Abstract: A test based on restriction enzyme analysis identifies and differentiates strains of porcine reproductive and respiratory syndrome virus (PRRSV). Amplified cDNA from the ORF 5 region of the viral genome has been targeted for identification of unique restriction sites that allow for the differentiation of the vaccine strain from field strains, and for differentiation of field strains from each other through the use of selected restriction enzymes. This assay is useful for both clinical diagnosis of PRRSV field strains in vaccinated pigs as well as for epidemiological studies in the evaluation of the source and transmission of PRRS field viruses.

Abstract: An attenuated pseudorabies virus (PRV) having a reduced ability to reactivate from latency is produced by introducing (1) a genomic modification in the early protein 0 (EP0) gene whereby said virus is characterized by the inability to express the early protein 0; or (2) a genomic modification in the large latency transcript (LLT) gene whereby said virus is characterized by disruption of the synthesis of said large latency transcript; or (3) the genomic modifications described in both (1) and (2). The attenuated virus is useful in a vaccine for psuedorabies-susceptible animals, particularly swine. Swine vaccinated with a deletion mutant in the EP0/LLT overlap region displayed reduced virus shedding and fewer clinical signs than animals inoculated with a wild type virus. The deletion mutant-vaccinated swine also harbored less PRV DNA in the nervous tissue and showed reduced ability to reactivate the virus.

Abstract: Single-stranded DNA probes complementary to a hypervariable region of Campylobacter 16S rRNA are useful in distinguishing species of this pathogen from one another. The probes find practical application in diagnosing human and animal diseases caused by this organism from clinical samples, such as fecal material. They are also useful in differentiating Campylobacter species based on RFLP analyses.