Different ACE2 mouse models available for your COVID-19 research needs:

Photos: BLiSC-ACRC facility staff handling/monitoring a humanized ACE2 mouse.

Understanding the pathogenesis of the virus causing COVID-19, its unexpected effects on multiple organs in the body, and the hope to develop effective treatments and vaccines highlight the need for animal models to understand viral infection and the complex host response they sometimes elicit.  Mouse models are the preeminent platform for pre-clinical studies and have provided insights into disease etiology as well as serving as a platform for vaccine and drug development.   Studies have shown that the virus causing COVID-19, Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2), enters the human body by binding to human angiotensin-converting enzyme 2 (ACE2). However, due to structural differences in mouse ACE2 compared to human ACE2 proteins, rodents are refractory to SARS-Cov-2 infection. Consequently, commonly used wild-type mouse strains are not appropriate for studying infections of this coronavirus.

In response to the immediate needs of researchers nationwide, the Mouse Genome Engineering Facility (MGEF) of the Bangalore Life Science Cluster (BLiSC), has leveraged its expertise and infrastructure that was established with generous support from the National Mouse Resource (NaMoR) grant from the DBT to address this public health crisis.  Together with experts from Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) and the TATA Institute for Genetics and Society – Centre at inStem the facility has designed 3 different sets of ACE2 mouse models to facilitate  SARS-CoV /COVID-19 related research and therapeutics projects:

 

1)   The first model is the Transgenic: Tg(K18-hACE2)/Blisc mouse. This is a humanized model expressing the human ACE2 gene under the regulatory sequences of the human keratin 18 (KRT18) promoter.  The regulatory elements contained in the K18 sequence targets hACE2 transgene expression to the lung airways and epithelia of other organs. The original transgene construct (schematized below) used for zygote pronuclear microinjection is the K18-hACE2 transgene plasmid kindly donated by Paul B. McCray et al. who designed the Tg(K18-hACE2)2Prlmn/J [PMID: 17079315] model in 2003 and currently made available at the Jackson Laboratory.

      

Six different Tg(K18-hACE2)/Blisc founder lines have been generated at MGEF- Bangalore. These founder lines are expected to vary in transgene copy number and in genome integration site which will therefore result in differences in organ specific hACE2 expression patterns and levels.

 

2)  The second humanized hACE2 mouse model we have generated is a Targeted Knock-IN hACE2-KI/Blisc model in which the mouseAce2 locus is replaced by the human ACE2 coding sequences. This model is expected to more faithfully recapitulate the full endogenous spatio-temporal expression levels of ACE2.

     

 

3) Finally two different mAce2 Knock OUT mice have been generated.

In the first Ace2-KO1/Blisc, only the first exon of mAce2 has been deleted. The second Ace2-KO2/Blisc is a deletion of the entire 47Kb mouse locus.

These mice would result in the complete loss and/or dramatically reduced Ace2 activity and function and would be will be resistant to Covid infection - they will be useful for understanding the normal function of Ace2. ACE2 receptors are involved in the degradation of AngiotensinII, which is an important vasoconstrictor. Recent studies demonstrating that ACE2 receptor deficiency in patients may be responsible for increased severity of  COVID19 disease symptoms such as vasoconstriction, enhanced inflammation and thrombosis upon SARS-CoV-2 infection [PMID: 32336612], So these Ace2 KO/Blisc models  can be combined with the KI model to further investigate ACE2’s role in COVID-19 progression.

     

 

ACE2 MODEL AVAILABILITY TIMELINE AND REQUIREMENTS

Founder lines of each ACE2 Mouse described above have been generated and are being characterized for transgene copy number, mosaicism, and organ specific expression levels of human and/or mouse ACE2 mRNA and protein.

Detailed characterization of these animals will be updated live online on this website as the results become available.

 

AVAILABILITY OF MICE

  1. Tg(K18-hACE2)/Blisc model the first characterized breeder pairs of animals will be available for redistribution by November / December 2020.
  2. Ace2-KO/Blisc mice are undergoing colony expansion- The first set of breeders will be available for redistribution by November / December 2020.
  3. Finally the hACE2-KI/Blisc mouse is being backrossed. The first breeder pairs should be available by January / February 2021.

 

Pre-Order HERE:

The different types of ACE2/Blisc models can be pre-ordered by filling out this ACE2 order FORM.

Please note that we will only initially be able to provide a maximum of 2 breeder pairs of each stock for each requesting Institute. The Institute will then be able to expand these stocks in their respective facilities- for their experimental requirements-

If you would like to request the service for ACRC to breed & expand these stocks for you in our High Barrier SPF Facility, please do mention this in the pre-order form.(see link above).

 

Important Biosafety Note:

The humanized hACE2 models should be handled, housed and maintained with extreme caution consistent with  CDC / ABSA / WHO guidelines for handling of and procedures involving  SARS-CoV-2 virus.  These are animals designed to be susceptible to SARS-CoV-2 infection- Dedicated and appropriate PPEs, animal housing and handling SOPs should be followed strictly when working with these mice.

 

 Due to IAEC and IBSC regulatory requirements involved in working with these Tg(K18-hACE2)/Blisc,  Ace2-KO/Blisc, and/or hACE2-KI/Blisc mice for SARS-CoV2 infectious studies: researchers are strongly encouraged to begin the statutory clearances as early as possible.