Scotomas in molecular virology and epidemiology of hepatitis C virus

Table 2 Summary of the properties of hepatitis C virus structural proteins

	Core	E1	E2	p7
Genome location	342-914	915-1490	1491-2579	2580-2769
Translation processing site	Rough ER
Amino acid composition	191	192	363	63
Molecular weight (kDa)	21-23	33-35	70-72	7
Glycosylation	No	Yes	Yes	No
Cleavage	ER signal peptidase and SPP
Crystal structure	Not available			Revealed
Functional unit	Dimer	Heterodimer?		Hexamer
Common function	Viral particle formation. Core, E1 and E2, together with p7 and NS2, are required for virus assembly (assembly module)
Unique function	Capsid protein, viral particle formation, viral genome recognizing and packaging. Interacts with cLDs in early viral particle formation process. Counters host antiviral factors and involves pathogenesis	Envelope glycoproteins, interact with SRB1, CD81, CLDN1, OCLN, etc. to trigger viral entry. Promote fusion with the endosomal membrane. Counter host immune response via hypervariable regions		Viroporin. Has key roles in organizing the virus assembly complex. p7-NS2 complex interacts with the NS3-4A enzyme to retrieve core protein from cLDs to form viral particle
Major scotomas	How do the core form the viral capsid? The signals and processes that mediate RNA packaging are largely unknown. What impeded us to resolve the structure of the viral glycoproteins? What is the real process in HCV entry? How are these receptors and co-receptors temporally and spatially used to ensure the early infection processes?

Start co-ordinates based on H77 (accession number, NC_004102). SRB1: Scavenger receptor class B member 1; CD81: Tetraspanin CD81; CLDN1: The tight junction protein claudin 1; OCLN: The tight junction protein occludin; cLDs: Cytosolic lipid droplets; ER: Endoplasmic reticulum; SPP: Signal peptidase and signal peptide peptidase; HCV: Hepatitis C virus. The molecular weights of E1 and E2 refer to the glycosylated forms.