CBA/CaHN-Btkxid/J, also known as CBA/N or CBA/CaN, is a strain of mutant mouse model that exhibits a particular kind of immunodeficiency resembling the human disease X-linked agammaglobulinemia.
CBA/N is derived from the ancestral CBA strain, which in turn was created by Strong in 1920 from a cross between a DBA mouse and a Bagg albino. CBA mice were obtained by Harwell in 1954, who developed CBA/N. CBA/N was passed to the National Institutes of Health in 1966.
The Jackson Laboratory must have obtained CBA/N at some point after 1966, although they do not detail this on their website.
Like normal CBA mice, the CBA/N strain has light brown fur. Externally, they do not exhibit any physical abnormalities compared to standard CBA. However, they have significantly smaller spleens, with a lower proportion of nucleated cells.
Behavioral Characteristics & Handling
As with all immunodeficient strains, great care must be taken when handling CBA/N. Mice should be kept in a sterile environment away from other strains, and handling should be avoided as much as possible. When handling is necessary, researchers should wear gloves and a face mask.
CBA/N mice have a point mutation in the gene Btk, coding for the enzyme Bruton agammaglobulinemia tyrosine kinase. This gene is located on the X chromosome, and so the effects of its mutation are more strongly felt in males (who are unable to compensate with a second non-mutant X chromosome).
Under normal circumstances, Btk phosphorylates and activates the enzyme phospholipase C, allowing this enzyme to catalyze the creation of signaling molecules involved in B lymphocyte maturation. The point mutation prevents Btk from playing this signaling role.
As a result of this deficit, precursors to B cells in CBA/N mice develop normally in the bone marrow, but then fail to mature, leading to a lack of B cells in the bloodstream and immunodeficiency. The mice cannot produce antibodies against thymus-independent type II antigens, and are thus vulnerable to infection (although they can produce some kinds of antibodies, such as IgD).
Major Experimental Uses
The CBA/N strain is of especial interest in the study of the rare immune deficiency X-linked agammaglobulinemia, on account of its health characteristics closely resembling the symptoms of that disease.
These mice are also of use in the general study of immune deficiency and immunology in general, as well as in the study of X-linked disorders.
- 001011 – CBA/CaHN-Btk/J. 2019. 001011 – CBA/CaHN-Btk/J. [ONLINE] Available at: https://www.jax.org/strain/001011. [Accessed 14 April 2019].
- MGI – Inbred Strains: CBA. 2019. MGI – Inbred Strains: CBA. [ONLINE] Available at: http://www.informatics.jax.org/inbred_strains/mouse/docs/CBA.shtml. [Accessed 14 April 2019].
- Scher, Irwin. 1982. The CBA/N Mouse Strain: An Experimental Model Illustration the Influence of the X-Chromosome on Immunity. Advances in Immunology. 33:1-71.
- Kim S, Lee S, Ryu S, Suk J, Park C. 2002. Comparative analysis of the anxiety-related behaviors in four inbred mice. Behav Processes. 60(2):181-190.
- Smith & Berglof. 2016. X-Linked Agammaglobulinemiam. GeneReviews. [ONLINE] Available at: https://www.ncbi.nlm.nih.gov/books/NBK1453/. [Accessed 14 April 2019].