African swine fever (ASF) is a complex, highly lethal, notifiable disease of swine. ASF is wide-spread in sub-Saharan Africa and East European countries and there is presently a great risk of spread to neighboring countries. Since there is no vaccine for ASF virus (ASFV), control is based on rapid and early detection of the disease via surveillance. This approach requires collecting blood samples from large number of animals. Laborious and expensive of itself, this process also presents an additional risk because ASFV is present at high concentrations in the blood. The objective of this study was to initiate studies into the potential use of oral fluid as an alternative to serum for ASF diagnosis, for latter studying its possible use in surveillance and control programs. To this end, oral fluid samples collected at different times post infection from eight pigs experimentally inoculated with an attenuated ASFV were assayed using modified protocols of the two validated serological techniques, the enzyme-immune-liked assay (ELISA) and immunoperoxidase technique (IPT). Antibodies against ASFV were detected in oral fluid samples of all animals from early post infection through the end of the experiment by ELISA and IPT. These results confirmed the presence of ASFV antibodies in swine oral fluids samples, the possibility of an oral fluid-based approach in ASF diagnosis and, potentially in ASF surveillance. (C) 2013 Elsevier B.V. All rights reserved.

African swine fever (ASF) is one of the most complex and lethally haemorrhagic viral diseases of swine, affecting all breeds and ages of pigs. In the absence of ASF vaccines, reliable laboratory diagnosis and restricted biosecurity are critical for disease prevention and control. A detection of ASF-specific antibodies in an unvaccinated pig is a good marker for the diagnosis of ASF. The immunoperoxidase test (IPT) is a sensitive test for detecting ASF virus (ASFV) antibodies. However, due to the complexity of the procedure, the IPT is only suitable to be used as a confirmatory test. The ASFV p30 protein-based enzyme-linked immunosorbent assay (ELISA) is widely used for ASFV antibody screening, but the sensitivity is not comparable to the IPT. It is essential to have a better understanding of the antigenic properties of ASFV p30 to improve p30-based serologic tests. In this study, we developed a panel of 21 monoclonal antibodies (mAbs) against ASFV p30. With 14 out of the 21 mAbs, we defined 4 antigenic regions that contain at least 4 linear epitopes. Nine of the 14 mAbs mapped to antigenic regions 3 and 4 reacted with p30 in all serologic methods tested in this study, such as indirect immunofluorescence assay (IFA), ELISA and Western blot. The antigenic regions 3 and 4 are highly conserved and immunodominant in host antibody response. These mAbs and the defined p30 antigenic regions 3 and 4 provide valuable tools for the development and improvement of ASF serologic assays.