Serodiagnostic potential of synthetic peptides derived from African swine fever virus putative protein pCP312R

Abstract

African swine fever (ASF) is a hemorrhagic disease of domestic swine, with often high mortality rates registered. To date there is still no vaccine produced against ASF, and disease management in countries including Uganda, where the disease is endemic is dependent on accurate and timely diagnosis programs and quarantine. This study aimed at contributing more knowledge towards ASF diagnosis by investigating the serodiagnostic potential of synthetic peptides of an ASF putative protein pCP312R. Antigenic regions of the pCP312R putative protein were identified using Kolaskar and Tongaonkar antigenicity prediction method and twelve (12) peptides were predicted, out of which four (4) peptides were selected and synthesised. An additional peptide derived from the carboxyl end of the ASFV p54 protein was also synthesised and used as a control. Polyclonal rabbit antibodies raised against each of the five peptides was used in immunohistochemistry, and each demonstrated ability to localize viral antigen in pig tissue albeit with slightly varying intensities, at a dilution of 1:200, with antibodies against peptides cpr1, cpr2, cpr3 and cpr4 all accurately staining infected macrophages. However all the peptides evaluated in this study performed moderately when used in indirect ELISA tests giving the following results; CP1; diagnostic sensitivity of 55% (95% CI, 0.3421-0.7418) and specificity of 96% (95% CI, 0.8046-0.9929), CP2; diagnostic sensitivity of 100% (95% CI, 0.8389-1) and specificity of 52% (95% CI, 0.335-0.6997), CP3; diagnostic sensitivity of 95% (95% CI, 76.39-99.11) and specificity of 88% (95% CI, 70.04-95.83), CP4; diagnostic sensitivity of 90% (95% CI: 0.699-0.9721) and specificity of 76% (95% CI: 0.5657-0.885) and p54; diagnostic sensitivity of 100% (95% CI, 0.8389-1) and specificity of 56% (95% CI, 0.3707-0.7333). This study presents the first time synthetic peptides have been successfully predicted, designed and evaluated for Serodiagnosis of African swine fever in domestic pigs. This study in addition showed that there is potential for use of polyclonal anti-peptide antibodies in the diagnosis of ASF using immunohistochemistry.