BRGS A2DR2 mouse
Immunodeficient mouse for immunology and oncology research
C-Rag2tm1Fwa -Il2rgtm1Cgn -SirpaNOD -Tg HLA-A*02-HHD Class I and HLA-DRB1*15 Class II
Mutant inbred mouse, Mus musculus, GMO
Use of this strain is restricted to private sector users
Institut Pasteur, France, 2022
Colour and related genotype:
Cryo, In vitro, In vivo
Description of our model and application areas
The BRGS A2DR2 or Balb/c Rag2 γc Sirpa strain is a severely immunodeficient inbred (Balb/c background) strain model with 2 Knock Out (KO) genetic mutations and a NOD background gene: the γc KO (Interleukin 2 receptor gamma chain, IL2rgTm1) gene, the Rag2 KO (recombinase 2 activating gene) gene and the Sirpa (NOD Background) gene. This model also carries two transgenes expressing the HLA A2 and DR2 molecules.
The Rag2Tm1 mutation, commonly known as Rag2, is a KO mutation in the gene coding for the recombinase 2 enzyme, which plays a key role in the generation of T and B receptors in lymphocytes. This absence blocks the development of T and B lymphocytes and induces an immune deficiency. Mice homozygous for this mutation have a complete absence of T and B lymphocytes in the periphery.
The IL2rgTm1 mutation called γc is a KO mutation of the gene encoding the gamma c chain common to (among others) interleukins (IL-2, IL-4, IL-7, IL-9 and IL-15). This gene is required for the differentiation and function of many haematopoietic cells with a complete impact on the development of Natural Killer (NK) cells.
The combination of these two mutations, Rag2Tm1–IL2rgTm1, induces a severe immunodeficiency with absence of T, B and NK lymphocyte compartments.
The BRGS A2DR2 strain carries the Sirpα gene from the NOD background with a particular polymorphism. Expression of the Sirpα protein (NOD fund alleles) on the surface of bone marrow macrophages allows high-affinity binding to CD47 markers of human haematopoietic cells.
This binding induces a “don’t eat me” signal that blocks murine macrophages and prevents phagocytosis of transplanted human cells.
This is a notable feature of the NOD background (transferred by backross to BRG Balb/c mutants) that gives it an advantage in human transplantation and xenotransplantation in general.
The BRGS A2DR2 strain carries transgenes expressing human HLA A2 and DR2 molecules (HLA-A*02-HHD Class I and HLA-DRB1*15 Class II).
BRGS A2DR2 differs from NXG (NOD-Prkdcscid–IL2rgTm1/Rj) strains by the absence of the Prkdcscid mutation, commonly referred to as “SCID” for Severe Combinated Immunodeficiency. The BRGS A2DR2 strain is thus more resistant to irradiation, injection of genotoxic products and stress, conferring a more stable and durable use to xenograft in general, and carry peripheral lymph nodes, allowing an optimisation of human immune system xenografts, by increasing the quality, quantity and functionality of the actors of immunity.
JANVIER LABS has licensed the BRGS A2DR2 strain from the Institut Pasteur.
The animals are bred to maintain both the genetic background and the mutations of interest in their homozygous forms.
The BRGS A2DR2 strain is bred in inbred mode and the phenotype is controlled in accordance with the JANVIER LABS GENETIC POLICY®.
Main application and research fields
This model has been entirely characterized. The immunological and hematological parameters were characterized by Center of Immunophenomics (Ciphe, Marseille, France).
Flow cytometry analysis, spleen
Representative flow cytometry analysis confirming the absence of positive B cells (CD19), positive T cells (CD4 and CD8) and NK cells (CD335) in the peripheral blood of BRGS A2DR2 mice.
- Fluorescence intensities (MFI) represent specific expressions of clusters of differentiations.
- Clouds of points are obtained, each point representing a cell.
- We can then determine the negative/single and positive/double positive cells in each populations (defined by « Cluster of Differentiation ») , fixing or not the two antibodies carrying the fluorochromes.
Phenotypical / Physiological observations
BRGS A2DR2 mice are viable, fertile, of normal size, and show no obvious physical or behavioral abnormalities. Histological examination of the lymphoid tissues reveals the absence of lymphoid cells and certain cystic structures in the thymus, an absence of follicles in the spleen, and markedly reduced cellularity of the lymph nodes.
BRGS A2DR2 mice are deficient in mature lymphocytes, serum Ig is not detectable.
These mice are resistant to the development of lymphomas even after treatment with sublethal radiation. These mutant mice have been shown to readily support the transplantation of human CD34+ hematopoietic stem cells and represent a superior long-lived model suitable for studies using xenotransplantation strategies.
Origin / Creation
Balb/c Rag2 γc Sirpa congenic animals were generated at the Institut Pasteur, and then backcrossed (speed congenics) to BALB/c(n) background for six generations.
The BRGS A2DR2 strain carries the transgenes expressing the human HLA molecules A2 and DR2.
HLA-A*02-HHD class I and HLA-DRB1*15 class II transgenic mice (B6 background), have been then backrossed (>10 generations) to the Balb/c Rag2 γc Sirpa strain (BRGS) , to create BRGS A2DR2 Strain
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