African swine fever virus pA104R protein acts as a suppressor of type I interferon signaling

Characterization of the monoclonal antibody and the immunodominant B-cell epitope of African swine fever virus pA104R by using mouse model

The African swine fever virus (ASFV) structural protein pA104R is the only histone-like protein encoded by eukaryotic viruses. pA104R is an essential DNA-binding protein required for DNA replication and genome packaging of ASFV, which are vital for pathogen survival and proliferation. pA104R is an important target molecule for diagnosing, treating, and immune prevention of ASFV. This study characterized monoclonal antibodies (mAbs) against pA104R and found them to recognize natural pA104R in ASFV strains with different genotypes, showing high conservation. Confirmation analyses of pA104R epitopes using mAbs indicated the presence of immunodominant B-cell epitopes, and further characterization showed the high antigenic index and surface accessibility coefficients of the identified epitope. Furthermore, the pA104R protein functions through the polar interactions between the binding amino acid sites; however, these interactions may be blocked by the recognition of generated mAbs. Characterizing the immunodominant B-cell epitope of the ASFV critical proteins, such as pA104R, may contribute to developing sensitive diagnostic tools and vaccine candidate targets.IMPORTANCEAfrican swine fever (ASF) is a highly pathogenic, lethal, and contagious viral disease affecting domestic pigs and wild boars. As no effective vaccine or other treatments have been developed, the control of African swine fever virus (ASFV) relies heavily on virus detection and diagnosis. A potential serological target is the structural protein pA104R. However, the molecular basis of pA104R antigenicity remains unclear, and a specific monoclonal antibody (mAb) against this protein is still unavailable. In this study, mAbs against pA104R were characterized and found to recognize natural pA104R in ASFV strains with different genotypes. In addition, confirmation analyses of pA104R epitopes using mAbs indicated the presence of immunodominant B-cell epitopes, and further characterization showed the high antigenic index and surface accessibility coefficients of the identified epitope. Characteristics of the immunodominant B-cell epitope of ASFV proteins, such as pA104R, may contribute to developing sensitive diagnostic tools and identifying vaccine candidate targets.

Interactome between ASFV and host immune pathway proteins

IMPORTANCE

African swine fever (ASF), caused by African swine fever virus (ASFV), has become a major crisis for the pork industry in recent years. The mechanism for ASFV pathology and the clinical symptoms difference of ASF between domestic pigs and reservoir hosts remain to be elucidated. We deciphered the comprehensive protein-protein interaction (PPI) network between ASFV and host immune pathways. The intensive PPI network contained both ASFV-host immune pathway PPI and ASFV-ASFV PPI information, providing a comprehensive ASFV-host interaction landscape. Furthermore, the ASFV-host PPI difference between domestic pigs and warthogs was explored, which will be instructive for exploring essential candidates involved in ASFV pathology. Moreover, we screened the inhibitory effect of ASFV proteins in the PPI with cGAS-STING pathway on IFN-I and NF-κB, further providing possible functions of ASFV-host PPI network in innate immune regulation.