The amount of effective information of Avian infectious bronchitis virus is: I=76,512 bits. The genome size is: C=length of genome 2 = 55,216 bits. So the I value is larger than the C value. After checking the virus genome, we find there is an overlap between genes. It's the overlap that makes the I value too large. When calculating the information of the overlapping part of the genes for the second time, because these base pairs already cannot change any more and there are no possibilities to be excluded, the amount of information for the second time calculation is 0. For example, sequences AACCC and CCCGG have overlapping part CCC. The information of the first sequence is 5 2 = 10 bits. The information of the second sequence is 2 2 = 4 bits because the information of sequence CCC is already known and this part contains no new information. So the information of sequence AACCCGG is 14 bits rather than 20 bits. The actual value of I 1 should be exactly equal to the size of the protein coding area. For virus genomes with overlapping genes, we use the actual size of protein coding area instead of Σn 6 to calculate the effective information. The effective information of some viruses is as follows ( Table 1) .