Disease relevance of PestiV2gp1

• This report shows that African swine fever virus (ASFV)--a large DNA-containing virus--synthesizes a polyprotein to produce several of its structural proteins [1].
• According to the results presented here, ASFV is the first example of a DNA virus that synthesizes a polyprotein as a strategy of gene expression [1].
• So far, polyprotein processing as a mechanism of gene expression had been found only in positive-strand RNA viruses and retroviruses [1].
• The subviral localization of the polyprotein products, examined on purified virions, was found to be the core shell [2].
• Cell-derived sequences in the N-terminal region of the polyprotein of a cytopathogenic pestivirus [3].

High impact information on PestiV2gp1

• Polyprotein processing in African swine fever virus: a novel gene expression strategy for a DNA virus [1].
• The identification of the ASFV protease will allow a better understanding of the role of polyprotein processing in virus assembly and may contribute to our knowledge of the emerging family of SUMO-1-specific proteases [4].
• On the other hand, transient expression of the CP2475L gene in COS cells showed that polyprotein pp220 assembles into electron-dense membrane-bound coats, whereas a mutant nonmyristoylated version of pp220 does not associate with cellular membranes but forms large cytoplasmic aggregates [5].
• 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 [6].
• We have identified an open reading frame (ORF), CP530R, within the EcoRI C' fragment of the African swine fever virus (ASFV) genome that encodes a polyprotein of 62 kDa (pp62) [7].

Chemical compound and disease context of PestiV2gp1

• Classical swine fever virus (CSFV) E2 glycoprotein contains a discrete epitope (TAVSPTTLR, residues 829-837 of CSFV polyprotein) recognized by monoclonal antibody (mAb) WH303, used to differentiate CSFV from related ruminant pestiviruses, Bovine Viral Diarrhea Virus (BVDV) and Border Disease Virus (BDV), that infect swine without causing disease [8].

Biological context of PestiV2gp1

• We have analyzed the structural role of polyprotein pp62, the precursor form of mature products p35 and p15, in virus morphogenesis [6].
• This proteolytic processing was found to take place at the consensus sequence Gly-Gly-X through an ordered cascade of proteolytic cleavages like that which also occurs with ASFV polyprotein pp220 (C. Simón-Mateo, G. Andrés, and E. Viñuela, EMBO J. 12:2977-2987, 1993) [7].
• It is composed of a 373-nt 5' terminal non-translated region (NTR), a 11697-nt open reading frame (ORF) encoding a polyprotein of 3898 amino acids (aa), and a 226-nt 3'-NTR [9].

Anatomical context of PestiV2gp1

• At the electron microscopic level, antibodies to pp220 labeled all identifiable forms of the virus from the precursor viral membranes onward, thus indicating an early role of the polyprotein pp220 in ASFV assembly [2].
• The single best-defined, SLA-I restricted porcine CD8(+) T-cell epitope currently known is a 9-residue peptide from the polyprotein of CSFV (J. Gen. Virol. 76 (1995) 3039) [10].

Analytical, diagnostic and therapeutic context of PestiV2gp1

• 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 [6].
• Immunofluorescence studies showed that polyprotein pp62 is localized in the viral factories [7].
• Electron microscopy revealed that pp220 repression leads to the assembly of icosahedral particles virtually devoid of the core structure [5].
• Analysis of recombinant v220i by immunoelectron microscopy, immunoblotting, and DNA hybridization showed that mutant particles essentially lack, besides the pp220-derived products, a number of major core proteins as well as the viral DNA [5].
• Furthermore, the use of polyprotein pp62 in an ELISA for testing poorly preserved sera allows performance of the diagnosis of ASF without the need to confirm the results by the immunoblot test [11].

References