BVD virus in a British alpaca.
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Animals↗
Biomedical subjects
G Ibata
Publications and source records attributed to G Ibata.
Characterisation of a type 2 bovine viral diarrhoea virus isolated from cattle in the UK.
Two genotypes of bovine viral diarrhoea virus (BVDV) are recognised. Type 2 was first recognised when virulent strains caused significant losses among cattle in North America. Subsequently, BVDV type 2 has been found in many other countries, but recent studies have shown that only type 1 BVDV is circulating in the UK herds (sheep and cattle) with type 1a predominating. During routine genotyping of UK BVDV isolates, a type 2 isolate was identified. Phylogenetic analysis of the 5'-untranslated region of the viral genome showed it to be a BVDV type 2a, most similar to a low virulent US strain of BVDV type 2. Antigenic typing with a panel of monoclonal antibodies verified this classification. This is the first confirmed isolation of BVDV type 2 found circulating in the UK.
5' Untranslated Regions↗
Bovine viral diarrhoea virus genotype 1 can be separated into at least eleven genetic groups.
Seventy-eight bovine viral diarrhoea viruses (BVDV) recently collected in Austria, France, Hungary, Italy, Slovakia, Spain and UK were genetically typed in the 5'-untranslated (5'UTR) and autoprotease (Npro) regions of the pestivirus genome. Seventy-six of the isolates were BVDV-1 and two French isolates were of the BVDV-2 genotype. Phylogenetic analysis of the 5'UTR (245 nt), including additional BVDV-1 sequences from USA, Canada, Germany, New Zealand, Mozambique and Sweden, taken from GenBank and from our previous works, indicated that these viruses were clustered not only into the two generally accepted groups (BVDV-1a-"NADL like" and BVDV-1b-"Osloss like"), but altogether into 11 phylogenetic groups. Similar clustering was observed with Npro region sequences (385 nt) and the highest bootstrap values (over 95%) were obtained by phylogeny combining 5'UTR and Npro sequences. Some associations between the genetic grouping and the origin of the isolates were apparent, probably reflecting historical trade contacts. Considering the variability of isolates it is recommended that diagnostic PCR primers should be re-examined to ensure coverage of all BVDV-1 groups. The genogroups were less clearly differentiated by monoclonal antibody typing, suggesting significant antigenic similarities within the BVDV-1 genotype.
5' Untranslated Regions↗
Giraffe strain of pestivirus: its taxonomic status based on the 5'-untranslated region.
The 5'-untranslated region (5'-UTR) of the 'Giraffe' strain of pestivirus was sequenced for comparison with those of other pestiviruses from cattle, sheep, goats, and swine. A phylogenetic tree constructed with these strains suggested that the 'Giraffe' strain was allocated to a new taxon. This observation was also confirmed by a newly proposed method based on palindromic nucleotide substitutions (PNS) at the three variable regions in the 5'-UTR. Other reported pestivirus strains isolated from deer were assigned as bovine viral disease virus (BVDV)-1 according to the PNS as well as phylogenetic analysis, suggesting that BVDV-1 strains can cross-infect deer as well as cattle, sheep, goats, and swine, and that wild deer may serve as a reservoir of BVDV-1. We also identified the genovar of a deer isolate, SH9/11, as BVDV-1c by the PNS method.
5' Untranslated Regions↗
Transmissible gastroenteritis and porcine epidemic diarrhoea in Britain.
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Animals↗
Closed one-tube reverse transcription nested polymerase chain reaction for the detection of pestiviral RNA with fluorescent probes.
An assay was developed in which reverse transcription (RT), nested polymerase chain reaction (PCR) and accumulation of amplicon-specific fluorescence could take place in a single, closed reaction tube. The assay, which was classical swine fever virus RNA-specific, was compared with other methods for detection of this virus, including various RT-PCR configurations, virus isolation and ELISA. The new method was very sensitive, and less prone to giving false positive results compared to nested PCR carried out in separate reaction tubes. Substitution of different fluorescent probes resulted in specific tests for border disease virus and for bovine viral diarrhoea type II (BVD-II), and one that could detect all pestiviruses except for some BVD-II viruses.
Animals↗
Foetal cross-protection experiments between type 1 and type 2 bovine viral diarrhoea virus in pregnant ewes.
A flock of 82 non-pregnant ewes was split into three immunisation groups and given an intranasal dose of either cell culture medium, or a type 1 or a type 2 bovine viral diarrhoea virus (BVDV-1 or BVDV-2). Two months later the flock was reconstituted and after a further three weeks, the ewes were bred to pestivirus negative rams after synchronisation of oestrus using progesterone sponges. Fifty-five ewes were segregated into three challenge groups, each of which comprised ewes from different immunisation groups. At 7 weeks gestation, one challenge group was given an intranasal dose of cell culture medium, whilst the other two were given intranasal doses of either BVDV-1 or BVDV-2, using the same inocula as for the immunisations. Three weeks later, the ewes were killed and their foetuses tested for the presence of BVDV-1 and BVDV-2. The results showed that immunisation of six ewes without subsequent challenge did not lead to infection of any of their 11 foetuses. Challenge with BVDV-1 or BVDV-2 in the absence of immunisation lead to 15 out of 15 or 11 out of 14 foetuses becoming infected, respectively. Immunisation with the homologous virus to that used for challenge resulted in complete protection of 32 foetuses from 15 ewes. Heterologous protection was one way. All 12 foetuses from ewes immunised with BVDV-1 were protected from challenge with BVDV-2, whereas 18 foetuses from ewes immunised with BVDV-2 were all infected after challenge with BVDV-1. This provides evidence that a recent exposure to infection with one pestivirus does not necessarily induce foetal protection against another. The one-way result suggests that factors other than antigenic differences are involved in cross-protection.
Administration, Intranasal↗
Classical swine fever in Sardinia: epidemiology of recent outbreaks.
A variable region of the gene encoding the major glycoprotein (E2) of Classical Swine Fever Virus (CSFV) was sequenced from 12 Sardinian isolates which had been obtained from three geographically distinct regions of the Island. Phylogenetic analysis of these viruses and others characterized in previous studies [1, 2] indicated that (a) the Sardinian viruses were all members of the common European subgroup 2.3 and were clearly distinct from live vaccines recently used in this area; (b) they could be resolved into four distinct groups in accordance with the region or date of isolation; (c) in at least two regions wild boar/domestic swine contact was implicated in virus spread; (d) the oldest isolate (1983) and some of the recent isolates were possibly introduced from mainland Italy. In addition, this study has wider implications for the interpretation of CSFV variation. We have been able to demonstrate that small variations within this region of the virus genome (possibly less than 2.7% or five nucleotide substitutions) can be used to separate isolates into groups that precisely fit their geographical distribution. This finding is especially important for deducing the epidemiological relationships between multiple outbreaks caused by similar viruses that occur in close proximity.
Animals↗
A novel approach to the detection of classical swine fever virus by RT-PCR with a fluorogenic probe (TaqMan).
Detection of classical swine fever virus (CSFV) and its discrimination from other pestiviruses can be achieved by virus isolation (VI) in cell cultures, antigen detection, or molecular analysis. To simplify the latter, a 5'-nuclease assay (TaqMan) was developed for the rapid and specific detection of CSFV with the minimum of downstream PCR processing. A pair of 5'-non-coding region, panpestivirus-specific PCR primers were assessed in a one-step reverse transcription-PCR with each of 36 diverse pestiviruses. The PCR products were subsequently reamplified, in conjunction with a CSFV-specific fluorogenic probe, in a nested-PCR with a second set of panpestivirus PCR primers. During nested PCR, when the target of interest was present, the CSFV probe annealed to the amplicon between the forward and reverse primers and was subsequently cleaved via the 5'-3' nucleolytic activity of the DNA polymerase resulting in the release of the fluorescent reporter dye. Each PCR tube was then placed directly into a luminescence spectrometer to monitor for any increase in fluorescence due to cleavage of the probe. This assay detected representatives of all genetic sub-groups of CSFV, but gave negative results for other pestiviruses. A preliminary assessment showed that the method could be used to detect CSFV RNA extracted from infected pig blood with a sensitivity greater than that of VI.
Age Factors↗
Detection of transmissible gastroenteritis virus by RT-PCR and differentiation from porcine respiratory coronavirus.
An RT-PCR method was developed that amplified genetic material from the 5' end of the S protein gene of both transmissible gastroenteritis virus (TGEV) and porcine respiratory coronavirus (PRCV), but discriminated between the two by the size of the product generated. A number of restriction endonuclease enzymes were assessed for recognition of the amplicons so produced. The assay was shown to detect viral RNA from all of the 26 different TGEV and PRCV isolates examined, covering a period from 1946 to 1996. Detection of TGEV in clinical specimens was possible using a spin column method to extract RNA and sensitivity was compared to virus isolation and antigen detection ELISA. The method could provide a means of confirming positive results from immunological screening tests such as FAT and ELISA, reducing the need for virus isolation and convalescent serology.
Animals↗
Classical swine fever virus diversity and evolution.
By analysing the nucleotide sequence data generated from both the E2 (gp55) and the NS5B genes of classical swine fever virus (CSFV), in addition to previously published data from the 5'NCR, we were able to divide 115 CSFV isolates into two major groups, five subgroups and two disparate isolates. Further discrimination was possible by analysis of sequence data from the E2 region. The three sequencing based methods were compared to monoclonal antibody (MAb) typing and to limited restriction enzyme (RE) mapping. Although both MAb and RE methods confirmed the previous classification the resolution was inferior. We estimated an approximate evolution rate for CSFV from an analysis of the virus variation observed in a single geographical area over a 6 year period. Applying this proposed rate to each of our deduced CSFV subgroups enabled us to calculate the approximate dates of divergence for each subgroup.
Animals↗
A proposed division of the pestivirus genus using monoclonal antibodies, supported by cross-neutralisation assays and genetic sequencing.
Sixty-six pestiviruses from ruminant and porcine hosts were analysed with a panel of 76 monoclonal antibodies raised against 9 different viruses. Reactivity was used to construct epitope similarity maps for all of the viruses. Four principal virus subgroups were demonstrated. One subgroup equated to classical swine fever virus (CSFV) and included most porcine pestiviruses but none from ruminants. A second subgroup contained mainly viruses of bovine origin, including reference bovine viral diarrhoea viruses (BVDV) such as NADL; however viruses from pigs and sheep were also represented. A third subgroup represented by reference strains of border disease virus (BDV) comprised mainly ovine isolates, but also viruses from pigs. The fourth and most recently defined subgroup contained no reference strains of CSFV, BVDV or BDV, but included atypical viruses from cattle, sheep and pigs. The subgrouping scheme was supported by genetic comparisons between representative viruses from the 4 subgroups and by virus neutralisation with polyclonal sera.
Animals↗
Associations between viral infections and respiratory disease in artificially reared calves.
Market-purchased, week-old, dairy bred calves entering a commercial calf-rearing unit were blood sampled at six-week intervals until three months old. Viral infections were monitored by ELISA for antibodies to bovine herpesvirus 1, bovine respiratory syncytial virus, parainfluenzavirus-3, bovine adenovirus subgroup 1 and bovine viral diarrhoea virus (BVDV). The immunoperoxidase test was used to detect BVDV in serum. The total immunoglobulin concentration in the initial blood sample was measured by the zinc sulphate turbidity test. The relationship between clinical respiratory disease, viral seroconversion and the initial concentration of serum immunoglobulin was investigated by the use of the relative risk statistic, Fisher's exact test, chi 2 techniques and the correlation coefficient. Treatment rates for respiratory disease of 45 per cent were observed during the first period of the study and 19 per cent during the second period. During the first period there was a significant positive association between clinical respiratory disease and seroconversion for all the viruses except parainfluenzavirus-3 and BVDV but in the second period there was no such relationship. Similarly, in the first period, but not in the second, there was a significant negative association between clinical respiratory disease and both antiviral immunoglobulin as measured by ELISA and total immunoglobulin as measured by the zinc sulphate turbidity test. Two of the 536 calves that survived to three months of age were found to be persistently infected with BVDV.
Animals↗
Clinical and virological observations of a mucosal disease outbreak with persistently-infected seropositive survivors.
A group of 14 four to nine month old calves, clinically healthy but persistently infected with bovine virus diarrhoea virus (BVDV), was obtained from a single farm, and reared as a group. Ten of them were male and were castrated soon after arrival. Signs of mucosal disease (MD) developed within a month and eight of the males had died or been killed on humane grounds by 2 months after purchase. The other two males and one of the females developed more chronic but progressive signs of MD and were killed during the next four months. The remaining three females showed only transient signs of MD followed by clinical recovery. They subsequently remained healthy up to slaughter at 2, 2.5 and 5 years respectively. These three survivors were persistently infected with BVDV, and shed virus in their mucous secretions, although two of them were also seropositive to the virus with fluctuating neutralizing antibody titres (at times as high as 1/960) to a range of BVDV strains including their own persisting virus.
Animals↗
A blocking ELISA to differentiate hog cholera virus antibodies in pig sera from those due to other pestiviruses.
The blocking ELISA technique was extended to comparative serology by using 3 different pestivirus strains: Hog cholera virus (HCV) Alfort strain propagated in PK15 cell line, Border disease virus (BDV) Aveyron strain in PK15 and BVD NADL** strain in fetal calf kidney (FCK) primary cells. Rabbit antisera to the Alfort HCV strain and Aveyron BDV strain were raised for use in the test. A bovine hyperimmune serum to BVD virus was also used for detecting antibodies specific to BVD virus. The ELISA was compared with the neutralisation test on various groups of field and experimetnal porcine sera. The results obtained with the ELISA were well correlated with the neutralisation test. Therefore the ELISA may be recommended as a differential serological test between HCV and other pestivirus antibodies in pig sera.
Animals↗
Aetiology of Kawasaki disease.
Thirteen serum samples from nine children with Kawasaki disease and 23 control samples gave negative results on screening for antibodies to hog cholera virus, border disease of sheep, bovine diarrhoea virus, and equine arteritis virus. The sera from two children with Kawasaki disease were cytotoxic; a possible link with cytotoxin from Propionibacterium acnes is considered.
Antibodies, Viral↗
Mastitis survey in Bolivia.
Quarter milk samples were taken from 1,090 cows on 24 dairy farms in southeastern Bolivia. Nineteen per cent were positive in the milk quality test for subclinical mastitis, 12% for presence of potentially pathogenic bacteria and 4% for both. The prevalence of infection was related to management factors.
Animals↗
Leptospirosis in cattle in Bolivia.
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Agglutination Tests↗