Recombinant African Swine fever virus (Pig/HLJ/18) p30 Protein [His]

African swine fever virus (ASFV) is a double-stranded DNA virus with a diameter of approximately 260 - 300 nm. The viruses are divided from outside to inside: envelope, capsid, inner membrane, core shell and genome. The outer envelope is the outermost structure of ASFV and may be involved in virus attachment and endocytosis. ASFV enters host cells via clathrin-mediated endocytosis (CME) and macropinocytosis. CD2v is an envelope protein consisting of a signal peptide, a transmembrane region and two immunoglobulin-like domains. CD2v has multiple proline-rich repeat regions within the cytoplasmic domain that interacts with the actin-binding adapter protein SH3P7 to promote vesicle transport and signal transduction. The capsid has an icosahedral structure adjacent to the outer envelope, which protects the virus from nucleases and other physical and chemical factors in the environment. The major capsid protein, p72, is the major structural component of the virions, accounting for 31%-33% of the total viral mass. The p72 protein induces antibody responses after viral infection. Due to its conservation and immunogenicity, it is widely used as an antibody detection target for ASFV infection. The inner membrane contains an icosahedral capsid that surrounds the nuclear envelope and nucleoid. The inner envelope contains p17, pE183L, p12, pE248R and pH108R. The inner membrane protein p17 is an essential and highly abundant protein required for capsid assembly and icosahedral morphogenesis. The proper assembly of the nuclear envelope depends on the assembly of the outer capsid and inner membrane, but not vice versa. The nuclear envelope serves to confine and protect the viral genome from host nucleases and dsDNA sensors, thereby suppressing the innate immune response during initial infection. The viral genome is surrounded by a core envelope of approximately 170-194 kb, which terminates in a hairpin loop and consists of variable regions including tandem repeat regions and multigene families. Following ASFV endocytosis, the viral genome is delivered to the cytoplasm where transcription of early viral genes is initiated.

Figure 1. Structure of African swine fever virus. (Sources: Fredmoore L Orosco, et al. 2023)

ASFV infects pigs mainly by infecting pig leukocytes, especially monocytes and macrophages. Of course, it can also be detected in later infect (vascular) endothelial cells, dendritic cells, megakaryocytes, Langerhans cells, neutrophils, liver cells, platelets, etc. Most of the time, the life cycle of African swine fever viruses proceeds in the cytoplasm; rarely, they enter the nucleus. The main life cycle of African swine fever virus is summarized as invasion-disintegration-gene expression-assembly-exocytosis. The molecular mechanisms of ASFV invasion are diverse and complex, so that the detailed changes are almost completely unknown. The known information is as follows: First, early scientists suspected that a protein on the cell surface, CD163, was a viral receptor, that is, a key protein for ASFV to attach to the cell surface and then invade, but later experiments proved that the cognition seemed to be wrong. Second, scientists found that this process is dependent on temperature and low pH, and it seems to consume energy. Third, cholesterol is very necessary for ASFV invasion. Fourth, ASFV can enter cells in many ways. For example, it enters cells through endocytosis of cells, where this endocytosis may be manifested in different forms, which may be endocytosis (a process that depends on the formation of vesicles of dynamin and clathrin), or phagocytosis of macrophages. There is relatively solid experimental evidence for these two processes. In macrophages, phagocytosis depends on sodium-proton exchange for energy, which also creates an acidic environment for the disintegration of the viral outer membrane and capsid. Specifically, it depends on this ion exchange, as well as the activation of epidermal growth factor receptor (EGFR) and Rac1 (Ras-related C3 botulinum toxin substrate 1), a member of the Rho family of small GTPases, and the phosphorylation of PI3K and Pak1 (p21-activated kinase 1), and under the guidance of actin, the cell membrane begins to be disturbed, producing bulges and wrinkles, and in the process, the virus is swallowed into itself.

African swine fever virus has a double-stranded DNA genome and encodes approximately 150 to 200 structural and non-structural proteins, which are involved in viral replication, virus-host interaction, and regulation of host innate immune responses. However, the functions of more than half of ASFV proteins remain unknown. More than 50 of them are structural proteins, including p72, p54, p30, and CD2v. The p30 protein is encoded by the CP204L gene, with a relative molecular mass of 30 kDa. It can appear in the early stage of viral infection and trigger the production of neutralizing antibodies in infected animals. At the same time, the p30 protein is also one of the most antigenic proteins in ASFV. In addition, ASFV p30 can also serve as an essential protein involved in the internalization of the virus into host cells. Therefore, the p30 protein can be used as a target protein for the development of African swine fever virus diagnosis and vaccines.

ASFV p30
p30 Protein
ASFV CP204L
Early Structural Protein p30
Early Viral Protein p30
CP204L Protein