After 3 days of lentivirus infection, obvious GFP fluorescence could be detected in the infected tooth germs, meanwhile, the Clcn7 mRNA level was decreased about 70% in the Clcn7-shRNA treated group, compared to the negative-shRNA group (P = 0.0001, data not shown). The gene discussed is CLCN7; the disease is lentivirus infection.