Serotype-Specific and Haemadsorption Protein of the African Swine Fever Virus

Abstract

This review presents comparative results of simultaneously conducted studies on proteins responsible for the haemadsorption and serotype-specific properties of African swine fever virus (ASFV). An ASFV gene EP402R (or LMW8-DR) encoding protein CD2v homologous to murine, human or porcine T-cell adhesive receptor was found. The CD2v was shown to be directly involved into a haemadsorption process, and expressed in ASFV-infected cells as a glycoprotein with a molecular weight of approximately 105-110 kDa. In the presence of a glycosylation inhibitor, tunicamycin, its molecular weight is about 42 kDa. In ASFV-infected cells labeled with 3 H-glucosamine or 14 C-sodium acetate, a virus-specific major glycoprotein with a molecular weight of 110-140 kDa (gp 110-140) was identified using radioimmunoprecipitation assay. Using ASFV reference strains belonging to seroimmunotypes I-IV and the corresponding antisera active in haemadsorption inhibition assay (HADIA), we determined that gp 110-140 defines the serotype specificity. Genotyping on the basis of the genetic locus encoding the CD2v and a C-type lectin protein also showed a concurrence with the grouping of ASFV isolates and strains based on their seroimmunotypes. Immunization of pigs with the gp 110-140 within liposomes, or a recombinant haemagglutinin (CD2v) protected 67 to 100% of animals from death due to their subsequent infection with homologous virulent ASFV strains. Based on the physico-chemical and biological characteristics of the gp 110-140 and CD2v it is suggested that they are one and the same virus-specific glycoprotein crucial for induction of the immunological protection against ASF.

Seroimmunotyping of African swine fever virus

“…For its detection, two principal conditions were required: (1) use of the metabolically 3 H-glycosamine-labeled proteins derived from lysates of PBM naturally susceptible A-cells infected with ASFV hemadsorbing strains as an antigen source; and (2) use of the homologous antisera with high activity in HAdI as an antibody source. Through extensive investigations, the serotype specificity of gp110-140 has been successfully determined ( Sereda et al, 2018 ). While using some homologous components in the radioimmunoprecipitation assay, the dumbbell-like bands of gp 110–140 manifested as the major ones.…”

Understanding and combatting African Swine Fever

“…Similar to the results obtained by Ruiz-Gonzalvo and Coll (1993) this purified haemadsorbing activity could protect pigs from severe disease after infection with a related strain of ASFV. The ability of the protein to induce antibodies capable of blocking haemadsorption and protecting pigs from disease was also found to be dependent on the sugar residues attached to the protein (Sereda, 2013;Sereda et al, 2018).…”

Subsequent Immunization of Pigs with African Swine Fever Virus (ASFV) Seroimmunotype IV Vaccine Strain FK-32/135 and by Recombinant Plasmid DNA Containing the CD2v Derived from MK-200 ASFV Seroimmunotype III Strain Does Not Protect from Challenge with ASFV Seroimmunotype III

“…Secondly, the virus exhibits notable genomic plasticity, utilized in its vector transmission by the Ornithodoros soft ticks. Lastly, the virus displays a considerable phenotypic variation, including virulence, serotypic and immunotypic characteristics, and hemadsorption-inducing ability [4][5][6][7][8][9][10][11][12][13][14].…”

“…In vitro, the grouping was based on a comprehensive assessment of ASFV isolates/strains by antigenic properties in haemadsorption inhibition assay using type-specific sera. In contrast, in vivo, this grouping used the data of an immunological test (bioassay) on pigs inoculated with attenuated strains [7][8][9][10][11].…”