Attempt to discriminate between bovine viral-diarrhoea virus strains using polymerase chain reaction

Genetic and Clinical Analyses of Bovine Viral Diarrhea Virus Isolates from Dairy Operations in the United States of America

To assess the prevalence of bovine viral diarrhea virus (BVDV) on the basis of the genotype and clinical signs, isolates from 16 dairy herds (bulk milk samples) and 37 BVDV-infected cattle were examined. Isolates for this study were selected from submissions that contained an adequate clinical history. A part of the E2 gene of BVDV from these isolates was amplified by reverse transcription-polymerase chain reaction. From the nucleotide sequence of the amplified products, phylogenetic analyses were performed and genotypes or subgenotypes were identified. Forty percent of the selected field isolates were BVDV-2, and 60% were BVDV-1. Eighty-one percent of BVDV-1 isolates were determined to be the BVDV-1b subgenotype. BVDV-1b and BVDV-2 formed more closely related clusters in each group than did the BVDV-1a isolates. There was no obvious association of any genotype or subgenotype with geographical localization or clinical manifestations. A higher prevalence of BVDV-2 infection was found in the United States than in other countries. BVDV-1a has been thought of as a prototype of BVDV; however, there were fewer isolations of BVDV-1a than of other subgenotypes of BVDV Phylogenetic analyses of BVDV isolates using the E2 region of the genome generated results similar to those of studies done in the United States using the 5' untranslated region.

Bovine viral diarrhea virus 1 is classified into different subgenotypes depending on the analyzed region within the viral genome

Phylogenetic analyses of bovine viral diarrhea virus (BVDV) were performed based on the nucleotide sequences of the 5' untranslated region (5'-UTR) and E2-coding gene. Thirty-six BVDV detected from naturally infected cattle in the northern region of Japan were divided into three genotypes, BVDV1a, BVDV1b and BVDV2, in a 5'-UTR phylogenetic tree. In a phylogenetic tree constructed from the E2-coding gene, BVDV1c was identified and the viruses classified in BVDV1c were included in BVDV1a in the 5'-UTR phylogenetic tree. Moreover, BVDV1a and BVDV1b in the E2-phylogenetic tree clustered closer together than in the 5'-UTR tree. These results suggested that phylogenetic analysis of the E2 gene was more useful for identification of subgenotypes within BVDV1.

Molecular cloning and phylogenetic analysis of Babesia gibsoni heat shock protein 70

The Babesia gibsoni heat shock protein 70 gene (BGHsp70) was cloned by polymerase chain reaction (PCR) and sequenced. The length of the gene was 1938 bp and the predicted polypeptide was 646 amino acids long with a calculated molecular weight of 70,627. The amino acid sequences of BGHsp70 from 17 isolates were identical, though there were six types of polymorphisms among the corresponding nucleotide sequences. There was no intron in the BGHsp70 gene. Phylogenetic analysis of the amino acid sequence of Hsp70 showed that B. gibsoni was most closely related to B. bovis and lies within a phylogenetic cluster with Theileria. These results suggest that Hsp70 was well conserved among intraerythrocytic protozoa.

Detection and genotyping of bovine diarrhea virus by reverse transcription-polymerase chain amplification of the 5' untranslated region

A reverse-transcription polymerase chain reaction (RT-PCR) was developed to differentiate the bovine diarrhea virus (BVDV) from other pestiviruses, and to determine the genotype of the BVDV isolates. For this purpose, primer pairs were selected in the 5' untranslated region (5'UTR). The primers BE and B2 were located in highly conserved regions and were pestivirus-specific. Two primer pairs named B3B4 and B5B6 were specific of BVDV genotypes I and II, respectively. With this technique, an amplification product of the expected size was obtained with either the B3B4 or the B5B6 primer pairs for the 107 BVDV isolates tested but not for BDV or CSFV. For some isolates that were grouped in the genotype II, sequence analysis of the PCR fragments confirmed their classification into this genotype.

Detection of bovine viral diarrhea virus (BVDV) using reverse transcription polymerase chain reaction assay

The reverse transcription polymerase chain reaction (RT-PCR) was applied to detect bovine viral diarrhea virus (BVDV) for the rapid diagnosis. The primers were selected from the p80 region of BVDV gene. The RT-PCR assay detected all of the 17 BVDV strains tested including cytopathogenic and non-cytopathogenic strains, while specific amplification was not observed from 17 bovine viruses other than BVDV. Detection limit of the assay was 10(1.5) TCID50/ml. Sera and organ samples were collected from four field bovine viral diarrhea-mucosal disease (BVD-MD) cases; mucosal disease, abortion, diarrhea and persistent infection. The RT-PCR assay detected BVDV from those samples more than conventional virus isolation method.

Detection of animal pathogens by using the polymerase chain reaction (PCR)

The polymerase chain reaction (PCR) is a nucleic acid-based technique that enables the rapid and sensitive detection of specific micro-organisms. Although this technique is widely used in veterinary research, it has not yet found applications in routine microbiological analysis of veterinary clinical samples. However, advances in sample preparation together with the increasing availability of specific gene sequences will probably lead to the more widespread diagnostic use of PCR in the future. PCR is likely to have a strong impact in the epidemiology, treatment and prevention of animal infectious diseases.

Detection and identification of ruminant and porcine pestiviruses by nested amplification of 5' untranslated cDNA regions

Based on published gene sequences of bovine viral diarrhoea virus (BVDV) type I and classical swine fever virus (CSFV), genus- and species-specific primers were designed to detect and identify pestivirus cDNA sequences in a nested polymerase chain reaction (PCR). The PCR primers were validated using cDNA synthesized from 146 pestivirus isolates, comprising representatives of all four so far described genotypes (BVDV type I, BVDV type II, CSFV and border disease virus), as well as others of uncertain classification. PCR products of the predicted size were amplified from all viruses with the genus-specific primers. All 53 cattle isolates, including 5 typed antigenically as BVDV type II were amplified by the internal BVDV-specific primers, but not the CSFV-specific primers. The same result was found for other BVDV type I and II viruses isolated from sheep and pigs. Seventy-seven CSF viruses were amplified by their respective internal primers. Available information strongly indicate that 4 CSF viruses also amplified by the BVDV-specific primers had been contaminated with BVDV in cell cultures. Border disease viruses were mostly not detected by the BVDV-specific primers, but were detected weakly by the CSFV-specific primer pair. Using carrier RNA for extraction of viral RNA, the sensitivity of detection of the single and nested PCR was, respectively, 5 and 50 times higher than obtained with a cell culture assay. The RT-PCR also detected BVDV in all of 15 commercial batches of fetal calf serum examined, and verified three earlier diagnoses of CSFV by detecting specific gene sequences in 30 year old frozen archival organ samples.