Virus Mor- bidity Mor- tality ELISA Virus isolation, ID50/ml3 (10 birds per group) Virus isolation, EID50/gram4(2 birds per group) Oral Cloacal Brain Heart Lung Kidney VN/H5N2 LAIV 0/101 0/101 0/82 ≤ 100.9 ≤ 100.9 ≤ 101.9 ≤ 101.9 ≤ 101.9 ≤ 101.9 VN/H5N1-RG LAIV 0/10 0/10  0/8 ≤ 100.9 ≤ 100.9 ≤ 101.9 ≤ 101.9 ≤ 101.9 ≤ 101.9 t/T/H5N2 LAIV 0/10 0/10  0/8 ≤ 100.9 ≤ 100.9 ≤ 101.9 ≤ 101.9 ≤ 101.9 ≤ 101.9 1The number of affected birds/in group of 10; 2the number of birds with detection of avian influenza virus specific antibodies/in group of 8; 3the minimum amount detected by the technique is 100.97 EID50/ml; the titer of negative samples is considered to be ≤ 100.9 EID50/ ml; 4the minimum amount detected by the technique is 101.97 EID50’s/gram of tissue; the titer of negative samples is considered to be ≤ 101.9 EID50’s/gram of tissue. All the tissues were prepared as a 10% weight/volume suspension.

Table 6: Attenuated phenotype of H5-LAIV candidates in experiments on chickens, the third day after intranasal administration.