The HA titre of lshi strain ND virus alter treatment with ether were elevated for 15-50 times (HA titre 40,960-1,310,720). The rise of HA titre of lshi strain after treatment was much higher than other standard strain such as sato strain, Miga-Tera strain and field strain isolated in Taiwan such as Chia-I and Shin-Ten strains. The antigencity were the same between the lshi strain and other strain being tested. To avoid the elution of the RBC after treatment with ether, M/25 KIO4 were added, and equal amount of protective agent which contained I% sodium glutamate acid, I% gelatin, and 20% lactose were added to substitute for I 0% glucose.
By the method memlioned above, the better frozen-drying antigen product were obtained. the titre of this product were 640 - 10,240, and will maintained it's titre for a year or above when being preserved in 2-5° C.