Bluetongue (BT) virus, an orbivirus of the Reoviridae family encompassing 24 known serotypes, is transmitted to ruminants via certain species of biting midges (Culicoides spp.) and causes thrombo-hemorrhagic fevers mainly in sheep. During the 20th century, BTV was endemic in sub-tropical regions but in the last ten years, new strains of BTV (serotypes 1, 2, 4, 8, 9, 16) have appeared in Europe leading to a devastating disease in naive sheep and bovine herds (serotype 8). BTV enters into insect cells via the viral inner core VP7 protein and in mammalian cells via the external capsid VP2 haemagglutinin, which is the major determinant of BTV serotype and neutralization. BTV replicates in mononuclear phagocytes and endothelial cells where it induces expression of inflammatory cytokines as well as apoptosis. BTV can remain as nonreplicating entities concealed in erythrocytes for up to five months. Homologous protection against one BTV serotype involves neutralizing antibodies and T cell responses directed to the external VP2 and VP5 proteins, whereas heterologous protection is supported by T cells directed to the NS1 non structural protein and inner core proteins. Classical inactivated vaccines directed to a specific serotype generate protective immunity and may help control current epidemic situations. New recombinant vaccine strategies that allow differentiating infected from vaccinated animals and that generate cross protective immunity are urgently needed to efficiently combat this worldwide threatening disease. bluetongue / orbivirus / arbovirus / viral haemorrhagic disease / ruminants

/pdf/bluetongue-virus-virology-pathogenesis-and-immunity-2p0bu1ylav.pdf

Bluetongue virus: virology, pathogenesis and immunity.

The outer capsid protein VP2 of Bluetongue virus (BTV) is a target for the protective immune response generated by the mammalian host. VP2 contains the majority of epitopes that are recognized by neutralizing antibodies and is therefore also the primary determinant of BTV serotype. Full-length cDNA copies of genome segment 2 (Seg-2, which encodes VP2) from the reference strains of each of the 24 BTV serotypes were synthesized, cloned and sequenced. This represents the first complete set of full-length BTV VP2 genes (from the 24 serotypes) that has been analysed. Each Seg-2 has a single open reading frame, with short inverted repeats adjacent to conserved terminal hexanucleotide sequences. These data demonstrated overall inter-serotype variations in Seg-2 of 29 % (BTV-8 and BTV-18) to 59 % (BTV-16 and BTV-22), while the deduced amino acid sequence of VP2 varied from 22.4 % (BTV-4 and BTV-20) to 73 % (BTV-6 and BTV-22). Ten distinct Seg-2 lineages (nucleotypes) were detected, with greatest sequence similarities between those serotypes that had previously been reported as serologically ‘related’. Fewer similarities were observed between different serotypes in regions of VP2 that have been reported as antigenically important, suggesting that they may play a role in the neutralizing antibody response. The data presented form an initial basis for BTV serotype identification by sequence analyses and comparison of Seg-2, and for development of molecular diagnostic assays for individual BTV serotypes (by RT-PCR).

Analysis and phylogenetic comparisons of full-length VP2 genes of the 24 bluetongue virus serotypes.

A review of RT-PCR technologies used in veterinary virology and disease control: sensitive and specific diagnosis of five livestock diseases notifiable to the World Organisation for Animal Health.

Introduction. Bluetongue virus (BTV) is the prototype virus of the Orbivirus genus in the Reoviridae family. Orbiviruses that infect and are transmitted by arthropod vectors (e.g. gnats, ticks, mosquitoes, etc.) include viruses that may cause disease in their vertebrate hosts with serious economic consequences in some regions of the world. The BTV group, which consists of at least 24 different serotypes (BTV-1, -2, etc.), infects field and domestic animals (e.g. sheep and cattle), occasionally with high morbidity and mortality but often with almost no apparent clinical symptoms. Other orbiviruses that may cause disease in animals include African horse sickness virus (AHSV; nine serotypes, AHSV-1, -2, etc.) and epizootic haemorrhagic disease virus (EHDV; seven serotypes, EHDV-1, -2, etc.) of deer. Although BTV and AHSV were isolated in 1900, and initial morphological and biochemical characterization were reported as early as 1969 (see review article, Gorman, 1990), much of the current knowledge on the molecular biology, genome structure and encoded products has been obtained only recently. The data are predominantly based on research on BTV.

Bluetongue virus proteins.

Segment 2 of bluetongue virus (BTV) serotype 10, which encodes the outer capsid protein VP2, was tagged with the S-peptide fragment of RNase A and expressed by a recombinant baculovirus. The recombinant protein was subsequently purified to homogeneity by virtue of the S tag, and the oligomeric nature of the purified protein was determined. The data obtained indicated that the majority of the protein forms a dimer and, to a lesser extent, some trimer. The recombinant protein was used to determine various biological functions of VP2. The purified VP2 was shown to have virus hemagglutinin activity and was antigenically indistinguishable from the VP2 of the virion. Whether VP2 is responsible for BTV entry into permissive cells was subsequently assessed by cell surface attachment and internalization studies with an immunofluorescence assay system. The results demonstrated that VP2 alone is responsible for virus entry into mammalian cells. By competition assay, it appeared that both VP2 and the BTV virion attached to the same cell surface molecule(s). The purified VP2 also had a strong affinity for binding to glycophorin A, a sialoglycoprotein component of erythrocytes, indicating that VP2 may be responsible for BTV transmission by the Culicoides vector to vertebrate hosts during blood feeding. Further, by various enzymatic treatments of BTV-permissive L929 cells, preliminary data have been obtained which indicated that the BTV receptor molecule(s) is likely to be a glycoprotein and that either the protein moiety of the glycoprotein or a second protein molecule could also serve as a coreceptor for BTV infection.

Expression and Functional Characterization of Bluetongue Virus VP2 Protein: Role in Cell Entry

The bluetongue virus (BTV) core particle contains 2 major polypeptides, P3 and P7, and is surrounded by an outer capsid layer that is composed of the 2 major polypeptides, P2 and P5. Analysis of the immune precipitates from soluble 14C-labelled BTV polypeptides and hyper-immune rabbit and guinea-pig sera indicated that polypeptide P2 precipitates only with homologous BTV sera. This would indicate that P2 is the main determinant of serotype specificity. It was also found that in sheep infected with BTV the P2-precipitating antibodies in the serum correlate with the neutralizing antibody titres, whereas the appearance and subsequent decline of P7-precipitating antibodies correspond well with those of the complement fixing antibodies. This suggests that BTV group specificity, as measured by a complement fixation tests, is determined by the core protein P7. This result was supported by the observation that mouse ascitic fluid, which contains a high titre of BTV-specific complement fixing antibodies and a very low titre of neutralizing antibodies, contains almost exclusively antibodies that precipitate P7.

Identification of the serotype-specific and group-specific antigens of bluetongue virus

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Erasmus Bj

Author Tools

Chat about Author

Papers

Identification of the serotype-specific and group-specific antigens of bluetongue virus