Search

Foot-and-mouth disease (FMD) is a highly contagious viral infection causing acute and severe vesicular lesions in cattle and pigs, which has prompted global vaccination policies. This study presents a technique for enhancing antigen yield in SAT1 BOT and SAT3 ZIM by treatment with calcium chloride (CaCl2). We tested changes in cell viability in BHK-21 suspension cells treated with varying concentrations of CaCl2. The optimal CaCl2 concentration was determined based on antigen yield. The timing of CaCl2 supplementation relative to FMD virus inoculation was tested. Finally, the optimal medium for antigen production was identified. We observed a concentration-dependent decrease in BHK-21 cell viability at >7.5 mM CaCl2. A CaCl2 concentration of 3 mM yielded the most antigens. CaCl2 supplementation relative to FMD virus infection was optimal 2 h before or with viral inoculation. CD-BHK 21 medium supplemented with CaCl2 was the most productive medium. Specifically, SAT1 BOT and SAT3 ZIM showed improved antigen production in CD-BHK 21 medium with 3 mM CaCl2, while Provero-1 and Cellvento BHK-200 media showed no significant enhancement. Overall, CaCl2 supplementation enhanced FMD antigen productivity. This study provides a useful framework for enhancing antigen production efficiently in the FMD vaccine industry. [ABSTRACT FROM AUTHOR]

Since the early 2000s outbreaks of foot-and-mouth disease (FMD) have been described in several previously FMD-free Asian nations, including the Republic of Korea (South Korea). One outbreak with FMD virus (FDMV) serotype A and two with serotype O occurred in South Korea in 2010/2011. The causative viruses belonged to lineages that had been spreading in South East Asia, far East and East Asia since 2009 and presented a great threat to the countries in that region. Most FMDV strains infect ruminants and pigs, as it happened during the outbreaks of FMDV serotype O in South Korea. Contrastingly, the strain of serotype A affected only ruminants. Based upon these findings, the intention of the work described in the current report was to characterize and compare the infectivity, virulence and transmission of both strains under laboratory conditions in cattle and pigs, by direct inoculation and contact exposure. As expected, FMDV serotype O was highly virulent in both cattle and swine by contact exposure and direct inoculation. Surprisingly, FMDV serotype A was highly virulent in swine, but was less infectious in cattle by contact exposure to infected swine or cattle. Interestingly, similar quantities of aerosolized FMDV RNA were detected during experiments with viruses of serotypes O and A. Specific virus-host interaction of A/SKR/2010 could affect the transmission of this strain to cattle, and this may explain in part the limited spread of the serotype A epizootic. [ABSTRACT FROM AUTHOR]

For effective control of foot-and-mouth disease (FMD), the development of rapid diagnostic systems and vaccines are required against its etiological agent, FMD virus (FMDV). To accomplish this, efficient large-scale expression of the FMDV VP1 protein, with high solubility, needs to be optimized. We attempted to produce high levels of a serotype O FMDV VP1 epitope in Escherichia coli. We identified the subtype-independent serotype O FMDV VP1 epitope sequence and used it to construct a glutathione S-transferase (GST) fusion protein. For efficient production of the FMDV VP1 epitope fused to GST (VP1e-GST), four E. coli strains and three temperatures were examined. The conditions yielding the greatest level of VP1e-GST with highest solubility were achieved with E. coli BL21(DE3) at 25 °C. For high-level production, fed-batch cultures were conducted in 5-l bioreactors. When cells were induced at a high density and complex feeding solutions were supplied, approximately 11 g of VP1e-GST was obtained from a 2.9-l culture. Following purification, the VP1 epitope was used to immunize rabbits, and we confirmed that it induced an immune response. [ABSTRACT FROM AUTHOR]

An outbreak of foot-and-mouth disease caused by serotype O virus occurred in cattle and pigs in South Korea during November 2010-April 2011. The highest rates of case and virus detection were observed 44 days after the first case was detected. Detection rates declined rapidly after culling and completion of a national vaccination program. [ABSTRACT FROM AUTHOR]

Abstract: A recombinant protein-based ELISA was evaluated for detecting antibodies to foot-and-mouth disease virus (FMDV) serotype Asia 1. The recombinant protein (rP13C) was derived from the P1 precursor and 3C protease genes that were cloned into a single expression vector and expressed in insect cells. This protein elicited a low titer of FMDV neutralizing antibodies in pigs. Its utility as a diagnostic antigen was explored in a blocking ELISA using monoclonal antibodies. The rP13C ELISA yielded higher endpoint titers than the liquid phase blocking (LPB) ELISA and virus neutralization test performed on sera from goats challenged with FMDV post-vaccination. The rP13C ELISA correctly scored the FMD international reference weak positive serum. The relative sensitivity between the rP13C ELISA and LPB ELISA was equivalent for vaccinated sera. With this comparable sensitivity, the rP13C ELISA exhibited a specificity of 99.7% for domestic naive swine, bovine and caprine sera. This report demonstrates that an ELISA using recombinant proteins has the potential to replace the LPB ELISA using an inactivated FMDV antigen as a simple and robust serological tool for screening antibodies to FMDV serotype Asia 1. [Copyright &y& Elsevier]

Abstract: Six field foot-and-mouth disease viruses (FMDVs), including four serotype O and two serotype Asia 1 strains, were collected from endemic outbreaks in 2005, 2006, and 2007 from four different provinces in Vietnam. The viruses were isolated and genetically characterized for their complete genomic sequences. The genetic analysis based on the complete genomic coding sequences revealed that the four serotype O FMDVs were related to each other, sharing 95.2% nucleotide (nt) identity and 97.5–97.6% amino acid (aa) identity. Genetic analysis and a phylogenetic tree, based on the VP1 gene of FMDV, showed that the four present Vietnamese serotype O strains have a high level of identity with other serotype O representatives of the Mya-98 lineage of the Southeast Asian (SEA) topotype. The four viruses were all clustered into the Mya-98 lineage of the SEA topotype, sharing 92.3–95.6% nt and 93.4–96.7% aa identity. This finding of the Mya-98 lineage was different from previous reports that the Vietnamese serotype O strains belonged to the Cam-94 lineage of the SEA topotype and two other topotypes, Middle East-South Asia (ME-SA) and Cathay. For the two serotype Asia 1 FMDVs, the genetic analysis based on the complete genomic coding sequences as well as on the VP1 gene revealed that they belonged to two genogroups, IV and V. Of note, the As1/VN/QT03/2007 strain of genogroup V, isolated in 2007, was very closely related to the pandemic Asia 1 strain which caused FMD outbreaks in China (Asia1/WHN/CHA/06, FJ906802) and Mongolia (Asia1/MOG/05, EF614458) in 2005, sharing 99.0–99.3% nt and 99.5–100% aa identity. In contrast, the second strain As1/VN/LC04/2005 of genogroup IV, isolated in 2005, was closely related to all referenced Vietnamese serotype Asia 1 strains found in the GenBank databases, sharing 86.4–100% nt and 90.9–100% aa identity with each. This study is the first description of the full-length genomic sequence of Vietnamese FMDV serotypes O and Asia 1 and may provide the evidence of the concurrent circulation of different serotypes and subtypes of FMDV in recent years in Vietnam. [Copyright &y& Elsevier]

Abstract: Foot-and-mouth disease (FMD) is a major cause of endemic outbreaks in Vietnam in recent years. In this work, six serotype A foot-and-mouth disease viruses (FMDV), collected from endemic outbreaks during January and February of 2009 in four different provinces in Vietnam, were genetically characterized for their complete genome sequences. Genetic analysis based on the complete viral genome sequence indicated that they were closely related to each other and shared 99.0–99.8% amino acid (aa) identity. Genetic and deduced aa analysis of the capsid coding gene VP1 showed that the six Vietnamese strains were all classified into the genotype IX from a total of 10 major genotypes worldwide, sharing 98.1–100% aa identity each other. They were most closely related to the type A strains recently isolated in Laos (A/LAO/36/2003, A/LAO/1/2006, A/LAO/6/2006, A/LAO/7/2006, and A/LAO/8/2006), Thailand (A/TAI/2/1997 and A/TAI/118/1987), and Malaysia (A/MAY/2/2002), sharing 88.3–95.5% nucleotide (nt) identities. In contrast, Vietnamese type A strains showed low nt identities with the two old type A FMDVs, isolated in 1960 in Thailand (a15thailand iso43) and in 1975 in the Philippines (aphilippines iso50), ranging from 77.3 to 80.9% nt identity. A multiple alignment based on the deduced amino acid sequences of the capsid VP1 coding gene of type A FMDV revealed three amino acid substitutions between Vietnamese strains and the strains of other Southeast Asian countries (Laos, Thailand, Malaysia, and the Philippines). Alanine was replaced by valine at residue 24, asparagine by arginine at residue 85, and serine by threonine at residue 196. Furthermore, type A FMDV strains recently isolated in Vietnam, Laos, Thailand, and Malaysia all have one amino acid deletion at residue 140 of the capsid VP1 protein compared with the two old type A FMDV strains from Thailand and the Philippines as well as most other type A representatives worldwide. This article is the first to report on the comprehensive genetic characterization of type A FMDV circulating in Vietnam. [Copyright &y& Elsevier]