Pathogenesis of Primary Foot-and-Mouth Disease Virus Infection in the Nasopharynx of Vaccinated and Non-Vaccinated Cattle

A time-course pathogenesis study was performed to compare and contrast primary foot-and-mouth disease virus (FMDV) infection following simulated-natural (intra-nasopharyngeal) virus exposure of cattle that were non-vaccinated or vaccinated using a recombinant adenovirus-vectored FMDV vaccine. FMDV genome and infectious virus were detected during the initial phase of infection in both categories of animals with consistent predilection for the nasopharyngeal mucosa. A rapid progression of infection with viremia and widespread dissemination of virus occurred in non-vaccinated animals whilst vaccinated cattle were protected from viremia and clinical FMD. Analysis of micro-anatomic distribution of virus during early infection by lasercapture microdissection localized FMDV RNA to follicle-associated epithelium of the nasopharyngeal mucosa in both groups of animals, with concurrent detection of viral genome in nasopharyngeal MALT follicles in vaccinated cattle only. FMDV structural and non-structural proteins were detected in epithelial cells of the nasopharyngeal mucosa by immunomicroscopy 24 hours after inoculation in both non-vaccinated and vaccinated steers. Co-localization of CD11c⁺/MHC II⁺ cells with viral protein occurred early at primary infection sites in vaccinated steers while similar host-virus interactions were observed at later time points in non-vaccinated steers. Additionally, numerous CD8⁺/CD3^- host cells, representing presumptive natural killer cells, were observed in association with foci of primary FMDV infection in the nasopharyngeal mucosa of vaccinated steers but were absent in non-vaccinated steers. Immunomicroscopic evidence of an activated antiviral response at primary infection sites of vaccinated cattle was corroborated by a relative induction of interferon -α, -β, -γ and -λ mRNA in micro-dissected samples of nasopharyngeal mucosa. Although vaccination protected cattle from viremia and clinical FMD, there was subclinical infection of epithelial cells of the nasopharyngeal mucosa that could enable shedding and long-term persistence of infectious virus. Additionally, these data indicate different mechanisms within the immediate host response to infection between non-vaccinated and vaccinated cattle.     

Modelling studies to estimate the prevalence of foot-and-mouth disease carriers after reactive vaccination

Foot-and-mouth disease (FMD) is a highly contagious and economically significant viral disease of cloven-hoofed animals. Vaccination can be used to help restrict the spread of the infection, but evidence must be provided to show that the infection has been eradicated in order to regain the FMD-free status. While serological tests have been developed, which can identify animals that have been infected regardless of vaccination status, it is vital to know the probable prevalence of herds with FMD carriers and the within-herd prevalence of those carriers in order to design efficient post-epidemic surveillance strategies that establish freedom from disease. Here, we present the results of a study to model the expected prevalence of carriers after application of emergency vaccination and the impact of this on the sensitivity of test systems for their detection. Results showed that the expected prevalence of carrier-containing herds after reactive vaccination is likely to be very low, approximately 0.2%, and there will only be a small number of carriers, most likely one, in the positive herds. Therefore, sensitivity for carrier detection can be optimized by adopting an individual-based testing regime in which all animals in all vaccinated herds are tested and positive animals rather than herds are culled.     

Engineering Foot-and-Mouth Disease Viruses with Improved Growth Properties for Vaccine Development

Background

No licensed vaccine is currently available against serotype A foot-and-mouth disease (FMD) in China, despite the isolation of A/WH/CHA/09 in 2009, partly because this strain does not replicate well in baby hamster kidney (BHK) cells.

Methodology/Principal Findings

A novel plasmid-based reverse genetics system was used to construct a chimeric strain by replacing the P1 gene in the vaccine strain O/CHA/99 with that from the epidemic stain A/WH/CHA/09. The chimeric virus displayed growth kinetics similar to those of O/CHA/99 and was selected for use as a candidate vaccine strain after 12 passages in BHK cells. Cattle were vaccinated with the inactivated vaccine and humoral immune responses were induced in most of the animals on day 7. A challenge infection with A/WH/CHA/09 on day 28 indicated that the group given a 4-µg dose was fully protected and neither developed viremia nor seroconverted to a 3ABC antigen.

Conclusions/Significance

Our data demonstrate that the chimeric virus not only propagates well in BHK cells and has excellent antigenic matching against serotype A FMD, but is also a potential marker vaccine to distinguish infection from vaccination. These results suggest that reverse genetics technology is a useful tool for engineering vaccines for the prevention and control of FMD.     

Virus Excretion from Foot-And-Mouth Disease Virus Carrier Cattle and Their Potential Role in Causing New Outbreaks

The role of foot-and-mouth disease virus (FMDV) carrier cattle in causing new outbreaks is still a matter of debate and it is important to find out these carrier animals by post-outbreak serosurveillance to declare freedom from FMDV infection. In this study we explore the differences in viral shedding between carrier and non-carrier animals, quantify the transmission rate of FMDV infection from carriers to susceptible animals and identify potential viral determinants of viral persistence. We collected nasal and saliva samples from 32 vaccinated and 7 unvaccinated FMDV carrier cattle and 48 vaccinated and 13 unvaccinated non-carrier cattle (total n=100) during the acute phase of infection (up to 28 days post-challenge) and then from limited number of animals up to a maximum 168 days post-challenge. We demonstrate that unvaccinated cattle excrete significantly higher levels of virus for longer periods compared with vaccinated cattle and this is independent of whether or not they subsequently become carriers. By introducing naïve cattle in to the FMDV carrier population we show the risk of new outbreaks is clearly very low in controlled conditions, although there could still be a potential threat of these carrier animals causing new outbreaks in the field situation. Finally, we compared the complete genome sequences of viruses from carrier cattle with the challenge virus and found no evidence for viral determinants of the carrier state.     

用口蹄疫病毒非结构蛋白区分注苗动物和自然感染动物研究进展

口蹄疫是由口蹄疫病毒引起的偶蹄类动物烈性传染病,疫苗接种是防治口蹄疫暴发的主要措施之一,而要控制口蹄疫流行,首先要将病毒感染动物从疫苗接种群体中区分开来。以口蹄疫病毒非结构蛋白（NSP）为抗原,检测动物体内的NSP抗体是一种很好的区分感染动物和疫苗免疫动物的诊断方法,许多实验室开展了相关研究,并取得了一定的成绩。     

Novel viral disease control strategy: adenovirus expressing alpha interferon rapidly protects swine from foot-and-mouth disease

We have previously shown that replication of foot-and-mouth disease virus (FMDV) is highly sensitive to alpha/beta interferon (IFN-alpha/beta). In the present study, we constructed recombinant, replication-defective human adenovirus type 5 vectors containing either porcine IFN-alpha or IFN-beta (Ad5-pIFNalpha or Ad5-pIFNbeta). We demonstrated that cells infected with these viruses express high levels of biologically active IFN. Swine inoculated with 10(9) PFU of a control Ad5 virus lacking the IFN gene and challenged 24 h later with FMDV developed typical signs of foot-and-mouth disease (FMD), including fever, vesicular lesions, and viremia. In contrast, swine inoculated with 10(9) PFU of Ad5-pIFNalpha were completely protected when challenged 24 h later with FMDV. These animals showed no clinical signs of FMD and no viremia and did not develop antibodies against viral nonstructural proteins, suggesting that complete protection from infection was achieved.     

Chimeric virus-like particles elicit protective immunity against serotype O foot-and-mouth disease virus in guinea pigs

Foot-and-mouth disease (FMD) is an acute and highly contagious disease caused by foot-and-mouth disease virus (FMDV) that can affect cloven-hoofed animal species, leading to severe economic losses worldwide. Therefore, the development of a safe and effective new vaccine to prevent and control FMD is both urgent and necessary. In this study, we developed a chimeric virus-like particle (VLP) vaccine candidate for serotype O FMDV and evaluated its protective immunity in guinea pigs. Chimeric VLPs were formed by the antigenic structural protein VP1 from serotype O and segments of the viral capsid proteins (VP2, VP3, and VP4) from serotype A. The chimeric VLPs elicited significant humoral and cellular immune responses with a higher level of anti-FMDV antibodies and cytokines than the control group. Furthermore, four of the five guinea pigs vaccinated with the chimeric VLPs were completely protected against challenge with 100 50% guinea pig infectious doses (GPID₅₀) of the virulent FMDV strain O/MAY98. These data suggest that chimeric VLPs are potential candidates for the development of new vaccines against FMDV.     

Protection from foot-and-mouth disease virus in naturally-susceptible animals by a linear polymer of a synthetic peptide]

Linear polymer of a peptide corresponding to the fragment 142-155 of the foot-and-mouth disease virus A22(550) protein (VP1) was synthesized. Whereas the monomeric peptide was only slightly immunogenic, the polymer induced virus-neutralizing antibodies in rabbits and protected 100% guinea pigs. Sheep vaccinated once and cattle vaccinated twice were stable against infection with the homologous virulent foot-and-mouth disease virus.     

Identification of foot-and-mouth disease virus-specific linear B-cell epitopes to differentiate between infected and vaccinated cattle

Foot-and-mouth disease (FMD) is a highly contagious viral disease of cloven-hoofed animals. For several years, vaccination of animals, which had proven to be successful for the eradication of the disease, has been forbidden in the United States and the European Community because of the difficulty of differentiating between vaccinated and infected animals. In this study, detailed investigations of the bovine humoral immune response against FMD virus (FMDV) were performed with the aim of identifying viral epitopes recognized specifically by sera derived from FMDV-infected animals. The use of overlapping 15-mer synthetic peptides, covering the whole open reading frame of FMDV strain O(1)K in a peptide enzyme-linked immunosorbent assay, allowed the identification of 12 FMDV strain O(1)K-specific linear B-cell epitopes. Six of these linear B-cell epitopes, located in the nonstructural proteins, were used in further assays to compare the reactivities of sera from vaccinated and infected cattle. Antibodies recognizing these peptides could be detected only in sera derived from infected cattle. In further experiments, the reactivity of the six peptides with sera from animals infected with different strains of FMDV was tested, and strain-independent infection-specific epitopes were identified. Thus, these results clearly demonstrate the ability of a simple peptide-based assay to discriminate between infected and conventionally FMD-vaccinated animals.     

An ELISA based on the repeated foot-and-mouth disease virus 3B epitope peptide can distinguish infected and vaccinated cattle

To develop a strategy of differentiating infected from vaccinated animals (DIVA) with foot-and-mouth disease virus (FMDV), a short (27aa) peptide containing three conserved linear B cell epitopes of the FMDV 3B nonstructural protein was designed. This novel BF peptide was synthesized using a gene splicing by overlap extension protocol with preferred codons for Escherichia coli. The resultant eight tandem repeat multimer (1, 2, 4, 6, 8, 16, 24, and 32BF) were expressed as soluble fusion proteins in E. coli. An indirect ELISA was developed based on the recombinant 8BF protein with the aim of specifically distinguishing antibodies induced by FMDV infection but not those induced by vaccination. Using the cut-off value of 0.3, the sensitivity of the assay was 96.8% and the specificities for naive and vaccinated cattle were 99.8 and 99.0%, respectively. The performance of the newly developed epitope-based ELISA was compared with three commercial NSP ELISA kits. The 8BF-ELISA appears to be a promising DIVA test for FMD control and eradication.     

Saponin Adjuvants. IV. Evaluation of The Adjuvant Quil a in the Vaccination of Cattle Against Foot-And-Mouth Disease

The saponin adjuvant Quil A has been investigated in the vaccination of cattle against foot-and-mouth disease. Using a Frenkel type vaccine a dose-response relationship has been established between Quil A and neutralizing antibody titres. Ten ml of vaccine was combined with 0, 50, 200, 800, and 3200 µg of Quil A. The combinations were each injected into 4 animals. The local reaction on the site of injection produced by injection of the vaccine alone and in combination with different doses of Quil A has been estimated. On this basis a therapeutical dose at 1 mg of Quil A has been estimated to combine maximum adjuvant effect with a minimum of adverse reactions. This dose has been tested in the vaccination of cattle with FMD vaccines derived from BHK suspension cell virus of type O and A respectively. The vaccines were tested in 10 ml and 5 ml doses with or without Quil A, and each in 4 animals. It is concluded that Quil A is a valuable adjuvant for use in the induction of neutralizing antibodies against foot-and-mouth disease in cattle.     

Incidence and Reproduction Numbers of Pertussis: Estimates from Serological and Social Contact Data in Five European Countries

Background

Despite large-scale vaccination programmes, pertussis has remained endemic in all European countries and has been on the rise in many countries in the last decade. One of the reasons that have been discussed for the failure of vaccination to eliminate the disease is continued circulation of the pathogen Bordetella pertussis by mostly asymptomatic and mild infections in adolescents and adults. To understand the impact of asymptomatic and undiagnosed infection on the transmission dynamics of pertussis we analysed serological data from five European countries in combination with information about social contact patterns from five of those countries to estimate incidence and reproduction numbers.

Methods and Findings

We compared two different methods for estimating incidence from individual data on IgG pertussis toxin (PT) titres. One method combines the cross-sectional surveys of titres with longitudinal information about the distribution of amplitude and decay rate of titres in a back-calculation approach. The second method uses age-dependent contact matrices and cross-sectional surveys of IgG PT titres to estimate a next generation matrix for pertussis transmission among age groups. The next generation approach allows for computation of basic reproduction numbers for five European countries. Our main findings are that the seroincidence of infections as estimated with the first method in all countries lies between 1% and 6% per annum with a peak in the adolescent age groups and a second lower peak in young adults. The incidence of infections as estimated by the second method lies slightly lower with ranges between 1% and 4% per annum. There is a remarkably good agreement of the results obtained with the two methods. The basic reproduction numbers are similar across countries at around 5.5.

Conclusions

Vaccination with currently used vaccines cannot prevent continued circulation and reinfection with pertussis, but has shifted the bulk of infections to adolescents and adults. If a vaccine conferring lifelong protection against clinical and subclinical infection were available pertussis could be eliminated. Currently, continuing circulation of the pathogen at a subclinical level provides a refuge for the pathogen in which it can evolve and adjust to infect vaccinated populations. Please see later in the article for the Editors'' Summary     

Evaluation of Monoclonal Antibody-Based Sandwich Direct ELISA (MSD-ELISA) for Antigen Detection of Foot-and-Mouth Disease Virus Using Clinical Samples

A monoclonal antibody-based sandwich direct ELISA (MSD-ELISA) method was previously developed for foot-and-mouth disease (FMD) viral antigen detection. Here we evaluated the sensitivity and specificity of two FMD viral antigen detection MSD-ELISAs and compared them with conventional indirect sandwich (IS)-ELISA. The MSD-ELISAs were able to detect the antigen in saliva samples of experimentally-infected pigs for a longer term compared to the IS-ELISA. We also used 178 RT-PCR-positive field samples from cattle and pigs affected by the 2010 type-O FMD outbreak in Japan, and we found that the sensitivities of both MSD-ELISAs were about 7 times higher than that of the IS-ELISA against each sample (P<0.01). In terms of the FMD-positive farm detection rate, the sensitivities of the MSD-ELISAs were about 6 times higher than that of the IS-ELISA against each farm (P<0.01). Although it is necessary to conduct further validation study using the other virus strains, MSD-ELISAs could be appropriate as a method to replace IS-ELISA for FMD antigen detection.     

Elimination of foot-and-mouth disease in South America: lessons and challenges

Foot-and-mouth disease (FMD) is a highly transmissible and economically devastating disease of cloven-hoofed livestock. Although vaccines are available and have been instrumental in eliminating the disease from most of the South American animal population, viral circulation still persists in some countries and areas, posing a threat to the advances of the last 60 years by the official veterinary services with considerable support of the livestock sectors. The importance of the disease for the social and economic development of the American continent led to the establishment in 1951 of the Pan American Centre for Foot-and-Mouth Disease (PANAFTOSA), which has been providing technical cooperation to countries for the elimination of the disease. The first FMD national elimination programmes were established in South America around the 1960s and 1970s. To advance the regional elimination efforts in the 1980s, countries agreed on a Plan of Action 1988–2009 of the Hemispheric Program for the Eradication of Foot-and-Mouth Disease. The Plan of Action 1988–2009 did not reach the goal of elimination from the continent; and a new Plan of Action 2011–2020 was developed in 2010 based on the experience acquired by the countries and PANAFTOSA during the past 60 years. This plan is now being implemented; several challenges are still to be overcome to ensure the elimination of FMD from the Americas by 2020, however, the goal is achievable.     

Non-replicating adenovirus based Mayaro virus vaccine elicits protective immune responses and cross protects against other alphaviruses

Mayaro virus (MAYV) is an alphavirus endemic to South and Central America associated with sporadic outbreaks in humans. MAYV infection causes severe joint and muscle pain that can persist for weeks to months. Currently, there are no approved vaccines or therapeutics to prevent MAYV infection or treat the debilitating musculoskeletal inflammatory disease. In the current study, a prophylactic MAYV vaccine expressing the complete viral structural polyprotein was developed based on a non-replicating human adenovirus V (AdV) platform. Vaccination with AdV-MAYV elicited potent neutralizing antibodies that protected WT mice against MAYV challenge by preventing viremia, reducing viral dissemination to tissues and mitigating viral disease. The vaccine also prevented viral-mediated demise in IFN⍺R1^-/- mice. Passive transfer of immune serum from vaccinated animals similarly prevented infection and disease in WT mice as well as virus-induced demise of IFN⍺R1^-/- mice, indicating that antiviral antibodies are protective. Immunization with AdV-MAYV also generated cross-neutralizing antibodies against two related arthritogenic alphaviruses–chikungunya and Una viruses. These cross-neutralizing antibodies were protective against lethal infection in IFN⍺R1^-/- mice following challenge with these heterotypic alphaviruses. These results indicate AdV-MAYV elicits protective immune responses with substantial cross-reactivity and protective efficacy against other arthritogenic alphaviruses. Our findings also highlight the potential for development of a multi-virus targeting vaccine against alphaviruses with endemic and epidemic potential in the Americas.     

Protective immune response against foot-and-mouth disease.

The causative agents of foot-and-mouth disease (FMD) are small icosahedral viruses of the Aphthovirus group within the Picornaviridae family. There is no evidence that these viruses infect cells of the immune system or otherwise interfere detrimentally with their function; additionally, it has not been possible to relate cytotoxicity reactions against virus-infected cells to the efficacy of the immune response against FMD virus infection. In contrast, there is a close association between FMD virus antibody and the protective immune response (10, 14, 15, 20, 24, 25, 29-32). Induction of this antibody is dependent on the structure of the viral antigenic sites (7-9, 11, 18) and on the concomitant presence of Th-lymphocyte epitopes (4, 5, 7, 8), although a Th-lymphocyte-independent response has been reported (2). Recent work by Piatti et al. (26) showed that the immune response induced by FMD virus was only Th-lymphocyte dependent when low doses of antigen were used. This latter work was performed in mice, and it is not certain that a similar situation would be found in cattle. As for the major effector immune defense, this relies on the interaction between antibody-virus complexes and the phagocytic cells of the reticuloendothelial system (17, 19).     

Production and characterization of single-chain antibody (scFv) against 3ABC non-structural protein in Escherichia coli for sero-diagnosis of Foot and Mouth Disease virus

Differentiation of Foot-and-Mouth Disease infected from vaccinated animals is essential for effective implementation of vaccination based control programme. Detection of antibodies against 3ABC non-structural protein of FMD virus by immunodiagnostic assays provides reliable indication of FMD infection. Sero-monitoring of FMD in the large country like India is a big task where thousands of serum samples are annually screened. Currently, monoclonal or polyclonal antibodies are widely used in these immunodiagnostic assays. Considering the large population of livestock in the country, an economical and replenishable alternative of these antibodies was required. In this study, specific short chain variable fragment (scFv) antibody against 3B region of 3ABC poly-protein was developed. High level of scFv expression in Escherichia coli system was obtained by careful optimization in four different strains. Two formats of enzyme immunoassays (sandwich and competitive ELISAs) were optimized using scFv with objective to differentiate FMD infected among the vaccinated population. The assays were statistically validated by testing 2150 serum samples. Diagnostic sensitivity/specificity of sandwich and competitive ELISAs were determined by ROC method as 92.2%/95.5% and 89.5%/93.5%, respectively. This study demonstrated that scFv is a suitable alternate for immunodiagnosis of FMD on large scale.     

BoLA-DRB3 gene polymorphism and FMD resistance or susceptibility in Wanbei cattle

For the further characterization of foot-and-mouth disease virus (FMDV)-induced foot-and-mouth disease, we investigated the association between polymorphism of BoLA-DRB3 gene and FMD resistance/susceptibility of Wanbei cattle challenged with FMDV. One hundred cattle were challenged with FMDV and exon 2 of BoLA-DRB3 genes was amplified by hemi-nested polymerase chain reaction from asymptomatic animals and from animals with FMD. PCR products were characterized by the RFLP technique using restriction enzymes Hae III. The results revealed extensive polymorphisms, 6 RFLP patterns were identified. By analyzing alleles and genotypic frequencies between healthy and infection with FMD cattle, we found that allele Hae III A was associated with susceptibility to FMD in Wanbei cattle (P < 0.05), whereas Hae III C was associated with resistance to FMD (P < 0.01) and may have a strong protective effect against FMD. Hae IIICC and Hae III BC genotype were associated with resistance to FMD (P < 0.01). By contrast, Hae III AA genotype was associated with susceptibility to FMD (P < 0.01). Sequence analysis show that 89 amino acids were translated in exon 2 of BoLA-DRB3 and 13.70 % of nucleotide mutated, which resulted in 14.61 % of amino acid change. One PKC, one Tyr and one CAMP phosphorylation were increased; the hydrophobicity and secondary structure of proteins produced change after amino acid substitution. These results revealed that Wanbei cattle had the ability of resistance to disease by mutation which result changes of the protein structure to perform the regulation of the cell using different signaling pathways in the long process of choice evolution.     

Immune potential of a novel multiple-epitope vaccine to FMDV type Asia 1 in guinea pigs and sheep

To develop a safe and efficient recombinant subunit vaccine to foot-and-mouth disease virus(FMDV)type Asia 1 in sheep,a tandem repeated multiple-epitope gene consisting of residues 137-160 and 197-211 of the VP1 gene of FMDV was designed and artificially synthesized.The biologically functional molecule,the ovine IgG heavy constant region(oIgG)as a protein carrier was introduced for design of the multiple-epitope recombinant vaccine and recombinant expression plasmids pET-30a-RE and pET-30a-RE-oIgG were successfully constructed.The recombinant proteins,RE and RE-oIgG,were expressed as a formation of inclusion bodies in E.coli.The immune potential of this vaccine regime in guinea pigs and sheep was evaluated.The results showed that IgG could significantly enhance the immune potential of antigenic epitopes.The recombinant protein RE-oIgG could not only elicit the high levels of neutralizing antibodies and lymphocytes proliferation responses in the vaccinated guinea pigs,but confer complete protection in guinea pigs against virus challenge.Although the recombinant protein RE could not confer protection in the vaccinated animals,it could delay the appearance of the clinical signs and reduce the severity of disease.Inspiringly,the titers of anti-FMDV neutralizing antibodies elicited in sheep vaccinated with RE-oIgG was significantly higher than that for the RE vaccination.Therefore,we speculated that this vaccine formulation may be a promising strategy for designing a novel vaccine against FMDV in the future.     

Serosurveillance for foot-and-mouth disease in Mongolian gazelles (Procapra gutturosa) and livestock on the Eastern Steppe of Mongolia

Foot-and-mouth disease (FMD) is a highly contagious, viral disease that affects most ruminant and porcine species, and periodic outbreaks on Mongolia's Eastern Steppe affect Mongolian gazelles (Procapra gutturosa) and livestock. During 2005-08, we collected sera from 36 and 57 calf and adult gazelles, respectively, and from adult domestic animals sympatric with the gazelles, including 138 sheep (Ovis aries), 140 goats (Capra aegagrus hircus), 139 Bactrian camels (Camelus bactrianus), and 138 cattle (Bos taurus). Our goal was to determine whether the prevalence of the antibody to foot-and-mouth disease virus (FMDV) in gazelles declined relative to previous estimates in the absence of FMD outbreaks. Overall, 2.0% (95% CI 0.7-3.3%, n=555) of the four livestock species were antibody-positive for nonstructural proteins of FMDV (FMDV-NS), whereas 30.3% (95% CI 26.5-34.1%, n=555) had antibodies for structural proteins (i.e., vaccination-derived antibodies). Seven of 57 free-ranging gazelle calves (7.5%, 95%CI 1.6-12.4%) were FMDV-NS positive. None of 36 adult gazelles sampled in 2008 were antibody-positive for exposure to FMDV, indicating a significant decline (χ(2)=18.99; P<0.001; df=1) in antibody prevalence among gazelles from the same area during a livestock outbreak in 2001. The episodic nature of FMD outbreaks on the Eastern Steppe, Mongolia, with evidence of FMDV exposure in gazelles only during or following concurrent outbreaks in livestock, suggests that FMDV may spill over into the gazelle population during livestock outbreaks and that successful control of FMD on the Eastern Steppe requires a focus on control in livestock populations through vaccination.