For Foot-and-mouth Disease Research Articles

Application of Heparin Affinity Chromatography to Produce a Differential Vaccine without Eliciting Antibodies against the Nonstructural Proteins of the Serotype O Foot-and-Mouth Disease Viruses.

Although polyethylene glycol (PEG) application is the most widely used method in removing nonstructural proteins (NSPs) for foot-and-mouth disease (FMD) vaccine production, some NSPs remaining in the antigen could elicit antibodies against these proteins after repeated vaccinations in livestock. Therefore, the purpose of this study was to purify the FMD virus (FMDV) via affinity chromatography using a heparin ligand to remove most proteins, including NSPs. Chromatography showed an intact virus (146S) particle recovery of 70% or more for three different strains of serotype O FMDV (two locally isolated strains and one genetically modified strain). The experimental vaccine made with antigens eluted via heparin affinity chromatography elicited virus-neutralizing antibodies against homologous viruses but did not induce antibodies against NSPs even after five immunizations in goats; this indicated that the NSPs were effectively removed from the vaccine antigen. This method can then be used to produce a higher-quality vaccine compared with PEG application in terms of the purity of the FMD vaccine. Therefore, this result would be an important groundwork for advanced FMD vaccine manufacturing in the near future.

Efficacy and application of a novel topical anaesthetic wound formulation for treating cattle with Foot‐and‐Mouth disease: A field trial in Cameroon

Recently, a wound dressing formulation, (Tri‐Solfen®, Medical Ethics Pty Ltd, Australia; TS) registered for use in ruminant husbandry in Australia, was registered for Foot‐and‐Mouth Disease (FMD) therapy in large ruminants in Laos, following clinical observations of improved welfare and healing following treatment of FMD lesions. In November 2019, an FMD outbreak in Cameroon provided an opportunity for a field trial, comparing clinical responses and recoveries to treatments on a sample of cattle (n = 36) comprising three equal groups of animals (n = 12), comparing responses to three treatments: (i) the application to lesions of TS, (ii) the administration of parenteral oxytetraycline commonly used for FMD in Cameroon; and (iii) an untreated control group (C). Appetite scores, lesion healing scores, and changes in dimensions of lesions, were recorded over a 15‐day study period. Cattle treated with TS achieved both superior appetite and lesion healing scores with more rapid reduction in dimensions of lesions than other groups. Farmer observations indicated the TS treatment group had a more rapid return to eating with cessation of excessive salivation, and more rapid return of mobility (walking) with absence of overt lameness. The findings indicate that although mortality is usually low in FMD outbreaks, the disease is a debilitating and painful disorder with negative animal welfare impacts that should be addressed. All farmers expressed their desire that the product be made available for use in their region and modelling indicates that TS therapy imposes no additional financial burden on farmers, with the treatment likely to be provided at a similar or reduced cost to current treatment choices. As use of antibiotics for treatment of a viral disease potentially increases pressures for development of antimicrobial resistance and residues in the food chain, TS as an alternative non‐antimicrobial therapy should be promoted for wider use in FMD outbreaks.

Identification of risk areas for foot and mouth disease in Thailand using a geographic information system-based multi-criteria decision analysis

In our study, we used geographic information system (GIS)-based multi-criteria decision analysis (MCDA) to predict suitable areas for foot and mouth disease (FMD) occurrence in Thailand. Eleven experts evaluated 10 spatial risk factors associated with the occurrence and spread of FMD in Thailand during 2014–2015. The analytic hierarchy process was used to conduct problem structuring and prioritising of pairwise comparisons with criterion weighting. Important spatial risk factors were converted to geographical layers using standardised fuzzy membership. Thus, weight linear combination was used to combine and create suitability and uncertainty maps as well as to perform sensitivity analysis. We identified areas in northern, north-eastern, western, and central Thailand as hotspots of FMD occurrence. In the predictive map, the suitable areas presented a moderate degree of agreement with those after FMD outbreaks in the year 2016 (AUC = 0.71, 95 %CI: 0.68–0.75). In conclusion, GIS-based MCDA mapping well supported veterinary services in identifying hotspot areas of FMD occurrence in Thailand. This tool was very useful for disease surveillance.

Monitoring the performance of foot-and-mouth disease vaccines prepared against local strains in the face of antigenic evolution in the field.

National programs for foot-and-mouth disease (FMD) eradication includes the use of vaccination; Turkey which is endemic to FMD virus (FMDV) (except for the Thrace region) and there is a risk of incursion of exotic strains from eastern borders. In 2015, a devastating outbreak was caused by the A/ASIA/G-VII (G-VII) lineage, which led to the inclusion of a new vaccine strain (A/TUR/15) derived from this lineage in 3months. Although most of the cattle population in Turkey was then immunized with A/TUR/15 (vaccine coverage: 92.8%), the G-VII lineage continued to cause outbreaks in the field despite the evidence of protection observed with A/TUR/15 in in vivo and in vitro tests. When G-VII field strains were examined, changes in their genomes were detected. As the lineage appeared to be evolving, an unconventional vaccination strategy was adapted which changed the vaccine strain with new variants of G-VII according to antigenic evolution. To assess the suitability of candidate vaccine strains derived from the variants of the G-VII lineage, three viral candidates were assessed (A/TUR/15, A/TUR/16 and A/TUR/17) by in vitro virus neutralization tests for r1 vaccine matching and in vivo heterologous challenge tests. Although all three vaccine strains were antigenically well matched with each other and other G-VII field viruses, due to continues outbreaks the vaccine strain was changed three times in 20months from A/TUR/15 (Dec 2015) to A/TUR/16 (Dec 2016) and then to A/TUR/17 (Aug 2017). With this strategy serotype A has not been observed in the field since January 2018. This study highlights the importance of adapting the vaccine strains according to antigenic evolution as this could be a valuable combat strategy in endemic countries, rather than using well-known vaccine strain and relying only on the relationship coefficient (r1 ) value.

Detection of Bovine Antibodies against a Conserved Capsid Epitope as the Basis of a Novel Universal Serological Test for Foot-and-Mouth Disease.

Diagnostic tests for foot-and-mouth disease (FMD) include the detection of antibodies against either the viral nonstructural proteins or the capsid. The detection of antibodies against the structural proteins (SP) of the capsid can be used to monitor seroconversion in both infected and vaccinated animals. However, SP tests need to be tailored to the individual FMD virus (FMDV) serotype and their sensitivity may be affected by antigenic variability within each serotype and mismatching between test reagents. As a consequence, FMD reference laboratories are required to maintain multiple type-specific SP assays and reagents. A universal SP test would simplify frontline diagnostics and facilitate large-scale serological surveillance and postvaccination monitoring. In this study, a highly conserved region in the N terminus of FMDV capsid protein VP2 (VP2N) was characterized using a panel of intertype-reactive monoclonal antibodies. This revealed a universal epitope in VP2N which could be used as a peptide antigen to detect FMDV-specific antibodies against all types of the virus. A VP2-peptide enzyme-linked immunosorbent assay (VP2-ELISA) was optimized using experimental and reference antisera from immunized, convalescent, and naïve animals (n = 172). The VP2-ELISA is universal and simple and provided sensitive (99%) and specific (93%) detection of antibodies to all FMDV strains used in this study. We anticipate that this SP test could have utility for serosurveillance during virus incursions in FMD-free countries and as an additional screening tool to assess FMD virus circulation in countries where the disease is endemic.

Timeliness of vesicular disease notification system in Brazilian foot-and-mouth disease surveillance programme.

Animal health surveillance programmes should be reliable and informative to ensure their effective implementation. As such, the regular assessment of those aiming to demonstrate the absence of disease, as well as the ability to detect outbreaks on time, is of vital importance. Several criteria make it possible to assess the performance of surveillance systems, including timeliness, which represents the speed between steps in a surveillance system. Therefore, the objective of this study was to evaluate the variability in the timeliness, within and between states, of the surveillance programme of the Brazilian Veterinary Services (BVS) for foot-and-mouth disease (FMD), for the notification of vesicular disease. A total of 14years (2004-2017) of data relating to vesicular syndromes from the Brazilian Continental Information and Surveillance System (SivCont) were included. A categorical variable was created with four classes to group the notified vesicular processes in the SivCont, according to two criteria, the similarity of the symptoms of the diseases reported with FMD and aetiology (viral, bacterial, fungal and non-infectious). The three timeliness values (TL-1, TL-2 and TL-3) related to different portions of the FMD surveillance system were analysed as a response in a generalized linear model in which the states of Brazil were the explanatory variables. The analyses were performed separately for each notification class (FMD, vesicular stomatitis, similar symptoms and similar non-infectious symptoms) and included comparisons within and between states. The study results provide an understanding and evaluation of the timeliness of the Brazilian FMD surveillance system, thereby providing a base of knowledge from which involved agents and decision-makers can evaluate BVS and reinforce surveillance measures in the states with poorer timeliness than permitted.

Utilizing milk from pooling facilities as a novel approach for foot-and-mouth disease surveillance.

This study investigated the potential of pooled milk as an alternative sample type for foot‐and‐mouth disease (FMD) surveillance. Real‐time RT‐PCR (rRT‐PCR) results of pooled milk samples collected weekly from five pooling facilities in Nakuru County, Kenya, were compared with half‐month reports of household‐level incidence of FMD. These periodic cross‐sectional surveys of smallholder farmers were powered to detect a threshold household‐level FMD incidence of 2.5% and collected information on trends in milk production and sales. FMD virus (FMDV) RNA was detected in 9/219 milk samples, and using a type‐specific rRT‐PCR, serotype SAT 1 was identified in 3/9 of these positive samples, concurrent with confirmed outbreaks in the study area. Four milk samples were FMDV RNA‐positive during the half‐months when at least one farmer reported FMD; that is, the household‐level clinical incidence was above a threshold of 2.5%. Additionally, some milk samples were FMDV RNA‐positive when there were no reports of FMD by farmers. These results indicate that the pooled milk surveillance system can detect FMD household‐level incidence at a 2.5% threshold when up to 26% of farmers contributed milk to pooling facilities, but perhaps even at lower levels of infection (i.e., below 2.5%), or when conventional disease reporting systems fail. Further studies are required to establish a more precise correlation with estimates of household‐level clinical incidence, to fully evaluate the reliability of this approach. However, this pilot study highlights the potential use of this non‐invasive, routinely collected, cost‐effective surveillance tool, to address some of the existing limitations of traditional surveillance methods.

Characterization of transboundary foot-and-mouth disease viruses in Nigeria and Cameroon during 2016.

Continuous surveillance for foot-and-mouth disease (FMD) in endemic settings such as West Africa is imperative to support improved local and regional control plans, with the long-term goal of regional eradication. This paper describes the genetic characterization of FMD viruses (FMDV) obtained from outbreaks in Nigeria (n=45) and Cameroon (n=15) during 2016 and from archival samples (n=3) retrieved from a 2014 outbreak in Nigeria. These viruses were analysed in the context of previously published FMDV sequences from the region. Four FMDV serotypes: O, A, SAT1 and SAT2, were detected. Phylogenetic analyses of the VP1 coding sequences indicate the continuity of FMDV serotype O East Africa-3 (O/EA-3), serotype A AFRICA genotype G-IV (A/AFRICA/G-IV) and serotype South African Territories (SAT) 2 lineage VII (SAT2/VII). The FMDV SAT1 topotype X (SAT1/X), which emerged in Nigeria in 2015, continued to be associated with outbreaks in the region during 2016, and SAT1 is reported for the first time from Cameroon. Additionally, a re-emergence or re-introduction of the serotype O West Africa (O/WA) topotype in Nigeria is described herein. Our findings indicate a consistent, pan-serotypic relationship between FMDV strains detected in Cameroon and Nigeria. Additionally, FMDV strains from West Africa obtained in this study were genetically related to those occurring in East and North Africa. These phylogenetic relationships suggest that animal movements (pastoralism and/or trade) are important factors for virus spread across the African continent. These data provide critical baselines which are a necessary component of Stages 0 and 1 of the Progressive Control Pathway of FMD (PCP-FMD). Specifically, characterizing the existing virus strains (risk) provides the basis for the comprehensive risk-based control plan which is the requisite criteria for Nigeria's transition to Stage 2 of PCP-FMD, and for coordinated regional control of FMD.

Duration of protection and humoral immunity induced by an adenovirus-vectored subunit vaccine for foot-and-mouth disease (FMD) in Holstein steers

Foot-and-mouth disease (FMD) is a highly contagious viral infection of cloven hooved animals that continues to cause economic disruption in both endemic countries or when introduced into a formally FMD free country. Vaccines that protect against clinical disease and virus shedding are critical to control FMD. The replication deficient human adenovirus serotype 5 (Ad5) vaccine vector expressing empty FMD virus (FMDV) capsid, AdtFMD, is a promising new vaccine platform. With no shedding or spreading of viral vector detected in field trials, this vaccine is very safe to manufacture, as there is no requirement for high containment faciitites. Here, we describe three studies assessing the proportion of animals protected from clinical vesicular disease (foot lesions) following live-FMDV challenge by intradermolingual inoculation at 6 or 9 months following a single vaccination with the commercial AdtFMD vaccine, provisionally licensed for cattle in the United States. Further, we tested the effect of vaccination route (transdermal, intramuscular, subcutaneous) on clinical outcome and humoral immunity. Results demonstrate that a single dose vaccination in cattle with the commercial vaccine vector expressing capsid proteins of the FMDV strain A24 Cruzeiro (Adt.A24), induced protection against clinical FMD at 6 months (100% transdermal, 80% intramuscular, and 60% subcutaneous) that waned by 9 months post-vaccination (33% transdermal and 20% intramuscular). Post-vaccination serum from immunized cattle (all studies) generally contained FMDV specific neutralizing antibodies by day 14. Anti-FMDV antibody secreting cells are detected in peripheral blood early following vaccination, but are absent after 28 days post-vaccination. Thus, the decay in antibody mediated immunity over time is likely a function of FMDV-specific antibody half-life. These data reveal the short time span of anti-FMDV antibody secreting cells (ASCs) and important performance characteristics of needle-free vaccination with a recombinant vectored subunit vaccine for FMDV.

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.

Effect of IL-2 co-expressed or co-inoculated with immuno-dominant epitopes from VP1 protein of FMD virus on immune responses in BALB/c mice.

Objective(s):The results of studies on vaccine development for foot-and-mouth disease (FMD) virus show that the use of inactivated vaccines for FMD virus is not completely effective. Novel vaccinations based on immuno-dominant epitopes have been shown to induce immune responses. Furthermore, for safety of immunization, access to efficient adjuvants against FMD virus seems to be critical.Materials and Methods:In this study, we produced epitope recombinant vaccines from the VP1 protein of the FMD virus for serotype O of Iran. Constructs were included polytope (tandem-repeat multiple-epitope), polytope coupled with interleukin-2 (polytope-IL 2) as a molecular adjuvant and IL-2. Three expression vectors were constructed and expressed in Escherichia coli BL21 (DE3). To evaluate whether these recombinant vaccines induce immune responses, BALB/c mice were injected with the recombinant vaccines and their immune responses were compared with a negative control group. The humoral and cellular immune responses were measured by ELISA.Results:The results showed that IL-2 co-expressed or co-inoculated with Polytope protein enhances the immune effect of multiple epitope recombinant vaccine against FMD virus. The results of total immunoglobulin G (IgG), IgG1, and IgG2a levels and secretion of interferon gamma (IFN-γ), IL-4 and IL-10 revealed that there were significant differences between negative control group and other injected mice with the recombinant vaccines (P<0.05).Conclusion:Observations indicated that the epitope recombinant plasmid of the VP1 protein co-expressed or co-inoculated with IL-2 was effective in inducing an enhanced immune response. Therefore, IL-2 can be recommended as a potential adjuvant for epitope recombinant vaccine of the VP1 protein from FMD virus.

Spatial and temporal risk as drivers for adoption of foot and mouth disease vaccination

Identifying the drivers of vaccine adoption decisions under varying levels of perceived disease risk and benefit provides insight into what can limit or enhance vaccination uptake. To address the relationship of perceived benefit relative to temporal and spatial risk, we surveyed 432 pastoralist households in northern Tanzania on vaccination for foot-and-mouth disease (FMD). Unlike human health vaccination decisions where beliefs regarding adverse, personal health effects factor heavily into perceived risk, decisions for animal vaccination focus disproportionately on dynamic risks to animal productivity. We extended a commonly used stated preference survey methodology, willingness to pay, to elicit responses for a routine vaccination strategy applied biannually and an emergency strategy applied in reaction to spatially variable, hypothetical outbreaks. Our results show that households place a higher value on vaccination as perceived risk and household capacity to cope with resource constraints increase, but that the episodic and unpredictable spatial and temporal spread of FMD contributes to increased levels of uncertainty regarding the benefit of vaccination. In addition, concerns regarding the performance of the vaccine underlie decisions for both routine and emergency vaccination, indicating a need for within community messaging and documentation of the household and population level benefits of FMD vaccination.

Methodological aspects of serosurveillance in resource-poor settings

Animal production is important for the agricultural economy in low-income countries, but is threatened by infectious diseases. Serosurveys are conducted for different reasons such as disease detection, risk factor studies,...

Criteria and indicators for foot and mouth disease control strategy decision-making in Asia-Oceania countries.

The objective of this study is to identify the relative importance of criteria that could be used to evaluate control strategies for foot and mouth disease (FMD). A questionnaire was distributed to 21 Chief Veterinary Officers (CVOs), or their representatives, at the 28th Conference of the Regional Commission for Asia, the Far East and Oceania of the World Organisation for Animal Health (OIE), held on 18-22 November 2013 in Cebu, the Philippines. The CVOs/CVO representatives were present on behalf of 21 of the 31 OIE Member Countries in the region, and the questionnaire evaluated the importance of epidemiologic, economic and social- environmental criteria in the FMD control strategy decision-making process. Within the epidemiologic criterion, the size of an FMD outbreak area, with a median relative importance score of 90 (range 45-100), was viewed as the most important indicator, while the direct cost of FMD control measures was considered to be the most important economic indicator, with a median relative importance score of 80 (range 30-100). Finally, within the social-environmental criterion, the mental health of FMD-affected farmers was viewed as the most important indicator, with a median relative importance score of 70 (range 5-100). With respect to the FMD status of a country, the economic criterion was considered more important in 'FMD-free' countries (countries where an FMD outbreak had not been reported to the OIE in the ten years prior to the survey) than in 'FMD-experienced' countries (countries where an FMD outbreak had been reported to the OIE within the same period). The median relative importance scores of FMD-experienced countries and FMD-free countries were 80 (range 50-95) and 95 (range 40-100), respectively. Regarding the percentage contribution of the agriculture sector to a country's gross domestic product, a statistically significant difference was not found between countries and indicators. In the future, the current survey of the relative importance of criteria and indicators should facilitate a transparent discussion on the implications of FMD control strategies and rapid response during an FMD outbreak.

Chemiluminescence Immunoassay for the Detection of Antibodies against the 2C and 3ABC Nonstructural Proteins Induced by Infecting Pigs with Foot-and-Mouth Disease Virus.

The potential diagnostic value of chemiluminescence immunoassays (CLIAs) has been accepted in recent years, although their use for foot-and-mouth disease (FMD) diagnostics has not been reported. Full-length 3ABC and 2C proteins were expressed in bacteria and purified by affinity chromatography to develop a rapid and accurate approach to distinguish pigs infected with foot-and-mouth disease virus (FMDV) from vaccinated pigs. The recombinant proteins were then used as antigens to develop two CLIAs for the detection of antibodies against nonstructural viral proteins. The diagnostic performance of the two assays was compared by analyzing serum from pigs (naive pigs, n = 63; vaccinated, uninfected pigs, n = 532; naive, infected pigs, n = 117) with a known infection status. The 3ABC-2C CLIA had a higher accuracy rate, with a diagnostic sensitivity of 100% and a diagnostic specificity of 96.5%, than the 3ABC CLIA, which had a diagnostic sensitivity of 95.7% and a diagnostic specificity of 96.0%. The results of the 3ABC-2C CLIA also had a high rate of concordance with those of two commercial FMDV enzyme-linked immunosorbent assay (ELISA) kits used to assess serum collected from 962 pigs in the field (96.2% and 97.8%, respectively). The 3ABC-2C CLIA detected infection in serum samples from infected pigs earlier than the commercial ELISA kits. In addition, the 3ABC-2C CLIA produced results within 15 min. On the basis of these findings, the 3ABC-2C CLIA could serve as the foundation for the development of penside FMD diagnostics and offers an alternative method to detect FMDV infections.

Spatial pattern of foot-and-mouth disease virus serotypes in North Central Nigeria.

Aim:This study aimed to determine the foot-and-mouth disease virus (FMDV) serotypes circulating, the prevalence of FMDV serotypes, and the spatial distribution of FMDV among sedentary and pastoral cattle herds in the North-Central Nigeria.Materials and Methods:A cross-sectional study was undertaken, during which a total of 155 sera that tested positive for foot-and-mouth disease (FMD) 3ABC non-structural protein antibodies were selected and screened for FMD structural protein serotypes, A, O, SAT 1, and SAT 2 using a solid-phase competitive enzyme-linked immunosorbent assay (ELISA). Epithelial tissue specimens were collected during outbreak investigations which were tested for FMD using an antigen capture ELISA for serotype A, O, SAT 1, and SAT 2.Results:An overall serotype-specific prevalence of 79.35 (95% confidence interval [CI]: 72.4-85.18) was recorded for serotype O, 65.2% (95% CI: 57.41-72.3) for serotype A, 52.9% (95% CI: 45.03-60.67) for SAT 2, and 33.55% (95% CI: 26.45-41.26) for SAT 1. Evidence of exposure to multiple FMDV serotypes showed that 12.26% of the sera samples had antibodies against four serotypes circulating, 30.97% had antibodies against three serotypes circulating, 22.58% had antibodies against two serotypes, and 17% showed exposure to only one serotype. Clinical specimens (epithelial tissue) collected during outbreak investigations showed that serotype O has the highest proportion of 50% with serotype A - 25%; SAT 2 - 20.8%; and SAT 1 - 4.1%.Conclusion:The study detected diffuse and co-circulation of serotypes A, O, SAT 1, and SAT 2 within the study area, and hence the need for the appropriately matched multivalent vaccine is strongly advocated for FMD control in Nigeria.

Detection and Molecular Characterization of Foot and Mouth Disease Viruses from Outbreaks in Some States of Northern Nigeria 2013-2015.

Control measures for foot and mouth disease (FMD) in Nigeria have not been implemented due to the absence of locally produced vaccines and risk-based analysis resulting from insufficient data on the circulating FMD virus (FMDV) serotypes/strains. In 2013-2015, blood and epithelial samples were collected from reported FMD outbreaks in four states (Kaduna, Kwara, Plateau and Bauchi) in northern Nigeria. FMDV non-structural protein (NSP) seroprevalence for the outbreaks was estimated at 80% (72 of 90) and 70% (131 of 188) post-outbreak. Antibodies against FMDV serotypes O, A, SAT1, SAT2 and SAT3 were detected across the states using solid-phase competitive ELISA. FMDV genome was detected in 99% (73 of 74) of the samples from FMD-affected animals using rRT-PCR, and cytopathic effect was found in cell culture by 59% (44 of 74) of these samples. Three FMDV serotypes O, A and SAT2 were isolated and characterized. The phylogenetic assessments of the virus isolates showed that two topotypes of FMDV serotype O, East Africa-3 (EA-3) and West Africa (WA) topotypes were circulating, as well as FMDV strains belonging to the Africa genotype (G-IV) of serotype A and FMDV SAT2 topotype VII strains. While the serotype O (EA-3) strains from Nigeria were most closely related to a 1999 virus strain from Sudan, the WA strain in Nigeria shares genetic relationship with three 1988 viruses in Niger. The FMDV serotype A strains were closely related to a known virus from Cameroon, and the SAT2 strains were most closely related to virus subtypes in Libya. This study provides evidence of co-occurrence of FMDV serotypes and topotypes in West, Central, East and North Africa, and this has implication for control. The findings help filling the knowledge gap of FMDV dynamics in Nigeria and West Africa subregion to support local and regional development of vaccination-based control plans and international risk assessment.

Construction of a stable w/o nano-emulsion as a potential adjuvant for foot and mouth disease virus vaccine

A stable and bio-compatible w/o nano-emulsion was developed as adjuvant for foot and mouth disease (FMD) vaccine with isopropyl myristate as oil phase, polyglycerol polyricinoleate, and Tween 80 as surfactants. Dissolving Tween 80 in aqueous phase decreased the droplet size and improved stability of the emulsion through narrowing size distribution, increasing viscosity, and reducing the interfacial tension between oil and water. The nano-emulsion was then formulated with inactivated FMD virus and ovalbumin to investigate its potential application as an adjuvant. Compared with commercial ISA-206 adjuvant, the novel w/o nano-emulsion was able to induce both humoral- and cell-mediated immune response.

Mapping the likelihood of foot-and-mouth disease introduction along the border between Brazil and Paraguay

Abstract: The objective of this work was to apply fuzzy majority multicriteria group decision-making to determine risk areas for foot-and-mouth disease (FMD) introduction along the border between Brazil and Paraguay. The study was conducted in three municipalities in the state of Mato Grosso do Sul, Brazil, located along the border with Paraguay. Four scenarios were built, applying the following linguistic quantifiers to describe risk factors: few, half, many, and most. The three criteria considered to be most likely to affect the vulnerability to introduction of FMD, according to experts' opinions, were: the introduction of animals in the farm, the distance from the border, and the type of property settlements. The resulting maps show a strong spatial heterogeneity in the risk of FMD introduction. The used methodology brings out a new approach that can be helpful to policy makers in the combat and eradication of FMD.

Altered adjuvant of foot-and-mouth disease vaccine improves immune response and protection from virus challenge

Vaccines for foot-and-mouth disease (FMD) generally use oil adjuvants. For better immunization and safety, an adjuvant should be selected only after careful consideration. In this study, we produced vaccines for O, A, and Asia1 serotypes by mixing oil adjuvants, Emulsigen-D (ED), ISA 201, and ISA 206 with and without an aluminum hydroxide (AL) gel and measured their immunogenicity and safety to obtain information regarding critical differences (survival or weight loss) of vaccine quality in mice; the goal of this test was to overcome the difficulties associated with experiments large or medium-sized animals. The groups immunized with the vaccines containing only the oil adjuvants (ED, ISA 201, and ISA 206) had similar or higher levels of neutralizing antibodies and structural protein antibodies for the FMD virus (FMDV) than the groups immunized with the vaccines including the oil adjuvants mixed with the gel. However, in a challenge test using a mouse model, the protection rate showed the highest results in ISA 201 and ISA 206 mixed with AL. The mice immunized with vaccines containing ED showed temporary weight loss in the early postvaccination stages. Cell-mediated immunity was formed relatively strongly in the group vaccinated with vaccines including ISA 201 and ISA 206. We proposed that combinations of these adjuvants represent candidates for future FMD vaccines.