Orbiviruses

Verwoerd, Daniel Wynand; Huismans, H.; Erasmus, B. J.

doi:10.1007/978-1-4684-3563-4_5

Cited by 49 publications

(37 citation statements)

References 114 publications

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“…African horse sickness virus (AHSV) is a member of the genus Orbivirus in the family Reoviridae and as such is morphologically similar to other orbiviruses such as bluetongue virus (BTV) of ruminants and equine encephalosis virus [117,119,129]. The virion is an unenveloped particle about 70 nm in diameter and is made up of a twolayered icosahedral capsid, which is composed of 32 capsomeres [25].…”

Section: Aetiologymentioning

confidence: 99%

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African horse sickness

2004

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-African horse sickness virus (AHSV) causes a non-contagious, infectious insect-borne disease of equids and is endemic in many areas of sub-Saharan Africa and possibly Yemen in the Arabian Peninsula. However, periodically the virus makes excursions beyond its endemic areas and has at times extended as far as India and Pakistan in the east and Spain and Portugal in the west. The vectors are certain species of Culicoides biting midge the most important of which is the AfroAsiatic species C. imicola. This paper describes the effects that AHSV has on its equid hosts, aspects of its epidemiology, and present and future prospects for control. The distribution of AHSV seems to be governed by a number of factors including the efficiency of control measures, the presence or absence of a long term vertebrate reservoir and, most importantly, the prevalence and seasonal incidence of the major vector which is controlled by climate. However, with the advent of climatechange the major vector, C. imicola, has now significantly extended its range northwards to include much of Portugal, Spain, Italy and Greece and has even been recorded from southern Switzerland. Furthermore, in many of these new locations the insect is present and active throughout the entire year. With the related bluetongue virus, which utilises the same vector species of Culicoides this has, since 1998, precipitated the worst outbreaks of bluetongue disease ever recorded with the virus extending further north in Europe than ever before and apparently becoming endemic in that continent. The prospects for similar changes in the epidemiology and distribution of AHSV are discussed.

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Section: Aetiologymentioning

confidence: 99%

“…Until recently serotyping AHSV has relied largely upon virus neutralisation (VN) tests using type specific antisera [58,129]. These tests depend upon the presence of live replicating virus and can be performed using mammalian cells [48] or suckling mice [76] as the indicator of VN.…”

Section: Antigen Identificationmentioning

confidence: 99%

African horse sickness

2004

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“…AHSV is a member of the genus Orbivirus, family Reoviridae (7). Nine serotypes of AHSV have been described (8) and (9).…”

Section: Introductionmentioning

confidence: 99%

Protective immunization of horses with a recombinant canarypox virus vectored vaccine co-expressing genes encoding the outer capsid proteins of African horse sickness virus

Guthrie¹,

Quan²,

Lourens³

et al. 2009

Vaccine

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We describe the development and preliminary characterization of a recombinant canarypox virus vectored (ALVAC ® ) vaccine for protective immunization of equids against African horse sickness virus (AHSV) infection. Horses (n = 8) immunized with either of two concentrations of recombinant canarypox virus vector (ALVAC-AHSV) co-expressing synthetic genes encoding the outer capsid proteins (VP2 and VP5) of AHSV serotype 4 (AHSV-4) developed variable titres (<10-80) of virus-specific neutralizing antibodies and were completely resistant to challenge infection with a virulent strain of AHSV-4. In contrast, a horse immunized with a commercial recombinant canarypox virus vectored vaccine expressing the haemagglutinin genes of two equine influenza H3N8 viruses was seronegative to AHSV and following infection with virulent AHSV-4 developed pyrexia, thrombocytopenia and marked oedema of the supraorbital fossae typical of the "dikkop" or cardiac form of African horse sickness. AHSV was detected by virus isolation and quantitative reverse transcriptase polymerase chain reaction in the blood of the control horse from 8 days onwards after challenge infection whereas AHSV was not detected at any time in the blood of the ALVAC-AHSV vaccinated horses. The control horse seroconverted to AHSV by 2 weeks after challenge infection as determined by both virus neutralization and ELISA assays, whereas six of eight of the ALVAC-AHSV vaccinated horses did not seroconvert by either assay following challenge infection with virulent AHSV-4. These data confirm that the ALVAC-AHSV vaccine will be useful for the protective immunization of equids against African horse sickness, and avoids many of the problems inherent to liveattenuated AHSV vaccines.

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“…The bluetongue serogroup comprises 24 virus serotypes which have been identified using virus neutralization tests. Bluetongue virus (BTV) contains 10 dsRNA segments (Verwoerd et al, 1979;Gorman et aL, 1983) each of which codes for a single protein (Grubman et al, 1983;Mertens et al, 1984). Morphologically, the virus consists of a core, composed of 32 capsomeres arranged in icosahedral symmetry, surrounded by an outer fibrillar coat (Bowne & Richie, 1970;Verwoerd et al, 1972).…”

Section: Introductionmentioning

confidence: 99%

Ultrastructural Distribution of the Major Capsid Proteins within Bluetongue Virus and Infected Cells

Hyatt

Eaton

1988

Journal of General Virology

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SUMMARYCore proteins VP7 and VP3 have been localized in bluetongue virus (BTV) and BTV-infected cells by immunoelectron microscopy. Gold-labelled monoclonal antibodies to VP7 gave intense labelling with purified BTV core particles and weaker labelling with both directly visualized viral particles, which require no purification, and purified virus particles. It is believed that VP7 is, in a small number of viruses, accessible from the outer surface. The intensity of labelling by anti-VP7 antibodies was markedly increased by treatment of the virus with methanol. Intracellularly, VP7 antibodies also reacted with virus-like particles which appeared to be leaving virus inclusion bodies (VIB), the presumed site of virus synthesis and assembly. These antibodies also reacted with virus-like particles which were bound to the cytoskeleton and did not appear to be virus cores because they also reacted with gold-labelled antibody to the outer coat protein VP2. VP3 was not detected immunologically in either virus or core particles nor in cytoskeleton-associated virus-like particles suggesting an inner core location. VP7 and to a lesser extent VP3 were localized within the matrix of VIB. Virus tubules, a major structure found in infected cells and known to contain the non-structural protein NS1, were found to react with antibodies to both VP3 and VP7.

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Orbiviruses

Cited by 49 publications

References 114 publications

African horse sickness

African horse sickness

Protective immunization of horses with a recombinant canarypox virus vectored vaccine co-expressing genes encoding the outer capsid proteins of African horse sickness virus

Ultrastructural Distribution of the Major Capsid Proteins within Bluetongue Virus and Infected Cells

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