抗体选择压作用下新城疫病毒HN和F基因的演化及其抗原性变异的比较分析

TZ060107株新城疫病毒(NDV)在含有对它抗体的鸡胚成纤维细胞(CEF)培养上分3个独立系列连传50代,每10代扩增其HN和F基因并测序。选择变异最大的系列A1-50病毒,再在含有抗A1-50抗体的CEF培养上分3个独立系列连续传50代,同时设3个不带抗体的独立传代系列作为对照。对第60、70、80、90、100代病毒的HN和F基因序列比较结果显示,有抗体组HN基因的非同义突变(NS)对同义突变(S)比值NS/S为5.25,明显高于无抗体组NS/S的2.375。前50代在抗体选择压作用下已发生的稳定NS突变在含有抗A1-50抗体的细胞培养中传代仍能稳定保持,且又出现了一个新的稳定的NS突变位点。在有抗体组经传50代后F基因发生的稳定非同义突变,在抗A1-50血清作用下再连传50代后也仍然保持,且又出现3个新的稳定的NS突变。不同传代病毒与原始病毒间的血清交叉血球凝聚抑制试验结果表明,随着在含有抗NDV血清的细胞培养上传代代数的增加,病毒与原始病毒间在抗原性的差异越来越大。

Antigenic Comparative Analysis of Newcastle Disease Viruses with Evolutional Mutations in HN and F Genes under Antibody Immune Pressures

In chicken fibroblast cell(CEF) cultures with antiserum against Newcastle disease virus(NDV) strain TZ060107,the virus was passed serially for 50 passages in 3 independent lineages.HN and F genes were amplified and sequenced every 10 passages.The derived virus A1-50 with most mutations among 3 lineages was further passed for another 50 passages in CEF with or without antiserum against A1-50,each in 3 independent lineages.Sequence comparisons for HN and F genes of 60,70,80,90 and 100 passages indicated that the ratio of nonsynonymous mutations(NS) vs synonymous mutations(S) for HN genes in the lineages passed with antiserum against A1-50 was 5.25,which was obviously higher than 2.375 of NS/S in the lineages without the antiserum.The stable NS mutations occurred in the first 50 passages with the antiserum against the original TZ060107 were still maintained and one more new stable NS mutation appeared.For the F gene,3 new stable NS mutations occurred during the second 50 passages in lineages with antiserum against A1-50 when the original NS mutations obtained in the first 50 passages with antiserum against TZ060107 still existed.Cross hemagglutination inhibition(HI) between original virus and its derivative viruses indicated that the more continuous passages in cell culture with antiserum passed,the bigger difference of antigenicity between the virus and the original virus had.