B6(Cg)-Ace2^{tm1.1(ACE2)Mdk}/J

Stock number: 035800
Product name: ACE2-GR
Strain synonyms: humanized Ace2 KI
Research areas: Developmental Biology Research, Immunology, Inflammation and Autoimmunity Research, Internal/Organ Research, Mouse/Human Gene Homologs, Research Tools, Virology Research

Description

ACE2-GR mice have the human ACE2 gene replacing the endogenous mouse Ace2 sequences. Expression is directed by the human ACE2 regulatory elements. Human ACE2 is the receptor used for cellular entry by several coronaviruses, including severe acute respiratory syndrome coronavirus-1 (SARS-CoV) and -2 (SARS-CoV-2). Because cells expressing human ACE2 are susceptible to SARS-CoV-2, these mice may be useful for studying antiviral therapies to COVID-19.

Of note, hACE2-KI (Stock No. 035000) has some similarities to this strain, yet have floxed human ACE2 cDNA replacing the endogenous sequence.

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Detailed description

Please note, these mice should be handled in a manner consistent with CDC/ABSA/WHO guidelines for prevention of human infection with the SARS-CoV-2 virus. Proper PPE and handling methods should be used at all times when working with these mice. Additional important guidelines for using SARS-CoV-2 susceptible mouse lines.

ACE2-GR mice have the human ACE2 gene replacing the endogenous mouse Ace2 sequences on the X Chromosome. These mice express human ACE2 in place of mouse Ace2, as directed by regulatory elements of the human ACE2 gene. Specifically, expression is evident via immunohistochemistry in the lung, heart and kidney tissue of homozygotes. The donating investigator reports that homozygous mice can be infected by intranasal infection of 2X10^4 PFU SARS-CoV-2 virus, with viral RNA detected in lung tissue at day 3, and mice develop a strong antibody response by day 14 postinfection. Wildtype C57BL/6J mice treated in the same way do not have any detectable viral RNA in their lung tissue at day 3, nor do they develop detectable levels of antibody at day 14.

Human ACE2 is the receptor used for cellular entry by several coronaviruses, including severe acute respiratory syndrome coronavirus-1 (SARS-CoV), severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2; 2019 novel coronavirus) and HCoV-NL63. This ACE2-GR mouse model may be useful in studying antiviral therapies for these coronaviruses, particularly SARS-CoV-2 pathogenesis and the disease outbreak COVID-19.

Hemizygous males and homozygous females are viable and fertile.

Of note, hACE2-KI (Stock No. 035000) mice have some similarities to this strain, yet contain loxP sites flanking human ACE2 cDNA which replaces the endogenous Ace2 sequence.

Development

The ACE2-GR allele has the entire X-linked angiotensin I converting enzyme (peptidyl-dipeptidase A) 2 gene [Ace2] replaced with the entire human ACE2 gene. First, a targeting vector was designed to replace 71 kb (70,987bp) on the mouse X chromosome stretching from, but not including, collectrin, amino acid transport regulator (Cltrn) gene to BMX non-receptor tyrosine kinase (Bmx) gene with a syntenic 66 kb (65,812bp) region from the human X chromosome. A loxN-flanked neomycin resistance (neo) cassette was inserted at the junction between the human ACE2 and mouse Bmx genes. The construct was electroporated into C57BL/6NTac-derived PRX-B6N embryonic stem (ES) cells. Correctly targeted ES cells were transiently transfected with a cre expression plasmid to delete the neo cassette. Resulting ES cells were injected into recipient blastocysts. Chimeric mice were bred to albino C57BL/6J mice (Stock No. 000058). Female mice were sent to The Jackson Laboratory Repository in 2020 (see SNP note below). Upon arrival, oocytes from these females were used with C57BL/6J sperm for IVF to generate a colony. Subsequently, the Tyr^c-2J albino gene was bred out of the colony.

IN 2021, a 48 SNP (single nucleotide polymorphism) panel analysis, with 43 markers covering all 19 chromosomes and the X chromosome, as well as 5 markers that distinguish between the C57BL/6J and C57BL/6N substrains, was performed on the mice sent to The Jackson Laboratory Repository. Three of the 5 markers that determine C57BL/6J from C57BL/6N were found to be segregating, including the rd8 recessive mutation associated with retinal degeneration on Chromosome 1 within the Crb1 locus. These data suggest the mice sent to The Jackson Laboratory Repository were on a mixed C57BL/6N;C57BL/6J genetic background.

Allele

Symbol: Ace2^{tm1.1(ACE2)Mdk}
Name: targeted mutation 1.1, Michael Koob
MGI accession ID: MGI:6509009
Generation method: Targeted
Attributes: Inserted expressed sequence; Humanized sequence
Marker symbol: Ace2
Marker name: angiotensin I converting enzyme (peptidyl-dipeptidase A) 2
Chromosome: X
Strain of origin: C57BL/6NTac
Molecular note: The targeting vector is designed to replace 71 kb (70,987bp) on the mouse X chromosome stretching from, but not including, collectrin, amino acid transport regulator (Cltrn) gene to BMX non-receptor tyrosine kinase (Bmx) gene with a syntenic 66 kb (65,812bp) region from the human X chromosome. A loxN-flanked neomycin resistance (neo) cassette was inserted at the junction between the human ACE2 and mouse Bmx genes. Transient cre-mediated recombination removed the floxed neo cassette.