CBA mice are a widely used inbred strain of laboratory mouse with a long history in scientific research. Their consistent genetic makeup ensures reproducible study outcomes, making them a standard choice across various disciplines.
Origin and Key Traits
The ancestral CBA strain was developed in 1920 by C.C. Strong, who initiated a cross between a Bagg albino female and a DBA male mouse. This lineage was selectively bred for a low incidence of breast cancer, leading to the establishment of the CBA strain. Over time, different substrains, such as CBA/J and CBA/CaJ, have emerged.
CBA/J mice are light/tan brown; CBA/CaJ mice have light brown fur. CBA/J mice have congenital early-onset blindness from the Pde6brd1 mutation, causing complete blindness by weaning age. CBA/CaJ mice lack this mutation and perform better in spatial memory tests like the Morris water maze.
Both CBA/J and CBA/CaJ mice maintain sensitive hearing into old age. CBA/J mice show minimal hearing loss by 18 months, but CBA/CaJ mice exhibit more rapid elevation of auditory brainstem response (ABR) thresholds at high frequencies after one year, with progressive decline in endocochlear potential.
CBA mice have specific immune responses, displaying alterations in eosinophils and spleen weight ratios following low inoculations of pathogens like Toxocara canis. The CBA strain has a low incidence of spontaneous tumors. However, CBA/J mice are susceptible to lymphoma, hepatoma, lung adenoma, and leukemia. Older CBA mice can develop spontaneous liver tumors.
Why Researchers Choose CBA Mice
CBA mice are suitable models for scientific inquiries, leading to widespread use, particularly in audiology and hearing research due to their robust auditory system and distinct age-related hearing loss patterns. CBA/J mice are often chosen to study sensorineural presbycusis, characterized by delayed high-frequency hearing loss and degeneration of spiral ganglion cells. CBA/CaJ mice are used to investigate strial presbycusis, which includes accelerated hearing loss and strial degeneration.
In immunology, CBA mice study immune responses and disorders. Researchers characterize CBA/J mice’s immunological responsiveness to graded infections, observing changes in eosinophil counts and spleen size with small pathogen exposures. Their immune system’s response to various antigens and infections, such as Mycobacterium tuberculosis or Toxocara canis, provides insights into host-pathogen interactions and vaccine development.
CBA mice are used in cancer research due to their low spontaneous tumor incidence and susceptibility to induced cancers. The CBA/CaJ substrain has a low spontaneous incidence of leukemia, but myeloid leukemia can be readily induced, making them suitable for leukemogenesis studies. This susceptibility to induced tumors after chemical injection or radiation exposure allows for investigation into cancer development and potential therapies.
CBA mice model radiation biology to understand radiation exposure effects. Male CBA/H mice exposed to radiation develop myeloid leukemia, modeling radiation-induced cancers and their progression. Inducing and studying leukemia in CBA mice after radiation exposure helps understand radiation’s long-term effects on biological systems and carcinogenesis mechanisms.
Advancements Driven by CBA Mouse Research
CBA mouse research has advanced understanding of biological processes and diseases, particularly in illuminating age-related hearing loss mechanisms. Comparisons between CBA/J and CBA/CaJ mice have shown distinct age-related cochlear pathologies, helping to differentiate between types of presbycusis, such as sensory versus strial, and informing potential interventions for human hearing decline.
CBA mouse research in immunology has contributed to understanding immune system functions and pathogen responses. Studies have characterized the immune system’s reaction to parasitic infections, showing how different host responses have varying thresholds of sensitization to antigens. This work helps define the magnitude and onset of humoral responses and informs vaccine strategies, as demonstrated by studies where CBA/J mice can generate protective immunity when antigens are delivered as a vaccine.
CBA mice have advanced cancer research, particularly leukemia studies. The inducibility of myeloid leukemia in CBA/CaJ mice, combined with their low spontaneous incidence, has allowed researchers to investigate genetic abnormalities associated with radiation-induced acute myeloid leukemia. Findings from these studies have provided insights into human myeloid disorders like myelodysplastic syndrome.
In radiation biology, CBA mice model radiation-induced cancers and evaluate treatment effectiveness. Research has examined the growth characteristics of radiation-induced myeloid leukemia, showing these cells can grow autonomously. These studies also explored how radiation affects hematopoietic stem cells and stromal cells in bone marrow, providing insights into changes contributing to radiation leukemogenesis.