Yellow fever virus, the prototype in the genus Flavivirus, was used to develop viruses in which the nonstructural protein NS1 is genetically fused to GFP in the context of viruses capable of autonomous replication. The GFP-tagging of NS1 at the amino-terminus appeared possible despite the presence of a small and functionally important domain at the NS1′s amino-terminus which can be distorted by such fusing.

GFP-tagged NS1 viruses were rescued from DNA-launched molecular clones. The initially produced GFP-tagged NS1 virus was capable of only poor replication. Sequential passages of the virus in cell cultures resulted in the appearance of mutations in GFP, NS4A, NS4B and NS5. The mutations which change amino acid sequences of GFP, NS4A and NS5 have the adaptive effect on the replication of GFP-tagged NS1 viruses. The pattern of GFP-fluorescence indicates that the GFP-NS1 fusion protein is produced into the endoplasmic reticulum. The intracellular GFP-NS1 fusion protein colocalizes with dsRNA. The discovered forms of extracellular GFP-NS1 possibly include tetramers and hexamers.

黄热病毒属的原型黄热病毒被用于开发病毒，其中非结构蛋白 NS1 在能够自主复制的病毒的背景下与 GFP 基因融合。尽管在 NS1 的氨基末端存在一个小的且功能重要的结构域，该结构域可能会被这种融合扭曲，但 NS1 在氨基末端的 GFP 标记似乎是可能的。

从 DNA 启动的分子克隆中拯救了 GFP 标记的 NS1 病毒。最初产生的带有 GFP 标记的 NS1 病毒只能进行较差的复制。病毒在细胞培养物中的连续传代导致出现 GFP、NS4A、NS4B 和 NS5 突变。改变 GFP、NS4A 和 NS5 氨基酸序列的突变对 GFP 标记的 NS1 病毒的复制具有适应性作用。GFP-荧光模式表明GFP-NS1融合蛋白是在内质网中产生的。细胞内 GFP-NS1 融合蛋白与 dsRNA 共定位。发现的细胞外 GFP-NS1 形式可能包括四聚体和六聚体。