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Bovine herpesvirus type 1 (BoHV-1) and bovine herpesvirus type 5 (BoHV-5) are important pathogens of cattle. The diseases they produce are quite different, with BoHV-5 being more neuropathogenic than BoHV-1 which mainly induces respiratory symptoms. The sequencing of the entire BoHV-5 genome has shown that most of the differences between these viruses are found in the immediate early and LR (latency related) genes. The LR gene is the only viral gene abundantly expressed in latently infected neurons, is essential for viral reactivation and seems to have an anti-apoptotic function which can be observed in vivo and in vitro. This gene spans two potential ORFs (1 and 2) which can also be found as a fused version, an ORF-E protein encoded within the promoter region and two miRNAs located within the 5' UTR segment. Most of the essential functions of the LR gene seem to be located within the ORF-2 which has been found to modulate components of cell signaling/cycle pathways. In this review we present a comparative sequence analysis of the LR gene of several BoHV-5 isolates, their differences with the BoHV-1 homologue and the potential impact this may have on its function. The LR gene was found to be highly conserved in all sequenced BoHV-5 strains. ORF-1 shares 60 % homology compared to BoHV-1 whereas the BoHV-5 homologue of ORF-2 is truncated at amino acid 51. Preliminary studies analyzing the emerging transcripts from the BoHV-5 LR gene in infected cells, as well as in stably transfected cells, indicates that their products are, in fact, missing crucial components of the anti-apoptotic function when compared to the BoHV-1 LR gene. In addition these transcripts maintain a region that, similar to what is found in BoHV-1, would produce a miRNA with the potential to recognize a region within the BoHV-5 immediate early gene. All together, these BoHV-5 characteristics suggest that this virus would not possess the same repertoire of latency maintaining functions as BoHV-1. Implications for BoHV-5 neuropathogenic potential are discussed.

A 4-bp deletion (c.230_233delATAG) of the ABCB1 gene, frequently found in various dog breeds, results in intolerance to certain drugs routinely used in veterinary medicine, including many chemotherapeutic agents and macrocyclic lactones. The use of rapid and reliable genetic testing is fundamental for early detection of the mutation and prevention of undesirable toxicoses. We developed and compared 2 genotyping tests: PCR–high-resolution melting (PCR-HRM) and PCR–restriction-fragment length polymorphism (PCR-RFLP) to identify the 4-bp deletion in the ABCB1 gene of canine breeds. Amplified PCR products were sequenced in order to confirm different genotypes. Both techniques were efficient in discriminating homozygous wild-type, homozygous mutated, and heterozygous ABCB1 genotypes, and proved to be reproducible and economical methods. The HRM analysis, a sensitive and specific method for the molecular detection of genetic disorders, does not require labeled probes, processing, or separations after PCR.

Calpastatin activity has a key role in the tenderization process that occurs during postmortem storage of meat under refrigerated conditioning. The regulation of calpastatin (CAST) expression is highly complex, the gene has four putative promoters and at least three different polyadenylation sites, and it is also alternatively spliced. We investigated the presence of alternative polyadenylation (APA) isoforms of CAST transcripts in three muscles (infraspinatus, triceps brachii and semitendinosus) of two bovine breeds (Angus and Brahman). The 3´ RACE-PCR was used to specifically amplify the different APA sites. The amplified fragments were cloned and sequenced. Sequencing confirmed the existence of three expected polyadenylation sites corresponding to short, medium and long polyadenylated transcripts. Also, transcripts with a novel APA site were found in the three muscles of both breeds. Because the same APAs isoforms were found between muscles and breeds, we could hypothesize a possible contribution to the relative abundance of different isoforms, probably in coordination with promoter preference and alternative splicing. This knowledge would be useful in the design of future experiments to analyze differential expression of CAST isoforms and their contribution to the definition of beef tenderness. Key words: Beef cattle; Alternative polyadenylation; 3´ RACE-PCR.