Detection of Foot-and-Mouth Disease Subclinical infection in sheep imported from free zones of Georgia during Hajj season 2009 in Kingdom of Saudi Arabia

Foot and mouth disease (FMD) sub-clinically infected animals, are always a threat to susceptible herds. During Hajj season 2009 (1431 Hijri) the kingdom of Saudi Arabia (KSA) imported about 204,583 sheep from FMD free areas from Republic of Georgia through Jeddah Islamic seaport. The animals were clinically free from FMD and authorized as not been previously vaccinated. However, but during the routine laboratory examination of serum samples using FMD-3ABC ELISA some sheep consignments exhibited positivness for FMD anti-bodies. The liquid phase blocking ELISA (LPBE) was performed as a confirmatory test which revealed antibodies against FMD serotype O, the suggesting that animals may be susceptible to FMD infection from any endemic countries passed through during overseas transportation. This study will contribute towards the development of an appropriate strategy for FMD control, including the choice of countries of the animal importation, as well as assist to improve our understanding of the epidemiology of FMD.


Introduction
impact in countries where it is endemic ( Astudillo et al., 1990 andPerry et al ., 1999).FMD provokes huge Foot-and-mouth disease virus (FMDV) is a economic consequences when outbreaks occur in member of the Picornaviridae family belongs to the disease free regions, and considered one of the most genus Aphthovirus that causes a highly contagious important barriers to world trade of livestock and vesicular disease of cattle and other cloven-hoofed animal products (Melo et al., 2002and Huang et al., animals (Bachrach, 1968and Pereira, 1981).Although 2000).mortality due to the foot-and-mouth disease (FMD) is An annual report on the global situation for FMD very low and mostly restricted to young animals, was provided by the World Reference Laboratory for drastic decrease in productivity and working capacity FMD at Pirbright, UK in 2006 and revealed that; FMD of the animals causes great losses to the livestock is present in many areas of the world, with the industry.One of the mechanisms of FMDV spread is exception of countries in north and central America the carriage of droplets and droplets nuclei exhaled in (North of panama), Australia, NewZealand ,Chile and the breath of infected animals, such spread can be rapid and extensive, and is known in certain circum-European union (EU) (OIE, 2006).stances to have transmitted disease over a distance of FMD was last reported to the OIE in the southern several hundred kilometers (Mikkelsen,T. et al., 2003).
Caucasus region, covering Georgia, Armenia and Sheep and goats are highly susceptible to Azerbaijan, in 2002(OIE, 2006).While serotypes A infection with FMDV by the aerosol route; the virus and O had frequently been found in Armenia and probably most often infects sheep and goats by direct Georgia, outbreaks of serotype Asia-1 have occurred contact (Kitching and Hughes 2002).
in the region in 2000/2001.Due to the passive disease The disease has an important socio-economic reporting systems, the true occurrence of FMD remains unclear.In the neighboring countries of Iran has been used to identify past or present infection (DeDiego ,et al., 1997;Brocchi ,et al., 1998; Dekker, and Turkey serotypes A, O are endemic (FAO, 2006;et.al et al et.al ., 1998 andMalirat, ., 1998).OIE, 2006 andGilbert, ., 2005).
In recent years, the potential value of the non-An FMD vaccination buffer zone has been maintained in Armenia, Azerbaijan and Georgia with structural proteins (NSP) 2C and 3ABC has been well documented for differentiation of infected from the support of the FAO.The buffer zone covers vaccinated animals with FMDV (DIVA) (Lu, et.al., districts of the three countries bordering Iran and 2010).Perhaps the most reliable single NSP indicator Turkey, and is between 10 and 60 km wide.Buffer is the polyprotein 3ABC antibodies which appears to zone vaccination using trivalent A/O/Asia-1 vaccine provide conclusive evidence of previous infection has regularly been carried out since spring 2004 (FAO, (Mackay,et.al., 1998).The antibodies against 3ABC 2006 and OIE 2006).Before 2004, vaccinations were have been detected up to 395 days post infection in often irregular.Besides the buffer zone vaccination both cattle and sheep (Sorensen,et.al., 1997).additional national campaigns, also using non- The present study aims to explain the rapid purified vaccines, have been carried out according to detection and sero-typing of FMD virus in sheep that the resources available and the risks perceived.The came from free zones in Georgia using the 3ABC risk of FMD introduction and spread is largely FMD ELISA and LPBE as a preliminary line of influenced by extensive regional movements to and preventing the entrance and spread of the FMD in to from summer pastures, and between production areas, Saudi Arabia.markets and slaughter locations, as well as cross border movements of animals.None of the countries Materials and Methods internationally trades FMD susceptible livestock on a 1. Serum samples: A total of 1140 sheep serum larger commercial scale (Potzch,et al., 2006).
samples were examined for FMD from different The FMD virus genome encodes a unique poly consignment of animals that came from Georgia protype from which the different viral polypeptides according to the animal quarantine laws of Jeddah are cleaved by viral proteases, including eight different Islamic seaport animal quarantine (Table1).non-structural proteins (NSPs).Both structural and 2. Foot-and-mouth disease antibody test kit non-structural antigens induce the production of (FMD-3ABC bo-ov): FMD-3ABC bo-ov was antibodies in infected animals.An immunoenzymatic provided by IDEXX Laboratories, Netherlands and assay (liquid phase blocking ELISA) can detect manufactured by IDEXX Lieberfeld-bern Switzerland.antibodies against FMDV structural protein in sheep, The test detects antibodies against non-structural indicating that unrecognized FMD-infected sheep proteins of FMD and was performed as described by could represent a potential risk of FMD dissemination ' the manufacturer s guide and according to the (Blanco et al., 2002).

Liquid phase blocking ELISA (LPBE): LPBE
The results in table 2 showed that some of the technique for the detection of FMDV antibodies in et.al collected sera from consignment numbers 2,3,4,5,6,9, serum was described by ( Hamblin, ., 1986 a, b).The test is based upon specific blocking of the FMDV 10,11 revealed positivness for specific antibodies against non-structural protein 3ABC by using FMD-antigen in liquid phase by antibodies in the test serum.
3ABC ELISA , percentage positive ranging from 35% Rabbit antisera specific for the different serotypes of FMDV are passively adsorbed to polystyrene micro to 109% .The LPBE serotyped all NSP positive sera wells.After the test serum is allowed to react with the FMD serotype O. specific FMDV antigen, the test serum/antigen mixture Discussion is then transferred to an ELISA plate coated with FMDV trapping antibodies (guinea pig antisera to the There are severe international trade restrictions 7 FMDV serotypes).The presence of antibodies to on FMD affected areas, so KSA government decided FMDV in the serum sample will result in the formation to import the animals for adahhi (2009) from free areas of immune complexes and consequently reduce the as Republic of Georgia.In animal quarantine of amount of free antigen trapped by the immobilized Jeddah Islamic seaport, one of the important strategies rabbit antisera.In turn, fewer guinea pig anti-FMDV for control and eradication of FMD is to detect and detecting antibodies will react in the next incubation prevent the entrance of infected or carrier animal to step.After the addition of enzyme-labeled (horse KSA.The identification of animals which are currently radish peroxidase, HRP) anti-guinea pig Ig conjugate or previously infected with FMD is very important, and substrate/chromogen solution, a reduction in color taking into consideration that, apparently healthy development will be observed when compared to animal may be the source of a new outbreak.The only way to efficiently identify infected or a routine diagnostic tool.In addition illegal animal carrier sheep serologically is by the detection of movements which are always a threat to susceptible antibodies against non-structural proteins of FMDV, herds especially in border areas must be prohibited.as NSP antibodies only develop initially following a specificity > 99% for bovine, ovine and porcine sera with (Gloster, et. al., 2007) who stated that the FMD is

Conclusion
European Commission for the control of FMD.12.

K
.,Tufan, M. and Sligenbergh, J. (2005)  : patterns of spread perception that FMD-3ABC ELISA alone or followed and persistence of Foot-and-mouth disease types A,O and Asia-1 in Turkey ;a meta-population approach.Epidemiol.by liquid phase blocking ELISA is a useful technique infec.133(3): 537-545.

:
Foot-and-mouth Quantification andit is noteworthy that lack of laboratory infrastructures size distribution of airborne particles emitted by healthy and in certain seaports or other border areas with high risk infected pigs .Vet.J.174 (1): 42-53.