为分析羊口疮病毒（ORFV/QD/2015株）B2L基因的分子特征，预测其编码蛋白的生物学功能，对其B2L基因进行PCR扩增、克隆及序列测定，应用生物信息学相关软件及方法，对扩增所得的基因进行序列分析，并对其编码蛋白的二级结构、细胞抗原表位、三级结构、跨膜结构域和信号肽等进行预测和分析。结果显示：ORFV/QD/2015株B2L基因序列长1 137 bp，编码379个氨基酸；该毒株与其他12株羊口疮病毒参考株的B2L基因核苷酸序列同源性为96.8%~99.7%，氨基酸序列同源性为96.8%~99.2%。系统进化分析显示，ORFV/QD/2015株与2015年分离到的ORFV/ShaanXi/2015/China株亲缘关系最近；B2L基因编码蛋白二级结构以α-螺旋区域和β-折叠区域所占比例较大，预测此蛋白可能存在7个细胞优势抗原表位，无跨膜区域，无信号肽区域；三级结构呈弯曲状螺旋结构。
In order to analyze molecular characteristics of B2L gene of Orf virus（ORFV/QD/2015） strain and to predict biological function of B2L protein. In this study，the B2L gene was amplified，cloned and sequenced. Using related bio-informatics softwares and methods，the amplified sequence was analyzed and B2L protein's secondary structure，tertiary structure，B-cell preponderant epitope，conserved domain，transmembrane domain and signal peptide were also predicted and analyzed. Results showed that the length of B2L gene was 1 137 bp，encoding 379 amino acids. The B2L gene of ORFV/QD/2015 strain shared amino acid identities of 96.8%~99.2% and nucleotide identities of 96.8%~99.7%，respectively，compared with other 12 ORFV reference strains. Phylogenetic analysis indicated a closest relationship between ORFV/QD/2015 strain and ORFV/ShaanXi/2015/China strain，the latter was isolated in 2015. Prediction of secondary structure of B2L protein indicated α-helix and β-sheet took up a large proportion.，and B2L protein possibly contained 7 potential antigen epitopes. However，no transmembrane domain or signal peptide was identified. The tertiary structure of B2L protein was curved spiral structure.