Foot-and-mouth Disease Virus Serotype Research Articles

Evaluation of commercial quadrivalent foot-and-mouth disease vaccines against east African virus strains reveals limited immunogenicity and duration of protection

Foot-and-mouth disease virus (FMDV) causes a contagious disease (FMD) in cloven-hoofed animals. For FMD-endemic countries, vaccination is critical for controlling disease but is rarely monitored, despite substantial funds spent on vaccine purchases. We evaluated antibody responses in cattle to two commercial vaccines each containing antigens of four FMDV serotypes. Sampling was done over 360 days, with serology for each serotype performed using commercially available solid phase competition ELISAs (SPCE) and with virus neutralization tests (VNT) employing regionally relevant test viruses. A primary course of each vaccine was administered to 37 calves, some of which received a second dose after 28 days. Using new production batches of vaccines, all calves received a booster vaccination 180 days post vaccination, while 10 additional naïve calves were also vaccinated using the new batches and followed up for ∼180 days. Simple and general linear models were used to compare antibody responses which varied substantially according to vaccine, dose regime, serotype, and test, but were mostly insufficient to ensure a high likelihood of adequate or sustained probable protection. One of the vaccines administered as a two-dose primary course of vaccination was superior to other options, but even then, data trajectories from VNT responses suggested probable protection of 75 % of calves for 6 months for only one virus serotype. Calves administered with the other vaccine and those given a single primary dose developed low levels of antibodies, offering predicted likely protection lasting less than two months. Individual SPCE results were weakly correlated (r2 = 0.48) to neutralization and associated likelihoods of protection but SPCE and VNT agreed on which vaccine and dose regime performed best. Our findings highlight gaps in immunogenicity of FMD vaccines used in East Africa and reinforce the importance of independent quality control studies to evaluate and improve commercial FMD vaccines and vaccination regimes.

Development and Validation of Serotype-Specific Blocking ELISA for the Detection of Anti-FMDV O/A/Asia1/SAT2 Antibodies

Foot-and-mouth disease (FMD) is one of the most infectious viral transboundary diseases of livestock, which causes devastating global economic losses. Different enzyme-linked immunosorbent assays (ELISAs) are used for sero-surveillance of the foot-and-mouth disease virus (FMDV). However, more sensitive, accurate, and convenient ELISAs are still required to detect antibodies against FMDV serotypes. The primary goal of this study was to establish serotype-specific monoclonal antibody (mAb)-based blocking ELISAs (mAb-bELISAs) that would provide better performance characteristics or be equivalent in performance characteristics compared with a conventional polyclonal antibody (pAb)-based competitive ELISA (pAb-cELISA). Four mAb-bELISAs were developed using FMDV serotype-specific mAbs for the detection of anti-FMDV/O/A/Asia1/SAT2 antibodies. Using a 50% cut-off, all four mAb-bELISAs exhibited species-independent 99.74%, 98.01%, 96.59%, and 98.55% diagnostic specificity (DSp) and 98.93%, 98.25%, 100%, and 87.50% diagnostic sensitivity (DSe) for FMDV serotypes O, A, Asia1, and SAT2, respectively. In addition, a 100% DSe of serotypes O- and SAT2-specific mAb-bELISAs was observed for porcine sera when the cut-off was 30%. All mAb-bELISAs developed in this study displayed high repeatability/reproducibility without cross-reactivity. Finally, the diagnostic performance of mAb-bELISAs was found to be better than or equivalent to compared with pAb-cELISAs, suggesting that mAb-bELISAs can be used to replace existing pAb-ELISAs for the detection of antibodies against these four FMDV serotypes.

Diagnostic and prophylactic potential of a stabilized foot-and-mouth disease serotype Asia1 virus like particles designed through a structure guided approach

Intact capsids of foot-and-mouth disease virus (FMDV) play a vital role in eliciting a protective immune response. Any change in the physico-chemical environment of the capsids results in dissociation and poor immunogenicity. Structural bioinfomatics studies have been carried out to predict the amino acids at the interpentameric region that resulted in the identification of mutant virus-like particles(VLPs) of FMDV serotype Asia1/IND/63/1972. The insect cell expressed VLPs were evaluated for their stability by sandwich ELISA. Among 10 mutants, S93H showed maximum retention of antigenicity at different temperatures, indicating its higher thermal stability as revealed by the in-silico analysis and retained the antigenic sites of the virus demonstrated by Sandwich ELISA. The concordant results of the liquid phase blocking ELISA for estimation of antibody titre of known sera with stable mutant VLP as antigen in place of virus antigen demonstrate its diagnostic potential. The stable mutant VLP elicited a robust immune response with 85.6 % protection in guinea pigs against virus challenge. The stabilized VLP based antigen requires minimum biosafety and cold storage for production and transit besides, complying with differentiation of infected from vaccinated animals. It can effectively replace the conventional virus handling during antigen production for prophylactic and diagnostic use.

Development of recombinant proteins for vaccine candidates against serotypes O and A of Foot-and-Mouth Disease virus in Bangladesh.

Frequent vaccine failure leading to recurrent outbreaks of Foot-and-Mouth Disease (FMD) in livestock populations necessitates the development of a customizable vaccine platform comprising potential antigenic determinants of circulating lineages of FMD viruses. Artificially designed, chimaeric protein-based recombinant vaccines are novel approaches to combat the phylogenetically diverse FMD Virus (FMDV) strains. Among seven recognized serotypes, only serotypes O and A are dominantly circulating in Bangladesh and neighbouring countries of Asia, where transboundary transmission, recurrent outbreaks and emergence of novel lineages of FMDV are highly prevalent. The objective of this study was to develop multi-epitope recombinant proteins, procuring immunogenicity against circulating diverse genotypes of FMDV serotypes O and A. Two chimaeric proteins, named B1 (41.0 kDa) and B3 (39.3 kDa), have been designed to incorporate potential B-cell and T-cell epitopes selected from multiple FMDV strains, including previously reported and newly emerged sub-lineages. After expression, characterization and immunization of guinea pigs with a considerable antigen load of B1 and B3 followed by serological assays revealed the significant protective immunogenicity, developed from the higher (100 µg) doses of both antigens, against most of the currently prevalent serotype O and A strains of FMDV. The efficient expression, antigenic stability, and multivalent immunogenic potency of the chimaeric proteins strongly indicate their credibility as novel vaccine candidates for existing serotypes O and A of FMDV in Bangladesh and surrounding territories.

Virus-like particle-based multipathogen vaccine of FMD and SVA elicits balanced and broad protective efficacy in mice and pigs

Inactivated vaccines lack the capability to serologically differentiate between infected and vaccinated animals, thereby impeding the effective eradication of pathogen. Conversely, vaccines based on virus-like particles (VLPs) emulate natural viruses in both size and antigenic structure, presenting a promising alternative to overcome these limitations. As the complexity of swine infectious diseases increases, the increase of vaccine types and doses may intensify the stress response. This exacerbation can lead to diminished productivity, failure of immunization, and elevated costs. Given the critical dynamics of co-infection and the clinically indistinguishable symptoms associated with foot-and-mouth disease virus (FMDV) and senecavirus A (SVA), there is a dire need for an efficacious intervention. To address these challenges, we developed a combined vaccine composed of three distinct VLPs, specifically designed to target SVA and FMDV serotypes O and A. Our research demonstrates that this trivalent VLP vaccine induces antigen-specific and robust serum antibody responses, comparable to those produced by the respective monovalent vaccines. Moreover, the immune sera from the combined VLP vaccine strongly neutralized FMDV type A and O, and SVA, with neutralization titers comparable to those of the individual vaccines, indicating a high level of immunogenic compatibility among the three VLP components. Importantly, the combined VLPs vaccines-immunized sera conferred efficient protection against single or mixed infections with FMDV type A and O, and SVA viruses in pigs. In contrast, individual vaccines could only protect pigs against homologous virus infections and not against heterologous challenges. This study presents a novel combined vaccines candidate against FMD and SVA, and provides new insights for the development of combination vaccines for other viral swine diseases.

Foot-and-mouth disease-associated myocarditis is age dependent in suckling calves

Myocarditis is considered a fatal form of foot-and-mouth disease (FMD) in suckling calves. In the present study, a total of 17 calves under 4 months of age and suspected clinically for FMD were examined for clinical lesions, respiratory rate, heart rate, and heart rhythm. Lesion samples, saliva, nasal swabs, and whole blood were collected from suspected calves and subjected to Sandwich ELISA and reverse transcription multiplex polymerase chain reaction (RT-mPCR) for detection and serotyping of FMD virus (FMDV). The samples were found to be positive for FMDV serotype “O”. Myocarditis was suspected in 6 calves based on tachypnoea, tachycardia, and gallop rhythm. Serum aspartate aminotransferase (AST), creatinine kinase myocardial band (CK-MB) and lactate dehydrogenase (LDH), and cardiac troponins (cTnI) were measured. Mean serum AST, cTn-I and LDH were significantly higher (P < 0.001) in < 2 months old FMD-infected calves showing clinical signs suggestive of myocarditis (264.833 ± 4.16; 11.650 ± 0.34 and 1213.33 ± 29.06) than those without myocarditis (< 2 months old: 110.00 ± 0.00, 0.06 ± 0.00, 1050.00 ± 0.00; > 2 months < 4 months: 83.00 ± 3.00, 0.05 ± 0.02, 1159.00 ± 27.63) and healthy control groups (< 2 months old: 67.50 ± 3.10, 0.047 ± 0.01, 1120.00 ± 31.62; > 2 months < 4 months: 72.83 ± 2.09, 0.47 ± 0.00, 1160.00 ± 18.44). However, mean serum CK-MB did not differ significantly amongst the groups. Four calves under 2 months old died and a necropsy revealed the presence of a pathognomic gross lesion of the myocardial form of FMD known as “tigroid heart”. Histopathology confirmed myocarditis. This study also reports the relevance of clinical and histopathological findings and biochemical markers in diagnosing FMD-related myocarditis in suckling calves.

Isolation, Genetic and Antigenic Characterization of Circulating Foot and Mouth Disease Virus

Foot and Mouth Disease (FMD) is a highly contagious viral illness that predominantly affects cloven-hoofed animals. To identify and profile the predominant FMDV serotypes circulating in Baluchistan bovine and buffalo populations. Twenty tissue samples were collected and analyzed using sandwich indirect ELISA and RT-PCR to identify the presence and genetic characteristics of FMD virus. We identified 'O' serotype of FMD virus in all specimens. RT-PCR analysis yielded an impressive 90% positivity rate, confirming its diagnostic efficacy. While observations of LFBK cell line lead to the isolation of 18 distinct viruses with distinct Cytopathic Effects, two samples lacked detectable CPEs. Lower CT values, those observed in sample PK- 16 with CT of 15, indicated higher initial concentration of the target nucleic acid, indicating a potential for higher viral burden.The endemic prevalence of 'O' serotype in Balochistan necessitated targeted serotype-specific interventions, strengthened surveillance and strategic vaccination campaigns.

Potent small molecule inhibitors against the 3C protease of foot-and-mouth disease virus.

Foot-and-mouth disease (FMD) is one of the most devastating diseases of livestock which can cause significant economic losses, especially when introduced to FMD-free countries. FMD virus (FMDV) belongs to the family Picornaviridae and is antigenically heterogeneous with seven established serotypes. The prevailing preventive and control strategies are limited to restriction of animal movement and elimination of infected or exposed animals, which can be potentially combined with vaccination. However, FMD vaccination has limitations including delayed protection and lack of cross-protection against different serotypes. Recently, antiviral drug use for FMD outbreaks has increasingly been recognized as a potential tool to augment the existing early response strategies, but limited research has been reported on potential antiviral compounds for FMDV. FMDV 3C protease (3Cpro) cleaves the viral-encoded polyprotein into mature and functional proteins during viral replication. The essential role of viral 3Cpro in viral replication and the high conservation of 3Cpro among different FMDV serotypes make it an excellent target for antiviral drug development. We have previously reported multiple series of inhibitors against picornavirus 3Cpro or 3C-like proteases (3CLpros) encoded by coronaviruses or caliciviruses. In this study, we conducted structure-activity relationship studies for our in-house focused compound library containing 3Cpro or 3CLpro inhibitors against FMDV 3Cpro using enzyme and cell-based assays. Herein, we report the discovery of aldehyde and α-ketoamide inhibitors of FMDV 3Cpro with high potency. These data inform future preclinical studies that are related to the advancement of these compounds further along the drug development pathway.IMPORTANCEFood-and-mouth disease (FMD) virus (FMDV) causes devastating disease in cloven-hoofed animals with a significant economic impact. Emergency response to FMD outbreaks to limit FMD spread is critical, and the use of antivirals may overcome the limitations of existing control measures by providing immediate protection for susceptible animals. FMDV encodes 3C protease (3Cpro), which is essential for virus replication and an attractive target for antiviral drug discovery. Here, we report a structure-activity relationship study on multiple series of protease inhibitors and identified potent inhibitors of FMDV 3Cpro. Our results suggest that these compounds have the potential for further development as FMD antivirals.

Porcine interferon-α linked to the porcine IgG-Fc induces prolonged and broad-spectrum antiviral effects against foot-and-mouth disease virus

Foot-and-mouth disease (FMD) is an economically important disease, and the FMD virus (FMDV) can spread rapidly in susceptible animals. FMD is usually controlled through vaccination. However, commercial FMD vaccines are only effective 4–7 days after vaccination. Furthermore, FMDV comprises seven serotypes and various topotypes, and these aspects should be considered when selecting a vaccine. Antiviral agents could provide rapid and broad protection against FMDV. Therefore, this study aimed to develop a fusion protein of consensus porcine interferon-α and Fc portion of porcine antibody IgG (poIFN-α-Fc) using a baculovirus expression system to develop a novel antiviral agent against FMDV. We measured the antiviral effects of the poIFN-α-Fc protein against FMDV and the enhanced duration in vitro and in vivo. The broad-spectrum antiviral effects were tested against seven FMDV serotypes, porcine reproductive and respiratory syndrome virus (PRRSV), and bovine enterovirus (BEV). Furthermore, the early protective effects and neutralizing antibody levels were tested by co-injecting poIFN-α-Fc and an FMD-inactivated vaccine into mice or pigs. Sustained antiviral effects in pig sera and mice were observed, and pigs injected with a combination of the poIFN-α-Fc and an inactivated FMD vaccine were protected against FMDV in a dose-dependent manner at 2- and 4-days post-vaccination. In addition, combined with the inactivated FMD vaccine, poIFN-α-Fc increased the neutralizing antibody levels in mice. Therefore, poIFN-α-Fc is a potential broad-spectrum antiviral and adjuvant candidate that can be used with inactivated FMD vaccines to protect pigs against FMDV.

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.

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. 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. 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). 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.

Evaluation of specific chicken IgY antibody value developing diagnostic capture antibody ELISA kit against Foot and Mouth disease.

The most preferred method for the detection of foot-and-mouth disease (FMD) viral antigen and identification of viral serotype is the enzyme-linked immunosorbent assay (ELISA). Diagnostic tests with high sensitivity are necessary both to distinguish infected vaccinated animals and execute disease control programs for the identification of the carrier animals. The current strategies for the detection of FMD virus are mainly based on the capture antibody (sandwich) ELISA test. The usage of laying pullets as an animal bioreactor for the production of specific egg yolk antibodies (IgY) has increased in recent years due to its high yield, affinity, low price, and quick production turnover. The present study aimed to produce a concentrated and purified IgY polyclonal antibody to design a capture antibody ELISA kit against the FMD virus (FMDV) serotype A. At first, laying hens were immunized with inactivated FMDV serotype virus, and then, on days 14, 21, and 28 following vaccination, the eggs and sera were collected. Afterward, the IgY polyclonal antibodies were extracted and purified from the chicken egg yolk using a polyethylene glycol 6000-ethanol precipitation procedure. Extracts were filtered, purified by ion exchange chromatography, and dialyzed. The purified IgY concentration, estimated by Bradford assay, confirmed its presence by SDS-PAGE and Western blot and also its specific immune reaction by Ouchterlony double immunodiffusion and Dot blot tests. Moreover, for achieving the optimum concentration of antigen/antibody (sera) in sandwich ELISA, a checkerboardtitrationtest was set up based on indirect ELISA results. Eventually, 119 previously confirmed samples (including 80 positive and 39 negative) by both real-time polymerase chain reaction (quantitative PCR, qPCR) and a commercial ELISA kit were used for evaluation of the sensitivity and accuracy of our developed Capture antibody ELISA kit. In this manner, the sensitivity and specificity of our designed kit were 100% and 98%, respectively. Accordingly, the present developed capture ELISA kit based on IgY had high sensitivity and specificity for FMD virus detection and it could be used in the future for both commercial detecting and serotyping applications.

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.

Analysis of Coinfection Pathogens From Foot‐and‐Mouth Disease Virus Persistently Infected Cattle Using Oxford Nanopore Sequencing

The persistent infection caused by foot‐and‐mouth disease virus (FMDV) still lacks a reliable explanation, as its etiology and maintenance are intricate and potentially involve concurrent infections with multiple pathogens. In this study, we utilized the nanopore platform for direct sequencing of clinical samples obtained from cattle persistently infected with FMDV serotype O and investigated the distribution characteristics of coinfecting pathogens in their pharyngeal region. Briefly, we exploited Oxford Nanopore sequencing technology to generate high‐quality and sufficient sequence data for the comprehensive characterization of microbial genomes. Furthermore, we performed sequence comparison, alignment, and phylogenetic tree construction. Our findings revealed a total of 23 viruses in FMDV carrier bovine, with FMDV, bovine orthopneumovirus, and Choristoneura fumiferana granulovirus emerging as the top three identified pathogens. The analysis unexpectedly revealed the presence of porcine circovirus type 2 and pepper mild mottle virus among the viral genes detected in the bovine FMDV carrier. Compared to noncarrier, carrier bovine of FMDV exhibited a greater diversity and abundance of mycoplasma types as well as reads counts. Therefore, we propose that the establishment and perpetuation of persistent FMDV infection may be attributed to the simultaneous presence of other viral agents and mycoplasmas. These findings highlight the significance of investigating multipathogen coinfection in elucidating the etiology of persistent FMD virus infection.

Detection of antibodies against structural proteins of foot-and-mouth disease virus in bovines of western Uttar Pradesh, India.

Foot-and-mouth disease (FMD) is considered as one of the most important contagious viral diseases affecting cloven-footed animals. For effective control of FMD, immunization along with herd immunity is essential in the field conditions. To assure and track the coverage and effectiveness of the vaccination program, the serological studies are very much required after the vaccination program. The present study was aimed to investigate the prevalence of antibodies against structural proteins of FMD virus (FMDV) serotypes of O, A and Asia-1 in seven districts of western Uttar Pradesh, India, and assure the efficacy of vaccination under National Animal Disease Control Program. A total of 308 sera samples were collected from apparent healthy vaccinated cattle and buffaloes from seven districts including Amroha, Baghpat, Bareilly, Bulandsahar, Gautam Budh Nagar, Meerut and Muzaffarnagar of western Uttar Pradesh, India. Determination of antibodies against structural proteins of FMDV was carried out using solid-phase blocking enzyme-linked immunosorbent assay. The protective level of the FMDV serotypes O, A and Asia-1 included in the inactivated trivalent vaccine was 66.55, 48.05 and 47.08% in bovines, respectively. To provide the higher level of protection against the circulating FMDV, the present study recommended the thorough investigation of the immunogenic interaction between the vaccine strains and the field strains. Further investigations should also be conducted with larger sample size and across diverse geographical regions to gain a more comprehensive understanding of herd immunity.

A STUDY ON HOMOLOGY AND HETEROLOGY BETWEEN PANASIA-II &amp; PAK-98 LINEAGES OF FOOT AND MOUTH DISEASE VIRUS SEROTYPE-O

To understand the dynamics of epidemics, it is crucial to evaluate prior exposure to infectious diseases as a possible defense against newly developing strains. The cross-protection prediction is unresolved matter that holds great importance, particularly in the field of Foot-and-Mouth Disease Virus (FMDV). The new methods for controlling FMD involve the implementation of vaccine, limited movement, containment and elimination of cattle that are either affected or vulnerable to the disease. Therefore, it is necessary to use a serological analysis strategy that applies association coefficients (r1-values) to identify effective vaccines. The primary objective of this study was aimed to explain the genetic homologous and heterologous association among two ancestries of FMDV serotype O found in Pakistan (Pk) and to find a suitable strain from field for selection of vaccinated seed that provide cross-protection against both ancestries. Virus neutralization tests (VNTs) were used to evaluate an antigenic association among the two groups of viruses, indicates a significant degree of antigenic similarity between stains within a particular cluster. Conversely, r1 values ranging from 0.07-0.2 were obtained from cross-combinations among clusters, suggesting antigenic variation amongst virus strains. These results were further supported by in vitro tests, which showed that heterologous combinations of PanAsia-II and PAK-98 isolates showed antigenic variation, except for 25-06-PK-19, SDG-43-FSD-PK, and TANWL-34PK, which showed a 0.3 (r1 value). In contrast, when considering homologous combination of strains from both lineages showed antigenic similarity. Furthermore, it was projected that these combinations would provide protective titers during in-vivo. As a conclusion, it is recommended that all strains, except 25-06-PK-19, SDG-43-FSD-PK, and TANWL-34PK considered as potential vaccine candidates for effectively managing outbreaks of FMDV serotype-O, due to their ability to confer broad-spectrum immunity.

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.

Isolation, molecular characterization, and genetic diversity of recently isolated foot-and-mouth disease virus serotype A in Egypt.

Foot-and-mouth Disease (FMD) is a highly contagious viral disease affecting all hoof-cloven animals. Serotypes A, O and SAT 2 of the foot-and-mouth disease virus (FMDV) are circulating in Egypt. The present study aimed to identify and molecularly characterize the FMDV strains circulating in Northern Egypt during an epidemic that struck the nation in 2022. RNA was extracted from the epithelial specimens, vesicular fluid from affected cattle. The samples were screened using real-time reverse-transcription polymerase chain reaction (RT-PCR) targeting the RNA-dependent RNA polymerase (RdRp) gene. Positive samples underwent individual serotype-specific amplification using primers designed for VP1 of O, A, and SAT 2 serotypes. Subsequently, direct sequencing was performed on the positive samples. The real-time RT-PCR detected positive samples from epithelial and vesicular fluid samples, but not in the blood of infected animals. Out of the 16 samples, seven tested positive for FMDV serotype A. Of these seven positive samples, six were categorized as serotype A-African topotype-G-IV, and these positive samples were isolated in BHK-21 cells, yielding an overt cytopathic effect caused by the virus. In conclusion, it is necessary to sustain continuous surveillance of the evolution of circulating FMDV strains to facilitate the assessment and aid in the selection of vaccine strains for the effective control of FMDV in Egypt.

Expression of VP1 protein of foot-and-mouth disease virus serotype O originated from Indonesia in mammalian cells as potential immunogen

In 2022, Indonesia experienced foot-and-mouth disease (FMD) outbreak resulting in the death of hundreds of cattle; after more than 30 years, the country maintained FMD-free status. The FMD viral polypeptides-1 (VP1) protein contains major antigenic sites, making the protein have an important role in diagnostic applications or vaccine development. In this study, a synthetic codon-optimized vp1 gene from FMD virus serotype O was integrated into pcDNA3.1 vector and transformed to Escherichia coli TOP10F’ for plasmid propagation. The pcDNA3.1-1D-VP1 FMDV plasmid was then verified using agarose gel, showing in 659 bp size of the DNA fragment. The VP1 recombinant plasmid was transfected into HEK293T cells in DMEM medium supplemented with 10% FBS. Protein profiles were determined with SDS-PAGE showing target protein at 33KDa. Protein expression was confirmed by in-cell western assay using anti-VP1 type O polyclonal antibody and IRDye® 800CW goat anti-rabbit IgG as the secondary antibody. The result revealed a high-intensity fluorescence signal, indicating a strong interaction between expressed protein and anti-VP1 antibody. Thus, the results of this study demonstrate the potential for VP1 protein to be used as an immunogen in vaccine or diagnostic development against FMD infection. Nonetheless, some additional studies should be conducted.

Conserved antigen structures and antibody-driven variations on foot-and-mouth disease virus serotype A revealed by bovine neutralizing monoclonal antibodies.

Foot-and-mouth disease virus (FMDV) serotype A is antigenically most variable within serotypes. The structures of conserved and variable antigenic sites were not well resolved. Here, a historical A/AF72 strain from A22 lineage and a latest A/GDMM/2013 strain from G2 genotype of Sea97 lineage were respectively used as bait antigen to screen single B cell antibodies from bovine sequentially vaccinated with A/WH/CHA/09 (G1 genotype of Sea97 lineage), A/GDMM/2013 and A/AF72 antigens. Total of 39 strain-specific and 5 broad neutralizing antibodies (bnAbs) were isolated and characterized. Two conserved antigenic sites were revealed by the Cryo-EM structures of FMDV serotype A with two bnAbs W2 and W125. The contact sites with both VH and VL of W125 were closely around icosahedral threefold axis and covered the B-C, E-F, and H-I loops on VP2 and the B-B knob and H-I loop on VP3; while contact sites with only VH of W2 concentrated on B-B knob, B-C and E-F loops on VP3 scattering around the three-fold axis of viral particle. Additional highly conserved epitopes also involved key residues of VP158, VP1147 and both VP272 / VP1147 as determined respectively by bnAb W153, W145 and W151-resistant mutants. Furthermore, the epitopes recognized by 20 strain-specific neutralization antibodies involved the key residues located on VP3 68 for A/AF72 (11/20) and VP3 175 position for A/GDMM/2013 (9/19), respectively, which revealed antigenic variation between different strains of serotype A. Analysis of antibody-driven variations on capsid of two virus strains showed a relatively stable VP2 and more variable VP3 and VP1. This study provided important information on conserve and variable antigen structures to design broad-spectrum molecular vaccine against FMDV serotype A.

Pathological and genetic characterization of foot and mouth disease viruses collected from cattle and water buffalo in Egypt.

Foot-and-mouth disease (FMD), a highly contagious viral disease caused by FMD virus (FMDV) that threatens Egypt's livestock industry. FMDV causes severe economic losses in the livestock, with restriction of international trade from endemic regions. Surveillance for FMDV serotypes circulating in Egypt is urgently needed to assess the epidemiological situation in the country. FMD outbreaks reported in Egypt in between December 2016 and January-March 2017. A cross-sectional study was conducted to identify the FMDV serotypes responsible for the outbreaks and to collect information on the virus's morphopathological effects. Postmortem tissue and clinical samples (oral swabs, vesicular fluids from ruptured vesicles, and blood) were collected from recently deceased and infected animals. Pathological examination revealed classical FMD lesions as vesicular and erosive lesions on epithelial tissues with non-suppurative lymphoplasmacytic myocarditis. Phylogenetic and sequencing analyses demonstrated that FMDV serotype O, EA-3 topotype, VP1 is the prevalent serotype responsible for the pathological alterations and the high mortality in young calves, adult cattle, and water buffalo. The outcomes indicate continuous mutations in the circulating FMDV, which result in the occasional failure of vaccination. Based on these findings, extensive continuous monitoring and serotyping of the existing circulating FMDV isolates and regular vaccination with reevaluation of the currently used vaccine in Egypt are recommended to prevent the recurrence of such outbreaks.