An enzyme-linked immunosorbent assay (ELISA) has been developed for identification of the Sp strain of infectious pancreatic necrosis virus (IPNV). This assay employed 2 monoclonal antibodies directed against 2 non-overlapping epitopes of the minor structural viral protein.It was used to demonstrate the virus antigen in cell cultures and was able to detect 10 ng ml-' of purified virus or 104 TCIDSo ml-l in tissue culture fluid. The assay could be reduced to one step and b e performed within 90 min with good sensitivity. No antigenic variation, affecting the epitopes recognized by these monoclonal antibodies, was observed on 17 IPNV isolates of Sp serotype tested.

African swine fever (ASF) is one of the most complex livestock diseases. The significant losses that it causes, coupled with the lack of a vaccine against ASF virus and the possible resemblance with other swine hemorrhagic diseases, make early detection and laboratory diagnosis essential for controlling and managing the disease. All the techniques currently used to diagnose ASF have been fully validated showing high sensitivity and specificity to detect both antigen and antibodies against all 22 known genotypes; and enable the correct diagnosis of ASF in all possible epidemiological situations. Because no vaccine is available, the presence of antibodies always indicates previous infection, and serological diagnosis must always be performed in parallel with antigen detection to increase the sensitivity and specificity of the analyses. Recent developments in ASF diagnosis, specifically the new field diagnostic tests, have improved and facilitated the likelihood of ASF early detection, essential to fighting the disease.

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This work describes the evaluation of two commercial ELISA kits for the detection of gI antibodies against Aujeszky's disease. A collection of experimental sera from infected pigs, field sample sera, and sera from pigs vaccinated with seven different modified gI-negative commercial vaccines were used to evaluate each test. Both ELISA kits showed good reproducibility, and specificity, but differences could be appreciated in sensitivity when sera obtained at early stages of infection was analysed. These results also indicated that both kits could be used in conjunction with the seven vaccines evaluated in this study.

Fifteen horses were experimentally infected with African horse sickness virus (AHSV) serotype 4. To learn more about the time course of production and specificity of AHSV-specific antibodies, sera were analyzed by immunoblot analysis. Only animals that survived for more than 9 days were able to develop a humoral immune response detectable by immunoblotting. The earliest serological markers corresponded mainly to VP5, VP6, and NS2 and to a lesser extent to VP3, NS1, and NS3. Neutralizing antibodies to VP2 were not detected by immunoblotting, suggesting that they are mostly conformation dependent. VP7-specific antibodies were detected later in infection. These results make NS2 and VP6 the most attractive candidates for the rapid diagnosis of the infection.