BTV-vector-host interaction: the epidemiological triangle in disease transmission

The survival and transmission of vector-borne pathogens is dependent on the interactions between the pathogen, its vertebrate host and the specific midge vector. Studies on the interactions between the vector and the vertebrate host have examined the host ranges of different vector species and determined the relative roles of different vertebrate species in supporting the haematophagous insect vector population (23). A comparatively new area of research is the study of the vector-host interface, i.e. the site of the midge attachment and feeding. It is the site at which midge-borne pathogens pass from an invertebrate to the vertebrate host system, which is a key step in the transmission dynamics and indeed the survival of the pathogen (37). Bluetongue virus (BTV) is one of the best-known examples of pathogen-vector-host interaction. Changes in the epidemiology of BTV in Europe, particularly since 1998, when the virus spread northwards into the Mediterranean Basin (36), have stimulated research on this subject. BTV (family Reoviridae, genus Orbivirus) causes the hemorrhagic disease bluetongue (BT) in both domestic and wild ruminants. It is an infectious but non-contagious disease that causes high socio-economic and sanitary consequences. The most common signs of the disease include fever, catarrhal, stomatitis, rhinitis, enteritis and lameness (21). BT is endemic in many tropical, sub-tropical and temperate regions of the world (Africa, southern Asia, Australia, the Middle East, and the Americas), between latitudes 40°N and 53°S, during times of the year that are optimal for vector activity (36). In August 2006, for the first time, BTV passed the latitude 50°N and disease caused by virus serotype 8 occurred in north-western Europe: the Netherlands, Belgium, Germany, France and Luxembourg. In the next two years, BTV spread to other regions of Europe, the number of outbreaks increased rapidly (about 50000 cases of disease were reported), and new BTV serotypes (BTV1 and BTV6) were detected (38). To date, twenty seven immunologically distinct serotypes of BTV have been identified worldwide (39). It is a small icosahedral virus (of about 90 nm in diameter) with a genome of approximately 19200 base pairs, composed of ten linear segments of double-stranded RNA (dsRNA) (28), which encode ten distinct virus proteins (35). Seven of these BTV-vector-host interaction: the epidemiological triangle in disease transmission

[1]  P. Roy,et al.  Bluetongue Virus Capsid Assembly and Maturation , 2014, Viruses.

[2]  G. Wilkie,et al.  Virus and Host Factors Affecting the Clinical Outcome of Bluetongue Virus Infection , 2014, Journal of Virology.

[3]  M. Stokstad,et al.  A review of experimental infections with bluetongue virus in the mammalian host , 2014, Virus Research.

[4]  J. Sánchez-Vizcaíno,et al.  Potential role of proinflammatory cytokines in the pathogenetic mechanisms of vascular lesions in goats naturally infected with bluetongue virus serotype 1. , 2013, Transboundary and emerging diseases.

[5]  H. Segner,et al.  Climate change and infectious diseases of wildlife: Altered interactions between pathogens, vectors and hosts , 2013 .

[6]  C. Batten,et al.  Bluetongue virus serotype 26: infection kinetics, pathogenesis and possible contact transmission in goats. , 2013, Veterinary microbiology.

[7]  D. Verwoerd.  History of Orbivirus research in South Africa. , 2012, Journal of the South African Veterinary Association.

[8]  C. Saegerman,et al.  Viral RNA load in semen from bluetongue serotype 8-infected rams: relationship with sperm quality. , 2012, Veterinary journal.

[9]  G. Meyer,et al.  Sensing and Control of Bluetongue Virus Infection in Epithelial Cells via RIG-I and MDA5 Helicases , 2012, Journal of Virology.

[10]  P. Mellor,et al.  Involvement of the skin during bluetongue virus infection and replication in the ruminant host , 2012, Veterinary Research.

[11]  M. Bonneau,et al.  The Double-Stranded RNA Bluetongue Virus Induces Type I Interferon in Plasmacytoid Dendritic Cells via a MYD88-Dependent TLR7/8-Independent Signaling Pathway , 2012, Journal of Virology.

[12]  N. Maclachlan,et al.  Bluetongue: history, global epidemiology, and pathogenesis. , 2011, Preventive veterinary medicine.

[13]  P. Roy,et al.  Generation of Replication-Defective Virus-Based Vaccines That Confer Full Protection in Sheep against Virulent Bluetongue Virus Challenge , 2011, Journal of Virology.

[14]  P. Mellor,et al.  Saliva Proteins of Vector Culicoides Modify Structure and Infectivity of Bluetongue Virus Particles , 2011, PloS one.

[15]  P. Roy,et al.  Bluetongue virus infection alters the impedance of monolayers of bovine endothelial cells as a result of cell death. , 2010, Veterinary immunology and immunopathology.

[16]  T. Jackson,et al.  A Clathrin Independent Macropinocytosis-Like Entry Mechanism Used by Bluetongue Virus-1 during Infection of BHK Cells , 2010, PloS one.

[17]  P. Mellor,et al.  Viraemia and clinical disease in Dorset Poll sheep following vaccination with live attenuated bluetongue virus vaccines serotypes 16 and 4. , 2010, Vaccine.

[18]  Anthony J. Wilson,et al.  Bluetongue in Europe: past, present and future , 2009, Philosophical Transactions of the Royal Society B: Biological Sciences.

[19]  P. V. van Rijn,et al.  Transplacental and oral transmission of wild-type bluetongue virus serotype 8 in cattle after experimental infection. , 2009, Veterinary microbiology.

[20]  C. Batten,et al.  Toggenburg Orbivirus, a new bluetongue virus: initial detection, first observations in field and experimental infection of goats and sheep. , 2009, Veterinary microbiology.

[21]  M. Bonneau,et al.  Bluetongue Virus Targets Conventional Dendritic Cells in Skin Lymph , 2009, Journal of Virology.

[22]  J. Anguita,et al.  Establishment of a Bluetongue Virus Infection Model in Mice that Are Deficient in the Alpha/Beta Interferon Receptor , 2009, PloS one.

[23]  A. Jandowsky,et al.  Seasonal dynamics of biting midges (Diptera: Ceratopogonidae, Culicoides spp.) on dairy farms of Central Germany during the 2007/2008 epidemic of bluetongue , 2009, Parasitology Research.

[24]  P. Roy,et al.  Bluetongue vaccines. , 2009, Vaccine.

[25]  C. Batten,et al.  A European field strain of bluetongue virus derived from two parental vaccine strains by genome segment reassortment. , 2008, Virus research.

[26]  P. Mellor,et al.  Evidence for transplacental and contact transmission of bluetongue virus in cattle , 2008, Veterinary Record.

[27]  P. V. van Rijn,et al.  Potential new Culicoides vector of bluetongue virus in northern Europe , 2007, Veterinary Record.

[28]  S. Barros,et al.  Molecular epidemiology of bluetongue virus in Portugal during 2004-2006 outbreak. , 2007, Veterinary microbiology.

[29]  P. Roy.  Bluetongue virus proteins and particles and their role in virus entry, assembly, and release. , 2005, Advances in virus research.

[30]  T. Meiring,et al.  A comparison of different orbivirus proteins that could affect virulence and pathogenesis. , 2004, Veterinaria italiana.

[31]  J. Diprose,et al.  The bluetongue virus core: a nano-scale transcription machine. , 2004, Virus research.

[32]  T. Walton.  The history of bluetongue and a current global overview. , 2004, Veterinaria italiana.

[33]  P. Kirkland,et al.  A comparison of laboratory and 'wild' strains of bluetongue virus--is there any difference and does it matter? , 2004, Veterinaria italiana.

[34]  P. Mellor,et al.  Culicoides biting midges: their role as arbovirus vectors. , 2000, Annual review of entomology.

[35]  S. Wikel.  Tick modulation of host immunity: an important factor in pathogen transmission. , 1999, International journal for parasitology.

[36]  P. Mellor,et al.  Enhanced infectivity of modified bluetongue virus particles for two insect cell lines and for two Culicoides vector species. , 1996, Virology.

[37]  A. Spielman,et al.  Capacity of European animals as reservoir hosts for the Lyme disease spirochete. , 1992, The Journal of infectious diseases.