Question: There are so many mouse strains. How should I choose for experiments?

Answer: Let's discuss the characteristics and applications of commonly used mouse strains.

 

01. Inbred Strains
 

Inbred strains are developed through at least 20 generations of sibling mating, resulting in high genetic homozygosity, uniform phenotypes among individuals, and a stable genetic background. Examples like C57BL/6 and BALB/c mice are the most widely used strains in research.

1) BALB/c Mice

● Coat Color: White (albino).

● Characteristics: Low incidence of mammary tumors. Both sexes develop arteriosclerosis. They have relatively high blood pressure compared to other inbred strains, with a tendency for spontaneous hypertension and frequent cardiac lesions.

● Applications: Commonly used in oncology, immunology, and inflammation research.
 

 

2) C57BL/6 Mice

● Coat Color: Black.

● Characteristics: Low spontaneous incidence of mammary tumors. Prone to age-related glomerulosclerosis. Relatively low sensitivity to chemically induced carcinogenesis. C57BL/6 was the first mouse strain to have its genome fully sequenced. It is frequently used for generating genetically modified animal models, ensuring high genetic background stability and consistency of experimental data.

● Applications: Research in genetics, immunology, physiology, and other fields.
 

 

3) C3H/He Mice

● Coat Color: Agouti (wild-type).

● Characteristics: High spontaneous incidence of hepatocellular carcinoma (85% by 14 months). High spontaneous mammary tumor incidence: averaging 90% in breeding females (100% by 318 days, 67% by 234 days), 84% in breeding males by 272 days. High complement activity. Sensitive to hepatocarcinogens and rabies virus. Resistant to Bacillus anthracis.

● Applications: Research in immunology, oncology, physiology, and nuclear medicine.
 

 

02. Outbred/Closed Colony Mice

 

Closed colonies are maintained by non-inbred mating. They have a high degree of genetic heterozygosity, with variation among individuals, but the gene frequency within the population is relatively stable. Common outbred stocks include KM mice and ICR mice, often used in fundamental research.

1) Kunming (KM) Mice

● Coat Color: White (albino).

● Characteristics: High fecundity, strong disease resistance, good adaptability. Common spontaneous tumor is mammary carcinoma, with an incidence around 25%.

● Applications: Pharmacology, toxicology, virology, and bacteriology studies, as well as the testing of biological products and drugs.

2) CD-1 (ICR) Mice

● Coat Color: White (albino).

● Characteristics: High adaptability, robust constitution, strong reproductive capacity, rapid growth, good experimental reproducibility.

● Applications: Research in pharmacology, toxicology, oncology, radiobiology, food science, biological products, and many other fields.

3) NIH Mice

● Coat Color: White (albino).

● Characteristics: Strong reproductive capacity, high pup survival rate. Males tend to be aggressive.

● Applications: Primarily used for drug toxicity studies and the testing of biological products like hepatitis B vaccines and pertussis vaccines.

 

03. Mutant Strains
 

Mutant strains are developed through spontaneous mutation, induced mutagenesis, or genetic engineering, possessing specific genetic traits. Examples like nude mice and SCID mice are commonly used as immunodeficient models.

1) BALB/c-nu (Nude Mice)

● Coat/Hair: Hairless.

● Characteristics: Impaired growth and development. Congenital thymic aplasia leads to T-cell deficiency. As nude mice age, functional T cells may increase ("immune leakage"). Therefore, tumor inoculation is typically performed in 4-8 week-old mice; older nude mice are less suitable for tumor studies.

● Applications: Research in immunology, oncology, microbiology, and disease mechanisms.
 

 

2) SCID Mice

Severe Combined Immunodeficiency (SCID) mice.

● Coat Color: White (albino).

● Characteristics: Profound lymphocyte deficiency. Drastically reduced T and B lymphocytes in the thymus, spleen, and lymph nodes, leading to defects in both cellular and humoral immunity. Macrophage and Natural Killer (NK) cell functions remain largely intact. Bone marrow structure is normal. Peripheral blood leukocyte and lymphocyte counts are low. SCID mice are extremely susceptible to infections and must be housed in barrier facilities. They can live over a year in a highly clean SPF environment. Litter size is typically 3-5 pups.

● Applications: Research in immunology, oncology, and monoclonal antibody production.

 

References:

[1] Tang Hongbin, Kong Lijia. (2006). Laboratory Animal Science. Wuhan: Hubei People's Publishing House.

[2] Qin Chuan. (2008). Medical Laboratory Animal Science. Beijing: People's Medical Publishing House.

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