Abstract: HCLV strain was grown in Primary bovine testicular cells, from 1 to 34serial passages were made continuously. The result of Sequence analysis showed
The homologies of 3’-UTR nucleotide sequence was 100％ from 1 to 25 serial passages. 12-nt(ttttttctttttt) insertion began to change from 26 serial passages, two T more than 1 serial passages in 69 place from 26 to 27 serial passages, Two T more than 1 serial passages in 69 place from 28 to 29 serial passages, six T more than 1 serial passages in 69 place from 30 to 31 serial passages, two T lack than 1 serial passages in 69 place from 32 to 33 serial passages, ten T more than 1 serial passages in 69 place 34 serial passages, A to G in 86 place, T to C in 92 place. HCLV strain from 1 to 34 serial passages cultured in PK-15 cells, immuno fluorescence assay in 72 h, Detection the difference of HCLV from 1 to 34 serial passages. detection indicated the titer of HCLV began to decrease from 28 serial passages.

Key words: hog cholcra lapinized vaccine; 3’-UTR; RT-PCR; sequencing