A universal 'one-tube' RT-PCR protocol for amplifying isolates of bovine viral diarrhoea virus

An ultra-sensitive detection of a whole virus using dual aptamers developed by immobilization-free screening

In this study, we successfully developed a ssDNA aptamer pairs by using an advanced immobilization-free SELEX method with affinity-based selection and counter-screening process at every round. By implementing this method, two different aptamers specifically binding to bovine viral diarrhea virus type 1(BVDV type 1) with high affinity were successfully screened. This aptamer pair was applied to ultrasensitive detection platform for BVDV type 1 in a sandwich manner. The ultrasensitive detection of BVDV type 1 using one of aptamers conjugated with gold nanoparticles was obtained in aptamer-aptamer sandwich type sensing format, with the limit of detection of 800 copies/ml, which is comparable to a real-time PCR method.

A universal heterologous internal control system for duplex real-time RT-PCR assays used in a detection system for pestiviruses

A heterologous in vitro transcript based on a specific primer-probe HEX system was generated as a universal internal control (IC) to improve virus-specific real-time reverse-transcriptase PCR (RT-PCR) assays. By using a set of different primers, several PCR fragments of desired sizes of an in vitro transcript of the enhanced green fluorescent protein (EGFP) gene were generated, and the fragments were detected using a HEX-labelled probe. For long-term storage of the in vitro transcript a special RNA-safe buffer (RSB) was developed. Freezing and thawing of the IC diluted in RSB did not result in any substantial loss of detectable IC copy numbers. The new IC system was used for the first time in a duplex real-time RT-PCR assay for the detection of pestivirus-derived RNA, in particular from bovine viral diarrhea virus (BVDV). Primers and TaqMan probes for the 'panpesti' assay were selected by analysing the consensus sequence of the 5' non-translated region (5' NTR) of more than 600 different pestiviruses. Finally, the optimised primer probe combination showed an analytical sensitivity of less than 10 copies/reaction. In the duplex set-up, the analytical sensitivity of the validated real-time RT-PCR was identical to the sensitivity of the single assay without IC, and the diagnostic sensitivity of the duplex assay was equal or higher if compared to virus isolation.

Genetic and antigenic characterization of an atypical pestivirus isolate, a putative member of a novel pestivirus species

The genus Pestivirus within the family Flaviviridae currently consists of four different main species: Classical swine fever virus, Bovine viral diarrhea virus types 1 and 2 and Border disease virus. A fifth tentative species is represented by an isolate from a giraffe. In this study, a completely new pestivirus, isolated from a batch of fetal calf serum that was collected in Brazil, is described. It is proposed that the isolate D32/00_'HoBi' may constitute a novel sixth pestivirus species, because it is genetically, as well as antigenically, markedly different from all other pestiviruses. Based on the entire N(pro)- and E2-encoding sequences, identities of <70 % to all other pestivirus species were determined. Similarly, cross-neutralization and binding studies using antisera and mAbs revealed marked antigenic differences between D32/00_'HoBi' and all other pestiviruses.

Laboratory diagnosis of bovine viral diarrhea virus infections

The past 20 years have witnessed dramatic improvements in laboratory methods for diagnosing bovine viral diarrhea virus(BVDV) infections. However, improvements in diagnostic technology have not necessarily led to improved diagnosis of BVDV at the individual animal or herd level. This article reviews BVDV laboratory diagnostic methods in the context of their rational application for improved detection of BVDV in the field.

Phylogenetic analysis of the 5'-untranslated region of german BVDV type II isolates

On the basis of genetic differences, bovine viral diarrhoea viruses (BVDV) are subclassified into two distinct genotypes, BVDV type I and BVDV type II. We selected German BVDV type II isolates using the BVDV type I-specific monoclonal antibody WB160 and flow cytometric analysis for further characterization. For molecular characterization, a 288-bp fragment of the 5'-untranslated region (5'-UTR) of the selected isolates was investigated by reverse transcription-polymerase chain reaction (RT-PCR) and sequencing. Sequence comparisons of the partial 5'-UTR sequences and their phylogenetic analyses demonstrated that the 18 German BVDV type II isolates all belong to either subtype IIa (10 isolates) or subtype IIc (eight isolates). Nevertheless, the German BVDV type II isolates were genetically different (89.9-94.3% sequence identity) from the standard BVDV type II strain 890 from North America, which was recently classified as BVDV type IIa. Furthermore, a clear subdivision of the German BVDV type II isolates into two distinct subtypes (BVDV IIa Germany and BVDV IIc Germany) is shown. Viruses of both subgroups differed in the analysed 5'-UTR fragment from each other (91.6-95.2% sequence identity), but were highly conserved within the same German subtype (97.2-100% sequence identity). These findings are discussed in the context of BVDV type II origin, possible introduction into Germany, its epidemiology and impact for vaccine development.