Ensemble learning methods of inference for spatially stratified infectious disease systems

Individual level models are a class of mechanistic models that are widely used to infer infectious disease transmission dynamics. These models incorporate individual level covariate information accounting for population heterogeneity and are generally fitted in a Bayesian Markov chain Monte Carlo (MCMC) framework. However, Bayesian MCMC methods of inference are computationally expensive for large data sets. This issue becomes more severe when applied to infectious disease data collected from spatially heterogeneous populations, as the number of covariates increases. In addition, summary statistics over the global population may not capture the true spatio-temporal dynamics of disease transmission. In this study we propose to use ensemble learning methods to predict epidemic generating models instead of time consuming Bayesian MCMC method. We apply these methods to infer disease transmission dynamics over spatially clustered populations, considering the clusters as natural strata instead of a global population. We compare the performance of two tree-based ensemble learning techniques: random forest and gradient boosting. These methods are applied to the 2001 foot-and-mouth disease epidemic in the U.K. and evaluated using simulated data from a clustered population. It is shown that the spatially clustered data can help to predict epidemic generating models more accurately than the global data.

Prophylactic treatment with PEGylated bovine IFNλ3 effectively bridges the gap in vaccine-induced immunity against FMD in cattle

Foot-and-mouth disease (FMD) is a vesicular disease of cloven-hoofed animals with devastating economic implications. The current FMD vaccine, routinely used in enzootic countries, requires at least 7 days to induce protection. However, FMD vaccination is typically not recommended for use in non-enzootic areas, underscoring the need to develop new fast-acting therapies for FMD control during outbreaks. Interferons (IFNs) are among the immune system's first line of defense against viral infections. Bovine type III IFN delivered by a replication defective adenovirus (Ad) vector has effectively blocked FMD in cattle. However, the limited duration of protection-usually only 1-3 days post-treatment (dpt)-diminishes its utility as a field therapeutic. Here, we test whether polyethylene glycosylation (PEGylation) of recombinant bovine IFNλ3 (PEGboIFNλ3) can extend the duration of IFN-induced prevention of FMDV infection in both vaccinated and unvaccinated cattle. We treated groups of heifers with PEGboIFNλ3 alone or in combination with an adenovirus-based FMD O1Manisa vaccine (Adt-O1M) at either 3 or 5 days prior to challenge with homologous wild type FMDV. We found that pre-treatment with PEGboIFNλ3 was highly effective at preventing clinical FMD when administered at either time point, with or without co-administration of Adt-O1M vaccine. PEGboIFNλ3 protein was detectable systemically for >10 days and antiviral activity for 4 days following administration. Furthermore, in combination with Adt-O1M vaccine, we observed a strong induction of FMDV-specific IFNγ+ T cell response, demonstrating its adjuvanticity when co-administered with a vaccine. Our results demonstrate the promise of this modified IFN as a pre-exposure prophylactic therapy for use in emergency outbreak scenarios.

Isoprinosine as a foot-and-mouth disease vaccine adjuvant elicits robust host defense against viral infection through immunomodulation

Background

Commercial foot-and-mouth disease (FMD) vaccines have limitations, such as local side effects, periodic vaccinations, and weak host defenses. To overcome these limitations, we developed a novel FMD vaccine by combining an inactivated FMD viral antigen with the small molecule isoprinosine, which served as an adjuvant (immunomodulator).

Method

We evaluated the innate and adaptive immune responses elicited by the novel FMD vaccine involved both in vitro and in vivo using mice and pigs.

Results

We demonstrated isoprinosine-mediated early, mid-term, and long-term immunity through in vitro and in vivo studies and complete host defense against FMD virus (FMDV) infection through challenge experiments in mice and pigs. We also elucidated that isoprinosine induces innate and adaptive (cellular and humoral) immunity via promoting the expression of immunoregulatory gene such as pattern recognition receptors [PRRs; retinoic acid-inducible gene (RIG)-I and toll like receptor (TLR)9], transcription factors [T-box transcription factor (TBX)21, eomesodermin (EOMES), and nuclear factor kappa B (NF-kB)], cytokines [interleukin (IL)-12p40, IL-23p19, IL-23R, and IL-17A)], and immune cell core receptors [cluster of differentiation (CD)80, CD86, CD28, CD19, CD21, and CD81] in pigs.

Conclusion

These findings present an attractive strategy for constructing novel FMD vaccines and other difficult-to-control livestock virus vaccine formulations based on isoprinosine induced immunomodulatory functions.

Optimization of a foot-and-mouth disease virus Southern African Territories-specific solid-phase competitive ELISA for small ruminant serum samples

We optimized and verified a single-spot solid-phase competitive ELISA (ss-SPCE) to detect antibodies against structural proteins of Southern African Territories (SAT) serotypes of foot-and-mouth disease virus (FMDV) in small ruminants. Sera from goats vaccinated and experimentally challenged with a SAT1 FMDV pool were tested in duplicate at 4 dilutions (1:10, 1:15, 1:22.5, 1:33.8) to optimize the assay. To assess the performance of the assay in naturally infected animals, we evaluated 316 goat and sheep field sera collected during active SAT2 outbreaks. Relative to results of the virus neutralization test, the optimal serum dilution and cutoff percentage inhibition (PI) were 1:15 and 50%, respectively. At these values, the Spearman rank correlation coefficient was 0.85 (p < 0.001), and the sensitivity and specificity (95% CI) were 80.3% (72.6, 87.2) and 91.1% (84.1, 95.9), respectively. Relative to the liquid-phase blocking ELISA and the nonstructural protein ELISA, the ss-SPCE exhibited divergent performance characteristics between the goat and sheep field sera. Repeatability was better for goats, but the correlation and agreement among all 3 assays were better for the sheep sera. The prevalence of SAT2 FMDV infection in the sampled sheep was 23.6%; sampled goats were seemingly FMDV-free. The ss-SPCE is an appropriate FMDV detection tool to investigate the role of small ruminants in the epidemiology of FMD in Africa.

D-galacto-D-mannan-mediated Dectin-2 activation orchestrates potent cellular and humoral immunity as a viral vaccine adjuvant

Introduction

Conventional foot-and-mouth disease (FMD) vaccines have been developed to enhance their effectiveness; however, several drawbacks remain, such as slow induction of antibody titers, short-lived immune response, and local side effects at the vaccination site. Therefore, we created a novel FMD vaccine that simultaneously induces cellular and humoral immune responses using the Dectin-2 agonist, D-galacto-D-mannan, as an adjuvant.

Methods

We evaluated the innate and adaptive (cellular and humoral) immune responses elicited by the novel FMD vaccine and elucidated the signaling pathway involved both in vitro and in vivo using mice and pigs, as well as immune cells derived from these animals.

Results

D-galacto-D-mannan elicited early, mid-, and long-term immunity via simultaneous induction of cellular and humoral immune responses by promoting the expression of immunoregulatory molecules. D-galacto-D-mannan also enhanced the immune response and coordinated vaccine-mediated immune response by suppressing genes associated with excessive inflammatory responses, such as nuclear factor kappa B, via Sirtuin 1 expression.

Conclusion

Our findings elucidated the immunological mechanisms induced by D-galacto-D-mannan, suggesting a background for the robust cellular and humoral immune responses induced by FMD vaccines containing D-galacto-D-mannan. Our study will help to facilitate the improvement of conventional FMD vaccines and the design of next-generation FMD vaccines.

Intradermal Inoculation of Inactivated Foot-and-Mouth Disease Vaccine Induced Effective Immune Responses Comparable to Conventional Intramuscular Injection in Pigs

All pigs in the Republic of Korea are given the foot-and-mouth disease virus (FMDV) vaccine intramuscularly (IM) as part of the country's vaccination policy. However, the IM administration of the FMDV vaccine to pig results in residual vaccine components in the muscle and undesirable changes in muscle and soft tissues, causing economic losses in swine production. In this study, we evaluated whether intradermal (ID) vaccination could be proposed as an alternative to IM administration. ID vaccination (0.2 mL on each side of the neck muscle) and IM vaccination (2 mL on each side of the neck muscle) were performed twice, separated by 14 days, using a commercial FMD vaccine in specific-pathogen-free pigs. We observed growth performance, gross and microscopic lesions at the inoculation site, FMDV-specific antibodies, and neutralizing antibodies for 35 days after vaccination. Side effects on the skin grossly appeared following ID administration, but most were reduced within two weeks. All ID-vaccinated pigs showed inflammatory lesions limited to the dermis, but IM-vaccinated pigs had abnormal undesirable changes and pus in the muscle. ID-vaccinated pigs performed comparably to IM-vaccinated pigs in terms of growth, FMD virus-specific antibodies, protection capability against FMDV, and T-cell induction. This study demonstrated that the ID inoculation of the inactivated FMD vaccine induced immune responses comparable to an IM injection at 1/10 of the inoculation dose and that the inoculation lesion was limited to the dermis, effectively protecting against the formation of abnormal undesirable changes in muscle and soft tissues.

Evaluation of Foot-and-Mouth Disease (FMD) Virus Asia1 Genotype-V as an FMD Vaccine Candidate: Study on Vaccine Antigen Production Yield and Inactivation Kinetics

South Korea has experienced outbreaks of foot-and-mouth disease (FMD) of serotypes O and A, leading to nationwide vaccination with a bivalent vaccine. Since the FMD virus (FMDV) Asia1 group-V genotype occurred in North Korea in 2007, an Asia1/MOG/05 vaccine strain belonging to the Asia1 group-V genotype was developed using a genetic recombination method (Asia1/MOG/05-R). This study aimed to evaluate the antigen productivity and viral inactivation kinetics of Asia1/MOG/05-R to assess its commercial viability. The antigen yield of Asia1/MOG/05-R produced in flasks and bioreactors was approximately 4.0 μg/mL. Binary ethylenimine (BEI) inactivation kinetics of Asia1/MOG/05-R showed that 2 mM and 1.0 mM BEI treatment at 26 °C and 37 °C, respectively, resulted in a virus titer <10-7 TCID50/mL within 24 h, meeting the inactivation kinetics criteria. During incubation at 26 °C and 37 °C, 10% antigen loss occurred, but not due to BEI treatment. When pigs were inoculated twice with the Asia1/MOG/05-R antigen, the virus neutralization titer increased to approximately 1:1000; therefore, it can sufficiently protect against Asia1/MOG/05-R and Asia1 Shamir viruses. The Asia1/MOG/05-R will be useful as a vaccine strain for domestic antigen banks.

Quantifying the relationship between within-host dynamics and transmission for viral diseases of livestock

Understanding the population dynamics of an infectious disease requires linking within-host dynamics and between-host transmission in a quantitative manner, but this is seldom done in practice. Here a simple phenomenological model for viral dynamics within a host is linked to between-host transmission by assuming that the probability of transmission is related to log viral titre. Data from transmission experiments for two viral diseases of livestock, foot-and-mouth disease virus in cattle and swine influenza virus in pigs, are used to parametrize the model and, importantly, test the underlying assumptions. The model allows the relationship between within-host parameters and transmission to be determined explicitly through their influence on the reproduction number and generation time. Furthermore, these critical within-host parameters (time and level of peak titre, viral growth and clearance rates) can be computed from more complex within-host models, raising the possibility of assessing the impact of within-host processes on between-host transmission in a more detailed quantitative manner.

Circulation of foot-and-mouth disease serotypes, risk factors, and their effect on hematological and biochemical profiles among cattle and buffalo in Quetta, Balochistan, Pakistan

Background and Aim

Foot-and-mouth disease (FMD) is an infectious disease of cloven-hoofed animals, including buffalo, cattle, sheep, goats, and pigs, causing major economic losses to the local farmers and, overall, to the national economy of the country. This study aimed to detect FMDV serotypes in year-round FMD outbreaks, hematological and biochemical changes, and oxidative stress in FMDV-infected cattle and buffaloes in the district of Quetta, Balochistan, Pakistan, and the socioeconomic impact of FMD outbreaks on farmers.

Materials and Methods

We conducted a cross-sectional study in the district of Quetta, Balochistan, Pakistan, where FMD virus (FMDV) serotypes were detected by enzyme-linked immunosorbent assay (ELISA). Hematological, biochemical, and oxidative analyses were performed by analyzing the blood of FMDV-infected and non-infected animals. Information on the associated risk factors was obtained through a structured questionnaire by interviewing farmers in each FMD-affected farm.

Results

Thirty-four out of 38 farms (89%, 95% confidence interval [CI]: 75%-97%) were positive for FMD by ELISA. Higher FMD infection was detected in farms with a herd size of <50 animals (50%, 17/34), followed by >100 animals (32%, 11/34) and 51-100 animals (18%, 6/34). Fifty-seven percent (114/200, 95% CI: 50%-64%) of animals were positive for FMD. Of these, 61% (69/114) were cattle and 39% (45/114) were buffalo. FMD positivity was higher in females (86%, 98/114) than in males (14%, 16/114) and higher in animals older than 2 years of age (52%, 59/114). On average, farmers lose U.S. dollars 3000 annually due to FMD outbreaks. Animals infected with FMDV had significantly (p ≤ 0.05) white blood cell counts and significantly (p ≤ 0.05) lower hemoglobin and total protein concentrations in buffalo and cattle, whereas infected cattle showed significantly (p ≤ 0.05) lower albumin levels. Globulin levels were lower in buffaloes infected. Alanine aminotransferase levels were lower in infected cattle (p ≤ 0.05). Creatinine levels were higher in infected buffalo (p ≤ 0.05). Urea and phosphorus concentrations were higher in FMDV-infected cattle and buffalo (p ≤ 0.05). Calcium levels were lower in infected cattle and buffalo (p ≤ 0.05). Catalase enzyme activity in infected cattle and buffaloes was significantly lower (p < 0.05). Lipid peroxidation was significantly higher in FMDV-infected cattle and buffalo (p ≤ 0.05).

Conclusion

This study confirmed serotype O circulation among cattle and buffalo in year-long FMD outbreaks in the Quetta District of Balochistan. Blood analysis identified a parameter deviated from the normal level due to FMDV infection. In addition, the outbreak of FMD has a significant negative economic impact on livestock farmers.

Surface-Plasmon-Resonance Amplification of FMD Detection through Dendrimer Conjugation

The amplification of the surface plasmon resonance (SPR) sensitivity for the foot-and-mouth disease (FMD) detection was studied using Poly(amidoamine) (PAMAM) succinamic-acid dendrimers. The dendrimers were conjugated with the complementary annealed with the aptamers capable of binding specifically to FMD peptides. The tethered layer of the dendrimer-conjugated double-stranded(ds)-aptamers was formed on the SPR sensor Au surface via a thiol bond between the aptamers and Au. After the tethered layer was formed, the surface was taken out of the SPR equipment. Then, the ds-aptamers on the surface were denatured to collect the dendrimer-conjugated single-stranded(ss)-complementary. The surface with only the remaining ss-aptamers was transferred again to the equipment. Two types of the injections, the FMD peptide only and the dendrimer-conjugated ss-complementary followed by the FMD peptides, were performed on the surface. The sensitivity was increased 20 times with the conjugation of the dendrimers, but the binding rate of the peptides became more than two times slower.

Evaluation of a Vaccine Candidate Designed for Broad-Spectrum Protection against Type A Foot-and-Mouth Disease in Asia

Foot-and-mouth disease (FMD) vaccines are currently the most powerful protective and preventive measures used to control FMD. In this study, the chimeric vaccine strain containing antigenic epitopes from the FMD virus serotype A, which belongs to the ASIA topotype, was produced and evaluated. The chimeric vaccine strains contain sea-97/G1 (VP4, VP2, VP3) and A22 Iraq (VP1) or G-VII (VP1) for use in FMD vaccines in Asia. The 50% protective dose was determined in mice. Vaccinated mice were challenged with three different type A viruses (Sea-97/G1, Sea-97/G2, G-VII clade) seven days post-vaccination (dpv), and mice that received the vaccine candidates were protected against the three viruses. The protective capability of one of the vaccine candidates was evaluated in pigs. Vaccinated pigs were challenged with three different type A viruses (Sea-97/G1, Sea-97/G2, G-VII clade) at 28 dpv, and pigs that received the vaccine candidate were protected against the three viruses. The results showed that this vaccine candidate, which was designed to provide protection against FMD in Asia, efficiently protected pigs against virus challenge and thus has potential as a broad-spectrum vaccine for various epidemic FMD viruses.

An Alternative Serological Measure for Assessing Foot-and-Mouth Disease Vaccine Efficacy against Homologous and Heterologous Viral Challenges in Pigs

To analyze the relationship between homologous and heterologous serological titers of immunized pigs and their protection statuses against FMD virus challenges, in the present study, the correlation between the virus neutralization titers at 21 and 28 dpv and the protection statuses at 28 dpv against challenge with FMD virus was analyzed using data sets comprising five different combinations of homologous or heterologous challenge experiments in pigs vaccinated with type O (n = 96), A (n = 69), and Asia 1 (n = 74). As a result, the experiments were divided into three groups (21D-1, 21D-2, and 21D-3) in the 21-dpv model and two groups (28D-1 and 28D-2) in the 28-dpv model. Each response curve of groups 21D-1 and 21D-2 in the 21-dpv model was very similar to each curve of groups 28D-1 and 28D-2 in the 28-dpv model, respectively, even though there was an exceptional extra group (21D-3) in the 21-dpv model. The average titers estimating 0.75 probability of protection ranged from 1.06 to 1.62 log10 in the 21-dpv model and from 1.26 to 1.64 log10 in the 28-dpv model. In summary, we demonstrated that the serological method is useful for predicting the homologous and heterologous protection statuses of vaccinated pigs.

Characterization of T-cell subsets in response to foot-and-mouth disease bivalent inactivated vaccine in Chinese Holstein cows

IMPORTANCE

Vaccination plays a crucial role in the prevention and control of FMD; however, outbreaks persist occurring worldwide. Assessing the immune response to FMD vaccines is essential for effective prevention of FMD. In this study, a seven-color flow cytometry protocol was developed to systematically evaluate the T-cell response of Chinese Holstein cows vaccinated with FMD bivalent inactivated vaccine. Our findings showed that while most T-cell subsets (%) decreased post-vaccination, a significant increase was observed in CD4+CD8+ DP T cells, which was consistent with the levels of specific foot-and-mouth disease virus (FMDV) antibodies. These findings suggested that CD4+CD8+ DP T cells could serve as a potential biomarker for the evaluation of cellular and humoral responses to FMDV vaccination. Additionally, we should be aware of the potential decline in cellular immunity among cattle during FMD vaccination, as this may increase the risk of other pathogen-related issues.

The Immunogenicity of a Foot-and-Mouth Disease Virus Serotype O Vaccine in Commercial and Subsistence Cattle Herds in Zambia

The recent introduction of foot-and-mouth disease (FMD) virus serotype O (O/EA-2 topotype) in Southern Africa has changed the epidemiology of the disease and vaccine requirements of the region. Commercial and subsistence cattle herds in Zambia were vaccinated with an FMD virus serotype O Manisa vaccine according to a double- or single-dose vaccination schedule. Heterologous antibody responses induced by this vaccine against a representative O/EA-2 virus from Zambia were determined. Virus neutralisation tests (VNTs) showed double-dosed cattle had a mean reciprocal log virus neutralisation titre of 2.02 (standard error [SE] = 0.16, n = 9) for commercial herds and 1.65 (SE = 0.17, n = 5) for subsistence herds 56 days after the first vaccination (dpv). Significantly lower mean titres were observed for single-dosed commercial herds (0.90, SE = 0.08, n = 9) and subsistence herds (1.15, SE = 0.18, n = 3) 56 dpv. A comparison of these results and those generated by solid-phase competitive ELISA (SPCE) tests showed a statistically significant positive correlation by Cohen's kappa coefficient. Therefore, SPCE might be used in assessing the immunogenicity of vaccines in place of VNT. Furthermore, for this vaccine and field strain, a vaccination regime employing a two-dose primary course and revaccination after 4-6 months is likely to be appropriate.

Analysis of Chromatin Accessibility Changes Induced by BMMC Recognition of Foot-and-Mouth Disease Virus-like Particles through ATAC-seq

Mast cells can recognize foot-and-mouth disease virus-like particles (FMDV-VLPs) via mannose receptors (MRs) to produce differentially expressed cytokines. The regulatory role of chromatin accessibility in this process is unclear. Bone marrow-derived mast cells (BMMCs) were cultured, and an assay of transposase-accessible chromatin sequencing (ATAC-seq) was applied to demonstrate the regulation of chromatin accessibility in response to the BMMCs' recognition of FMDV-VLPs. A pathway enrichment analysis showed that peaks associated with the nuclear factor-κB (NF-κB), mitogen-activated protein kinase (MAPK), phosphatidylinositol 3 kinase-protein kinase B (PI3K-Akt), and other signaling pathways, especially the NF-κB pathway, were involved in the BMMCs' recognition of VLPs. Moreover, transcription factors including SP1, NRF1, AP1, GATA3, microphthalmia-associated transcription factor (MITF), and NF-κB-p65 may bind to the motifs with altered chromatin accessibility to regulate gene transcription. Furthermore, the expression of NF-κB, interleukin (IL)-9, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ in the BMMCs of the VLP group increased compared with that of the BMMCs in the control group, whereas the expression of IL-10 did not differ significantly between groups. After inhibiting the MRs, the expression of NF-κB, IL-9, TNF-α, and IFN-γ decreased significantly, whereas the expression of IL-10 increased. The expression of MAPK and IL-6 showed no significant change after MR inhibition. This study demonstrated that MRs expressed on BMMCs can affect the NF-κB pathway by changing chromatin accessibility to regulate the transcription of specific cytokines, ultimately leading to the differential expression of cytokines. These data provide a theoretical basis and new ideas for the development of a novel vaccine for FMD.

Novel pathologic findings and viral antigen distribution in cattle and buffalo calves naturally infected with Foot-and-Mouth disease virus

The Foot-and-Mouth disease is highly contagious acute viral disease of livestock inflicting huge economic loss to the farmers. The limited knowledge regarding the pathological lesions vis-a-vis distribution of the FMDV in lesser explored endocrine glands and important vital organs other than the target organs of infected calves prompted us to take the present investigation to have detailed insight into the pathogenesis. The systematic necropsy of 37 dead calves (cattle-28 and buffalo-9) was conducted, and thin representative tissue pieces from the affected organs were collected in 10% neutral buffered formalin (NBF) for pathological and immunohistochemical investigations. The genomic detection and its serotyping were done by RT-PCR and multiplex-PCR, respectively. Necropsy examination in all cases showed myocardial lesions resembling 'tigroid heart appearance'. Other organ specific lesions include vesiculo-ulcerative stomatitis, edema of the lungs, petechial hemorrhages, edema of the endocrines, and gastroenteritis. Histopathological examination showed varying sizes of vesicles and ulcerations in stratified squamous epithelium of the tongue, acute necrotizing myocarditis, lymphoid depletion in lymphoid tissues, hepatitis, pancreatitis, thymic hyperplasia, thyroiditis, adrenitis, and enteritis. Positive immunolabeling for viral antigens was observed in endocrine glands, lymphoid organs, lungs, liver, kidneys, and intestine, in addition to other typical locations. The thyroid, adrenal glands, and pancreas, in addition to the tongue and heart, are the tissue of choice for sampling in the field during epidemics. Further, the viral genome and serotype A was confirmed in the affected tissues. This study provides insights into novel tissue tropism and pathogenesis in young calves naturally infected with FMDV.

Dose-responses of zinc as zinc-methionine supplements on antioxidant status, hematological parameters, immune response and the expression of IL-4 and IL-6 genes of ewes in the hot season

This study was implemented to evaluate the effects of different zinc doses as Zinc-Met supplement (Zinpro®) on the antioxidant status, blood immune cells, antibody titers, and the expression of IL-4 and IL-6 genes of ewes in the hot season. In a completely randomized design, 24 ewes were assigned to treatments as follow: 0, 15, 30 and 45 mg/kg zinc as Zinc-Met supplementation for 40 days in region with 40 °C and vaccinated against food-and-mouth disease as an immune challenge at day 30, and then blood samples were collected on day 40. Ewes were fed a basal diet containing 29.9 mg zinc/kg. The highest activity of the antioxidant enzyme and the lowest lipid peroxidation values were found in ewes receiving 30 and 45 mg/kg zinc following a linear trend. The highest lymphocytes count and antibody titers were found in ewes received 30 mg zinc/kg. There were no significant differences among treatments for the relative expression of genes. In overall, zinc supplementation non-significantly up-regulate interleukin-4 and down-regulate interleukin-6. It was concluded that zinc supplementation as Zinc-Met could enhance the antioxidant status and immune response of ewes under heat stress; supplementation of diet with 30 mg zinc/kg (300 mg/kg Zinpro®) appeared to be the most effective dose.

Application of the Nagoya Protocol to veterinary pathogens: concerns for the control of foot-and-mouth disease

The Nagoya Protocol is an international agreement adopted in 2010 (and entered into force in 2014) which governs access to genetic resources and the fair and equitable sharing of benefits from their utilisation. The agreement aims to prevent misappropriation of genetic resources and, through benefit sharing, create incentives for the conservation and sustainable use of biological diversity. While the equitable sharing of the benefits arising from the utilisation of genetic resources is a widely accepted concept, the way in which the provisions of the Nagoya Protocol are currently being implemented through national access and benefit-sharing legislation places significant logistical challenges on the control of transboundary livestock diseases such as foot-and-mouth disease (FMD). Delays to access FMD virus isolates from the field disrupt the production of new FMD vaccines and other tailored tools for research, surveillance and outbreak control. These concerns were raised within the FMD Reference Laboratory Network and were explored at a recent multistakeholder meeting hosted by the European Commission for the Control of FMD. The aim of this paper is to promote wider awareness of the Nagoya Protocol, and to highlight its impacts on the regular exchange and utilisation of biological materials collected from clinical cases which underpin FMD research activities, and work to develop new epidemiologically relevant vaccines and other diagnostic tools to control the disease.

Bestatin, A Pluripotent Immunomodulatory Small Molecule, Drives Robust and Long-Lasting Immune Responses as an Adjuvant in Viral Vaccines

An inactivated whole-virus vaccine is currently used to prevent foot-and-mouth disease (FMD). Although this vaccine is effective, it offers short-term immunity that requires regular booster immunizations and has several side effects, including local reactions at the vaccination site. To address these limitations, herein, we evaluated the efficacy of bestatin as a novel small molecule adjuvant for inactivated FMD vaccines. Our findings showed that the FMD vaccine formulated with bestatin enhanced early, intermediate-, and particularly long-term immunity in experimental animals (mice) and target animals (pigs). Furthermore, cytokines (interferon (IFN)α, IFNβ, IFNγ, and interleukin (IL)-29), retinoic acid-inducible gene (RIG)-I, and T-cell and B-cell core receptors (cluster of differentiation (CD)28, CD19, CD21, and CD81) markedly increased in the group that received the FMD vaccine adjuvanted with bestatin in pigs compared with the control. These results indicate the significant potential of bestatin to improve the efficacy of inactivated FMD vaccines in terms of immunomodulatory function for the simultaneous induction of potent cellular and humoral immune response and a long-lasting memory response.

Inactivated vaccine with glycyrrhizic acid adjuvant elicits potent innate and adaptive immune responses against foot-and-mouth disease

Background

Foot-and-mouth disease (FMD) is an extremely contagious viral disease that is fatal to young animals and is a major threat to the agricultural economy by reducing production and limiting the movement of livestock. The currently commercially-available FMD vaccine is prepared using an inactivated viral antigen in an oil emulsion, with aluminum hydroxide [Al(OH)3] as an adjuvant. However, oil emulsion-based options possess limitations including slow increases in antibody titers (up to levels adequate for defense against viral infection) and risks of local reactions at the vaccination site. Further, Al(OH)3 only induces a T helper 2 (Th2) cell response. Therefore, novel adjuvants that can address these limitations are urgently needed. Glycyrrhizic acid (extracted from licorice roots) is a triterpenoid saponin and has great advantages in terms of price and availability.

Methods

To address the limitations of the currently used commercial FMD vaccine, we added glycyrrhizic acid as an adjuvant (immunostimulant) to the FMD bivalent (O PA2 + A YC) vaccine. We then evaluated its efficacy in promoting both innate and adaptive (cellular and humoral) immune reactions in vitro [using murine peritoneal exudate cells (PECs) and porcine peripheral blood mononuclear cells (PBMCs)] and in vivo (using mice and pigs).

Results

Glycyrrhizic acid has been revealed to induce an innate immune response and enhance early, mid-, and long-term immunity. The studied bivalent vaccine with glycyrrhizic acid increased the expression of immunoregulatory genes such as pattern-recognition receptors (PRRs), cytokines, transcription factors, and co-stimulatory molecules.

Conclusion

Collectively, glycyrrhizic acid could have utility as a novel vaccine adjuvant that can address the limitations of commercialized FMD vaccines by inducing potent innate and adaptive immune responses.

Serological Conversion through a Second Exposure to Inactivated Foot-and-Mouth Disease Virus Expressing the JC Epitope on the Viral Surface

Foot-and-mouth disease (FMD) is a fatal contagious viral disease that affects cloven-hoofed animals and causes severe economic damage at the national level. There are seven serotypes of the causative foot-and-mouth disease virus (FMDV), and type O is responsible for serious outbreaks and shows a high incidence. Recently, the Cathay, Southeast Asia (SEA), and ME-SA (Middle East-South Asia) topotypes of type O have been found to frequently occur in Asia. Thus, it is necessary to develop candidate vaccines that afford protection against these three different topotypes. In this study, an experimental FMD vaccine was produced using a recombinant virus (TWN-JC) with the JC epitope (VP1 140-160 sequence of the O/SKR/Jincheon/2014) between amino acid 152 and 153 of VP1 in TWN-R. Immunization with this novel vaccine candidate was found to effectively protect mice against challenge with the three different topotype viruses. Neutralizing antibody titers were considerably higher after a second vaccination. The serological differences between the topotype strains were identified in guinea pigs and swine. In conclusion, a significant serological difference was observed at 56 days post-vaccination between animals that received the TWN-JC vaccine candidate and those that received the positive control virus (TWN-R). The TWN-JC vaccine candidate induced IFNγ and IL-12B.

Antiviral agents and disinfectants for foot‑and‑mouth disease (Review)

Fluorouracil, 5-azacytidine, 6-azauridine, ribavirin, favipiravir (T-705) and its derivative (T-1105) exhibit anti-foot-and-mouth disease virus (FMDV) effects. In particular, T-1105 exhibits promising results when administered to guinea pigs orally, and pigs in their feed. FMDV is excreted in the early stages of infection in aerosols and oral or nasal droplets from animals. T-1105 along with the FMDV vaccine can be used to combat foot-and-mouth disease (FMD) epidemics. Several studies have shown that sodium hypochlorous solutions are widely used to inactivate viruses, including FMDV. However, these solutions must be stored under cool and dark conditions to maintain their virucidal effects. Interestingly, a study indicated that the virucidal activity of a calcium bicarbonate solution with a mesoscopic structure (CAC-717) did not decrease after storage at room temperature for at least four years outside direct sunlight. Numerous lessons acquired from the 2010 FMD outbreak in Japan are relevant for the control of COVID-19. However, the widespread use of chlorite can cause environmental issues. Chlorite can be combined with nitrogen to produce chloramine or N-nitrosodimethylamine, which plays a role in carcinogenesis. Therefore, risk assessments should be conducted in aquatic environments. Moreover, there is a need to develop nonchlorine disinfectants that can be used during epidemics, including FMD. The approach of 'One Health' should be shared between the public health and veterinary fields to improve the management of viral outbreaks, including those due to FMD.

In Vitro and In Silico Anti-Picornavirus Triterpene Alkanoic Acid Ester from Saudi Collection of Rhazya stricta Decne

The total alcohol extract obtained from the aerial parts of R. stricta and fractions of the liquid-liquid fractionation process were tested against picornavirus-causing foot-and-mouth disease (FMD) based on the traditional use of the plant in Saudi Arabia. The most active petroleum ether soluble fraction was subjected to chromatographic purification, and nine compounds were isolated, identified using various chemical and spectroscopic methods, and tested for their anti-viral potential. The new ester identified as α-Amyrin 3-(3'R-hydroxy)-hexadecanoate (1) was the most active compound with 51% inhibition of the viral growth and was given the name Rhazyin A. Compounds with ursane skeleton were more active than those with lupane skeleton except in the case of the acid derivatives where betulenic acid showed 26.1% inhibition against the viral growth, while ursolic acid showed only 16.6% inhibition. Moreover, molecular docking analysis using a glide extra-precision module was utilized for investigating the possible molecular interactions accounting for anti-viral activity against picornavirus of the nine isolated compounds. Molecular docking studies revealed a strong binding of the discovered hits within the active site of FMDV 3C^pro. Compound 1 showed the lowest docking score within the nine isolated compounds comparable to the two known anti-viral drugs; glycyrrhizic acid and ribavirin. The results of this research will provide lead candidates from natural origin with potential safety and efficacy compared to the synthetic ones with lower production costs for managing FMVD.

Deoptimization of FMDV P1 Region Results in Robust Serotype-Independent Viral Attenuation

Foot-and-mouth disease (FMD), caused by the FMD virus (FMDV), is a highly contagious disease of cloven-hoofed livestock that can have severe economic impacts. Control and prevention strategies, including the development of improved vaccines, are urgently needed to effectively control FMD outbreaks in endemic settings. Previously, we employed two distinct strategies (codon pair bias deoptimization (CPD) and codon bias deoptimization (CD)) to deoptimize various regions of the FMDV serotype A subtype A12 genome, which resulted in the development of an attenuated virus in vitro and in vivo, inducing varying levels of humoral responses. In the current study, we examined the versatility of the system by using CPD applied to the P1 capsid coding region of FMDV serotype A subtype, A24, and another serotype, Asia1. Viruses carrying recoded P1 (A24-P1Deopt or Asia1-P1Deopt) exhibited different degrees of attenuation (i.e., delayed viral growth kinetics and replication) in cultured cells. Studies in vivo using a mouse model of FMD demonstrated that inoculation with the A24-P1Deopt and Asia1-P1Deopt strains elicited a strong humoral immune response capable of offering protection against challenge with homologous wildtype (WT) viruses. However, different results were obtained in pigs. While clear attenuation was detected for both the A24-P1Deopt and Asia1-P1Deopt strains, only a limited induction of adaptive immunity and protection against challenge was detected, depending on the inoculated dose and serotype deoptimized. Our work demonstrates that while CPD of the P1 coding region attenuates viral strains of multiple FMDV serotypes/subtypes, a thorough assessment of virulence and induction of adaptive immunity in the natural host is required in each case in order to finely adjust the degree of deoptimization required for attenuation without affecting the induction of protective adaptive immune responses.

Household production and consumption impacts of foot and mouth disease at the Uganda-Tanzania border

Introduction

Foot-and-mouth disease (FMD) is a highly contagious viral disease that is endemic in East Africa. FMD virus infection incurs significant control costs and reduces animal productivity through weight loss, lowered milk yield, and potentially death but how household's respond to these losses may differentially affect household income and food consumption.

Methodology

To address this, we use unique data from a FMD outbreak to assess how household production and consumption activities change from before to during the outbreak. Data came from a 2018 survey of 254 households in selected Tanzanian wards and sub-counties in Uganda. The data includes household recall of before and during an outbreak in the past year on livestock and livestock product sales, milk and beef consumption, as well as related changes in market prices. We apply both difference-in-difference and change in difference ordinary least squares regressions with fixed effects to evaluate the impact of FMD on household production and consumption.

Results and discussion

We find that households reported the largest reductions in livestock and livestock product sales, followed by reduced milk consumption and animal market prices. The changes in household income from livestock sales appears to be driven by FMD virus infection within the household herd while changes in market prices of substitute protein sources are primary associated with changes in milk and beef consumption. The role of widespread market price effects across both infected and uninfected herds and countries, tends to suggest that stabilizing prices will likely have a large impact on household nutritional security and income generation. We also propose that promoting diversity in market activity may mitigate differing impacts on households in FMD endemic regions.

Dectin-1 signaling coordinates innate and adaptive immunity for potent host defense against viral infection

Background

Most commercial foot-and-mouth disease (FMD) vaccines have various disadvantages, such as low antibody titers, short-lived effects, compromised host defense, and questionable safety.

Objectives

To address these shortcomings, we present a novel FMD vaccine containing Dectin-1 agonist, β-D-glucan, as an immunomodulatory adjuvant. The proposed vaccine was developed to effectively coordinate innate and adaptive immunity for potent host defense against viral infection.

Methods

We demonstrated β-D-glucan mediated innate and adaptive immune responses in mice and pigs in vitro and in vivo. The expressions of pattern recognition receptors, cytokines, transcription factors, and co-stimulatory molecules were promoted via FMD vaccine containing β-D-glucan.

Results

β-D-glucan elicited a robust cellular immune response and early, mid-, and long-term immunity. Moreover, it exhibited potent host defense by modulating host's innate and adaptive immunity.

Conclusion

Our study provides a promising approach to overcoming the limitations of conventional FMD vaccines. Based on the proposed vaccine's safety and efficacy, it represents a breakthrough among next-generation FMD vaccines.

Assessing complexity and dynamics in epidemics: geographical barriers and facilitators of foot-and-mouth disease dissemination

Introduction

Physical and non-physical processes that occur in nature may influence biological processes, such as dissemination of infectious diseases. However, such processes may be hard to detect when they are complex systems. Because complexity is a dynamic and non-linear interaction among numerous elements and structural levels in which specific effects are not necessarily linked to any one specific element, cause-effect connections are rarely or poorly observed.

Methods

To test this hypothesis, the complex and dynamic properties of geo-biological data were explored with high-resolution epidemiological data collected in the 2001 Uruguayan foot-and-mouth disease (FMD) epizootic that mainly affected cattle. County-level data on cases, farm density, road density, river density, and the ratio of road (or river) length/county perimeter were analyzed with an open-ended procedure that identified geographical clustering in the first 11 epidemic weeks. Two questions were asked: (i) do geo-referenced epidemiologic data display complex properties? and (ii) can such properties facilitate or prevent disease dissemination?

Results

Emergent patterns were detected when complex data structures were analyzed, which were not observed when variables were assessed individually. Complex properties-including data circularity-were demonstrated. The emergent patterns helped identify 11 counties as 'disseminators' or 'facilitators' (F) and 264 counties as 'barriers' (B) of epidemic spread. In the early epidemic phase, F and B counties differed in terms of road density and FMD case density. Focusing on non-biological, geographical data, a second analysis indicated that complex relationships may identify B-like counties even before epidemics occur.

Discussion

Geographical barriers and/or promoters of disease dispersal may precede the introduction of emerging pathogens. If corroborated, the analysis of geo-referenced complexity may support anticipatory epidemiological policies.

Comparison of vaccination schedules for foot-and-mouth disease among cattle and sheep in Mongolia

Vaccines are a critical tool for the control strategy for foot-and-mouth disease (FMD) in Mongolia where sporadic outbreaks regularly occur. A two-dose primary vaccination course is recommended for most commercial vaccines though this can be logistically challenging to deliver among nomadic pastoralist systems which predominate in the country. Although there is evidence that very high potency vaccines can provide prolonged duration of immunity, this has not been demonstrated under field conditions using commercially available vaccines. This study compared neutralizing titres to a O/ME-SA/Panasia strain over a 6-month period following either a two-dose primary course or a single double-dose vaccination among Mongolian sheep and cattle using a 6.0 PD50 vaccine. Titers were not significantly different between groups except in sheep at six-months post vaccination when the single double-dose group had significantly lower titers. These results indicate the single double-dose regimen may be a cost-effective approach for vaccination campaigns supporting FMD control in Mongolia.

[Expression of antigens of foot-and-mouth disease virus in plants: a review]

Foot-and-mouth disease (FMD) is an acute, severe, and highly contagious infectious disease caused by foot-and-mouth disease virus (FMDV), which seriously endangers the development of animal husbandry. The inactivated FMD vaccine is the main product for the prevention and control of FMD, which has been successfully applied to control the pandemic and outbreak of FMD. However, the inactivated FMD vaccine also has problems, such as the instability of antigen, the risk of spread of the virus due to incomplete inactivation during vaccine production, and the high cost of production. Compared with traditional microbial and animal bioreactors, production of antigens in plants through transgenic technology has some advantages including low cost, safety, convenience, and easy storage and transportation. Moreover, since antigens produced from plants can be directly used as edible vaccines, no complex processes of protein extraction and purification are required. But, there are some problems for the production of antigens in plants, which include low expression level and poor controllability. Thus, expressing the antigens of FMDV in plants may be an alternative mean for production of FMD vaccine, which has certain advantages but still need to be continuously optimized. Here we review the main strategies for expressing active proteins in plants, as well as the research progress on the expression of FMDV antigens in plants. We also discuss the current problems and challenges encountered, with the aim to facilitate related research.

Heterogeneity and Recombination of Foot-and-Mouth Disease Virus during Multi-Strain Coinfection of Cattle

Superinfection of cattle persistently infected with foot-and-mouth disease virus (FMDV), with a heterologous FMDV strain has been shown to generate novel recombinant viruses. In this study, we investigated the pathogenesis events within specific tissues associated with FMDV coinfections in cattle subjected to either simultaneous or serial exposure to two distinct strains of FMDV. Both strains of FMDV (one each of serotypes O and A) were similarly localized to the nasopharyngeal mucosa during the early stages of infection. However, while no recombinant FMDV genomes were recovered from simultaneously coinfected cattle, interserotypic recombinants were isolated from nasopharyngeal tissue samples obtained at 48 h after heterologous superinfection of a persistently infected FMDV carrier. Additionally, analysis of FMDV genomes obtained from replicate nasopharyngeal tissue samples demonstrated that adjacent segments of the mucosa were sometimes infected by distinct viruses, demonstrating a multifocal and heterogeneous distribution of FMDV infection during primary and persistent phases of infection. This work indicates that superinfection of FMDV carriers may be an important source of emergent recombinant strains of FMDV in areas where multiple strains are co-circulating. IMPORTANCE Foot-and-mouth disease (FMD) is a socioeconomically impactful livestock disease with a complex epidemiology and ecology. Although recombinant viruses have been identified in field samples, the mechanisms of emergence of those viruses have never been elucidated. This current study demonstrates how serial infection of cattle with two distinct serotypes of FMD virus (FMDV) leads to rapid generation of recombinant viruses in the upper respiratory tracts of infected animals. This finding is particularly relevant in relation to the management of persistently infected FMDV carrier cattle that can maintain subclinical FMDV infection for months to years after an initial infection. Such carrier animals may function as mixing vessels that facilitate the emergence of novel recombinant FMDV strains in areas where multiple virus strains are in circulation.

Epidemiological Dynamics of Foot-and-Mouth Disease in the Horn of Africa: The Role of Virus Diversity and Animal Movement

The Horn of Africa is a large area of arid and semi-arid land, holding about 10% of the global and 40% of the entire African livestock population. The region's livestock production system is mainly extensive and pastoralist. It faces countless problems, such as a shortage of pastures and watering points, poor access to veterinary services, and multiple endemic diseases like foot-and-mouth disease (FMD). Foot-and-mouth disease is one of the most economically important livestock diseases worldwide and is endemic in most developing countries. Within Africa, five of the seven serotypes of the FMD virus (FMDV) are described, but serotype C is not circulating anymore, a burden unseen anywhere in the world. The enormous genetic diversity of FMDV is favored by an error-prone RNA-dependent RNA polymerase, intra-typic and inter-typic recombination, as well as the quasi-species nature of the virus. This paper describes the epidemiological dynamics of foot-and-mouth disease in the Horn of Africa with regard to the serotypes and topotypes distribution of FMDV, the livestock production systems practiced, animal movement, the role of wildlife, and the epidemiological complexity of FMD. Within this review, outbreak investigation data and serological studies confirm the endemicity of the disease in the Horn of Africa. Multiple topotypes of FMDV are described in the literature as circulating in the region, with further evolution of virus diversity predicted. A large susceptible livestock population and the presence of wild ungulates are described as complicating the epidemiology of the disease. Further, the husbandry practices and legal and illegal trading of livestock and their products, coupled with poor biosecurity practices, are also reported to impact the spread of FMDV within and between countries in the region. The porosity of borders for pastoralist herders fuels the unregulated transboundary livestock trade. There are no systematic control strategies in the region except for sporadic vaccination with locally produced vaccines, while literature indicates that effective control measures should also consider virus diversity, livestock movements/biosecurity, transboundary trade, and the reduction of contact with wild, susceptible ungulates.

Immunogenicity and Protection against Foot-and-Mouth Disease Virus in Swine Intradermally Vaccinated with a Bivalent Vaccine of Foot-and-Mouth Disease Virus Type O and A

Following the worst outbreak of foot-and-mouth disease (FMD), a highly contagious disease in cloven-hoofed animals caused by the FMD virus, from November 2010-April 2011, the Korean government enforced a mandatory vaccination policy. A bivalent (FMD type O and A; O + A) vaccine has been recently implemented. Although the FMD outbreak was suppressed by vaccination, the intramuscular (IM) injection presents side effects. Therefore, improving FMD vaccine quality is necessary. Here, we investigated the side effects and immune efficacy of the O + A bivalent vaccine using two different routes of administration: intradermal (ID) and IM. To compare the immune efficacy of the two inoculation routes, virus neutralization titers and structural protein (antigen) levels were measured. The protective efficacy of ID vaccines was confirmed using two viruses (FMDV O/AS/SKR/2019 and A/GP/SKR/2018) isolated in the Republic of Korea. Serological analysis revealed that both animals administered by ID and IM injections exhibited equal immune efficacy. A virus challenge test in the target animal (swine) revealed no (or extremely low) clinical symptoms. Swine in the ID injected group exhibited no side effects. In conclusion, we suggest that the ID route of vaccination is an effective alternative to the existing IM route, which is associated with more frequent side effects.

On-Site Remote Monitoring System with NIR Signal-Based Detection of Infectious Disease Virus in Opaque Salivary Samples

Infectious disease viruses, such as foot-and-mouth disease virus (FMDV), are highly contagious viruses that cause significant socioeconomic damage upon spreading. Developing an on-site diagnostic tool for early clinical detection and real-time surveillance of FMDV outbreaks is essential to prevent the further spread of the disease. However, early diagnosis of FMDV is still challenging due to the limited sensitivity and time-consuming manual result entry of commercial on-site tests for salivary samples. Here, we report a near-infrared (NIR) signal nanoprobe-based highly accurate detection and remote monitoring system toward FMDVs, which automates the analysis and reporting of diagnosis data. The NIR signal lateral flow immunoassay (LFA) was assembled with a nanoprobe with a stable emission intensity at 800 nm, minimizing the interference signal of opaque salivary samples. We investigated the clinical applicability of the NIR signal LFA at biosafety level 3 (BSL-3) laboratories using 147 opaque salivary samples. The NIR signal LFA achieved a 32-fold lower limit of detection (LOD) than a commercial LFA in detecting live FMDVs, including all isolates occurring in the Republic of Korea during 2010-2017. Our results showed that the NIR signal LFA successfully discriminated the FMDV-positive clinical salivary samples from healthy controls with a sensitivity of 96.9%, specificity of 100.0%, and AUC (area under the receiver operator characteristic curve) value of 0.999. Finally, we substantiated the real-time collection of diagnostic results using a customized portable NIR reader at nine different laboratories of government-certified quarantine institutions for foot-and-mouth disease (FMD).

Knowledge, attitude and practice (KAP) of smallholder farmers on foot-and-mouth disease in Cattle in West Kazakhstan

BACKGROUND

This study was performed to assess the knowledge, attitudes and practices (KAPs) of farmers and veterinary professionals towards foot-and-mouth disease (FMD) in the area studied.

METHODS

The study was based on a comprehensive questionnaire administered through face-to-face interviews. Between January and May 2022, 543 households and 27 animal health practitioners (AHP) were visited in 4 provinces of the West Kazakhstan region to assess their KAPs towards FMD.

RESULTS

A large proportion of herd owners (84%) had known the name of the disease, and nearly a half (48) of respondents had heard of FMD cases on farms in the neighbourhood. Oral mucosa lesions were the most consistent with clinical sign characteristic of FMD among farmers (31.4%), followed by hoof blisters (27.6%) and excessive salivation (18.6%). Farmers reported that new animal introduction was potentially the main factor associated with FMD occurrence in their herds. Over half of farmers (54%) interviewed prefer not to purchase livestock from unknown or potentially epidemiologically disadvantaged areas.

CONCLUSION

All AHPs (27) reported that in their zone of veterinary responsibilities, vaccination against FMD is not practised because the area investigated possesses FMD-free status. However, in the past few years, numerous FMD outbreaks have been detected throughout the region. For this reason, immediate actions need to be taken to prevent further FMD occurrences by giving the region a status of an FMD-free zone with vaccination. The current study demonstrated that inadequate quarantine controls of imported animals, absence of regular vaccination and unrestricted animal movement within the country were the primary obstacles in controlling and preventing FMD in the investigated area.

Formulation and Evaluation of Lipidized Imiquimod as an Effective Adjuvant

Adjuvants are essential for the induction of robust immune responses against vaccine antigens. Small-molecule TLR7 agonists hold high potential for this purpose. In this communication, imiquimod (IMQ) bearing a cholesterol lipid moiety derivative, IMQ-Chol, was designed and synthesized as a vaccine adjuvant, which could release parent IMQ molecules in aqueous conditions via amide bond hydrolysis. We performed a series of immunological evaluations by cooperating with the inactivated foot-and-mouth disease virus (FMDV). All of the results confirmed that IMQ-Chol could stimulate the body for a prolonged time to produce strong humoral and cellular immunity with a balanced Th1/Th2 immune response through a TLR7-related MAPK pathway. In addition, the results of the proof-of-concept vaccine indicated IMQ-Chol had a good effect on preventing and treating FMD in pigs.

Evaluation of Vaccine Strains Developed for Efficient, Broad-Range Protection against Foot-and-Mouth Disease Type O

Foot-and-mouth disease (FMD) type O includes 11 genetic topotypes. The Southeast Asia (SEA), Middle East-South Asia (ME-SA), and Cathay topotypes belong to FMD type O and occur frequently in Asia. Therefore, it is necessary to develop a potent vaccine strain with a broad antigenic coverage in order to provide complete protection against these three topotypes. In this study, an experimental vaccine was produced using chimeric vaccine strains (JC-VP1 or PA2-VP1) that contained VP4, VP2, and VP3 of the ME-SA topotype (O Manisa) and VP1 of the SEA topotype (Mya98 lineage; O/SKR/Jincheon/2014) or ME-SA topotype (PanAsia2 lineage; O/PAK/44). Mice were immunized with the experimental vaccines, and they were fully protected against the three topotypes. The neutralizing antibody titers of PA2-VP1 were significantly higher than those of JC-VP1 in the early vaccination phase in pigs. Here, we confirmed complete protection in pigs vaccinated with JC-VP1 or PA2-VP1, when challenged against the SEA (O/SKR/Jincheon/2014), ME-SA (O/SKR/Boeun/2017) and Cathay (O/Taiwan/97) topotype viruses, with moderately higher protection provided by PA2-VP1 than by JC-VP1.

Advances in the eradication of foot-and-mouth disease in South America: 2011-2020

For more than 70 years, the countries of South America have been attempting to eliminate foot-and-mouth disease (FMD), but a regional strategy had not been established by all the affected countries until 1988. The Action Plan 1988-2009 of the Hemispheric Program for the Eradication of Foot-and-Mouth Disease (PHEFA 1988-2009) resulted in an FMD-free status in 88.4% of the bovine population of South America. However, countries of the Andean sub-region maintained an FMD endemic. In addition, sporadic outbreaks in vaccinated cattle populations have been reported in countries of the Southern Cone, endangering the disease-free status in these countries. Within this context, the PHEFA 2011-2020 was approved to eliminate FMD from the subcontinent, and this review describes the most important milestones during its execution. FMD in Ecuador and sporadic outbreaks in the Southern Cone sub-region were effectively eliminated. The outbreaks that occurred in Colombia in 2017 and 2018 were successfully controlled. The type C virus was removed from the vaccines in use in most countries, based on a risk assessment. This review also describes the progress made by the countries advancing toward official recognition as FMD-free in all their territories, with Bolivia, Brazil, and Peru leading the progressive suspension of vaccination to achieve FMD-free status without vaccination. Consequently, at the end of PHEFA 2011-2020, Venezuela was, and still is, the only country in the region whose control program has suffered setbacks, and no evidence has suggested that the transmission and infection of the bovine population have been eliminated. At the end of 2020, a new PHEFA Action Plan 2021-2025 was approved with a five-year horizon, to complete the eradication of the disease in the Americas.

The progressive control of foot-and-mouth disease (FMD) in the Republic of Kazakhstan: Successes and challenges

Foot-and-mouth disease (FMD) has historically caused far-reaching economic losses to many regions worldwide. FMD control has been problematic, and the disease is still prevalent in many West and Central Asia countries. Here, we review the progress made by Kazakhstan in achieving freedom from FMD and discuss some of the challenges associated with maintaining the FMD-free status, as evidenced by the occurrence of an outbreak in 2022. A combination of zoning, movement control, vaccination, and surveillance strategies led to eliminating the disease in the country. However, the circulation of the FMD virus in the region still imposes a risk for Kazakhstan, and coordinated strategies are ultimately needed to support disease elimination. The results presented here may help design effective pathways to progressively eliminate the disease in West and Central Asia while promoting the design and implementation of regional actions to support FMD control.

Temporal-spatial analysis of a foot-and-mouth disease model with spatial diffusion and vaccination

Foot-and-mouth disease is an acute, highly infectious, and economically significant transboundary animal disease. Vaccination is an efficient and cost-effective measure to prevent the transmission of this disease. The primary way that foot-and-mouth disease spreads is through direct contact with infected animals, although it can also spread through contact with contaminated environments. This paper uses a diffuse foot-and-mouth disease model to account for the efficacy of vaccination in managing the disease. First, we transform an age-space structured foot-and-mouth disease into a diffusive epidemic model with nonlocal infection coupling the latent period and the latent diffusive rate. The basic reproduction number, which determines the outbreak of the disease, is then explicitly formulated. Finally, numerical simulations demonstrate that increasing vaccine efficacy has a remarkable effect than increasing vaccine coverage.

Predicting cross-protection against foot-and-mouth disease virus strains by serology after vaccination

Serology is widely used to predict whether vaccinated individuals and populations will be protected against infectious diseases, including foot-and-mouth disease (FMD), which affects cloven-hoofed animals. Neutralising antibody titres to FMD challenge viruses correlate to protection against FMD, for vaccinated cattle that are infected with the same strain as in the vaccine (homologous protection). Similar relationships exist for cross-strain protection between different vaccine and challenge viruses, although much less data are available for these heterologous studies. Poor inter-laboratory reproducibility of the virus neutralisation test (VNT) also hampers comparisons between studies. Therefore, day-of-challenge sera (n = 180) were assembled from 13 previous FMD cross-protection experiments for serotypes O (n = 2), A (n = 10), and SAT 2 (n = 1). These were tested by VNT against the challenge viruses at the FMD FAO World Reference Laboratory (WRLFMD) and the titres were compared to challenge outcomes (protected or not). This dataset was combined with equivalent serology and protection data for 61 sera from four cross-protection experiments carried out at WRLFMD for serotypes O (n = 2), A (n = 1), and Asia 1 (n = 1). VNT results and protection outcomes were also analysed for a serotype O cross-protection experiment involving 39 cattle, where the sera were not available for retesting at WRLFMD. Three categories of association between heterologous neutralising antibody titre and heterologous protection were found (Group 1-3). The log10 reciprocal titres associated on average with 75% protection (with 95% credible limits) were: Group 1: 2.46 (2.11-2.97); Group 2: 1.67 (1.49-1.92); Group 3: 1.17 (1.06-1.30). Further cross-protection data are needed to understand the factors that underpin this variability and to develop more robust antibody thresholds. Establishing cut-off serological titres that can be used to score the adequacy of vaccine-induced immunity will facilitate the monitoring and thereby the performance of FMD vaccination in the field.

FTA Cards as a Rapid Tool for Collection and Transport of Infective Samples: Experience with Foot-and-Mouth Disease Virus in Libya

Foot-and-mouth disease (FMD) is a viral disease, widespread and highly contagious, that mainly affects cloven-hoofed domestic and wild animals. FMD can lead to high economic losses due to the reduction in animal production such as a drop in milk production, loss of body weight, and a high mortality rate in young ruminants. Sixteen samples were collected from animals showing typical clinical signs of FMD during the last FMD outbreak in Libya in 2018-2019. Flinders Technology Associates (FTA) cards impressed with blood, swabs, or vesicular epithelium samples were shipped to the WOAH FMD reference laboratory in Brescia, Italy, and tested for the detection of FMD viruses. Nucleic acids were extracted from the FTA cards, and molecular testing based on real-time RT-PCR assays was carried out, of which one was specifically designed for the detection of the FMD virus of serotype O, topotype O/East Africa-3 (O/EA-3), that was further confirmed by a sequence analysis of the VP1 gene. The phylogenetic analysis of the VP1 gene showed a nucleotide identity of more than 99% between the virus circulating in Libya and the FMD virus strains isolated in Algeria in 2019.

FMD vaccine allocation and surveillance resourcing options for a potential Australian incursion

Australian Animal Disease Spread (AADIS) epidemiological simulation modelling of potential foot-and-mouth disease outbreaks in the state of Victoria, Australia examined the targeted use of limited vaccine supplies in combination with varying surveillance resources. Updated, detailed estimates of government response costs were prepared based on state level data inputs of required and available resources. Measures of outbreak spread such as duration and numbers of animals removed through depopulation of infected and vaccinated herds from the epidemiological modelling were compared to summed government response costs. This comparison illustrated the trade-offs between targeted control strategies combining vaccination-to-remove and varying surveillance capacities and their corresponding costs. For this intensive cattle and sheep producing region: (1) Targeting vaccination toward intensive production areas or toward specialized cattle operations had outbreak control and response cost advantages similar to vaccination of all species. The median duration was reduced by 27% and response costs by 11%. (2) Adding to the pool of outbreak surveillance resources available further decreased outbreak duration and outbreak response costs. The median duration was reduced by an additional 13% and response costs declined by an additional 8%. (3) Pooling of vaccine resources overcame the very early binding constraints under proportional allocation of vaccines to individual states with similar reductions in outbreak duration to those with additional surveillance resources. However, government costs rose substantially by over 40% and introduced additional risk of a negative consumer response. Increased knowledge of the outbreak situation obtained from more surveillance led to better-informed vaccination deployment decisions in the short timeframe they needed to be made.

Modelling the field personnel resources to control foot-and-mouth disease outbreaks in New Zealand

The objective of the study was to simulate New Zealand's foot-and-mouth disease (FMD) operational plan to determine personnel requirements for an FMD response and understand how the numbers of front-line staff available could affect the size and duration of FMD outbreaks, when using stamping-out (SO) measures with or without vaccination. The model utilized a national dataset of all known livestock farms. Each simulation randomly seeded infection into a single farm. Transmission mechanisms included direct and indirect contacts, local and airborne spread. Prior to each simulation, the numbers of personnel available for front-line tasks (including contact tracing, surveillance of at-risk farms, depopulation and vaccination) were set randomly. In a random subset of simulations, vaccination was allowed to be deployed as an adjunct to SO. The effects of personnel numbers on the size and duration of epidemics were explored using machine learning methods. In the second stage of the study, using a subset of iterations where numbers of personnel were unconstrained, the number of personnel used each day were quantified. When personnel resources were unconstrained, the 95^th percentile and maximum number of infected places (IPs) were 78 and 462, respectively, and the 95^th percentile and maximum duration were 69 and 217 days, respectively. However, severe constraints on personnel resources allowed some outbreaks to exceed the size of the UK 2001 FMD epidemic which had 2026 IPs. The number of veterinarians available had a major influence on the size and duration of outbreaks, whereas the availability of other personnel types did not. A shortage of veterinarians was associated with an increase in time to detect and depopulate IPs, allowing for continued transmission. Emergency vaccination placed a short-term demand for additional staff at the start of the vaccination programme, but the overall number of person days used was similar to SO-only strategies. This study determined the optimal numbers of front-line personnel required to implement the current operational plans to support an FMD response in New Zealand. A shortage of veterinarians was identified as the most influential factor to impact disease control outcomes. Emergency vaccination led to earlier control of FMD outbreaks but at the cost of a short-term spike in demand for personnel. In conclusion, a successful response needs to have access to sufficient personnel, particularly veterinarians, trained in response roles and available at short notice.

Epidemiology of foot-and-mouth disease outbreaks in Thailand from 2011 to 2018

Foot-and-mouth disease (FMD) is one of the most important animal diseases hindering livestock production in Thailand. In this study, a temporal and spatial analysis at the subdistrict level was performed on FMD outbreak reports in Thailand from 2011 to 2018. Risk factors associated with FMD outbreaks were furthermore investigated using generalized estimating equations. The results showed that the incidence of FMD outbreaks was the highest in 2016 and was affected by season, with a peak in FMD outbreaks occurring in the rainy-winter season, during October to December. FMD outbreaks were mostly distributed in small clusters within a few subdistricts. Some high-risk areas with repeated outbreaks were detected in the central regions. Risk factors, including the increase of subdistrict's size of the dairy population, beef population or pig population, the low percentage of forest area, subdistricts in the provinces adjacent to Malaysia, the presence of a livestock market and the occurrence of an FMD outbreak in a neighbouring subdistrict in the previous month significantly increased the odds of having an FMD outbreak. The increase in proximity to the nearest subdistrict with an FMD outbreak in the previous month decreased the odds of having FMD outbreaks. This study helped to identify high-risk areas and periods of FMD outbreaks in Thailand. Together with the identified risk factors, its results can be used to optimize the FMD control programme in Thailand and in other countries having a similar livestock industry and FMD situation.

Development of Foot-and-Mouth Disease Vaccines in Recent Years

Foot-and-mouth disease (FMD) is a serious disease affecting the global graziery industry. Once an epidemic occurs, it can lead to economic and trade stagnation. In recent decades, FMD has been effectively controlled and even successfully eradicated in some countries or regions through mandatory vaccination with inactivated foot-and-mouth disease vaccines. Nevertheless, FMD still occurs in some parts of Africa and Asia. The transmission efficiency of foot-and-mouth disease is high. Both disease countries and disease-free countries should always be prepared to deal with outbreaks of FMD. The development of vaccines has played a key role in this regard. This paper summarizes the development of several promising vaccines including progress and design ideas. It also provides ways to develop a new generation of vaccines for FMDV and other major diseases.

Risk of transmission of foot-and-mouth disease by wild animals: infection dynamics in Japanese wild boar following direct inoculation or contact exposure

Understanding of disease dynamics and viral shedding in wild boar and of the potential for disease spreading within wild boar and domestic pig populations is critical for developing effective control and eradication measures for foot-and-mouth disease (FMD). Accordingly, we infected experimentally wild boar and domestic pigs with FMD virus (FMDV) strains O/TAI/315/2016 and A/MOG/2013, and studied their susceptibility and viral transmissibility in both populations. Similar to FMDV-infected pigs, wild boar inoculated with both viruses exhibited vesicular lesions on their feet, snout, tongue and lip, although they did not show lameness. Further, inoculated wild boar were equally capable of transmitting the virus to all of their contact animals. While all contact pigs developed vesicular lesions after contact with inoculated animals, in contrast, no wild boar when exposed to the same infected animals showed obvious clinical signs. These results will be useful for further understanding of the critical roles in occurring and sustaining an FMD outbreak, and will be useful for establishing epidemiological surveillance programs and effective countermeasures for wild boar.

Genotyping of foot-and-mouth disease viruses collected in Sudan between 2009 and 2018

Foot-and-mouth disease (FMD) is widely distributed in Sudan where outbreaks occur on an annual basis especially during the winter months (December-February). This study aimed to increase our understanding of the epidemiological patterns of FMD in Sudan and connections to neighbouring countries by characterizing the genetic sequences of FMD viruses (FMDV) collected from samples collected in 10 Sudanese states over a 10-year period (between 2009 and 2018). FMDV was detected in 91 of the 265 samples using an antigen-detection ELISA. Three serotypes were detected: O (46.2%), A (34.0%), and SAT 2 (19.8%). Fifty-two of these samples were submitted for sequence analyses, generating sequences that were characterized as belonging to O/EA-3 (n = 17), A/AFRICA/G-IV (n = 23) and SAT 2/VII/Alx-12 (n = 12) viral lineages. Phylogenetic analyses provided evidence that FMDV lineages were maintained within Sudan, and also highlighted epidemiological connections to FMD outbreaks reported in neighbouring countries in East and North Africa (such as Ethiopia and Egypt). This study motivates continued FMD surveillance in Sudan to monitor the circulating viral lineages and broader initiatives to improve our understanding of the epidemiological risks in the region.

A systematic review of the methods used to analyze the economic impact of endemic foot-and-mouth disease

Foot-and-mouth disease (FMD) has large economic consequences in livestock systems, which must be robustly assessed to support disease control policy. This study described and assessed methods used within economic analyses of FMD and its control in endemic contexts. A systematic literature search was conducted in six academic search engines. Studies were included if they applied an economic analysis to a context with endemic FMD, producing a result articulated as a monetary figure. Data collected from each article included country of study, animal population, geographical level of analysis, time horizon and type of economic analysis. Each study was scored using a quality assessment tool containing a checklist of 42 reporting criteria. Sixty-four articles were included, from 12,087 identified in the searches, describing results for 26 countries. Over half of the articles (56%) described economic impact of FMD retrospectively, often only accounting for a selection of direct costs at farm or household level. Median quality score calculated was 41% (range 8%-86%). Methods were generally poorly reported, confirming previously described difficulties in using published data to evaluate economic impact of endemic FMD. Few studies included disaggregation of public and private costs, or benefits, of FMD control, or accounted for economic or social influences of scale in vaccination programmes. Many of the studies included had gaps in both premise and methodology. If these analyses are used when planning and budgeting FMD control programmes in endemic contexts, there is a risk of inefficient resource allocation.

Adaptive risk-based targeted surveillance for foreign animal diseases at the wildlife-livestock interface

Animal disease surveillance is an important component of the national veterinary infrastructure to protect animal agriculture and facilitates identification of foreign animal disease (FAD) introduction. Once introduced, pathogens shared among domestic and wild animals are especially challenging to manage due to the complex ecology of spillover and spillback. Thus, early identification of FAD in wildlife is critical to minimize outbreak severity and potential impacts on animal agriculture as well as potential impacts on wildlife and biodiversity. As a result, national surveillance and monitoring programs that include wildlife are becoming increasingly common. Designing surveillance systems in wildlife or, more importantly, at the interface of wildlife and domestic animals, is especially challenging because of the frequent lack of ecological and epidemiological data for wildlife species and technical challenges associated with a lack of non-invasive methodologies. To meet the increasing need for targeted FAD surveillance and to address gaps in existing wildlife surveillance systems, we developed an adaptive risk-based targeted surveillance approach that accounts for risks in source and recipient host populations. The approach is flexible, accounts for changing disease risks through time, can be scaled from local to national extents and permits the inclusion of quantitative data or when information is limited to expert opinion. We apply this adaptive risk-based surveillance framework to prioritize areas for surveillance in wild pigs in the United States with the objective of early detection of three diseases: classical swine fever, African swine fever and foot-and-mouth disease. We discuss our surveillance framework, its application to wild pigs and discuss the utility of this framework for surveillance of other host species and diseases.

The first detection of a serotype O foot-and-mouth disease virus in Namibia

This report describes the molecular characterization of a serotype O foot-and-mouth disease virus (FMDV) recovered from a field outbreak in the Zambezi region, Namibia during July 2021. Sequence analysis demonstrates that this FMDV belongs to the O/EA-2 topotype sharing closest nucleotide identity (99.5%) to FMD viruses collected since 2018 in Zambia. This is the first detection of serotype O in Namibia, and together with the cases that have been recently detected in southern Zambia, represent the first time that this serotype has been detected in the Southern African FMD endemic pool since 2000, when a virus of Asian origin (O/ME-SA/PanAsia) caused an outbreak in South Africa. This incursion poses a new threat for the region and the potential onward spread of O/EA-2 will now need to be closely monitored since serotype O vaccines are not widely used in Namibia, nor in neighbouring countries.