specific HFH4/FOXJ1 promoter (HFH4-hACE2 mice) or by the cytomegalovirus enhancer followed by the chicken β-actin promoter ( Bao et al, 2020a , Bao et al, 2020b ; Jiang et al, 2020 ; Oladunni et al, 2020 ; Tseng et al, 2007 ; Winkler et al, 2020 ).…”

Sex-dependent immune response and lethality of COVID-19

“…Mouse models have been generated to investigate the infection and pathogenic mechanisms of the SARS-CoV, MERS-CoV and SARS-CoV-2 ( Bao et al, 2020 , Dinnon et al, 2020 , Gu et al, 2020 , Jiang et al, 2020 , Li and McCray, 2020 , Roberts et al, 2007 , Sun et al, 2020a , Sun et al, 2020b ). Similar sex and age effects had been observed in the mice upon the viral infection ( Dinnon et al, 2020 , Gargaglioni and Marques, 2020 ).…”