PMID:12438573

Citation	Andrés, G, Alejo, A, Salas, J and Salas, ML (2002) African swine fever virus polyproteins pp220 and pp62 assemble into the core shell. J. Virol. 76:12473-82
Abstract	African swine fever virus (ASFV), a complex enveloped DNA virus, expresses two polyprotein precursors, pp220 and pp62, which after proteolytic processing give rise to several major components of the virus particle. We have analyzed the structural role of polyprotein pp62, the precursor form of mature products p35 and p15, in virus morphogenesis. Densitometric analysis of one- and two-dimensional gels of purified virions showed that proteins p35 and p15, as well as the pp220-derived products, are present in equimolecular amounts in the virus particle. Immunoelectron microscopy revealed that the pp62-derived products localize at the core shell, a matrix-like domain placed between the DNA-containing nucleoid and the inner envelope, where the pp220-derived products are also localized. Pulse-chase experiments indicated that the processing of both polyprotein precursors is concomitant with virus assembly. Furthermore, using inducible ASFV recombinants, we show that pp62 processing requires the expression of the pp220 core precursor, whereas the processing of both precursors pp220 and pp62 is dependent on expression of the major capsid protein p72. Interestingly, when p72 expression is blocked, unprocessed pp220 and pp62 polyproteins assemble into aberrant zipper-like elements consisting of an elongated membrane-bound protein structure reminiscent of the core shell. Moreover, the two polyproteins, when coexpressed in COS cells, interact with each other to form zipper-like structures. Together, these findings indicate that the mature products derived from both polyproteins, which collectively account for about 30% of the virion protein mass, are the basic components of the core shell and that polyprotein processing represents a maturational process related to ASFV morphogenesis.
Links	PubMed PMC136718
Keywords	African Swine Fever Virus/chemistry; African Swine Fever Virus/physiology; Animals; COS Cells; Capsid/physiology; Polyproteins/analysis; Polyproteins/chemistry; Polyproteins/physiology; Protein Precursors/chemistry; Viral Proteins/chemistry; Virus Assembly
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ASFB7:PP220		GO:0019069: viral capsid assembly	ECO:0006003:		P		Figure 8 shows through electron microscopy that the expression of polyprotein pp220 in the African Swine Fever Virus allows for the assembly of coating on the membrane. This can be seen to lead to the formation of a viral core-shell when joined with another polyprotein, pp62. Uniprot: Polyprotein pp220, Ba71V-92	complete CACAO 13678
ASFB7:PP62		GO:0019069: viral capsid assembly	ECO:0006003:		P		Figure 8 shows through electron microscopy that the expression of polyprotein pp62 in the African Swine Fever Virus allows for the assembly of shell-like membrane, when it is joined with the presence of polyprotein pp220. Figure 8 also shows the interaction of the two polyproteins to form this shell through the use of gold-labelling. Uniprot: Polyprotein pp62, Ba71V-94	complete CACAO 13679

References

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