Abstract: Two field strains of Newcastle disease virus(NDV) from Yunnan province had been isolated and identified by chick embryo inoculation, hemagglutination test(HA), hemagglutination inhibition test(HI) and reverse transcriptase-polymerase chain reaction(RT-PCR). The F genes of two field strains were amplified by specific RT-PCR, then purified and cloned into pMD18-T vector for sequencing. The homologies of F genes of the two field strains showed 99.4% to 99.6%, 99.7% to 99.8%, 89.0% to 89.1% at nucleotide level and 99.3% to 99.5%, 99.5% to 99.6%, 91.8% to 92.0% at amino acid level with La Sota vaccine strain, SP13 and NDV027344, and F48E9 field strains, respectively. Phylogenetic analysis results showed that the two strains were both belonged to genotypeⅡ, and the amino acid sequence of cleavage site was G-R-Q-G-R-L, possessed molecular characteristics of low virulent strains of NDV.

Key words: font-size: 10.5pt; mso-bidi-font-family: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA" lang="EN-US">genotype font-size: 10.5pt; mso-bidi-font-family: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">Ⅱ；Newcastle disease virus；F genes；sequence analysis