Experimental infection of cattle and goats with a foot-and-mouth disease virus isolate from the 2010 epidemic in Japan

Effect of doubled dose administration of foot-and-mouth disease vaccine against heterologous virus infection in cattle

Vaccination is a feasible approach for controlling foot-and-mouth disease (FMD). In FMD-free countries, vaccines are stored as a precautionary measure to control potential outbreaks. However, the challenge lies in pre-stocking optimal vaccines against the newly emerging strains. This study examined the potency of pre-stocked vaccines administered at elevated doses during emergencies. We vaccinated the cows with either a single or double trivalent vaccine dose containing two serotype O and one serotype A strains. Subsequently, vaccinated and unvaccinated cows were exposed to virulent strains of serotype O (O/JPN/2010; topotype Southeast Asia/Mya-98 lineage) or A (A/IRN/2016; topotype ASIA/G-VII lineage), which were genetically and antigenically distinct from the vaccine strains. Following challenge infections, all cows that received a single dose vaccination exhibited vesicular lesions with excreted viruses in the oral and nasal discharges. However, a substantial reduction was observed in the total clinical scores and virus titers in the sera and nasal discharges compared to those in the unvaccinated group. Cows receiving a doubled dose vaccination were completely protected from infection with O/JPN/2010 or demonstrated a significant decrease in viral shedding and clinical scores against A/IRN/2016. To note, vesicular lesions harbor significant amounts of viruses; thus, by mitigating their formation, viral transmission can be impeded, thereby slowing viral spread in the field. Furthermore, increasing the vaccine dose induced higher neutralizing antibody titers against heterologous strains. These findings suggest an alternative strategy for the effective management of future epidemics using pre-stocked vaccines.

Quantitative analysis of infection dynamics of foot-and-mouth disease virus strain O/CATHAY in pigs and cattle

Foot-and-mouth disease virus (FMDV) serotype O, topotype CATHAY is a known porcinophilic virus that has caused devastating damage to the pig industry. However, the minimum infectious dose via a natural infection route in pigs, the infection dynamics in cattle, and risk of viral transmission from infected cattle to pigs have not been quantitatively analyzed. The FMDV strain O/HKN/1/2015 was serially diluted and inoculated into pigs via an intraoral route to determine the infectious dose. We found that a 10^4.0 tissue culture infectious dose (TCID₅₀) of the virus was insufficient, but 10^5.5 TCID₅₀ was sufficient to infect pigs via the oral route. While cows inoculated with the strain showed increased temperature in their feet, typical clinical signs including vesicular development were not observed. The cows showed short-term and low levels of viremia and virus excretion only before the detection of virus neutralizing antibodies. FMDV genes were not detected in esophageal-pharyngeal fluid from cows after 14 days post inoculation. No genetic insertions that could be associated with host adaptation were observed in viruses isolated from infected cows. These findings indicate that cows infected with FMDV of O/CATHAY have a low risk of viral transmission or persistence. Information on the dynamics of virus infection is essential for ensuring the rapid and accurate diagnosis of this disease, and its surveillance.

A Meta-Population Model of Potential Foot-and-Mouth Disease Transmission, Clinical Manifestation, and Detection Within U.S. Beef Feedlots

Foot-and-mouth disease (FMD) has not been reported in the U.S. since 1929. Recent outbreaks in previously FMD-free countries raise concerns about potential FMD introductions in the U.S. Mathematical modeling is the only tool for simulating infectious disease outbreaks in non-endemic territories. In the majority of prior studies, FMD virus (FMDv) transmission on-farm was modeled assuming homogenous animal mixing. This assumption is implausible for U.S. beef feedlots which are divided into multiple home-pens without contact between home-pens except fence line with contiguous home-pens and limited mixing in hospital pens. To project FMDv transmission and clinical manifestation in a feedlot, we developed a meta-population stochastic model reflecting the contact structure. Within a home-pen, the dynamics were represented assuming homogenous animal mixing by a modified SLIR (susceptible-latent-infectious-recovered) model with four additional compartments tracing cattle with subclinical or clinical FMD and infectious status. Virus transmission among home-pens occurred via cattle mixing in hospital-pen(s), cowboy pen rider movements between home-pens, airborne, and for contiguous home-pens fence-line and via shared water-troughs. We modeled feedlots with a one-time capacity of 4,000 (small), 12,000 (medium), and 24,000 (large) cattle. Common cattle demographics, feedlot layout, endemic infectious and non-infectious disease occurrence, and production management were reflected. Projected FMD-outbreak duration on a feedlot ranged from 49 to 82 days. Outbreak peak day (with maximum number of FMD clinical cattle) ranged from 24 (small) to 49 (large feedlot). Detection day was 4-12 post-FMD-introduction with projected 28, 9, or 4% of cattle already infected in a small, medium, or large feedlot, respectively. Depletion of susceptible cattle in a feedlot occurred by day 23-51 post-FMD-introduction. Parameter-value sensitivity analyses were performed for model outputs. Detection occurred sooner if there was a higher initial proportion of latent animals in the index home-pen. Shorter outbreaks were associated with a shorter latent period and higher bovine respiratory disease morbidity (impacting the in-hospital-pen cattle mixing occurrence). This first model of potential FMD dynamics on U.S. beef feedlots shows the importance of capturing within-feedlot cattle contact structure for projecting infectious disease dynamics. Our model provides a tool for evaluating FMD outbreak control strategies.

Transmission network reconstruction for foot-and-mouth disease outbreaks incorporating farm-level covariates

Transmission network modelling to infer 'who infected whom' in infectious disease outbreaks is a highly active area of research. Outbreaks of foot-and-mouth disease have been a key focus of transmission network models that integrate genomic and epidemiological data. The aim of this study was to extend Lau's systematic Bayesian inference framework to incorporate additional parameters representing predominant species and numbers of animals held on a farm. Lau's Bayesian Markov chain Monte Carlo algorithm was reformulated, verified and pseudo-validated on 100 simulated outbreaks populated with demographic data Japan and Australia. The modified model was then implemented on genomic and epidemiological data from the 2010 outbreak of foot-and-mouth disease in Japan, and outputs compared to those from the SCOTTI model implemented in BEAST2. The modified model achieved improvements in overall accuracy when tested on the simulated outbreaks. When implemented on the actual outbreak data from Japan, infected farms that held predominantly pigs were estimated to have five times the transmissibility of infected cattle farms and be 49% less susceptible. The farm-level incubation period was 1 day shorter than the latent period, the timing of the seeding of the outbreak in Japan was inferred, as were key linkages between clusters and features of farms involved in widespread dissemination of this outbreak. To improve accessibility the modified model has been implemented as the R package 'BORIS' for use in future outbreaks.

Experimental Infection of Foot and Mouth Disease in Indian Sheep and Goats

Foot-and-mouth disease (FMD) is an economically important contagious disease of livestock mainly cattle, buffalo, sheep, goats, and pig. There is limited data available on pathogenesis of foot and mouth disease in goats. In the study, the sheep and goats were infected experimentally with a serotype O foot-and-mouth disease virus by different challenge routes. The sheep and goats challenged by coronary band route and coronary band and intra-dermo-lingual route exhibited FMD clinical signs at 2-5 days post challenge. Whereas intra-dermo-lingual challenged sheep and goats did not exhibit FMD clinical signs. Live virus could be isolated from blood of infected sheep and goats at 2-5 days post challenge. Viral RNA could be detected from blood of infected sheep and goats at 1-10 days post challenge. The neutralizing antibody titre was detected at 10 days post challenge and maintained up to 35 days post challenge in all infected sheep and goats. Non structural protein (NSP) antibodies were detected as early as 5-10 days post challenge and remain positive up to 35 days post challenge in the infected sheep and goats. In conclusion, the pathogenesis of sheep and goats with serotype O foot and mouth disease virus by different challenge routes could be demonstrated.

Development and evaluation of silver amplification immunochromatography kit for foot-and-mouth disease virus antigen detection

A silver amplification immunochromatography (SAI) kit for the detection of all seven serotypes of foot-and-mouth disease virus (FMDV)-FMDV-Ag SAI-was developed using the monoclonal antibody 1H5 recognizing the highly conserved N terminus region of VP2. The FMDV-Ag SAI can be used under conditions of high biosecurity containment as it does not require any apparatus. The FMDV-Ag SAI exhibited 10-100 times higher sensitivity against the five serotypes (O, A, Asia1, C, and SAT1) and similar sensitivity against SAT2 and SAT3, compared with the Svanodip® FMDV-Ag kit immunochromatography kit. The Svanodip kit showed inhibitory results with several saliva samples but not with the FMDV-Ag SAI kit. In a validation study using clinical samples (n = 132; vesicular epithelium = 92, vesicular lesion swabs = 20, saliva = 20) in Mongolia, the sensitivity of FMDV-Ag SAI in comparison with real-time reverse transcription-polymerase chain reaction revealed the following data: vesicular epithelium, 85.4% (76/89); vesicular lesion swab, 46.7% (7/17); and saliva, 36.8% (7/19). No cross-reactivity with the non-FMDV vesicular-forming viruses and taxonomically related viruses of the Picornaviridae family occurred. The FMDV-Ag SAI is a highly sensitive diagnostic tool that enables pen-side diagnosis without requiring the use of any equipment.

Horizontal transmission of foot-and-mouth disease virus O/JPN/2010 among different animal species by direct contact

Foot-and-mouth disease (FMD) is highly contagious and easily transmitted among species of cloven-hoofed animals. To investigate the transmission of FMD virus (FMDV) among different animal species, experimental infections using the O/JPN/2010 strain were performed in cows, goats and pigs. One cow or two goats/pigs were housed with a different species of inoculated animals, and clinical observations, virus shedding and antibody responses were analysed daily. Whilst all cows and goats were infected horizontally by contact with inoculated pigs, transmission from cows to goats/pigs and from goats to cows/pigs was not observed in all in-contact animals. In particular, no pigs were infected horizontally by contact with inoculated goats. Comparison with our previous study on experimental infections among animals of the same species indicates that horizontal transmission occurred more easily between animals of the same species than between those of the different species. These findings will be useful for establishing and performing species-specific countermeasures in farms and regions where multiple species of animals coexist in potential future outbreaks.

Genetic Determinants of Virulence between Two Foot-and-Mouth Disease Virus Isolates Which Caused Outbreaks of Differing Severity

Individual foot-and-mouth disease virus (FMDV) strains reveal different degrees of infectivity and pathogenicity in host animals. The differences in severity among outbreaks might be ascribable to these differences in infectivity among FMDV strains. To investigate the molecular mechanisms underlying these differences, we estimated the infectivity of O/JPN/2000 and O/JPN/2010, which caused outbreaks of markedly different scales, in cell lines, Holstein cattle, and suckling mice. Viral growth of the two strains in cells was not remarkably different; however, O/JPN/2000 showed apparently low transmissibility in cattle. Mortality rates of suckling mice inoculated intraperitoneally with a 50% tissue culture infective dose (TCID₅₀) of 10 for O/JPN/2000 and O/JPN/2010 also differed, at 0% and 100%, respectively. To identify genes responsible for this difference in infectivity, genetic regions of the full-length cDNA of O/JPN/2010 were replaced with corresponding fragments of O/JPN/2000. A total of eight recombinant viruses were successfully recovered, and suckling mice were intraperitoneally inoculated. Strikingly, recombinants having either VP1 or 3D derived from O/JPN/2000 showed 0% mortality in suckling mice, whereas other recombinants showed 100% mortality. This finding indicates that VP1, the outermost component of the virus particle, and 3D, an RNA-dependent RNA polymerase, are individually involved in the virulence of O/JPN/2010. Three-dimensional structural analysis of VP1 confirmed that amino acid differences between the two strains were located mainly at the domain interacting with the cellular receptor. On the other hand, measurement of their mutation frequencies demonstrated that O/JPN/2000 had higher replication fidelity than O/JPN/2010.IMPORTANCE Efforts to understand the universal mechanism of foot-and-mouth disease virus (FMDV) infection may be aided by knowledge of the molecular mechanisms which underlie differences in virulence beyond multiple topotypes and serotypes of FMDV. Here, we demonstrated independent genetic determinants of two FMDV isolates which have different transmissibility in cattle, namely, VP1 and 3D protein. Findings suggested that the selectivity of VP1 for host cell receptors and replication fidelity during replication were important individual factors in the induction of differences in virulence in the host as well as in the severity of outbreaks in the field. These findings will aid the development of safe live vaccines and antivirals which obstruct viral infection in natural hosts.

Parameterization of the Durations of Phases of Foot-And-Mouth Disease in Cattle

The objective of the current study was to update parameterization of mathematical simulation models for foot-and-mouth disease (FMD) spread in cattle utilizing recent knowledge of FMD virus (FMDV) pathogenesis and infection dynamics to estimate the duration of distinct phases of FMD. Specifically, the durations of incubation, latent, and infectious periods were estimated for 3 serotypes (O, Asia1, and A) of FMDV, individually and collectively (pan-serotypic). Animal-level data were used in Accelerated Failure Time (AFT) models to estimate the duration of the defined phases of infection, while also investigating the influence of factors related to the experimental design (exposure methods) and virus serotype on disease progression. Substantial influences upon the estimated duration of distinct phases of FMD included the quantity of viral shedding used as a proxy for the onset of infectiousness, virus serotypes, and experimental exposure methods. The use of detection of any viral RNA in nasal secretions as a proxy of infectiousness lengthened the total infectious period compared to use of threshold-based detection. Additionally, the experimental system used to infect the animals also had significant effects on the duration of distinct phases of disease. Overall, the mean [95% Confidence Interval (CI)] durations of pan-serotype disease phases in cattle were estimated to be: incubation phase = 3.6 days (2.7–4.8), latent phase = 1.5 days (1.1–2.1), subclinical infectious phase = 2.2 days (1.5–3.5), clinical infectious phase = 8.5 days (6.2–11.6), and total infectious phase = 10.8 days (8.2–14.2). This study highlights the importance of identifying appropriate proxy measures to define the onset and duration of infectiousness in FMDV-infected cattle in the absence of actual transmission data. Additionally, it is demonstrated herein that factors associated with experimental design, such as virus exposure methods, may significantly affect disease progression in individual animals and should be considered when data is extrapolated from experimental studies. Given limitations in experimental data availability, pan-serotypic parameters which include all routes of exposure and a threshold-defined onset of infectiousness may be the most robust parameters for exploratory disease spread modeling approaches, when information on the specific virus of interest is not available.

Reconstructing a transmission network and identifying risk factors of secondary transmissions in the 2010 foot-and-mouth disease outbreak in Japan

Research aimed at understanding transmission networks, representing a network of "who infected whom" for an infectious disease outbreak, have been actively conducted in recent years. Transmission network models incorporating epidemiological and genetic data are valuable for elucidating disease transmission pathways. In this study, we reconstructed the transmission network of the foot-and-mouth disease (FMD) epidemic in Japan in 2010, and explored farm-level risk factors associated with increased risk of secondary transmission. A published, systematic Bayesian transmission network model was applied to epidemiological data of 292 infected farms and whole genome sequence data of 104 of the infected farms. This model can make inferences for known infected farms even lacking genetic data. After estimating the consensus network, the accuracy of the network was examined by comparison with epidemiological data. Then, risk factors inferred to have been sources of secondary transmission were explored using zero-inflated Poisson regression model. As far as we are aware, this study represents the largest FMD outbreak transmission network to be published by such means combining epidemiological and genetic data. The consensus network reasonably generated the epidemiological links, which were estimated from the actual epidemiological investigation. Among 292 farms, 101 farms (35%) were inferred to have been the sources of secondary transmission, and amongst these farms, the median number of secondary cases was 2 (min:1-max:18) farms. The farm-type (small and large -sized pig farms), the number of days from onset to notification, and the number of susceptible farms within a 1-km radius were significantly associated with secondary transmission. Transmission network modelling enabled inference of the connections between infected farms during the FMD epidemic and identified important factors for controlling the risk of secondary transmission. This study demonstrated that the predominant susceptible species held on a farm, farm size, and animal density were associated with increased onwards transmission.

Reverse transcription-PCR using a primer set targeting the 3D region detects foot-and-mouth disease virus with high sensitivity

The potential of foot-and-mouth disease (FMD) to spread extensively means that rapid and accurate methods are needed for its diagnosis. Therefore, reverse transcription-PCR (RT-PCR) plays an important diagnostic role. Here, we designed the primer set FM8/9 to amplify 644 bases in the conserved 3D region of all seven serotypes of the FMD virus (FMDV). We compared the performance of RT-PCR assays using FM8/9 with those using the primer set 1F/R, which targets the 5'-UTR, and real-time RT-PCR (rRT-PCR) assays described in the World Organization for Animal Health manual. Detection limits of the RT-PCR assays were determined for 24 strains, representing all serotypes. The sensitivities of RT-PCR assays using FM8/9 were 10^0.6 - to 10^3.8 -fold higher than those of 1F/R assays for 21 strains. To assess the validity of the methods for analysing clinical samples, sera and saliva samples collected daily from pigs and cows infected with FMDV were analysed using the four PCR assays. FM8/9 assays detected FMDV from all infected pigs and cows for longer periods than 1F/R assays, indicating that FM8/9 assays have higher sensitivity for the clinical samples. Our results suggest that the FM8/9 RT-PCR assay is highly sensitive and is therefore suitable for the diagnosis of FMD.

Clinical and infection dynamics of foot-and-mouth disease in beef feedlot cattle: An expert survey

Parameterizing mathematical models of foot-and-mouth disease virus (FMDv) transmission is challenging due to knowledge gaps on the variable dynamics in susceptible populations. Expert opinion surveys are an approach to gather data on topics where no data have been reported. The objective of this study was to collect-via an expert-opinion survey-key parameter values of the potential FMD natural history and transmissibility in beef feedlot cattle in the U.S. Experts with experience working with FMD in endemic and non-endemic settings were targeted. Parameters surveyed were: duration of infection and disease stages, proportions of animals with specific clinical manifestations, duration and extent of the reduction in feed consumption, and probabilities of severe clinical disease and FMDv transmission. We surveyed the parameter values for infections by strains of different virulence, different infection doses, and routes of transmission. Twenty-seven experts from around the world agreed to participate and 16 (59%) completed the survey. The expert responses to individual questions were resampled via Monte Carlo simulations; to the resulting distributions, candidate theoretical distributions were fitted using the maximum likelihood method and the sought parameter values estimated based on the best-fit distributions. Of the infection stages, the estimates of the expected FMD latent period in beef feedlot ranged from 1.7 to 5.3 days and the infectious period from 5.6 to 10.9 days. Of the disease stages, the estimated incubation period ranged from 2.9 to 6.1 days, subclinical period from 1.2 to 2.8 days, and clinical period from 4.2 to 7.5 days. Probability of developing clinical disease after infection varied from 82% (IQ range 90-70%) with high-virulent to 63% (IQ range 89-60%) with low-virulent strains. Reduction in feed consumption was estimated to last 5 (SD ± 2) days in cattle infected by a low-virulent FMDv strain and 7 (SD ± 2) days for high virulent strains. The study results can be used in combination with experimental and outbreak investigation data to parameterize FMDv-transmission models to evaluate intervention responses during hypothetical FMD epidemics in beef feedlot populations in the U.S.

Comparative evaluation of two ELISA kits for detecting antibodies to a nonstructural protein of foot-and-mouth disease virus using serum samples collected from naturally and experimentally infected cows

When foot-and-mouth disease (FMD) occurs and a “vaccination-to-live” policy is adopted in a country, the country must perform serological surveillance of a nonstructural protein (NSP) of FMD virus. The NCPanaftosa kit is the only kit for detecting antibodies to NSPs that is officially recognized as the reference regent by the World Organization for Animal Health; however, it is only used in South American countries. In this study, the specificity and sensitivity of the NCPanaftosa kit were compared with those of the PrioCHECK kit sold by an international company. Results in this study suggest that the PrioCHECK kit performs similarly to the NCPanaftosa kit in detecting antibodies to the NSP in the cattle population.

Early pathogenesis of the foot-and-mouth disease virus O/JPN/2010 in experimentally infected pigs

We examined the histological distribution of the lesions and the viral antigen associated with the virus and virus RNA in multisystemic organs in the early stages of foot-and-mouth disease virus (FMDV) O/JPN/2010 infection in pigs. Characteristic lesions commonly observed in pigs with FMD arise following inoculation with 10⁶ tissue culture infectious dose (TCID)₅₀/ml of FMDV O/JPN/2010 in pigs at 3 days post inoculation (dpi) by a natural infectious route. However, none of the six pigs inoculated with 10³ TCID₅₀/ml of FMDV O/JPN/2010 showed any evidence of infection up to 6 dpi. Immunohistochemical detection for the FMDV antigen and terminal deoxynucleotidyl transferase-mediated dUTP-nick end labeling (TUNEL) showed that FMDV predominantly infected prickle cells in the stratum spinosum in the tongue, coronet and bulb of the heel, and caused these infected cells to undergo cell death by apoptosis. However, there was no evidence that FMDV O/JPN/2010 infected epithelial/epidermal basal cells in the basal layer. Epithelial lesions with viral antigen in the tongue were distributed in the dorsal surface but not in the papillae, corpus linguae or inferior surface of the tongue. Non-suppurative myocarditis and epithelial lesions in the esophagus with FMDV antigen were observed in all three pigs examined at 3 dpi.

Experimental infections using the foot-and-mouth disease virus O/JPN/2010 in animals administered a vaccine preserved for emergency use in Japan

The effectiveness of a vaccine preserved for emergency use in Japan was analyzed under experimental conditions using cows and pigs in order to retrospectively evaluate the effectiveness of the emergency vaccination performed in the 2010 epidemic in Japan. Cows and pigs were administered a vaccine preserved for emergency use in Japan at 3 or 30 days before virus infection (dbv) and were subsequently infected with the foot-and-mouth disease virus (FMDV) O/JPN/2010, which was isolated in the 2010 epidemic in Japan. All animals vaccinated at 30 dbv and one of three pigs vaccinated at 3 dbv showed no vesicular lesions during the experimental period. The virus titers and viral RNA loads obtained from clinical samples were lower in the vaccinated cows than in the non-vaccinated cows. The viral excretion periods were shorter in the vaccinated cows than in the non-vaccinated cows. In contrast, in the vaccinated pigs, the virus titers and viral RNA loads obtained from the samples, except for those obtained from sera, were not decreased significantly, and the viral excretion periods were not sufficiently shortened. These results suggest that the vaccine can protect against clinical signs of infection by the FMDV O/JPN/2010 in animals; however, it should be noted that in vaccinated and infected animals, especially pigs, clinical samples, such as saliva and nasal swabs, may contain excreted viruses, even if no clinical signs were exhibited.

Construction and characterization of a full-length infectious cDNA clone of foot-and-mouth disease virus strain O/JPN/2010 isolated in Japan in 2010

A full-length infectious cDNA clone of the genome of a foot-and-mouth disease virus isolated from the 2010 epidemic in Japan was constructed and designated pSVL-f02. Transfection of Cos-7 or IBRS-2 cells with this clone allowed the recovery of infectious virus. The recovered virus had the same in vitro characterization as the parental virus with regard to antigenicity in neutralization and indirect immunofluorescence tests, plaque size and one-step growth. Pigs were experimentally infected with the parental virus or the recombinant virus recovered from pSVL-f02 transfected cells. There were no significant differences in clinical signs or antibody responses between the two groups, and virus isolation and viral RNA detection from clinical samples were similar. Virus recovered from transfected cells therefore retained the in vitro characteristics and the in vivo pathogenicity of their parental strain. This cDNA clone should be a valuable tool to analyze determinants of pathogenicity and mechanisms of virus replication, and to develop genetically engineered vaccines against foot-and-mouth disease virus.

Further evaluation of an ELISA kit for detection of antibodies to a nonstructural protein of foot-and-mouth disease virus

An ELISA kit for detection of antibodies to a nonstructural protein of foot-and-mouth disease (FMDV) was further evaluated using sequentially collected serum samples of experimentally infected animals, because the sensitivity of the kit used in a previous study was significantly low in field animals. The kit fully detected antibodies in infected animals without vaccination; however, the first detections of antibodies by the kit were later than those by the liquid-phase blocking ELISA that is used for serological surveillance in the aftermath of outbreaks in Japan, for detection of antibodies to structural proteins of FMDV. Additionally, although the kit effectively detected antibodies in infected cattle with vaccination, there were several infected pigs with vaccination for which the kit did not detect antibodies during the experimental period. Taken together, the kit may not be suitable for serological surveillance after an FMD outbreak either with or without emergency vaccination in FMD-free countries.

Comparative performance of fetal goat tongue cell line ZZ-R 127 and fetal porcine kidney cell line LFBK-αvβ6 for Foot-and-mouth disease virus isolation

The fetal goat tongue cell line ZZ-R 127 and the fetal porcine kidney cell line LFBK-α(v)β(6) have been reported to have high sensitivity to various Foot-and-mouth disease virus (FMDV) strains. The suitability of ZZ-R 127 cells for FMDV isolation not only from epithelial suspensions but also from other clinical samples has already been confirmed in a previous study. However, to our knowledge, the suitability of LFBK-α(v)β(6) cells has not been evaluated using clinical samples other than epithelial materials. In addition, both cell lines have never been compared, in terms of use for FMDV isolation, under the same conditions. Therefore, in the current study, the virus isolation rates of both cell lines were compared using clinical samples collected from animals infected experimentally with FMDV. Viruses were successfully isolated from clinical samples other than epithelial suspensions for both cell lines. The virus isolation rates for the 2 cell lines were not significantly different. The Cohen kappa coefficients between the virus isolation results for both cell lines were significantly high. Taken together, these results confirmed the suitability of LFBK-α(v)β(6) cells for FMDV isolation from clinical samples other than epithelial suspensions. The levels of susceptibility of both cell lines to FMDV isolation were also confirmed to be almost the same.