Polyprotein processing in African swine fever virus: a novel gene expression strategy for a DNA virus.

Abstract

This report shows that African swine fever virus (ASFV)‐‐a large DNA‐containing virus‐‐synthesizes a polyprotein to produce several of its structural proteins. By immunoprecipitation analysis, we have found that ASFV polyprotein is a 220 kDa myristoylated polypeptide (pp220) which, after proteolytic processing, gives rise to four major structural proteins: p150, p37, p34 and p14. Processing of the ASFV polyprotein takes place at the consensus sequence Gly‐Gly‐X and occurs through an ordered cascade of proteolytic cleavages. So far, polyprotein processing as a mechanism of gene expression had been found only in positive‐strand RNA viruses and retroviruses. 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.

African Swine Fever Virus Protease, a New Viral Member of the SUMO-1-specific Protease Family

“…During ASFV infection, polyprotein pp220 is firstly cleaved at the Gly-Gly-Gly sequence at positions 43-45 and the Gly-Gly-Ala sequence at positions 892-894 to give rise to the mature product p150 and the intermediate precursor protein pp90 (6) (Fig. 2A).…”

“…This antibody, as well as the rabbit polyclonal anti-p150, anti-p34, and anti-p37/p14 sera, which also recognize polyprotein pp220, have been previously characterized (6,8,25).…”

“…African swine fever virus (ASFV), 1 a large and complex virus containing a 170-kb double-stranded DNA molecule with 151 potential genes (4,5), is atypical among DNA viruses in that it encodes two polyproteins, pp220 and pp62, which are cleaved to produce six major structural components of the virus particle (6,7). These proteins, p150, p37, p34, and p14, derived from polyprotein pp220 and p35 and p15, products of polyprotein pp62, are the major components of the core shell, a thick protein layer that surrounds the DNA-containing central nucleoid and that is enwrapped by the inner lipoprotein envelope and the icosahedral capsid (8).…”

Molecular epidemiology of African swine fever in East Africa

“…The complex virus particle is formed by proteins in excess of 50, including those with structural functions and enzymes packaged for use early in infection. Genes encoding 15 of the structural proteins have been characterized, with two of these encoding polyproteins that are processed into four and two virion proteins each (Simon-Mateo et al, 1993,1997Andres et al, 2001).…”

Mapping and sequence of the gene encoding the African swine fever virion protein of Mr 11500

“…This result suggested strongly that a low M r protein is also encoded by the 5' end of the previously reported gene. In accordance with this hypothesis, a protein of M r 14000 has been found to be derived from a large precursor that gives rise to several ASFV proteins which become incorporated into virions, including p37, after proteolytic cleavage at a Gly-Gly-X sequence (Simdn-Mateo et al, 1993). The sequence of the two clones of group C showed that they expressed an ORF known to encode a polypeptide of approximate Mr 15 000, present in the virus particle (L. Martinez & E. Vifiuela, unpublished results).…”