AFRICAN SWINE FEVER VIRUS PP62 POLYPROTEIN, HIS-TAG

African Swine Fever virus pp62 polyprotein is a recombinant protein expressed and purified from mammalian cells. This polyprotein is the precursor for structural proteins p15 and p35 which are essential components of the viral capsid.

PRODUCT DETAILS – AFRICAN SWINE FEVER VIRUS PP62 POLYPROTEIN, HIS-TAG

• Recombinant African Swine Fever virus pp62 polyprotein (NCBI accession number NP_042787.1, aa1-530, strain BA71V).
• Protein contains a C-terminal glycine-serine linker and a His-tag.
• Expressed in HEK293 cells and purified from cell pellets by immobilised metal affinity and ion exchange chromatography.
• Presented in 50mM Tris-HCl pH8.0, 200mM NaCl, sterile filtered.

BACKGROUND

African swine fever (ASF) is a highly contagious haemorrhagic viral disease affecting domestic and wild pigs. It is caused by an enveloped deoxyvirus of the Asfarviridae family that infects domestic and wild pigs as well as soft-bodied ticks of the Ornithodoros genus. Outbreaks have been reported in Africa and parts of Europe, South America, and the Caribbean. More recently (since 2007) the disease has been reported in multiple countries across Africa, Asia and Europe, in both domestic and wild pigs (OIE, 2018). There is currently no approved vaccine for ASFV infection.

African swine fever virus (ASFV) has a double-stranded DNA genome of 170-190 kbp, that encodes more than 150 polypeptides, including pp220, p72, p54, p30, and CD2v. To date, 110 ORFs have been identified and two of those encode the ASFV polyprotein precursors pp220 and pp62 (or pp60).  Pp62 has a relative molecular weight of 60.5 kDa and is encoded by the gene CP530R. It can be proteolytically cleaved into the mature virion proteins p35 and p15 by S273R (Alonso et al., 2001). Pp220, pp62, and their mature proteins have important functions in the assembly of virions and viral infection (Jia et al., 2017). Extracellular mature virus particles are composed of a viral core consisting of a central DNA-containing nucleoid, a surrounding core shell, an ER-derived inner lipid envelope, an icosahedral protein capsid, and a plasma membrane derived envelope. Particles are assembled within cytoplasmic viral factories from endoplasmic reticulum-derived viral membranes which become icosahedral particles by the gradual formation of the outer capsid layer. Immunoelectron microscopy showed that pp62 cleavage products reside within the core shell (Suárez et al., 2010).  This shell is formed underneath the viral envelope, and subsequently the viral DNA and nucleoproteins are packaged and condensed to form the electron-dense nucleoid. Intracellular mature virions made at the assembly sites are infectious and a fraction of them are transported to the plasma membrane, where they bud, and become infectious extracellular enveloped virions. Processing of polyproteins pp220 and pp62 requires the expression of the major capsid protein p72 and proper processing is an important sign of mature virions. Incomplete processing of pp220 and pp62 results in virus particles without a core or lacking infectiveness (Andrés et al., 2002).

Recombinant insect cell expressed pp62, p32, and p54 antigenicity has been tested in ELISA and immunoblot (IB) for ASF serological diagnosis. Reaction specificity in the IB test were shown to be higher than in ELISA, and the specificities of pp62 and p32 were higher than that of p54 (Gallardo et al., 2006).

The Native Antigen Company is pleased to offer a recombinant pp62 protein which has been manufactured in our state-of-the-art mammalian cell line, ensuring a more native environment for correct processing and stability. This protein is suitable for use in vaccine and diagnostic research and development studies.

REFERENCES

• Alonso et al. (2001). African swine fever virus protein p54 interacts with the microtubular motor complex through direct binding to light-chain dynein. J Virol. 75, 9819–9827.
• Andrés et al. (2002). African Swine Fever Virus Polyproteins pp220 and pp62 Assemble into the Core Shell. J Virol. (24): 12473–12482.
• Gallardo et al. (2006). Antigenic properties and diagnostic potential of African swine fever virus protein pp62 expressed in insect cells. J Clin Microbiol. 44, 950–956.
• Jia et al. (2017). Roles of African swine fever virus structural proteins in viral infection. J Vet Res. 61, 135-143.
• Suárez et al. (2010). African swine fever virus polyprotein pp62 is essential for viral core development.  J Virol, 84, 176–187.
• The World Organisation for Animal Health (OIE). African Swine Fever. Oct 2018.