FMD Serotype Research Articles

Seromonitoring, Serotyping and Histopathology of Foot and Mouth Disease in Mithun (Bos Frontalis) in the Northeastern Hilly Terrain of India

Frequent FMD outbreaks have been one of the major challenges faced by the farmers and breeders of Mithun animals in Nagaland, owing to a lack of adequate knowledge and proper vaccination programs for the disease. Therefore, this study aimed to determine the extent of FMD serotype O virus infection, which is the most common serotype causing FMD specifically in the Mithun population in the northeastern state of Nagaland, India. In-vitro screening of serotype O virus antibodies in the blood serum of the Mithun population was carried out by ELISA kit. A total of 213 blood samples of Mithun animals were collected and screened where 67% of the samples tested were found to be positive and only 32% of the samples were found to be negative for the virus. All the samples collected from the neighbouring states of Mizoram and Arunachal Pradesh were found to be negative for the antibodies against the serotype O virus. Through m-RT PCR, O serotype was detected from all the clinically affected animals from the cells of the tongue epithelium, blood, and saliva of animals. During the histopathological studies, in the pericardium, severe interstitial myocarditis and liver showed focal areas of coagulative necrosis, focal necrosis, and pulmonary oedema were prominent and ballooning degeneration of epithelium in the tongue was evident in all cases. In conclusion, we were able to show the prevalence of FMDV serotype O antibodies in a very high percentage of the Mithun population that were tested along with pathological alterations, which should be addressed immediately with proper vaccination programs and by informing and educating the farmers and breeders about the disease before an outbreak occurs.

ADAPTATION OF FOOT & MOUTH DISEASE VIRUS SUBTYPES PAN ASIA-II, TUR-06 AND SINDH-08 TOWARDS THE VACCINE DEVELOPMENT AND SEROLOGICAL FINDINGS BY SPC ELISA AND SERUM NEUTRALIZATION TEST

FMD serotype “O” with subtype PAN Asia-II, serotype “A” with subtype Tur-06 and serotype “Asia-1” with subtype Sindh-08 were adapted on the LFBK cell line and subsequently on BHK-21. After inactivation these subtypes were introduced for the development of oil based trivalent vaccine against FMD. The study was conducted on the experimental animals (cow calves) at Livestock Production Research Institute (LPRI), Okara. Twenty one unvaccinated cattle calves of age group 4-6 month were used in the study, 16 were injected with experimentally prepared oil based FMD vaccine at the dose rate of 2cc per cow calf at day 0 and 28 post priming while five cattle calves were kept as control. The FMD oil based vaccine containing subtypes PAN ASIA-II, TUR-06 and SINDH-08 showed satisfactory immune response on ELISA and Serum Neutralization Test (SNT) at day 28 post priming and day 28 post booster. The study aimed to strengthen the national control strategy against FMD by the incorporation of prevalent field strains of FMD virus for the vaccine development.

EPIDEMIOLOGICAL STATISTICS OF FMD VIRUS SEROTYPES A, O AND ASIA-1 IN PUNJAB, PAKISTAN DURING 2014-2019

Foot and Mouth Disease is an endemic disease and three serotypes (A, O, Asia-1) are prevalent in Pakistan. The present study shows the frequency of Foot and Mouth Disease Virus (FMDV) serotypes (A, O, Asia-1) in Punjab Province of Pakistan by using antigenic Enzyme-Linked Immunosorbent Assay (ELISA). This study was conducted from 2014-2019 by using a total of 184 epithelial samples from field. Out of 184 samples, 106 samples showed positive results. Out of three serotypes, serotype „A‟ was the most prevalent (39.62%) followed by serotype „O‟ (33.96%) while the least prevalent was serotype Asia-1 (26.41%). It was marked that no other serotype of FMD reported during this study. This study also described the year wise prevalence of three prevailing FMD serotypes (A, O, Asia-1). During year 2014, the serotype „A‟ was more prevalent (95.83%) followed by serotype „Asia-1‟ (4.16%) while no case of serotype „O‟ was found. During year 2015, the prevalence trend was almost the same as in 2014. In this year, serotype „A‟ was 55.55% while serotype „Asia-1‟ 37.03% followed by the least prevalent serotype „O‟ as 7.40%. During year 2016, 19 positive cases were reported from which the maximum prevalence was serotype „O‟ and „Asia-1‟ (42.10%) followed by serotype „A‟ (15.78%) as least prevalent. During year 2017, the positive cases for FMD increased remarkably i.e. 29 in number. This year serotype „O‟ was highest in number with prevalence 75.86%, and serotype „Asia-1‟ 20.68% whereas only one case reported for serotype „A‟ with only 3.44% prevalence. During year 2018 and 2019, only 7 cases described with no evident case ofserotype „A‟. During these two years 4 cases of serotype „O‟ were observed followed by 3 cases of serotype „Asia-1‟.

An Extensive Analysis of Codon Usage Pattern, Evolutionary Rate and Phylogeographic Reconstruction in Foot and Mouth Disease (Fmd) Serotypes (a, Asia 1 and O) of Six Major Climatic Zones of India: A Comparative Study

An Extensive Analysis of Codon Usage Pattern, Evolutionary Rate and Phylogeographic Reconstruction in Foot and Mouth Disease (Fmd) Serotypes (a, Asia 1 and O) of Six Major Climatic Zones of India: A Comparative Study

An Extensive Analysis of Codon Usage Pattern, Evolutionary Rate and Phylogeographic Reconstruction in Foot and Mouth Disease (Fmd) Serotypes (a, Asia 1 and O) of Six Major Climatic Zones of India: A Comparative Study

An Extensive Analysis of Codon Usage Pattern, Evolutionary Rate and Phylogeographic Reconstruction in Foot and Mouth Disease (Fmd) Serotypes (a, Asia 1 and O) of Six Major Climatic Zones of India: A Comparative Study

Immunological Evaluation of Influence of Dose and Route of Immunization with FMD Serotype ‘A’ Vaccine in Guinea Pigs

A study has been conducted to measure the immunization efficacy of route of inoculation between intra dermal (ID) and intra muscular (IM) in guinea pigs, using FMD vaccines. Three different vaccine formulations of varying concentrations containing full dose, 1/5th dose, 1/10th dose were prepared and injected either intra muscularly or intra dermal to six different groups of guinea pigs. At 30th day post vaccination, all the animals were challenged. Efficacy of route was defined in terms of serum neutralizing antibodies, IgG1 and IgG2 isotype response and challenge studies. When compared with guinea pigs that were intramuscularly vaccinated with a full dose vaccine, guinea pigs vaccinated intra dermal with 1/5th dose of the vaccine were 60% protected against clinical disease. Thus, we conclude that ID route is a good alternative for IM route, as ID route has shown to induce a very efficient immunological response against FMD. Moreover, the dose required by the ID route is lower compared to the IM route with an added benefit of reduced requirement of antigen and costs per dose of FMD vaccine.

Comparison of antibody response between intradermal and intramuscular administration of a foot-and-mounth disease vaccine in pigs

Since the 2010 foot and mouth (FMD) epidemic, the Korean government has applied a FMD vaccination to pigs. A FMD vaccine is injected to pigs by intramuscular (IM) route. One of the drawbacks in FMD vaccine IM injection is that it would result in an abnormal meat on the injection spot. An abnormal meat due to FMD vaccine IM injection would cause economic loss to pig farmers. An intradermal (ID) injection would be an alternative method for FMD vaccination. The goal of current study was to compare the antibody formation rate between FMD vaccine IM injection and ID injection. The antibody formation rate was measured by the FMD serotype O vaccination percent inhibition (PI) value. In total 350 pigs (175 for FMD vaccine IM injection and 175 for FMD vaccine ID injection) were included in the study. In results, the PI values of FMD vaccine IM injection group were significantly higher than it of FMD vaccine ID injection group. However, the proportions of pigs with PI value was higher than 50, which is a legislative requirement for marketing pigs, for both FMD vaccine IM and ID injection groups at week 20 or 23 were not significantly different. The current results indicated that a FMD vaccine ID injection could be an alternative method of IM injection.

Genetic and antigenic relationship of foot–and–mouth disease virus serotype O isolates with the vaccine strain O1/BFS

Foot–and–mouth disease serotype O viruses (FMDV/O) are responsible for the most outbreaks in FMD endemic countries. O1/BFS is one of the recommended FMD/O vaccine strains by World Reference Laboratory for FMD. In the current study, FMDV/O1 BFS vaccine strain and serotype O field isolates (45) were analyzed phylogenetically and antigenically to gain more insight into the genetic and antigenic characteristics of the vaccine strain and field isolates.O1/BFS showed similarity with 89% of the field isolates using a virus neutralization test (VNT). The P1 region encoding the FMDV capsid was sequenced and analysed for 46 strains of FMDV/O. Phylogenetic analysis showed these viruses originated from five continents and covered eight of 11 reported topotypes. Five isolates that demonstrated low antigenic similarities with O1/BFS were analyzed for their antigenic variation at the known neutralizing antigenic sites. Three of the five isolates demonstrated unique amino acid substitutions at various antigenic sites. No unique amino acid substitutions were observed for the other two unmatched isolates. Positively selected residues were identified on the surface of the FMD virus capsid supporting that it is important to continuously monitor field isolates for their antigenic and phenotypic changes.In conclusion, the vaccine strain O1/BFS is likely to confer protection against 89% of the 45 FMDV/O isolates based on VNT. Thus O1/BFS vaccine strain is still suitable for use in global FMD serotype O outbreak control. Combining data from phylogenetic, molecular and antigenic analysis can provide improvements in the process of vaccine selection.

Outbreak of foot and mouth disease and peste des petits ruminants in sheep flock imported for immediate slaughter in Riyadh.

Aim:To detect and identify the causative agent or agents of the following clinical symptoms which were fever, lack of appetite, salivation, vesiculation, erosions of the buccal mucosa, nose, and feet. The signs vary from mild to severe. The mortality rate of the disease is high. The morbidity rate reaches up to 100%. Sheep also show bloody diarrhea and rapid respiration. Sheep flock resident in El-Kharje Governorate.Materials and Methods:A total of 50 serum samples and 50 buffy coat samples were collected from Marino sheep flock suffered from high mortalities, fever, lameness, diarrhea, stomatitis, and respiratory distress. PrioCHECK® foot and mouth disease virus (FMDV) nonstructural (NS) (marketable enzyme-linked immunosorbent assay [ELISA] kit) was used for revealing of the NS antibodies and liquid phase blocking enzyme immunoassay (LPBE) for identifying the FMD serotype and examined by competitive ELISA (cELISA) for detection of peste des petits ruminants (PPR) antibodies. The buffy coat samples were examined by immunocapture ELISA (Ic ELISA) for detection of PPR antigen.Results:Using PrioCHECK® FMDV NS: Commercial ELISA kit: 38/50 (76%) of the serum samples were positive for the presence of FMD NS viral proteins. In addition, using LPBE the positive samples were identified as FMD serotype O. Examination of the serum sample by cELISA for detection of PPR antibodies gave positive results in 32/50 (64%). While the Ic ELISA identified 32 (64%) positive reactors for PPR antigen.Conclusion:This study reflected high susceptibility of the imported sheep flocks to the infection with FMD and PPR viruses, which are endemic in the Kingdom of Saudi Arabia (KSA). Hence, the imported flocks that prepared for slaughter must be vaccinated with the used vaccine in KSA in the quarantine for the control of FMD especially when importation occurs from counters that are free from these diseases.

Use of nucleic acid recognition methods (m-PCR and RT-LAMP) for the detection of foot-and-mouth disease virus excreted in cow milk

The present study was undertaken to see the excretion of FMD virus in milk during and after the subset of FMD outbreak. Fore-milk (50 ml) was sampled from 12 clinically infected and 3 asymptomatic cows in the morning. Analytical sensitivity of NAR methods was estimated using uninfected negative milk sample spiked with 105.7 TCID50/ml FMD serotype O virus (IND R2/1975) in 10 fold serial dilution. Detection limit of mPCR and RT- LAMP assay was 102.7 and 101.7 TCID50/ml, respectively. 15 individual and pooled cows’ milk samples infected with FMD virus were processed for virus isolation (VI) and detection till 37 days post clinical manifestation (dpm). Virus isolation from individual and pooled milk from infected cow was positive till 6 and 4 dpm, respectively. Individual milk and pooled milk samples were found positive by m-PCR till 37 and 14 dpm, respectively, but by RT-LAMP till 37 and 21 dpm, respectively. In case of asymptomatic cows, viral genome was detected 2–5 days before appearance of disease in other animals. Milk virus isolate had 100% nucleotide identity at VP1 coding region. mPCR and RT LAMP assays has potential to detect FMD virus in milk and help to prevent the spread of FMD virus from one place to another place.

Immunostimulant Activity of Levamisole to Polyvalent FMD Vaccine in Buffaloes

In Egypt, many challenges facing eradication strategy of FMD concerning the short term immunity induced by inactivated polyvalent FMD vaccine. The aim of the study was directed to ascertain whether post vaccination antibodies against FMDV in buffaloes could be enhanced by administration with levamisole. To achieve the goal, 24 buffaloes were divided into 4 groups, G1 is non vaccinated non adjuvanted group, G2 is vaccine control group, G3 is simultaneously FMD vaccinated and levamisole stimulated group and G4 is FMD vaccinated 7 days after levamisole stimulation. Blood samples were examined for 16 succesive weeks post vaccination for FMD antibodies to serotypes O, A and SAT-2 by ELISA test. The results revealed that animalssimultinously vaccinated and treated with levamisole was higher than the group adjuvinated with levamisole 7 days before FMD vaccination. Levamisole has stimulant effect on the vaccinalimmunity of buffaloes to FMD serotypes O, A and SAT2. Antibody titers of FMD in animal groups were parallel in each group with a high titer in serotype A than O and SAT2. Further investigations are needed to explore the effect of levamisole on cell mediated immune response and challenge test in buffaloes.

Serological response of commercial dairy cattle to inactivated foot-and-mouth disease vaccine (type-O & A) in Nigeria

An observational study was conducted in a peri-urban dairy establishment in Jos South, Plateau State Nigeria to determine immune response of dairy cattle to commercial inactivated foot-and-mouth disease vaccine serotypes (O and A). Thirty seven Friesian cattle aged ?2years old with their crosses (15 selected pre-vaccination and 22 selected 21 days post-vaccination) were investigated for immune response to vaccination with an inactivated trivalent FMD vaccine containing serotypes O, A and SAT 2). Sera collected on day 0 pre-vaccination and 21 days post-vaccination was tested for structural protein antibodies to FMD serotypes O and A using the Solid Phase Competitive ELISA assay. The mean OD value for serum end point titre of FMD serotype O pre-vaccination was 11.64% with 6.67% (95%CI: 0.33 – 28.73) of the selected cattle being seropositive, at 21 days post-vaccination the mean OD value in selected cattle was 52.83% with 68.18% (95%CI: 46.95 – 84.89) of the selected cattle seropositive. For the FMD serotype A, 26.67% (95%CI: 9.10 – 52.53) of the selected cattle were seropositive pre-vaccination with a mean OD value of 29.21% and by 21 days post-vaccination, 72.73% (95%CI: 51.67 – 88.13) of the selected cattle were seropositive with a mean OD value of 61.70%. Serological response to vaccination improved in most selected cattle by 21 days post-vaccination. This study result has indicated that commercial inactivated FMD vaccines used for the prophylactic control of FMD in commercial dairy farm in Nigeria provoked immune response after a single shot.Asian J. Med. Biol. Res. June 2015, 1(2): 163-168

Evaluation of cross-protection between FMD serotypes O and A local Egyptian isolate with vaccinal strains in the local commercial and imported vaccines by challenge test

Evaluation of cross-protection between FMD serotypes O and A local Egyptian isolate with vaccinal strains in the local commercial and imported vaccines by challenge test

Antigenic relatedness of FMD serotypes O and A local Egyptian isolate with vaccinal strains in the local commercial and imported vaccines

Antigenic relatedness of FMD serotypes O and A local Egyptian isolate with vaccinal strains in the local commercial and imported vaccines

Occurrence of Foot and Mouth Disease serotypes in trade cattle sold in Kwara state, Nigeria

Aims: Serological detection of Foot and Mouth Disease Virus (FMDV) serotype specific antibodies in trade cattle was conducted to determine occurrence of FMDV serotypes. Methodology and results: Cross-sectional study based on randomly sampled sera in cattle with unknown FMD vaccination history was carried out in five cattle markets in Kwara state over a period of 3 months (August-SeptemberOctober) in 2011. The sera were screened for antibodies to FMDV non-structural protein (NSP) using NS-Blocking ELISA Kit (PrioCHECK®) and serotype specific antibodies determined by a Solid-Phase Competitive ELISA. Out of 253 sera positive for FMDV serotypes, 74.3% (188) sera were from recovered and 25.7% (65 sera) infected trade cattle. The percentage serotype distribution was 18.6%, 46.6%, 21.3%, and 13.4% for serotype A, O, SAT1 and SAT2 respectively. However, combination of O and A, A and SAT2 as well as O and SAT2 occurred in some cattle. Serotype distribution according to location showed serotype O and SAT2 was highest in Ajasse and serotype A and SAT1 was highest in Bode Sadu and Ilesha baruba markets respectively. Conclusion, significance and impact study: Specific antibody detection confirmed FMD serotypes endemicity and ongoing infections in trade cattle within the Nigerian local markets. The identification of these circulating FMDV serotypes is necessary as a baseline for vaccination control strategy, in conjunction with international livestock trade regulation to enhance potentials of national dependence on beef exportation.

Clinical Study on Egyptian Cattle Affected With Recent Isolate of Foot and Mouth Disease Virus SAT2/2012

Foot and mouth disease is one of the economically important viral diseases of cattle resulting in high mortalities in young calves and reduction of production in adult animals. Egypt was endemic with serotypes O and A till march 2012 outbreak where serotype SAT2/2012 was isolated and resulted in high mortalities in young calves and adult cattle. Our study was carried out during 2012 FMD outbreak on 22 adult cattle with clinical picture suggesting FMD infection. Saliva, tongue epithelium and vesicular fluids were collected from clinically affected animals and FMD serotype SAT2/2012 was isolated from all animals. Hematological and biochemical examination was carried out on affected animals and revealed that, there's significant reduction in total protein, albumin, globulin, cholesterol and calcium. CPK level was increased in 3 samples out of 22 samples which is an indication of the degenerative effect of SAT2/2012 on the myocardium. Postmortem and histopathological examinations were carried out on the heart of died adult animals and compared with the heart of young calves died from FMD during 2012 outbreak. There's grayish white small foci of necrosis present mainly at heart base, these areas were friable and appeared as cooked and pale. There's hyaline degeneration and zenker's necrosis of some myocytes. There were myolysis and complete disappearance of some myocytes with presence of large numbers of mononuclear cells infiltration.

Genetic heterogeneity in the leader and P1-coding regions of foot-and-mouth disease virus serotypes A and O in Africa

Genetic information regarding the leader (L) and complete capsid-coding (P1) region of FMD serotype A and O viruses prevalent on the African continent is lacking. Here, we present the complete L-P1 sequences for eight serotype A and nine serotype O viruses recovered from FMDV outbreaks in East and West Africa over the last 33 years. Phylogenetic analysis of the P1 and capsid-coding regions revealed that the African isolates grouped according to serotype, and certain clusters were indicative of transboundary as well as intra-regional spread of the virus. However, similar analysis of the L region revealed random groupings of isolates from serotypes O and A. Comparisons between the phylogenetic trees derived from the structural coding regions and the L region pointed to a possibility of genetic recombination. The intertypic nucleotide and amino acid variation of all the isolates in this study supported results from previous studies where the externally located 1D was the most variable whilst the internally located 1A was the most conserved, which likely reflects the selective pressures on these proteins. Amino acids identified previously as important for FMDV structure and functioning were found to be highly conserved. The information gained from this study will contribute to the construction of structurally designed FMDV vaccines in Africa.Electronic supplementary materialThe online version of this article (doi:10.1007/s00705-013-1838-9) contains supplementary material, which is available to authorized users.

Effect of administration of ultra-corn with bivalent Foot and Mouth disease oil vaccine in calves

Aim: The present work was established in order to investigate the effect of ultra-corn administration on the immune response of vaccinated calves with FMD bivalent oil vaccine. Material and Methods: Forty calves; at a private farm in EL-Fayoum Governorate (Locality A); were divided into 4 groups where the first group was vaccinated with the locally produced FMD bivalent oil vaccine alone while the 2nd, 3rd and 4th group were vaccinated with the same vaccine simultaneously with the inoculation of 1, 1.5 and 2mL/100kg body weight of ultra-corn respectively to estimate the antibody titer, the suitable dose and effect of ultra-corn as immunostimulant using SNT and ELISA. Also after that used the effective and lowest dose of ultra-corn simultaneously with the vaccine in comparison with the vaccine alone by using 26 calves (Locality B) to study the efficacy of ultra-corn simultaneously with vaccine and the vaccine alone via challenge test using the virulent FMDV serotype A,O. Results: Tested serum samples obtained on week intervals post vaccination of all calve groups were subjected for estimation of induced FMD antibodies type A and O using serum neutralization test (SNT) and enzyme linked immune sorbent assay (ELISA). Both tests indicate that 1.5mL, 2mL of ultra-corn enhanced the immune response of vaccinated calves exhibiting higher and longer immunity than those received the vaccine alone. In addition 26 calves housed under restrict hygienic measures at Veterinary Serum and Vaccine Research Institute, were divided into 4 groups where group-1 of 10 calves were vaccinated with the bivalent FMD vaccine alone and group-2 was vaccinated with the same vaccine simultaneously with 1.5mL of ultra-corn while group 3 and 4 were kept as control for the challenge test. On the 4th week post vaccination group 1, 2 of these animals was subdivided into 2 subgroups where the challenge test was carried out against type A in a subgroup and O in other subgroup. SNT and ELISA showed similar results obtained from the vaccinated farm animals and challenge test via inoculation of virulent virus of FMD serotype A, O indicated that animals received ultra-corn showed 100% protection against both types of FMD virus while those did not receive ultra-corn showed 80% protection (vaccine alone). Conclusion: So it could be concluded that ultra-corn has a potentiate effect on the immunogenicity of bivalent oil FMD vaccine providing high immune levels of long duration.

Prevalence of Foot and Mouth Disease in Cattle and Buffaloes in Central Punjab, Pakistan

An epidemiological investigation conducted in 25 randomly selected villages of the six districts of central Punjab which reported foot and mouth disease. 100 swab samples from buffaloes and cattle were subjected to CFT and then ELISA which determined that FMD serotype “O” was the most prevalent type of antibodies with 67.11%. This was followed by serotype-A with 50.15% and serotype Asia-1 with 39.31%. Statistically significant differences were detected among districts for prevalence of serotypes of FMD. Highest prevalence of FMD serotypes (A, O, Asia-1) were observed in Okara followed by Faisalabad, Multan, Pakpattan, Sahiwal and Khanewal. The high positivity of larger ruminants against FMD serotypes might be due to infectious process or the outbreak wave that comes every year. The effect of the infectious process led to the high production of antibodies in the cattle and buffaloes in the selected districts of Central Punjab. However the role of weekly and monthly livestock markets held every month in Okara and Sahiwal and livestock movements due to sedentary lifestyle of the people and at the eve of Eid ul Azha needs further investigation. Concurrent infections due to all the three serotypes have been confirmed. This suggests to exploring the use of multi-variant vaccine policy for effective control of FMD in the given situation.

EPIZOOTIOLOGY AND CONTROL MEASUREMENTS OF FOOT AND MOUTH DISEASE (FMD) IN SAUDI ARABIA FROM 1999 TO 2004

Over a period of five years from July 1999 to June 2004, five outbreaks of FMD serotype O and one outbreak of FMD serotype SAT 2 were reported among livestock in Saudi Arabia. Four out of the six outbreaks were limited to cattle, while the other two outbreaks were expanded to all livestock including cattle, sheep and goats. Two extensive outbreaks of FMD virus serotype O were recorded in the five regions of the country (central, eastern, western, northern and southern regions) in February-April/2001 and August/2001-November/2001. While two out of three limited outbreaks of FMDV serotype O were occurred only in the central region in October-November/1999 and in March-April/2000. The last outbreak was reported recently in the southern region (Jizan) in June/2004. Infection with FMDV serotype SAT 2 was reported for the first time in Saudi Arabia during an outbreak of FMDV serotype O in the central region (AL-Karj, Riyadh) on March-April/2000. Morbidity, mortality and case fatality rates during six FMD outbreaks from 1999 to 2004 in Saudi Arabia were calculated. The most common clinical symptoms were high fever, anorexia, vesicular stomatitis, vesicular dermatitis in coronet and cleft of feet, teat and udder. Indirect sandwich-enzyme linked immunesorbent assay (IS)-ELISA was used for detection and typing of FMD virus in the collected tissue specimens. Some selected tissue specimens which given positive result to FMD virus-antigen detection by indirect sandwich-ELISA were submitted to FMD reference world laboratory, Pribright, UK for determination of the antigenic relationship between field and vaccinal strains. Where, A 167-bp fragment, of VP1 gene 472-639, was amplified and sequenced. The results indicated that field strains of FMD virus serotype O isolated from different regions in Saudi Arabia during FMD outbreaks between July 1999 and January 2002 were homolgous and closely related to O1 monisa strain of FMDV serotype O that already incorporated in formulation of Saudi vaccine against FMD. The current study concluded that national vaccination program against FMD in Saudi Arabia should be strictly continue in traditional cattle population in all the kingdom regions. Legalization of the restriction of the animal movement should be practiced for cattle, sheep and goats populations during the risk period of FMD in different localities in SA. Absence of FMD outbreaks in SA between May/2002 and May/2004 may act as an indicator for the success of the applied control measures. Molecular epidemiological studies and monitoring of the relationship between the vaccine and the field viruses should be continued.