The control of infectious bovine rhinotracheitis induced by bovine herpesvirus 1 (BoHV-1) requires sensitive and specific diagnostic assays. As BoHV-1 is antigenically and genetically related to four other alphaherpesviruses of ruminants-namely, BoHV-5, caprine herpesvirus 1 (CpHV-1), cervine herpesvirus 1 (CvHV-1) and CvHV-2-diagnostic tests able to discriminate BoHV-1 from these related viruses are needed to avoid misdiagnosis, especially because some of these viruses are able to cross the species barrier. In this study, murine monoclonal antibodies (MAbs) specific for BoHV-1, BoHV-5, CpHV-1, CvHV-1, and CvHV-2 were produced with the aim of setting up an immunofluorescence assay able to discriminate between these related herpesviruses. Produced MAbs were selected for their viral specificity by enzyme-linked immunosorbent assay and indirect immunofluorescence staining of virus-infected cells. Radioimmunoprecipitation characterization of the selected MAbs revealed that four of them are directed against glycoprotein C (gC) and one of them is directed against gD of these related viruses. The obtained results demonstrate that the antibodies produced allow an unambiguous discrimination of each of the four alphaherpesviruses related to BoHV-1.

This paper describes an enzyme-linked immunosorbent assay (ELISA) for the diagnosis of cryptosporidiosis. A monoclonal antibody with a high affinity against an oocyst antigen was used to set up the test. The efficiency of this assay was compared with that of the flotation test; 275 calf faecal samples were examined by the two methods. There was 96% agreement between the two tests. For the 11 conflicting samples, the two tests were repeated and a modified Ziehl-Neelsen staining was performed on faecal smears. All these 11 samples contained few oocysts, but only five and six of them were shown to be positive by the ELISA and flotation tests, respectively. The degree of sensitivity of the ELISA and flotation tests is comparable; samples heavily or moderately contaminated with oocytes are detected by both methods. This ELISA is reliable and never gives rise to false positive results. Nevertheless, as with the flotation test, the occasional case containing very few oocysts will not always be detected by this test. If necessary, very accurate diagnosis can be made by a staining technique or by a direct immunofluorescent assay. In veterinary medicine, the ELISA seems to be a method of choice; it appears to be a fast and reliable technique which could be used as a routine test for the detection of Cryptosporidium oocysts. Nevertheless the degree of sensitivity must always be borne in mind. There is no need for a microscopic examination, which is an additional advantage.

Abstract. Bovine respiratory syncytial virus (BRSV) is associated with severe respiratory disease in cattle. BRSV infection frequently leads to the death of young infected animals. The presence of BRSV in postmortem specimens is routinely detected using indirect immunofluorescence (IIF). However, this technique requires special equipment and considerable expertise. The present paper describes the development of a 1-step ELISA for rapid (1.5 hours) detection of BRSV antigen in organ homogenates. The performance of the new 1-step ELISA was evaluated using bovine postmortem specimens (n 5 108) in comparison with 3 other BRSV diagnostic techniques: indirect immunofluorescence, the Clearview respiratory syncytial virus (RSV) test, and real-time reverse transcriptase polymerase chain reaction (RT-PCR). The relative sensitivity, specificity, and the kappa coefficient of 1-step ELISA, the Clearview RSV electroimmunoassay (EIA), and IIF were calculated, using real-time RT-PCR as the reference test. The new 1-step ELISA was the most sensitive and specific of the 3 tests. Thus, the new 1-step ELISA is a reliable test for detecting BRSV antigen in organ homogenates.

In order to test the use of a subunit recombinant vaccine for its capacity to induce antibodies against the nonimmunogenic heat-stable enterotoxin STa from Escherichia coli and the TEM-1 beta-lactamase, cattle were immunized with a hybrid protein created by insertion of the STa sequence at position 197 of the TEM-1 beta-lactamase. Specific anti-STa IgG and IgG1 antibodies were detected at low levels, while no IgG2 antibodies were detected. In contrast, high levels of the different anti-TEM IgG subtypes were detected in cattle sera. In addition, beta-lactamase activity was inhibited by the sera. The presence of antibodies against STa and TEM-1 beta-lactamase was assessed in sera from 366 cattle taken from the field. No significant level of IgGs against the toxin or the TEM-1 was detected. A comparison of the antibody level between the immunized and the nonimmunized animals clearly demonstrated that STa was not able to induce a significant level of antibodies in the vaccinated animals. In contrast, a strong antibody response against TEM-1 beta-lactamase was demonstrated.

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