囊膜病毒可能采用相似的病毒-宿主细胞膜融合机制，即病毒表面糖蛋白结合到宿主细胞受体后，启动了病毒融合蛋白的一系列构象变化，根据囊膜蛋白构象变化特征，囊膜病毒可采用两种以上的方式发生膜融合，并据此分为两类：Ⅰ型病毒膜融合和Ⅱ型病毒膜融合。Ⅱ型病毒膜融合以黄病毒为代表，其分子机制与Ⅰ型病毒膜融合不同，但不很清楚。而Ⅰ型病毒膜融合中，如艾滋病毒，流感病毒等，在囊膜蛋白变构形成稳定折叠的发夹三聚体结构时，拉近了两膜之间的距离，此过程释放出来的能量进一步促使两膜融合。膜融合使病毒蛋白及病毒RNA基因组释放到宿主细胞内而感染宿主。以上述研究为基础设计的C肽/N肽小分子抑制子，可以在病毒糖蛋白中间体构象形成的短时间内，高效、特异地竞争结合其配体，从而阻止糖蛋白的进一步折叠，达到抑制病毒入侵的目的，为病毒疾病的防治提供了新思路和策略。针对艾滋病毒设计的C肽，即T2O或Enfuvirtide在临床应用效果很好。以艾滋病毒和流感病毒为例，主要对Ⅰ型病毒膜融合的研究进展进行了讨论。

Paramyxovirus might adopt a molecular mechanism of membrane fusion similar to that of other class I viruses in which the heptad repeat (HR) regions of fusion protein (F) HR1 and HR2 form a six-helix bundle structure inducing membrane fusion. In this study, we examined the structure and function of HR1 and HR2 from the avian paramyxovirus-2 (APMV-2) Fprotein. The study showed that APMV-2 HR1 and HR2 formed a stable six-helix bundle. Only a soluble APMV-2 HR2 peptide showed potent and speciWc virus-cell fusion inhibition activity. Cross-inhibiting activity with APMV-1 (Newcastle disease virus, NDV) was not found. A possible mechanism of membrane fusion inhibition by the paramyxovirus HR2 peptide is discussed.

In an attempt to construct a DNA vaccine against chicken coccidiosis, the TA4 gene of Eimeria tenella strain BJ was ligated to the mammalian expression vector pcDNA3.1/Zeo (+) to give pcDNA3.1-TA4 (pcDT). Then, Et1A (E. tenella refractile body gene) was ligated to it, upstream, aiming to be expressed in fusion with TA4, giving pcDNA3.1-Et1A-TA4 (pcDET). The constructed DNA vaccines were given to broilers intramuscularly 10-15min after the breasts had been pretreated with 25% sucrose solution. At 7 days after the second vaccination, chickens were challenged with 3

It is emerging that enveloped viruses may adopt a unique entry/fusion mechanism; in paramyxoviruses, including Sendai virus (SeV), the attachment protein HN (or its homologue Hor G) binds a cellular receptor which triggers conformational changes of its fusion protein, F. There are at least three conformations of the F protein in the current fusion model: the pre-fusion native conformation, the prehairpin intermediate conformation and the post-fusion coiled-coil conformation. The fusion mechanism of SeV, a member of the Paramyxoviridae family, has been well established and several structural and functional domains or modules have been proposed from studies of its Fprotein. However, biochemical and biophysical studies of the heptad-repeat (HR) regions (HR1 and HR2) have not been systematically carried out. HR1 and HR2 strongly interact with each other to form a stable six-helix coiled-coil bundle as the postfusion conformation. In this study, a single-chain HR1