Host cell-mediated selection of influenza C variants

1. 为了研究宿主细胞类型对丙型流感病毒抗原变异选择的影响，分离了6株流感病毒，分别在胚胎母鸡的羊膜囊和人恶性黑色素瘤细胞HMV-II细胞系中传代，用一组单克隆抗体（mab）检测其对血凝素酯酶（HE）糖蛋白的反应性。用Yamagata/4/88和Yamagata/7/88两株病毒在HMV-II细胞中连续传代的HE蛋白与在卵细胞中培养的病毒具有抗原性差异。研究还发现，在HMV-II细胞中重复传代后获得的所有病毒克隆，在细胞培养物中的复制能力都明显高于从蛋培养病毒制剂中获得的克隆，尽管HMV-II细胞和蛋培养病毒克隆在蛋中生长的能力没有差异。这些观察结果表明，在HMV-II细胞中分离和传代更多的C型流感病毒有时会导致在该宿主细胞类型中具有生长优势的抗原变体的选择。为了解HMV-II细胞中抗原变异选择的分子机制，测定了C/Yamagata/4/88和C/Yamagata/ 7/88连续传代的HE基因序列，并与卵细胞传代的病毒序列进行了比较。结果表明，适应于HMV-II细胞的C/Yamagata/4/88和C/Yamagata/7/88病毒在283位（Asp - b> Asn）和212位（Glu -> Lys）上的氨基酸发生了变化。最近，我们发现单克隆抗体选择的抗原变体具有与HMV-II细胞适应病毒相同的氨基酸变化，对鸡红细胞受体具有更高的亲和力。因此，在C/Yamagata/ 4/88和C/Yamagata/7/88株在HMV-II细胞传代过程中出现的抗原变异体很可能是选择与宿主细胞受体结合能力增强的变异体的结果。少

1. To study the influence of the host cell type on the selection of antigenie variants of influenza C virus, six strains were isolated and passaged in the amniotic sac of embryonated hen's eggs or in the HMV-II line of human malignant melanoma cells and were tested for the reactivity with a panel of monoclonal antibodies (MAbs) to the hemagglutininesterase (HE) glycoprotein. It was observed with two strains (Yamagata/4/88, Yamagata/7/88) that the HE protein of the virus serially passaged in HMV-II cells was antigenically distinguishable from that of the virus cultivated in eggs. It was also found that all virus clones obtained after repeated passages of these two strains in HMV-II cells possessed a markedly increased ability to replicate in the cell culture compared to the clones derived from egg-grown virus preparations, although no difference was seen in the ability to grow in eggs between HMV-II cell-and egg-grown virus clones. These observations suggest that isolation and passage o … More f influenza C virus in HMV-II cells sometimes result in the selection of antigenie variants which have the growth advantage in this host cell type.2. To obtain informations about the molecular mechanisms for the selection of antigenic variants in HMV-II cells, the HE gene sequences were determined for the C/Yamagata/4/88 and C/ Yamagata/7/88 strains serially passaged in the cell culture and then compared with the sequences of the viruses passaged exclusively in eggs. The results showed that the C/Yamagata/4/88 and C/Yamagata/7/88 viruses adapted to HMV-II cells had amino acid changes at positions 283(Asp -> Asn)and 212(Glu -> Lys), compared with the viruses cultivated in eggs. Recently, we revealed that the MAb-selected antigenic variants which had the same amino acid changes as those found in HMV-II cell-adapted viruses exhibited the increased affinity to chicken erythrocyte receptors. It appears likely, therefore, that the emergence of antigenic variants which occurred during the passages of the C/Yamagata /4/88 and C/Yamagata/7/88 strains in HMV-II cells is the result of the selection of variants having the increased binding capacity to host cell receptors. Less