Foot-and-mouth Disease Virus Serotype Research Articles

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 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.

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.

Experimental infection of foot and mouth disease virus (FMDV) upregulates the expression of Coxsackie and adenovirus receptor (CAR) in the myocardium of suckling mice

The relative overexpression of Coxsackie and adenoviral receptor (CAR) predisposes children to viral myocarditis. As the foot and mouth disease virus (FMDV) causes fatal myocarditis in calves, lambs, and piglets and belongs to the same family as the Coxsackie virus, we investigated the role of CAR in FMDV induced myocarditis in the suckling mice model. Swiss albino suckling mice of 5 days (n = 24) were divided into two equal groups. One group was inoculated with suckling mice adapted FMDV serotype O at 10 LD50, while the other group served as uninfected control. In addition, adult mice (n = 12) served as the control for age related CAR expression and lack of pathogenicity to FMDV. The establishment of myocarditis was confirmed by histopathological changes typical of myocarditis along with immunolocalization of FMDV antigens in the heart of suckling mice. The FMDV inoculated suckling mice group showed a significant upregulation of CAR transcripts by 2.5 folds, overexpression of CAR protein by densitometric analysis of immunoblots, and intense immunolocalization of CAR in the sarcolemma and intercalated discs of cardiomyocytes as compared to the uninfected suckling mice group and adult mice. It was concluded that FMDV infection induced overexpression of CAR in the myocardium of suckling mice.

A reverse transcription-multiplex PCR strategy devised for concomitant detection and differentiation of foot and mouth disease virus serotypes O, A and Asia 1 in India

Serotype identification occupies the central part of foot and mouth disease (FMD) diagnosis workflow and vaccination decision tree. In this study, a reverse transcription-multiplex PCR (RT-mPCR) strategy wherein three assays with unique combinations of serotype specific primers targeting the VP1 region was developed to differentiate FMD virus serotypes O, A and Asia 1 based on differential size of the PCR amplicons on agarose gel. Their diagnostic performance relative to the mPCR assay in use in India was evaluated on 169 clinical samples and 210 cell culture grown virus isolates. The relative diagnostic sensitivity was found to be 99.69%, 98.78% and 99.08% for primer combinations 1, 2 and 3, respectively. These assays proved their worth by detecting serotype in three FMD suspected specimens that went undiagnosed in the existing mPCR and also by identifying multiple serotypes in the same sample. Their detection limits varied from log10 2 to log10 4 viral RNA dilution and from 100 to 0.1 TCID50 virus depending on the serotype. The validated novel mPCR assays show promise to be included in the routine diagnostic tool-box to augment the efficiency of diagnosis of FMD virus serotypes that display extreme genetic diversity and a tendency of transboundary dispersal.

Characterization of Foot-and-Mouth Disease Virus Serotype O-Specific Single Domain Antibody Expressed in the pET Expression System.

Foot and mouth disease (FMD) is an extremely contagious disease of cloven-hoofed domesticated and wild animals, resulting in significant economic losses in many parts of the world. FMD virus (FMDV) serotype O is responsible for approximately 70% of global outbreaks. For detection of FMDV antigen or antibody, ELISAs are used worldwide and have several limitations, such as batch-to-batch variation in generating immunobiologicals, high production cost and ethical concerns over animal sacrifice. The use of single domain antibody (sdAb) or variable N-terminal domain of the heavy chain of heavy chain antibody (VHH) found naturally in camels has proven their effectiveness in diagnostics and therapeutics. In the present study, the anti-FMDV serotype O-specific VHH-C1 gene sequence (Accession no. KJ751546) was retrieved from the NCBI database. The gene was synthesized commercially in the pBluescript KS+ cloning vector and expressed in E. coli BL21 (DE3) cells using the pET303/CT-His expression system with a C-terminal 6X-His tag. The expressed sdAb, verified by SDS‒PAGE and western blotting, was purified by Ni-chelate chromatography and used as a coating antibody in double antibody sandwich (DAS) ELISA for FMDV detection and typing. The sdAb exhibited a high binding affinity for FMDV serotype O, without any cross-reactivity toward serotypes A and Asia-1. It exhibited better thermostability up to 85°C than conventional rabbit polyclonal anti-FMDV sera. The potential of sdAbs thus produced without sacrificing lab animals could be explored for replacing polyclonal sera in DAS-ELISA as well as for developing biosensors or lateral flow devices for FMDV type O detection.

Persistence of maternal antibodies in calves born of combined foot-and-mouth disease + haemorrhagic septicaemia vaccinated buffaloes at organized dairy farm

Twelve apparently healthy and recently parturiated Murrah buffaloes, vaccinated with Foot-and-mouth disease (FMD) + Haemorrhagic septicaemia (HS) combined vaccine at an organized farm along with their newborn calves were inducted for detection of antibodies in serum and colostrum against FMD virus (FMDV) serotypes O, A and Asia-1, and Pasteurella multocida using enzyme linked immunosorbent assay. The calves born to vaccinated dams showed the presence of protective maternal antibody titre (≥1.8 log10) from birth till the period of study (16th week of age) against FMDV serotypes O, A and Asia-1. The maternal antibody titre against P. multocida were protective (≥1.8 log10) till fifth day of age which became partially protective thereafter till the period of study. It is recommended to avoid vaccination of the calves before 16th week of age with FMD+HS combined vaccine.

Outbreak investigation of foot-and-mouth disease in cattle in Tigray region, Northern Ethiopia.

An investigation of a foot-and-mouth disease (FMD) outbreak was conducted between late October and mid-December 2019 in Tigray region. The outbreak investigation team collected epidemiological data from the six villages of Kafta Humera and Seharti Samre districts, including morbidity proportions, mortality proportions, and clinical signs, and cattle management and vaccination history were collected via participatory methods, including interviews and group discussions with local experts and farmers in Kafta Humera and reports from the district veterinarians in Seharti Samre. Twenty-two tissue samples were collected for laboratory confirmation. Overall, 4,299/9,811 (43.8%) and 13,654/16,921 (80.6%) cattle showed clinical signs for FMD in Kafta Humera and Seharti Samre, respectively. In Kafta Humera, the highest morbidity proportion was found in adult cows and heifers (48.1%), followed by 27.8% in oxen and 15.9% in calves. In Seharti Samre, the morbidity proportion was similar in all age groups at ~81%. No death of FMD-suspected cattle was reported throughout the outbreak. The serotype of foot-and-mouth disease virus (FMDV) identified by laboratory analysis differed between the two districts (serotype O in Kafta Humera and serotype A in Seharti Samre). We, therefore, suggest that the outbreaks in the two districts occurred independently from each other. Experts and farmers were interviewed and believed that the outbreak in Kafta Humera was most likely caused by interaction between cattle and wildlife from the surrounding Kafta Sheraro National Park, which share common grazing land. This outbreak investigation showed that FMD can cause devastating cattle morbidity. A regular vaccination program against the identified circulating FMDV serotypes with sufficient coverage is required to avoid future outbreaks.

Lack of antiviral activity of ivermectin against foot-and-mouth disease virus serotype O in BALB/c mice

Ivermectin is an FDA approved drug and showed in vitro antiviral activity against different serotypes of Foot-and-mouth disease virus (FMDV). We here assessed the effect of ivermectin in 12 day old female BALB/c mice infected with 50LD50 FMDV serotype O intraperitoneally. Initially FMDV was adopted on 3-day old BALB/c mice by blind passages. After successful adaptation of virus mice showed hind limb paralysis. Mice were divided in 6 different groups and each group has 6 mice. Ivermectin was given at clinically prescribed dose of 500 μg/kg subcutaneously at different time interval. Ivermectin was given at 0 h post infection (hpi) and 12 hpi. Moreover we compared commercially available ivermectin with purified ivermectin preparation in sterilized DMSO. Viral load was evaluated through RT-qPCR and ELISA in different groups. Results showed that positive control and negative control has CT-value 26.28 and 38 respectively. Treated groups at 0hpi, 12hpi, purified ivermectin and pre-post treatment group has CT values 24.89, 29.44, 27.26 and 26.69 respectively that showed there was no significant reduction in virus load in treated groups as compare to positive control. In histopathology of lung tissue perialveolar capillaries were congested and alveoli were altelactic. Some emphysema was seen in alveoli and mild thickening in the alveolar wall was observed. In the alveolar epithelium mononuclear cells infiltration was seen. There was discoloration haemorrhages and enlargement of heart. Degeneration, fragmentation and loss of sarcoplasm were seen in the cardiac muscle fibers. Above results showed that ivermectin did not lessen lung and heart viral load. This study contributes that ivermectin does not have a significant antiviral effect when used in mice against FMDV serotype O, according to a growing body of research.

The prevalence of foot-and-mouth disease in Asia.

Foot-and-mouth disease (FMD) is listed among the highly contagious diseases in animals and is endemic throughout the Asian continent. The disease is caused by the Foot-and-mouth disease virus (FMDV) and affects a wide variety of domesticated animals as well as wild ungulates. Clinically, the disease is described as a vesicular lesion on the tongue, muzzle, lips, gum, dental pad, interdigital cleft, coronary band, and heel of the foot. Sometimes these lesions give rise to lameness. Mastitis is also caused due to teat lesions. A biochemical test reveals that during FMD infection, there are elevated levels of interleukin-1 (IL-1), tumor necrosis factor-alpha, interferon-gamma (IFN-γ), interleukin-6, serum amyloid A protein, lactoferrin, mannose-binding lectin, and monocytes chemo-attractant protein-1 in the serum of infected animals. There is no specific treatment for FMD although some antivirals are given as prophylaxis and antibiotics are given to prevent secondary bacterial infection. This review presents comprehensive data on the prevalence of FMD and serotypes of FMDV that are attributable to the cause of FMD from a regional point of view. It also explains the worldwide dynamics of the seven serotypes of FMD and tries to identify epidemiological clusters of FMD in various geographical areas. Furthermore, the pathology associated with the foot and mouth disease virus along with the pathophysiology is discussed. The continent-wide prevalence and diversity patterns of FMD suggest that there is a need for stringent policies and legislation implementation regarding research and development aimed at manufacturing strain-specific vaccination, infection prevention, and control of the disease.

Emergence of a novel sublineage, MYMBD21 under SA-2018 lineage of Foot-and-Mouth Disease Virus serotype O in Bangladesh

Foot-and-Mouth Disease (FMD) hinders the growth of the livestock industry in endemic countries like Bangladesh. The management and prevention of FMD are severely impacted by the high mutation rate and subsequent frequent generation of newer genotypes of the causative agent, Foot-and-Mouth Disease Virus (FMDV). The current study was conducted in nine districts of Bangladesh during 2019–21 to characterize the circulating FMDV strains based on the VP1 sequence analysis, the major antigenic recognition site providing serotype specificity and high variability of FMDV. This study detected the first emergence of the SA-2018 lineage in Bangladesh along with the predominance of Ind-2001e (or Ind-2001BD1) sublineage of ME-SA topotype under serotype O during 2019–21. The mutational spectrum, evolutionary divergence analysis and multidimensional plotting confirmed the isolates collected from Mymensingh districts, designated as MYMBD21 as a novel sublineage under the SA-2018 lineage. Analysis of the amino acid sequence revealed several changes in the G-H loop, B-C loop and C-terminal region of VP1, revealing a 12–13% divergence from the existing vaccine strains and a 95% VP1 protein homology, with most of the mutations potentially considerable as vaccine escape mutations, evidenced by three-dimensional structural analysis. This is the first report on the emergence of the SA-2018 lineage of ME-SA topotype of FMDV serotype O in Bangladesh, as well as a possible mutational trend towards the emergence of a distinct sublineage under SA-2018 lineage, which calls for in-depth genome-wide analysis and monitoring of the FMD situation in the country to implement a strategic vaccination and effective FMD control program.

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.

Production and characterization of monoclonal antibodies against foot-and-mouth disease virus serotype O and development of a sandwich ELISA for virus antigen detection.

Foot-and-mouth disease (FMD) is endemic in India with a majority of outbreaks caused by FMD virus (FMDV) serotype O. In the present study a panel of eight (2F9, 2G10, 3B9, 3H5, 4C8, 4D6, 4G10 and 5B6) mouse monoclonal antibodies (MAbs) were developed against FMDV serotype O Indian vaccine strain, O/IND/R2/75 via hybridoma systems. The MAbs generated were FMDV/O specific without cross-reactivity against FMDV type A and Asia 1. All the MAbs were identified as IgG1/kappa type. Out of eight, three MAbs (3B9, 3H5 and 4G10) demonstrated virus neutralizing activity. The reactivity of all MAbs increased with heat treated (@560C) serotype O antigen compared to untreated antigen in sandwich ELISA indicating that their binding epitopes are linear. Six MAbs (except 2F9 and 4D6) reacted with recombinant P1 protein of homologous virus in an indirect ELISA among which only MAb 3B9 bound to VP1. MAb profiling of 37 serotype O field viruses isolated between the years 1962 and 2021 demonstrated antigenic similarity between field isolates and reference vaccine strain. MAbs 5B6 and 4C8 consistently reacted with all 37 isolates. In indirect immunofluorescence assay MAb 5B6 bound well with FMDV/O antigen. Finally, a sandwich ELISA was successfully developed using rabbit polyclonal anti-FMDV/O serum and MAb 5B6 for detection of FMDV/O antigen in clinical samples (n = 649). The new assay exhibited 100% and 98.89% diagnostic sensitivity and specificity respectively compared to traditional polyclonal antibody-based sandwich ELISA suggesting that the MAb-based ELISA developed here could be an effective method for detection of FMDV serotype O.