Foot-and-mouth Disease Virus Serotype Research Articles

Cross-Serotype Reactivity of ELISAs Used to Detect Antibodies to the Structural Proteins of Foot-and-Mouth Disease Virus.

Antibodies to the foot-and-mouth disease virus (FMDV) capsid induced by infection or vaccination can provide serotype-specific protection and be measured using virus neutralization tests and viral structural-protein (SP-)ELISAs. Separate tests are needed for each serotype, but cross-serotype reactions complicate serotyping. In this study, inter-serotypic responses were quantified for five SP-ELISA formats by testing 294 monovalent mainly bovine sera collected following infection, vaccination, or vaccination and infection with one of five serotypes of FMDV. Over half of the samples, representing all three immunization categories, scored positive for at least one heterologous serotype and some scored positive for all serotypes tested. A comparative approach to identifying the strongest reaction amongst serotypes O, A and Asia 1 improved the accuracy of serotyping to 73–100% depending on the serotype and test system, but this method will be undermined where animals have been infected and/or vaccinated with multiple FMDV serotypes. Preliminary studies with stabilized recombinant capsid antigens of serotypes O and A that do not expose internal epitopes showed reduced cross-reactivity, supporting the hypothesis that capsid integrity can affect the serotype-specificity of the SP-ELISAs. The residual cross-reactivity associated with capsid surface epitopes was consistent with the evidence of cross-serotype virus neutralization.

An anti-picornaviral strategy based on the crystal structure of foot-and-mouth disease virus 2C protein.

The foot-and-mouth disease virus (FMDV) 2C protein shares conserved motifs with enterovirus 2Cs despite low sequence identity. Here, we determine the crystal structure of an FMDV 2C fragment to 1.83Å resolution, which comprises an ATPase domain, a region equivalent to the enterovirus 2C zinc-finger (ZFER), and a C-terminal domain harboring a loop (PBL) that occupies a hydrophobic cleft (Pocket) in an adjacent 2C molecule. Mutations at ZFER, PBL, and Pocket affect FMDV 2C ATPase activity and are lethal to FMDV infectious clones. Because the PBL-Pocket interaction between FMDV 2C molecules is essential for its functions, we design an anti-FMDV peptide derived from PBL (PBL-peptide). PBL-peptide inhibits FMDV 2C ATPase activity, binds FMDV 2C with nanomolar affinity, and disrupts FMDV 2C oligomerization. FMDV 2C targets lipid droplets (LDs) and induces LD clustering in cells, and PBL-peptide disrupts FMDV 2C-induced LD clustering. Finally, we demonstrate that PBL-peptide exhibits anti-FMDV activity in cells.

Determination of TCID50 of O, A, Asia-1 serotypes foot-and-mouth disease virus to the production of trivalent vaccine in bioreactor

This research work was designed to ensure the production of quality Foot and Mouth Disease (FMD) vaccine. For ensuring the standard quality of vaccine, it is important to propagate the FMD Virus (FMDV) into the cell line. Tissue Culture Infective Dose50 (TCID50) assay was used to determine the biological titer of FMD virus serotypes. Baby Hamster Kidney-21 (BHK-21) Monolayer cell and BHK-21 Clone 13 Suspension cell were used to determine the TCID50 of FMDV. The result for calculating TCID50 under Monolayer cell showed that the highest biological titer of O, A, Asia-1 serotype were 10-9.83/ml, 10-9.36/ml and 10-9.70/ml respectively. On the other hand, the result for calculating TCID50under BHK-21 Clone 13 suspension cell of O, A, Asia-1 serotypes were10-6.66\ml,10-6.50\ml and 10-6.50/ml respectively. BHK-21 cell line, either the monolayer or the suspension cell culture system were used in FMD vaccine production to ensure the potency and the quality of the vaccine to be produced.BHK-21 monolayer cell sub-cultured by applying roller cell culture cultivation system and BHK-21 clone 13 suspension cell sub-cultured by using suspension cell culture cultivation system. Suspension culture of BHK-21 cells allows large-scale virus propagation and cost-efficient vaccine production by using Bioreactor with capacity of 50 liters maintaining biosafety and biosecurity. Asian J. Med. Biol. Res. 2022, 8 (2), 63-68

Enhanced detection and serotyping of foot-and-mouth disease virus serotype O, A, and Asia1 using a novel multiplex real-time RT-PCR.

Rapid and accurate detection and serotyping of foot-and-mouth disease (FMD) virus (FMDV) is essential for implementing control policies against emergent FMD outbreaks. Current serotyping assays, such as VP1 reverse transcription-polymerase chain reaction (RT-PCR)/sequencing (VP1 RT-PCR/sequencing) and antigen detection enzyme-linked immunosorbent assay (ELISA), have problems with increasing serotyping failure of FMDVs from FMD outbreaks. This study was conducted to develop a multiplex real-time RT-PCR for specific detection and differential serotyping of FMDV serotype O, A, and Asia 1 directly from field clinical samples. Primers and probes were designed based on 571 VP1 coding region sequences originated from seven pools. Multiplex real-time RT-PCR using these primers and probes demonstrated serotype-specific detection with enhanced sensitivity compared to VP1 RT-PCR/sequencing for reference FMDV (n = 24). Complete serotyping conformity between the developed multiplex real-time RT-PCR and previous VP1 RT-PCR/sequencing was demonstrated using FMDV field viruses (n = 113) prepared in cell culture. For FMDV field clinical samples (n = 55), the serotyping rates of multiplex real-time RT-PCR and VP1 RT-PCR/sequencing were 92.7% (51/55) and 72.7% (40/55), respectively. Moreover, the developed multiplex real-time RT-PCR demonstrated improved FMDV detection (up to 33.3%) and serotyping (up to 67.7%) capabilities for saliva samples when compared with 3D real-time RT-PCR and VP1 RT-PCR/sequencing, during 10 days of challenge infection with FMDV serotype O, A, and Asia 1. Collectively, this study suggests that the newly developed multiplex real-time RT-PCR assay may be useful for the detection and differential serotyping of FMDV serotype O, A, and Asia 1 in the field.

Outbreaks of Foot-and-Mouth Disease in Burundi, East Africa, in 2016, Caused by Different Serotypes.

Burundi is a small, densely populated country in the African Great Lakes region. In March 2016, several hundreds of cattle were reported with vesicular lesions, suggesting foot-and-mouth disease (FMD). Epithelial samples, saliva, and blood were collected in six of the affected provinces spread over the country. The overall seroprevalence of FMD virus (FMDV) in the affected herds, as determined by antibodies against FMDV non-structural proteins, was estimated at 87%. Antibodies against FMDV serotypes O (52%), A (44%), C (19%), SAT1 (36%), SAT2 (58%), and SAT3 (23%) were detected across the provinces. FMDV genome was detected in samples from five of the six provinces using rRT-PCR. FMDV was isolated from samples from three provinces: in Cibitoke province, serotypes A and SAT2 were isolated, while in Mwaro and Rutana provinces, only serotype SAT2 was isolated. In Bururi and Cankuzo provinces, the serological profile suggested a recent incursion with serotype SAT2, while in Bubanza province, the serological profile suggested past incursions with serotype O and possibly serotype SAT1. The phylogenetic assessments showed the presence of topotypes A/Africa/G-I and SAT2/IV, similarly to previously characterized virus strains from other countries in the region, suggesting a transboundary origin and necessitating a regional approach for vaccination and control of FMD.

Epidemiological and clinical characteristics of the foot and mouth disease outbreaks in cattle in central Ethiopia

Foot and mouth disease (FMD) is an acute highly contagious viral disease of all cloven-hoofed animals that causes significant economic problems in Ethiopia. The objectives of this study were to assess the morbidity and clinical features of FMD in sick cattle and identify causal serotypes of FMD outbreaks in central Ethiopia. Outbreaks of FMD were investigated in a total of 150 herds of cattle from January 2021 to April 2021. Seven epithelial tissue and 23 oral swab samples were collected and subjected to a real-time polymerase chain reaction (rRT-PCR) and Sandwich Enzyme-linked Immunosorbent Assay (ELISA) for detection and serotyping of FMD virus, respectively. A total of 150 herds of cattle were examined, of which 114 (76%) herds of cattle were clinically affected with FMD. In this study, 75.9% animal-level morbidity was recorded. Exotic breeds and adult cattle were more affected by Foot and Mouth Disease Virus (FMDV) with morbidity of 100% and 77.4%, respectively. The clinical features in sick cattle showed that profuse salivation was the most frequently observed clinical sign (40%) followed by oral cavity vesicle formation (30%), and interdigital space lesion (15%). Out of 30 samples subjected to rRT-PCR and ELISA test, 28 (93.33%) and 27 (90%) samples were found positive, respectively. In this study, three types of FMD serotypes were detected in which SAT-2 (n = 13) was the predominant serotype followed by serotype O (n = 9), and serotype A (n = 5). The current study revealed that FMD serotype SAT-2 was highly responsible for the occurrence of FMD outbreaks in central Ethiopia. Although the FMD vaccine produced in Ethiopia contains all the identified serotypes, detailed studies on topotypes identification have to be performed to provide full protection.

Ecological and Anthropogenic Spatial Gradients Shape Patterns of Dispersal of Foot-and-Mouth Disease Virus in Uganda.

Using georeferenced phylogenetic trees, phylogeography allows researchers to elucidate interactions between environmental heterogeneities and patterns of infectious disease spread. Concordant with the increasing availability of pathogen genetic sequence data, there is a growing need for tools to test epidemiological hypotheses in this field. In this study, we apply tools traditionally used in ecology to elucidate the epidemiology of foot-and-mouth disease virus (FMDV) in Uganda. We analyze FMDV serotype O genetic sequences and their corresponding spatiotemporal metadata from a cross-sectional study of cattle. We apply step selection function (SSF) models, typically used to study wildlife habitat selection, to viral phylogenies to show that FMDV is more likely to be found in areas of low rainfall. Next, we use a novel approach, a resource gradient function (RGF) model, to elucidate characteristics of viral source and sink areas. An RGF model applied to our data reveals that areas of high cattle density and areas near livestock markets may serve as sources of FMDV dissemination in Uganda, and areas of low rainfall serve as viral sinks that experience frequent reintroductions. Our results may help to inform risk-based FMDV control strategies in Uganda. More broadly, these tools advance the phylogenetic toolkit, as they may help to uncover patterns of spread of other organisms for which genetic sequences and corresponding spatiotemporal metadata exist.

Viral Population Diversity during Co-Infection of Foot-And-Mouth Disease Virus Serotypes SAT1 and SAT2 in African Buffalo in Kenya.

African buffalo are the natural reservoirs of the SAT serotypes of foot-and-mouth disease virus (FMDV) in sub-Saharan Africa. Most buffalo are exposed to multiple FMDV serotypes early in life, and a proportion of them become persistently infected carriers. Understanding the genetic diversity and evolution of FMDV in carrier animals is critical to elucidate how FMDV persists in buffalo populations. In this study, we obtained oropharyngeal (OPF) fluid from naturally infected African buffalo, and characterized the genetic diversity of FMDV. Out of 54 FMDV-positive OPF, 5 were co-infected with SAT1 and SAT2 serotypes. From the five co-infected buffalo, we obtained eighty-nine plaque-purified isolates. Isolates obtained directly from OPF and plaque purification were sequenced using next-generation sequencing (NGS). Phylogenetic analyses of the sequences obtained from recombination-free protein-coding regions revealed a discrepancy in the topology of capsid proteins and non-structural proteins. Despite the high divergence in the capsid phylogeny between SAT1 and SAT2 serotypes, viruses from different serotypes that were collected from the same host had a high genetic similarity in non-structural protein-coding regions P2 and P3, suggesting interserotypic recombination. In two of the SAT1 and SAT2 co-infected buffalo identified at the first passage of viral isolation, the plaque-derived SAT2 genomes were distinctly grouped in two different genotypes. These genotypes were not initially detected with the NGS from the first passage (non-purified) virus isolation sample. In one animal with two SAT2 haplotypes, one plaque-derived chimeric sequence was found. These findings demonstrate within-host evolution through recombination and point mutation contributing to broad viral diversity in the wildlife reservoir. These mechanisms may be critical to FMDV persistence at the individual animal and population levels, and may contribute to the emergence of new viruses that have the ability to spill-over to livestock and other wildlife species.

Effect of the Faradarmani Consciousness Field on immune response induced by an inactivated vaccine against Foot and Mouth disease virus (FMDV) in rats and replication of FMDV in vitro

Foot-and-mouth disease (FMD) is one of the highest risk factors affecting the animal industry throughout the world. Currently, available commercial FMD vaccines have numerous limitations, such as slow induction and short-term maintenance of antibody titers. Therefore, a novel approach is needed that can induce high neutralizing antibody titers to protect the host in the early stages of FMD virus (FMDV) infection and maintain high antibody titers for long periods after one vaccination dose. There are several T-Consciousness Fields (TCFs), introduced by Mohammad Ali Taheri. TCFs are not matter or energy, so they cannot be measured directly. However, we can evaluate their effects indirectly through several reproducible experiments in the laboratory. The present study aimed to evaluate the effect of Faradarmani CF as a type of the TCFs on FMDV replication, titer, and RNA copy number as well as the humoral immune response against two types of inactivated FMDV vaccines with different adjuvants in rats. Two types of FMD vaccines with different adjuvants (Freund and Alum) were prepared, and then 30 male Wistar rats were immunized with vaccines. Rats were divided into 6 groups (n=5 per group). Four groups of rats were studied using the different combinations of treatments and two groups served as positive and negative controls. Vaccination intervals were every 14 days three times. Serum neutralization test (SN) and Enzyme-linked immunosorbent assay (ELISA) were used to assess changes in antibody levels in the serum samples of rats after each immunization. The results showed that Faradarmani CF induced the replication of the virus in vitro. In addition, antibody levels in treated groups under both Freund adjuvant and Alum adjuvant vaccines increased significantly compared to groups without Faradarmani CF treatment. In conclusion, our data suggest that Faradarmani CF may provide an effective approach to increase the success of immunization and vaccination against FMDV serotype O. It is recommended that the effects of TCFs on different types of vaccines be investigated.

Combining a Universal Capture Ligand and Pan-Serotype Monoclonal Antibody to Develop a Pan-Serotype Lateral Flow Strip Test for Foot-and-Mouth Disease Virus Detection.

Foot-and-mouth disease virus (FMDV) causes FMD, a highly contagious disease of cloven-hoofed animals including cattle, goats, pigs and sheep. Rapid detection of FMDV is critical to limit the devastating economic losses due to FMD. Current laboratory methods for FMDV detection such as virus isolation, real-time reverse transcription PCR and antigen detection enzyme-linked immunosorbent assay (AgELISA) are labor-intensive, requiring trained personnel and specialized equipment. We present the development and validation of a pan-serotype lateral flow strip test (LFST) that uses recombinant bovine integrin αvβ6 as a universal capture ligand and a pan-serotype monoclonal antibody (mAb) to detect FMDV. The LFST detected all seven FMDV serotypes, where the diagnostic sensitivity was comparable to the AgELISA, and the diagnostic specificity was 100% without cross-reactivity to other viruses causing vesicular disease in livestock. This rapid test will be useful for on-site FMDV detection, as well as in laboratories in endemic countries where laboratory resources are limited.

Development and Validation of a Competitive ELISA Based on Bovine Monoclonal Antibodies for the Detection of Neutralizing Antibodies against Foot-and-Mouth Disease Virus Serotype A.

The level of neutralizing antibodies in vaccinated animals is directly related to their level of protection against a virus challenge. The virus neutralization test (VNT) is a "gold standard" method for detecting neutralizing antibodies against foot-and-mouth disease virus (FMDV). However, VNT requires high-containment facilities that can handle live viruses and is not suitable for large-scale serological surveillance. In this study, a bovine broadly neutralizing monoclonal antibody (W145) against FMDV serotype A was successfully produced using fluorescence-based single-B-cell antibody technology. Using biotinylated W145 as a detector antibody and another bovine cross-reactive monoclonal antibody, E32, which was produced previously as a capture antibody, a competitive enzyme-linked immunosorbent assay for the detection of neutralizing antibodies (NAC-ELISA) against FMDV serotype A was developed. The specificity and sensitivity of the assay were evaluated to be 99.04% and 100%, respectively. A statistically significant correlation (r = 0.9334, P < 0.0001) was observed between the NAC-ELISA titers and the VNT titers, suggesting that the NAC-ELISA could detect neutralizing antibodies against FMDV serotype A and could be used to evaluate protective immunity.

Deciphering Molecular Dynamics of Foot and Mouth Disease Virus (FMDV): A Looming Threat to Pakistan’s Dairy Industry

Milk is seen as a chief source of protein and other biologically available nutrients for human beings. Pakistan, the fourth largest milk-producing country, is badly affected by the contagious transboundary apthoviral disease of ungulate animals; the foot and mouth disease (FMD) virus. FMD is endemic in Pakistan and has caused significant economic loss to the dairy industry in the form of a profound decrease in milk production and increased morbidity and deaths of dairy animals. Inclusively, the case fatality ratio of FMD was 15.11%. Of the seven FMDV serotypes, (O, A, C, Asia 1, SAT 1, SAT 2, and SAT 3), three serotypes (O, A, and Asia-1) are endemic in Pakistan. Rapid and highly sensitive diagnostic tools are required for efficient control of this disease. Presently, FMD in the laboratory is diagnosed via ELISA and molecular approaches, i.e., RT-PCR. Serotype-specific RT-PCR analysis not only confirms ELISA serotyping results but can also be used for the screening of ELISA negative samples. Genotypically, FMDV serotype O has a topotype (Middle East–South Asia (ME–SA) and lineage PanAsia-2) that is reported frequently from different areas of Pakistan. Confirmed cases of serotype A and Asia-1 are also reported. The information gathered can be used for understanding the molecular epidemiology of FMD in Pakistan. Further studies on the molecular dynamics of FMD could be useful for ensuring the timely diagnosis of this deadly pathogen, which would ultimately be beneficial for the mass vaccination programs of FMD in Pakistan.

A Five-Year Retrospective Study of Foot-and-Mouth Disease Outbreaks in Southern Africa, 2014 to 2018.

Foot-and-mouth disease (FMD) virus (FMDv), like other ribonucleic acid (RNA) genome viruses, has a tendency to mutate rapidly. As such, available vaccines may not confer enough cross-protection against incursion of new lineages and sublineages. This paper is a retrospective study to determine the topotypes/lineages that caused previous FMD outbreaks in 6 southern African countries and the efficacy of the current vaccines to protect cattle against them. A total of 453 bovine epithelial tissue samples from 33 FMD outbreaks that occurred in these countries from 2014 to 2018 were investigated for the presence of FMDv. The genetic diversity of the identified Southern African Type (SAT)-FMD viruses was determined by comparing sequences from outbreaks and historical prototype sequences. Of the 453 samples investigated, 176 were positive for four FMDv serotypes. Out of the 176 FMD positive cases there were 105 SAT2 samples, 32 SAT1 samples, 21 SAT3 samples, and 18 serotype O samples. Phylogenetic analysis grouped the SATs VP1 gene sequences into previously observed topotypes in southern Africa. SAT1 viruses were from topotypes I and III, SAT2 viruses belonged to topotypes I, II, III, and IV, and SAT3 viruses were of topotypes I and II. Vaccine matching studies on the field FMDv isolates produced r1-values greater than or equal to 0.3 for the three SAT serotypes. This suggests that there is no significant antigenic difference between current SAT FMD vaccine strains and the circulating SAT serotypes. Therefore, the vaccines are still fit-purpose for the control FMD in the region. The study did not identify incursion of any new lineages/topotypes of FMD into the sampled southern African countries.

Molecular Characterization of Newly Emerging Foot-and-Mouth Disease Virus Serotype SAT 2 of Lib-12 Lineage Isolated from Egypt

An outbreak of foot-and-mouth disease virus (FMDV) serotype SAT 2 occurred in Egypt in 2018, which affected cattle and water buffalo. Previous phylogenetic studies on FMDV circulating in Egypt have mainly focused on genomic regions encoding structural proteins which determine FMDV serotype. So far, none of these studies have analyzed the open reading frame (ORF) sequence of Egyptian SAT 2/Lib-12 lineage. The present study aimed to analyze and identify the ORF genome sequence of Lib-12 lineage which belongs to FMDV serotype SAT 2 topotype VII in Egypt. The protocol workflow was optimized and tested using a representative field isolate of FMDV/SAT 2/Lib-12 from a bovine tongue sample collected in 2018 from Ismailia governorate (SAT2/EGY/Ismailia/2018). The protocol was based on reverse transcription polymerase chain reaction with multiple overlapping primers, amplicons sequencing, and assembly to complete the ORF consensus sequence. Alignments of the sequence fragments formed consensus genome sequence of 7219 nucleotides in length. The complete nucleotide sequence of the Egyptian isolate was related to Ethiopian, Nigerian, and Ghanaian strains, with identity not exceeding 95%. The divergence in the genetic identity of the Egyptian SAT 2/Lib-12 lineage from other Egyptian strains and Libyan isolates was 7%, and this may be attributed to the absence of the Lib-12 lineage ORF sequence from Egypt and Libya in the database. The present study significantly advances knowledge of the molecular analysis of FMDV SAT 2 and the design of vaccine selection for FMDV SAT 2 in Egypt. The study protocol could be applied to other FMDV serotypes.

Subdistrict-Level Reproductive Number for Foot and Mouth Disease in Cattle in Northern Thailand.

Foot and mouth disease (FMD) is an important contagious transboundary disease that causes a significant economic loss for several countries. The FMD virus (FMDV) can spread very rapidly by direct and indirect transmission among susceptible animals. The complexity and magnitude of FMDV transmission at the initial stages of the epidemic can be expressed by the basic reproductive number (R0), and furthermore, control strategies can be assessed by the estimation of the effective reproductive number. In this study, we aimed to describe FMD outbreaks among smallholder cattle farms by subdistricts in the northern Thailand and compute the effective reproductive number for outbreaks caused by FMDV serotype O and overall serotypes, including serotype O, serotype A, and unidentified serotype, at the subdistrict level (Rsd) using an epidemic doubling time method. Field data of FMD outbreaks during 2015–2017 that affected 94 subdistricts in northern Thailand were assessed to estimate the Rsd. Results showed that 63.38% (90/142) of the FMD outbreak episodes in cattle were caused by FMDV serotype O. The average doubling time and the Rsd estimated of the outbreaks caused by FMDV serotype O and overall serotype were 2.80 and 4.67 months, and 1.06 and 1.04, respectively. Our results indicated that transmission of FMD in cattle at the subdistrict level in northern Thailand was not controlled (Rsd > 1), which indicates the endemicity of the disease in the region. Although control measures are in place, the results from this study highlighted the need for enhancing FMD monitoring and control strategies in northern Thailand.

Immune Responses to Orally Administered Recombinant Lactococcus lactis Expressing Multi-Epitope Proteins Targeting M Cells of Foot-and-Mouth Disease Virus.

Foot and mouth disease virus (FMDV), whose transmission occurs through mucosal surfaces, can also be transmitted through aerosols, direct contact, and pollutants. Therefore, mucosal immunity can efficiently inhibit viral colonization. Since vaccine material delivery into immune sites is important for efficient oral mucosal vaccination, the M cell-targeting approach is important for effective vaccination given M cells are vital for luminal antigen influx into the mucosal lymph tissues. In this study, we coupled M cell-targeting ligand Co1 to multi-epitope TB1 of FMDV to obtain TB1-Co1 in order to improve delivery efficiency of the multi-epitope protein antigen TB1. Lactococcus lactis (L. lactis) was engineered to express heterologous antigens for applications as vaccine vehicles with the ability to elicit mucosal as well as systemic immune responses. We successfully constructed L. lactis (recombinant) with the ability to express multi-epitope antigen proteins (TB1 and TB1-Co1) of the FMDV serotype A (named L. lactis-TB1 and L. lactis-TB1-Co1). Then, we investigated the immunogenic potential of the constructed recombinant L. lactis in mice and guinea pigs. Orally administered L. lactis-TB1 as well as L. lactis-TB1-Co1 in mice effectively induced mucosal secretory IgA (SIgA) and IgG secretion, development of a strong cell-mediated immune reactions, substantial T lymphocyte proliferation in the spleen, and upregulated IL-2, IFN-γ, IL-10, and IL-5 levels. Orally administered ligand-conjugated TB1 promoted specific IgG as well as SIgA responses in systemic and mucosal surfaces, respectively, when compared to orally administered TB1 alone. Then, guinea pigs were orally vaccinated with L. lactis-TB1-Co1 plus adjuvant CpG-ODN at three different doses, L. lactis-TB1-Co1, and PBS. Animals that had been immunized with L. lactis-TB1-Co1 plus adjuvant CpG-ODN and L. lactis-TB1-Co1 developed elevated antigen-specific serum IgG, IgA, neutralizing antibody, and mucosal SIgA levels, when compared to control groups. Particularly, in mice, L. lactis-TB1-Co1 exhibited excellent immune effects than L. lactis-TB1. Therefore, L. lactis-TB1-Co1 can induce elevations in mucosal as well as systemic immune reactions, and to a certain extent, provide protection against FMDV. In conclusion, M cell-targeting approaches can be employed in the development of effective oral mucosa vaccines for FMDV.

Antibody Response of Buffalo Calves to Different Levels of Foot and Mouth Disease Virus Immunogen

Antibody response of buffalo calves to different levels of Foot and Mouth Disease (FMD) virus immunogen was investigated. Vaccine containing 106.2 units of immunogen/TCID50 of FMD virus (O, A and Asia-1) serotypes induced log2 (1.3± 0.4) units of anti-FMD O Complement Fixing Geometric Mean antibody (FMD O CFT-CGM) titer, log2 (1.4±0.3) units of anti-FMD A CFT-CGM titer and log2 (2.0±0.7) units of anti-FMD Asia-1 CFT-CGM titer. The vaccine containing 2x106.2 units of immunogen of each of the virus serotypes induced log2 (2.2±0.2) units of anti- FMD O CFT-CGM titer, log2 (2.1±0.25) units of anti- FMD A CFT-CGM titer and log2 (3.4±0.8) units of anti-FMD Asia-1 CFT-CGM titer. The vaccine containing 3x106.2 units of TCID50 of each of the virus serotypes induced log2 (5.3 ± 2.0) units of anti-FMD O CFT-CGM titer, log2 (4.6±1.9) units of anti-FMD A CFT-CGM titer and log2 (5.0±2.2) units of anti- FMD Asia-1 CFT-CGM titer. Moreover, buffalo calves (n=3) which were primed and boosted with 60 days interval using vaccine containing 2x106.2 units of immunogen of each of the virus serotype, showed log25.0 and log26.3 units of anti FMD O CFT-GMT antibody titer, log24.6 and log26.0 units of anti FMD A CFT GMT antibody titer, log25.6 and log26.0 units of anti FMD Asia-1 CFT GMT antibody titer, on 30 and 120 days post boosting.&#x0D; Antibody response of buffalo calves was directly proportional to amount of FMD virus immunogen serotypes in the vaccine. 

Selective isolation of foot-and-mouth disease virus from coinfected samples containing more than one serotype.

The foot-and-mouth disease virus (FMDV) causes a highly infectious disease of all cloven-footed animals. The RNA genome of the virus continuously evolves, leading to the generation of new strains; this necessitates the selection of new vaccine strains to ensure complete protection. Infection with one FMDV serotype does not provide cross-protection against the other FMDV serotypes. Many of the recovered animals may become carriers of the FMDV, but they still remain susceptible to the other serotypes. Coinfection with multiple FMDV serotypes has been reported and studied to understand the virus evolution. Isolation and characterization of all the involved serotypes in the mixed infection case is essential to understand the molecular evolution of the virus. In this study, two cases of coinfection were studied by selective isolation of each of the FMDV serotypes under the cross-serotype-specific immune pressure. It was estimated that the virus present in a minimum of 10-0.92 TCID50 could be isolated from the mixed population containing other serotypes in infective doses of 100.25 TCID50 or less. All involved serotypes present in the mixed infection cases were isolated, without any cross-contamination. Virus characterization revealed that genotype 2 was of serotype A virus from a sample collected in 1995, which was last reported in 1986, indicating a possible subdued prevalence of the genetic group even after vanishing from the field.

Isolation and characterization of porcine monoclonal antibodies revealed two distinct serotype-independent epitopes on VP2 of foot-and-mouth disease virus.

Pigs are susceptible to foot-and-mouth disease virus (FMDV), and the humoral immune response plays an essential role in protection against FMDV infection. However, little information is available about FMDV-specific mAbs derived from single B cells of pigs. This study aimed to determine the antigenic features of FMDV that are recognized by antibodies from pigs. Therefore, a panel of pig-derived mAbs against FMDV were developed using fluorescence-based single B cell antibody technology. Western blotting revealed that three of the antibodies (1C6, P2-7E and P2-8G) recognized conserved antigen epitopes on capsid protein VP2, and exhibited broad reactivity against both FMDV serotypes A and O. An alanine-substitution scanning assay and sequence conservation analysis elucidated that these porcine mAbs recognized two conserved epitopes on VP2: a linear epitope (2KKTEETTLL10) in the N terminus and a conformational epitope involving residues K63, H65, L66, F67, D68 and L81 on two β-sheets (B-sheet and C-sheet) that depended on the integrity of VP2. Random parings of heavy and light chains of the IgGs confirmed that the heavy chain is predominantly involved in binding to antigen. The light chain of porcine IgG contributes to the binding affinity toward an antigen and may function as a support platform for antibody stability. In summary, this study is the first to reveal the conserved antigenic profile of FMDV recognized by porcine B cells and provides a novel method for analysing the antibody response against FMDV in its natural hosts (i.e. pigs) at the clonal level.

Foot-and-mouth disease virus serotype O, East African Topotype 3 (EA-3) in a pastoral herd in Kaduna state, Nigeria

A case of foot and mouth disease involving an uncommon serotype of the Foot and Mouth disease virus (FMDV) is reported in a 6-year-old Bunaji bull from a pastoralist herd in Tohu, Sabon Gari Local Government Area of Kaduna State, Nigeria. Clinical examination revealed erosions in the inter-digital spaces, dorsum and ventrum of the tongue and raised hair coat. The epithelial lining of the lesions on the foot and mouth were gently peeled off and used as samples for diagnosis. A confirmatory diagnosis of FMDV serotype O strain was done by virus isolation using Bovine thyroid gland primary cell line, antigen ELISA for FMD virus, while a phylogenetic analyses of VP1 nucleotide sequences revealed East African topotype 3 (EA-3). Presenting lesions in the interdigital space were cleaned with cotton wool soaked in a solution of 5% chlorhexidine and then sprayed with Oxyspray® after which Tetranor® long acting antibiotic was administered through deep intramuscular route at 20mg/kg body weight. The diagnosis of relatively alien topotype of FMDV in Nigeria calls for a holistic epidemiological survey of all the serotypes and topotypes present in the country in order to plan for effective control measures. Keywords: Bunaji bull, FMD, Nigeria, Serotype O, Topotype EA-3