In the case of U2OS, CCF-STTG1 and HFL-1 cells, which have long telomeric repeats (over 10 kb), the band intensity of telomeric repeats decreased drastically when EN-T adenovirus was infected, but did not change when GFP-TRF1 (G-T) and FN-T viruses were infected, in comparison with no virus infection (Figure 4a-d). This evidence concerns the gene TERF1 and viral infectious disease.