this study were to measure antibody titres in Arabian oryx in ... Ten male Arabian oryx (Oryx leucoryx) were vaccinated with a commercially available standard ...
Papers & Articles Temporal assessment of seroconversion in response to inactivated foot-and-mouth disease vaccine in Arabian oryx (Oryx leucoryx) C. P. Kilgallon, T. A. Bailey, D. O’Donovan, U. Wernery, S. Alexandersen Ten male Arabian oryx (Oryx leucoryx) were vaccinated with a commercially available standard aqueous foot-and-mouth-disease vaccine containing aluminium hydroxide as an adjuvant, and their antibody titres against serotypes O and A were measured using solid-phase blocking ELISA and the virus neutralisation test. Mean ELISA antibody titres greater than 1·45 log10 were recorded for serotype A, but low ELISA titres were recorded for serotype 0; low titres were recorded by VNT for both serotypes.
Veterinary Record (2008) 163, 717-720 C. P. Kilgallon, MVB, MSc, MRCVS, T. A. Bailey, BSc, BVSc, MSc, PhD, DipECAMS, CertZooMed, MRCVS,
Dubai Falcon Hospital, PO Box 23919, Dubai,
United Arab Emirates D. O’Donovan, DipHEd, BSc, MSc, CBiol, MIBiol, Wadi Al Safa Wildlife Centre, PO Box 27875, Dubai, United Arab Emirates U. Wernery, DVM, PhD, Central Veterinary Research Laboratory, PO Box 597, Dubai, United Arab Emirates, S. Alexandersen, DVM, PhD, DVSc, FRCPath, MRCVS, Institute for Food and Veterinary Research, Exotic Virus Experimental Epidemiology Unit, Department of Virology, Lindholm, DK- 4771, Kalvehave, Denmark Mr Kilgallon’s present address is San Diego Zoo, 2920 Zoo Drive, San Diego, CA 92112, USA
FROM an economic perspective, foot-and-mouth disease (FMD) is one of the most important animal diseases (Thompson and others 2001). It is a highly contagious, vesicular disease of all cloven-hoofed animals caused by a virus of the family Picornaviridae, genus Aphthovirus (Knowles and others 2005, Thompson 1994, Alexandersen and Mowat 2005). There are seven immunologically distinct serotypes of FMD virus (FMDV): A, O, C, SAT1, SAT2, SAT3 and Asia1 (World Organisation for Animal Health [OIE] 2004). The virus is endemic in the domestic livestock populations of several South American countries, much of Africa and the Middle East (types O and A), central and south-east Asia, and probably China (types O, A and Asia1) (Knowles and others 2005). Recent outbreaks of FMD have occurred in Taiwan (1997 to 2001), the UK, France, Holland and Ireland (2001), Japan, Korea and South Africa (2000), and the UK (2007), all countries that had been free of the virus. Apart from European bison (Bison bonasus) and Cape buffaloes (Syncerus caffer), in which maintenance cycles have been recognised (Thompson and others 2001, OIE 2004, Hargreaves and others 2004), wild artiodactylids are infected by contact with, or viral spillover from, either Cape buffaloes or domestic livestock. In domestic livestock, control of the disease by means of a test-and-slaughter policy is presently favoured during outbreaks in regions where the disease is not endemic, and was the main method employed during the European outbreak in 2001. In the past, zoo and wildlife vaccination regimens were loosely based upon domestic livestock protocols, but since the implementation in 1991 by EU member states of the 85/511/EEC directive, preventive vaccination against FMD is no longer permitted in Europe, including zoos (Schaftenaar 2002). The main reason is that although vaccination may protect animals against clinical disease, they remain susceptible to infection, and may actively shed the virus, thereby propagating the disease (Alexandersen and others 2003). In addition, the efficacy of most vaccines, and the titres of antibody that confer protection in wildlife species, have yet to be established. In one study in Cape buffaloes, the titres recorded were lower than those in domestic cattle (Schaftenaar 2002). Outbreaks of the disease can cause significant morbidity in susceptible populations of endangered exotic ungulates, and necessitate international restrictions on the dissemination of valuable germplasm (OIE 2004). This was recognised during and in the aftermath of the European outbreak in 2001. Since then, the international committee of the OIE/ Food and Agriculture Organization of the United Nations (FAO) has accepted proposals to provide for the emergency The Veterinary Record, December 13, 2008
prophylactic vaccination of susceptible endangered species in the face of impending outbreaks. Modern ELISA technology makes it possible to distinguish antibodies due to vaccination from antibodies due to a natural infection, because antibodies to viral non-structural proteins (NSPs) are detectable only after a natural infection (Bergmann and others 1993, Mackay and others 1998, Sorensen and others 2005). The technique is possible only when using high-quality vaccines incorporating highly purified viral antigens. The method has been accredited by the OIE for use on a herd basis and may be valuable as an adjunct in future vaccination programmes in zoos (Schaftenaar 2002). The small numbers involved and the value of the animals from a conservation standpoint justify the use of emergency prophylactic vaccination in the face of an outbreak. In domestic livestock, the dose that protects 50 per cent of animals challenged (PD50) for a formulated vaccine is calculated on the basis of the protection it provides from clinical disease, that is, prevention of the generalisation of FMD to the feet (Cox and others 2006). Emergency vaccines, containing antigens incorporated on the basis of a cattle potency test, as described by the OIE Manual of Standards, are maintained in reserve and are theoretically for use in the face of an outbreak. For a vaccine to be acceptable as an emergency vaccine, it has to achieve a potency value of 6 PD50 or more (Cox and others 2006). Such vaccines are often referred to as ‘high potency’ and they induce a slightly more rapid response and long-lasting protective titres (Cox and others 2006). In contrast, vaccines prepared for routine prophylactic campaigns need only achieve a potency value of 3 PD50 or more, but they require primary and booster inoculations. However, the vaccine potency test system of the European Pharmacopoeia provides only a rough estimate of the actual PD50 because of its low in vivo repeatability and reproducibility (Goris and others 2007). The measured potency of one FMDV O vaccine with a reported overall potency value of 9·99 PD50 actually varied between 4·59 and 24·25 PD50 (Goris and others 2007). Emergency vaccines with the highest potency should therefore be chosen. At the present time, the nature and extent of the immunological response to any FMD vaccine, of either high or standard potency, has not been established in exotic ungulates (Schaftenaar 2002, Ryan and others 2004). The objectives of this study were to measure antibody titres in Arabian oryx in response to a single inoculation with a commercially available FMD vaccine using a type-specific solid-phase blocking ELISA and the virus neutralisation test (VNT), and to consider the likely efficacy of these titres in conferring protective immunity upon the animals.
Papers & Articles
TABLE 1: Mean log 10 solid-phase blocking ELISA and virus neutralisation test (VNT) antibody titres to O1-Manisa band A22-Iraq strains of foot-and-mouth disease in 10 Arabian oryx at intervals after they were vaccinated intramuscularly with a single dose of a commercial vaccine Strains of virus
Assay
0
7
O1-Manisa A22-Iraq O1-Manisa A22-Iraq
ELISA ELISA VNT VNT
