Abstract: IBRS-2 cells appeared differentiation and were effective on using. In order not to affect the normal scientific studies, the study referred to repurify the IBRS-2 cells by single cell cloning method. For 3 weeks culture in 96 wells plate independently, the 4 representative cells were chosen to passage by single cell cloning. The 4 cloning cells strains were vaccinated respectively and tested the TCID₅₀ with low virulence FMDV, that its virus titer was known. The result is that, the pathological change of the B1 cells strain was the best, its TCID₅₀ was 7.60. It was more close to the factual virus titers 7.85 than the same before purifying 4.52. The TCID₅₀ of the known FMDV from the B1 cells strain and the factual TCID₅₀ of the known FMDV, they have no salient difference.

Key words: single cell cloning; IBRS-2 cells; differentiation; purification