Mutation of FMDV Lpro H138 residue drives viral attenuation in cell culture and in vivo in swine

The foot-and-mouth disease virus (FMDV) leader proteinase (L^pro) is a papain like protease that cleaves the viral polyprotein and several host factors affecting host cell translation and induction of innate immunity. Introduction of L^pro mutations ablating catalytic activity is not tolerated by the virus, however, complete coding sequence deletion or introduction of targeted amino acid substitutions can render viable progeny. In proof-of-concept studies, we have previously identified and characterized FMDV L^pro mutants that are attenuated in cell culture and in animals, while retaining their capacity for inducing a strong adaptive immunity. By using molecular modeling, we have now identified a His residue (H138), that resides outside the substrate binding and catalytic domain, and is highly conserved across serotypes. Mutation of H138 renders possible FMDV variants of reduced virulence in vitro and in vivo. Kinetics studies showed that FMDV A12-L_H138L mutant replicates similarly to FMDV A12-wild type (WT) virus in cells that do not offer immune selective pressure, but attenuation is observed upon infection of primary or low passage porcine epithelial cells. Western blot analysis on protein extracts from these cells, revealed that while processing of translation initiation factor eIF-4G was slightly delayed, no degradation of innate sensors or effector molecules such as NF-κB or G3BP2 was observed, and higher levels of interferon (IFN) and IFN-stimulated genes (ISGs) were induced after infection with A12-L_H138L as compared to WT FMDV. Consistent with the results in porcine cells, inoculation of swine with this mutant resulted in a mild, or in some cases, no clinical disease but induction of a strong serological adaptive immune response. These results further support previous evidence that L^pro is a reliable target to derive numerous viable FMDV strains that alone or in combination could be exploited for the development of novel FMD vaccine platforms.

Phylogeographic analysis of foot-and-mouth disease virus serotype O dispersal and associated drivers in East Africa

The continued endemicity of foot and mouth disease virus (FMDV) in East Africa has significant implications for livestock production and poverty reduction, yet its complex epidemiology in endemic settings remains poorly understood. Identifying FMDV dispersal routes and drivers of transmission is key to improved control strategies. Environmental heterogeneity and anthropogenic drivers (e.g., demand for animal products) can impact viral spread by influencing host movements. Here, we utilized FMDV serotype O VP1 genetic sequences and corresponding spatiotemporal data in order to (i) infer the recent dispersal history, and (II) investigate the impact of external factors (cattle density, human population density, proximity to livestock markets, and drought) on dispersal velocity, location, and direction of FMDV serotype O in East Africa. We identified statistical evidence of long-distance transmission events, and we found that FMDV serotype O tends to remain circulating in areas of high cattle density, high human population density, and in close proximity to livestock markets. The latter two findings highlight the influence of anthropogenic factors on FMDV serotype O spread in this region. These findings contribute to the understanding of FMDV epidemiology in East Africa and can help guide improved control measures.

Use of Synonymous Deoptimization to Derive Modified Live Attenuated Strains of Foot and Mouth Disease Virus

Foot-and-mouth disease (FMD) is one of the most economically important viral diseases that can affect livestock. In the last 70 years, use of an inactivated whole antigen vaccine has contributed to the eradication of disease from many developed nations. However, recent outbreaks in Europe and Eastern Asia demonstrated that infection can spread as wildfire causing economic and social devastation. Therefore, it is essential to develop new control strategies that could confer early protection and rapidly stop disease spread. Live attenuated vaccines (LAV) are one of the best choices to obtain a strong early and long-lasting protection against viral diseases. In proof of concept studies, we previously demonstrated that “synonymous codon deoptimization” could be applied to the P1 capsid coding region of the viral genome to derive attenuated FMDV serotype A12 strains. Here, we demonstrate that a similar approach can be extended to the highly conserved non-structural P2 and P3 coding regions, providing a backbone for multiple serotype FMDV LAV development. Engineered codon deoptimized P2, P3 or P2, and P3 combined regions were included into the A₂₄Cruzeiro infectious clone optimized for vaccine production, resulting in viable progeny that exhibited different degrees of attenuation in cell culture, in mice, and in the natural host (swine). Derived strains were thoroughly characterized in vitro and in vivo. Our work demonstrates that overall, the entire FMDV genome tolerates codon deoptimization, highlighting the potential of using this technology to derive novel improved LAV candidates.

Novel Foot-and-Mouth Disease Vaccine Platform: Formulations for Safe and DIVA-Compatible FMD Vaccines With Improved Potency

Inactivated, wild-type foot-and-mouth disease virus (FMDV) vaccines are currently used to control FMD around the world. These traditional FMD vaccines are produced using large quantities of infectious, virulent, wild-type FMD viruses, with the associated risk of virus escape from manufacturing facilities or incomplete inactivation during the vaccine formulation process. While higher quality vaccines produced from wild-type FMDV are processed to reduce non-structural antigens, there is still a risk that small amounts of non-structural proteins may be present in the final product. A novel, antigenically marked FMD-LL3B3D vaccine platform under development by Zoetis, Inc. and the USDA-ARS, consists of a highly attenuated virus platform containing negative antigenic markers in the conserved non-structural proteins 3D^pol and 3B that render resultant vaccines fully DIVA compatible. This vaccine platform allows for the easy exchange of capsid coding sequences to create serotype-specific vaccines. Here we demonstrate the efficacy of the inactivated FMD-LL3B3D-A₂₄ Cruzeiro vaccine in cattle against wild-type challenge with A₂₄ Cruzerio. A proprietary adjuvant system was used to formulate the vaccines that conferred effective protection at low doses while maintaining the DIVA compatibility. In contrast to wild-type FMDV, the recombinant FMD-LL3B3D mutant viruses have been shown to induce no clinical signs of FMD and no shedding of virus in cattle or pigs when inoculated as a live virus. The FMD-LL3B3D vaccine platform, currently undergoing development in the US, provides opportunities for safer vaccine production with full DIVA compatibility in support of global FMDV control and eradication initiatives.

Diagnostic and Epitope Mapping Potential of Single-Chain Antibody Fragments Against Foot-and-Mouth Disease Virus Serotypes A, SAT1, and SAT3

Foot-and-mouth disease (FMD) affects cloven-hoofed domestic and wildlife animals and an outbreak can cause severe losses in milk production, reduction in meat production and death amongst young animals. Several parts of Asia, most of Africa, and the Middle East remain endemic, thus emphasis on improved FMD vaccines, diagnostic assays, and control measures are key research areas. FMD virus (FMDV) populations are quasispecies, which pose serious implications in vaccine design and efficacy where an effective vaccine should include multiple independent neutralizing epitopes to elicit an adequate immune response. Further investigation of the residues that comprise the antigenic determinants of the virus will allow the identification of mutations in outbreak strains that potentially lessen the efficacy of a vaccine. Additionally, of utmost importance in endemic regions, is the accurate diagnosis of FMDV infection for the control and eradication of the disease. To this end, a phage display library was explored to identify FMDV epitopes for recombinant vaccines and for the generation of reagents for improved diagnostic FMD enzyme-linked immunosorbent assays (ELISAs). A naïve semi-synthetic chicken single chain variable fragment (scFv) phage display library i.e., the Nkuku ^® library was used for bio-panning against FMD Southern-African Territories (SAT) 1, SAT3, and serotype A viruses. Biopanning yielded one unique scFv against SAT1, two for SAT3, and nine for A22. SAT1 and SAT3 specific scFvs were exploited as capturing and detecting reagents to develop an improved diagnostic ELISA for FMDV. The SAT1 soluble scFv showed potential as a detecting reagent in the liquid phase blocking ELISA (LPBE) as it reacted specifically with a panel of SAT1 viruses, albeit with different ELISA absorbance signals. The SAT1svFv1 had little or no change on its paratope when coated on polystyrene plates whilst the SAT3scFv's paratope may have changed. SAT1 and SAT3 soluble scFvs did not neutralize the SAT1 and SAT3 viruses; however, three of the nine A22 binders i.e., A22scFv1, A22scFv2, and A22scFv8 were able to neutralize A22 virus. Following the generation of virus escape mutants through successive virus passage under scFv pressure, FMDV epitopes were postulated i.e., RGD+3 and +4 positions respectively, proving the epitope mapping potential of scFvs.

Foot-and-Mouth Disease Virus Lacking the Leader Protein and Containing Two Negative DIVA Markers (FMDV LL3B3D A24) Is Highly Attenuated in Pigs

Inactivated whole-virus vaccines are widely used for the control of foot-and-mouth disease (FMD). Their production requires the growth of large quantities of virulent FMD virus in biocontainment facilities, which is expensive and carries the risk of an inadvertent release of virus. Attenuated recombinant viruses lacking the leader protease coding region have been proposed as a safer alternative for the production of inactivated FMD vaccines (Uddowla et al., 2012, J Virol 86:11675-85). In addition to the leader deletion, the marker vaccine virus FMDV LL3B_PVKV3D_YR A₂₄ encodes amino acid substitutions in the viral proteins 3B and 3D that allow the differentiation of infected from vaccinated animals and has been previously shown to be effective in cattle and pigs. In the present study, two groups of six pigs each were inoculated with live FMDV LL3B_PVKV3D_YR A₂₄ virus either intradermally into the heel bulb (IDHB) or by intra-oropharyngeal (IOP) deposition. The animals were observed for 3 or 5 days after inoculation, respectively. Serum, oral and nasal swabs were collected daily and a thorough postmortem examination with tissue collection was performed at the end of the experiment. None of the animals had any signs of disease or virus shedding. Virus was reisolated from only one serum sample (IDHB group, sample taken on day 1) and one piece of heel bulb skin from the inoculation site of another animal (IDHB group, necropsy on day 3), confirming that FMDV LL3B_PVKV3D_YR A₂₄ is highly attenuated in pigs.

Duration of protection and humoral immunity induced by an adenovirus-vectored subunit vaccine for foot-and-mouth disease (FMD) in Holstein steers

Foot-and-mouth disease (FMD) is a highly contagious viral infection of cloven hooved animals that continues to cause economic disruption in both endemic countries or when introduced into a formally FMD free country. Vaccines that protect against clinical disease and virus shedding are critical to control FMD. The replication deficient human adenovirus serotype 5 (Ad5) vaccine vector expressing empty FMD virus (FMDV) capsid, AdtFMD, is a promising new vaccine platform. With no shedding or spreading of viral vector detected in field trials, this vaccine is very safe to manufacture, as there is no requirement for high containment faciitites. Here, we describe three studies assessing the proportion of animals protected from clinical vesicular disease (foot lesions) following live-FMDV challenge by intradermolingual inoculation at 6 or 9 months following a single vaccination with the commercial AdtFMD vaccine, provisionally licensed for cattle in the United States. Further, we tested the effect of vaccination route (transdermal, intramuscular, subcutaneous) on clinical outcome and humoral immunity. Results demonstrate that a single dose vaccination in cattle with the commercial vaccine vector expressing capsid proteins of the FMDV strain A24 Cruzeiro (Adt.A24), induced protection against clinical FMD at 6 months (100% transdermal, 80% intramuscular, and 60% subcutaneous) that waned by 9 months post-vaccination (33% transdermal and 20% intramuscular). Post-vaccination serum from immunized cattle (all studies) generally contained FMDV specific neutralizing antibodies by day 14. Anti-FMDV antibody secreting cells are detected in peripheral blood early following vaccination, but are absent after 28 days post-vaccination. Thus, the decay in antibody mediated immunity over time is likely a function of FMDV-specific antibody half-life. These data reveal the short time span of anti-FMDV antibody secreting cells (ASCs) and important performance characteristics of needle-free vaccination with a recombinant vectored subunit vaccine for FMDV.

Spatial distribution and risk factors for foot and mouth disease virus in Uganda: Opportunities for strategic surveillance

Foot-and-mouth disease virus (FMDV) has a substantial impact on cattle populations in Uganda, causing short- and long-term production losses and hampering local and international trade. Although FMDV has persisted in Uganda for at least 60 years, its epidemiology there and in other endemic settings remains poorly understood. Here, we utilized a large-scale cross-sectional study of cattle to elucidate the dynamics of FMDV spread in Uganda. Sera samples (n = 14,439) from 211 herds were analyzed for non-structural protein reactivity, an indication of past FMDV exposure. Serological results were used to determine spatial patterns, and a Bayesian multivariable logistic regression mixed model was used to identify risk factors for FMDV infection. Spatial clustering of the disease was evident, with higher risk demonstrated near international borders. Additionally, high cattle density, low annual rainfall, and pastoralism were associated with increased likelihood of FMD seropositivity. These results provide insights into the complex epidemiology of FMDV in Uganda and will help inform refined control strategies in Uganda and other FMDV-endemic settings.

Serological and phylogenetic characterization of foot and mouth disease viruses from Uganda during cross-sectional surveillance study in cattle between 2014 and 2017

Here, we report the results of a cross-sectional study designed to monitor the circulation and genetic diversity of foot and mouth disease virus (FMDV) in Uganda between 2014 and 2017. In this study, 13,614 sera and 2,068 oral-pharyngeal fluid samples were collected from cattle and analysed to determine FMDV seroprevalence, circulating serotypes and their phylogenetic relationships. Circulation of FMDV was evidenced by the detection of antibodies against non-structural proteins of FMDV or viral isolations in all districts sampled in Uganda. Sequence analysis revealed the presence of FMDV serotypes A, O, SAT 1 and SAT 2. FMDVs belonging to serotype O, isolated from 21 districts, were the most prevalent and were classified into six lineages within two East African topotypes, namely EA-1 and EA-2. Serotype A viruses belonging to the Africa G-I topotype were isolated from two districts. SAT 1 viruses grouped within topotypes I and IV and SAT 2 viruses within topotypes VII, IV and X were isolated from six and four districts respectively. Phylogenetic analysis of SAT 1 and SAT 2 sequences from cattle clustered with historical sequences from African buffalo, indicating possible interspecies transmission at the wildlife-livestock interface. In some cases, Uganda viruses also shared similarities to viral strains recovered from other regions in East Africa. This 3-year study period provides knowledge about the geographical distribution of FMDV serotypes isolated in Uganda and insights into the genetic diversity of the multiple serotypes circulating in the country. Knowledge of circulating FMDV viruses will assist in antigenic matching studies to devise improved FMDV control strategies with vaccination and vaccine strain selection for Uganda.

The evolution of a super-swarm of foot-and-mouth disease virus in cattle

Foot-and-mouth disease (FMD) is a highly contagious viral disease that severely impacts global food security and is one of the greatest constraints on international trade of animal products. Extensive viral population diversity and rapid, continuous mutation of circulating FMD viruses (FMDVs) pose significant obstacles to the control and ultimate eradication of this important transboundary pathogen. The current study investigated mechanisms contributing to within-host evolution of FMDV in a natural host species (cattle). Specifically, vaccinated and non-vaccinated cattle were infected with FMDV under controlled, experimental conditions and subsequently sampled for up to 35 days to monitor viral genomic changes as related to phases of disease and experimental cohorts. Consensus-level genomic changes across the entire FMDV coding region were characterized through three previously defined stages of infection: early, transitional, and persistent. The overall conclusion was that viral evolution occurred via a combination of two mechanisms: emergence of full-genomic minority haplotypes from within the inoculum super-swarm, and concurrent continuous point mutations. Phylogenetic analysis indicated that individuals were infected with multiple distinct haplogroups that were pre-existent within the ancestral inoculum used to infect all animals. Multiple shifts of dominant viral haplotype took place during the early and transitional phases of infection, whereas few shifts occurred during persistent infection. Overall, this work suggests that the establishment of the carrier state is not associated with specific viral genomic characteristics. These insights into FMDV population dynamics have important implications for virus sampling methodology and molecular epidemiology.

The evolution of a super-swarm of foot-and-mouth disease virus in cattle

Foot-and-mouth disease (FMD) is a highly contagious viral disease that severely impacts global food security and is one of the greatest constraints on international trade of animal products. Extensive viral population diversity and rapid, continuous mutation of circulating FMD viruses (FMDVs) pose significant obstacles to the control and ultimate eradication of this important transboundary pathogen. The current study investigated mechanisms contributing to within-host evolution of FMDV in a natural host species (cattle). Specifically, vaccinated and non-vaccinated cattle were infected with FMDV under controlled, experimental conditions and subsequently sampled for up to 35 days to monitor viral genomic changes as related to phases of disease and experimental cohorts. Consensus-level genomic changes across the entire FMDV coding region were characterized through three previously defined stages of infection: early, transitional, and persistent. The overall conclusion was that viral evolution occurred via a combination of two mechanisms: emergence of full-genomic minority haplotypes from within the inoculum super-swarm, and concurrent continuous point mutations. Phylogenetic analysis indicated that individuals were infected with multiple distinct haplogroups that were pre-existent within the ancestral inoculum used to infect all animals. Multiple shifts of dominant viral haplotype took place during the early and transitional phases of infection, whereas few shifts occurred during persistent infection. Overall, this work suggests that the establishment of the carrier state is not associated with specific viral genomic characteristics. These insights into FMDV population dynamics have important implications for virus sampling methodology and molecular epidemiology.

The Development and Validation of a Novel Nanobody-Based Competitive ELISA for the Detection of Foot and Mouth Disease 3ABC Antibodies in Cattle

Effective management of foot and mouth disease (FMD) requires diagnostic tests to distinguish between infected and vaccinated animals (DIVA). To address this need, several enzyme-linked immunosorbent assay (ELISA) platforms have been developed, however, these tests vary in their sensitivity and specificity and are very expensive for developing countries. Camelid-derived single-domain antibodies fragments so-called Nanobodies, have demonstrated great efficacy for the development of serological diagnostics. This study describes the development of a novel Nanobody-based FMD 3ABC competitive ELISA, for the serological detection of antibodies against FMD Non-Structural Proteins (NSP) in Uganda cattle herds. This in-house ELISA was validated using more than 600 sera from different Uganda districts, and virus serotype specificities. The evaluation of the performance of the assay demonstrated high diagnostic sensitivity and specificity of 94 % (95 % CI: 88.9-97.2), and 97.67 % (95 % CI: 94.15-99.36) respectively, as well as the capability to detect NSP-specific antibodies against multiple FMD serotype infections. In comparison with the commercial PrioCHECK FMDV NSP-FMD test, there was a strong concordance and high correlation and agreement in the performance of the two tests. This new developed Nanobody based FMD 3ABC competitive ELISA could clearly benefit routine disease diagnosis, the establishment of disease-free zones, and the improvement of FMD management and control in endemically complex environments, such as those found in Africa.

An improved, rapid competitive ELISA using a novel conserved 3B epitope for the detection of serum antibodies to foot-and-mouth disease virus

The highly contagious foot-and-mouth disease virus (FMDV) afflicts cloven-hoofed animals, resulting in significant costs because of loss of trade and recovery from disease. We developed a sensitive, specific, and rapid competitive ELISA (cELISA) to detect serum antibodies to FMDV. The cELISA utilized a monoclonal blocking antibody specific for a highly conserved FMDV nonstructural 3B epitope, a recombinant mutant FMDV 3ABC coating protein, and optimized format variables including serum incubation for 90 min at 20-25°C. Samples from 16 animals experimentally infected with one FMDV serotype (A, O, Asia, or SAT-1) demonstrated early detection capacity beginning 7 d post-inoculation. All samples from 55 vesicular stomatitis virus antibody-positive cattle and 44 samples from cloven-hoofed animals affected by non-FMD vesicular diseases were negative in the cELISA, demonstrating 100% analytical specificity. The diagnostic sensitivity was 100% against sera from 128 cattle infected with isolates of all FMDV serotypes, emphasizing serotype-agnostic results. Diagnostic specificities of U.S. cattle ( n = 1135) and swine ( n = 207) sera were 99.4% and 100%, respectively. High repeatability and reproducibility were demonstrated with 3.1% coefficient of variation in percent inhibition data and 100% agreement using 2 kit lots and 400 negative control serum samples, with no difference between bench and biosafety cabinet operation. Negative results from vaccinated, uninfected cattle, pig, and sheep sera confirmed the DIVA (differentiate infected from vaccinated animals) capability. This rapid (<3 h), select agent-free assay with high sensitivity and specificity, DIVA capability, and room temperature processing capability will serve as a useful tool in FMDV surveillance, emergency preparedness, response, and outbreak recovery programs.

The Roles of Picornavirus Untranslated Regions in Infection and Innate Immunity

Viral genomes have evolved to maximize their potential of overcoming host defense mechanisms and to induce a variety of disease syndromes. Structurally, a genome of a virus consists of coding and noncoding regions, and both have been shown to contribute to initiation and progression of disease. Accumulated work in picornaviruses has stressed out the importance of the noncoding RNAs, or untranslated 5′- and 3′-regions (UTRs), in both replication and translation of viral genomes. Unsurprisingly, defects in these processes have been reported to cause viral attenuation and affect viral pathogenicity. However, substantial evidence suggests that these untranslated RNAs may influence the outcome of the host innate immune response. This review discusses the involvement of 5′- and 3′-terminus UTRs in induction and regulation of host immunity and its consequences for viral life cycle and virulence.

Update on the management of Barrett's esophagus in Austria

Background

Barrett’s esophagus (BE) is the premalignant manifestation of gastroesophageal reflux disease (GERD). Radiofrequency ablation (RFA) with and without endoscopic resection (ER) is a novel treatment for BE.

Methods

Here we present a single-center update of the recommendations of a recent (June 2015) interdisciplinary expert panel meeting on the management of BE with dysplasia as well as cancer-positive and cancer-negative BE. We conducted a PubMed search of studies published in 2016 and 2017 on the topic of BE and RFA.

Results

Our update reconfirms that BE positive for T1a cancer as well as low- and high-grade dysplasia justifies the use of RFA ± ER, offering an 80–100% rate of BE clearance. RFA ± ER of dysplastic BE is tenfold more effective for cancer prevention when compared with surveillance. Risk factors for recurrence and follow-up treatments include baseline histopathology (dysplasia/T1a cancer), esophagitis, hiatal hernia >3 cm, smoking habits, BE segments >3 cm, and >10 years of GERD symptoms. A baseline diagnosis for dysplasia and T1a cancer should include a second expert pathologist opinion. Recent data justify the use of RFA for nondysplastic BE only in controlled clinical trials. Antireflux surgery can be offered to those with function-test-proven, GERD-symptom-positive BE before, during, or after RFA ± ER. Additionally, there is growing evidence that the intake of a sugar-rich diet is positively correlated with the development of GERD, BE, and cancer.

Conclusion

RFA ± ER should be offered for dysplastic BE and T1a cancer after ER as well as for nondysplastic BE with additional risk factors in controlled trials. Antireflux surgery can be offered to patients with function-test-proven GERD-symptom-positive BE. Diet considerations should be included in the management of GERD and BE.

Dietary sugar and Barrett's esophagus

Introduction

Barrett’s esophagus (BE) represents the premalignant morphology of gastroesophageal reflux disease (GERD). Evidence indicates a positive correlation between GERD vs. obesity and increased sugar consumption.

Methods

Here we analyzed recently published data (2006–2017) on the role of dietary sugar intake for BE development (main focus year 2017).

Results

Recent investigations found a positive association between obesity, hip waist ratio and dietary sugar intake and Barrett’s esophagus.

Conclusion

Sugar intake positively associates with BE. A low carbohydrate diet should be recommended for persons with BE and GERD.

Attenuation of Foot-and-Mouth Disease Virus by Engineered Viral Polymerase Fidelity

Foot-and-mouth disease virus (FMDV) RNA-dependent RNA polymerase (RdRp) (3Dpol) catalyzes viral RNA synthesis. Its characteristic low fidelity and absence of proofreading activity allow FMDV to rapidly mutate and adapt to dynamic environments. In this study, we used the structure of FMDV 3Dpol in combination with previously reported results from similar picornaviral polymerases to design point mutations that would alter replication fidelity. In particular, we targeted Trp237 within conserved polymerase motif A because of the low reversion potential inherent in the single UGG codon. Using biochemical and genetic tools, we show that the replacement of tryptophan 237 with phenylalanine imparts higher fidelity, but replacements with isoleucine and leucine resulted in lower-fidelity phenotypes. Viruses containing these W237 substitutions show in vitro growth kinetics and plaque morphologies similar to those of the wild-type (WT) A24 Cruzeiro strain in BHK cells, and both high- and low-fidelity variants retained fitness during coinfection with the wild-type virus. The higher-fidelity W237F (W237FHF) mutant virus was more resistant to the mutagenic nucleoside analogs ribavirin and 5-fluorouracil than the WT virus, whereas the lower-fidelity W237I (W237ILF) and W237LLF mutant viruses exhibited lower ribavirin resistance. Interestingly, the variant viruses showed heterogeneous and slightly delayed growth kinetics in primary porcine kidney cells, and they were significantly attenuated in mouse infection experiments. These data demonstrate, for a single virus, that either increased or decreased RdRp fidelity attenuates virus growth in animals, which is a desirable feature for the development of safer and genetically more stable vaccine candidates.IMPORTANCE Foot-and-mouth disease (FMD) is the most devastating disease affecting livestock worldwide. Here, using structural and biochemical analyses, we have identified FMDV 3Dpol mutations that affect polymerase fidelity. Recombinant FMDVs containing substitutions at 3Dpol tryptophan residue 237 were genetically stable and displayed plaque phenotypes and growth kinetics similar to those of the wild-type virus in cell culture. We further demonstrate that viruses harboring either a W237FHF substitution or W237ILF and W237LLF mutations were highly attenuated in animals. Our study shows that obtaining 3Dpol fidelity variants by protein engineering based on polymerase structure and function could be exploited for the development of attenuated FMDV vaccine candidates that are safer and more stable than strains obtained by selective pressure via mutagenic nucleotides or adaptation approaches.

Enhanced sensitivity in detection of antiviral antibody responses using biotinylation of foot-and-mouth disease virus (FMDV) capsids

Analysis of the immune response to infection of livestock by foot-and-mouth disease virus (FMDV) is most often reported as the serum antibody response to the virus. While measurement of neutralizing antibody has been sensitive and specific, measurements of the quality of the antibody response are less robust. Determining the immunoglobulin (Ig) isotype of the serum antibody response provides a deeper understanding of the biology of the response and more sensitive methods for these assays will facilitate analyses of B cell mediated immunity. We tested the hypothesis that using the virus as the molecular probe could be achieved by adding tags to the surface of the FMDV capsid, and that would enhance sensitivity in assays for anti-FMDV antibody responses. The use of a FLAG-tagged virus in these assays failed to yield improvement whereas chemically biotinylating the virus capsid resulted in significant enhancement of the signal. Here we describe methods using biotinylated virus for measuring anti-viral antibody in serum and antibody secreting cells (ASCs) in blood that are sensitive and specific. Finally, we describe using the biotinylated virus in flow cytometry where such assays should greatly enhance the analysis of anti-virus antibody producing B cells, allowing the investigator to focus on only the FMDV specific B cells when analyzing the development of the B cell response to either infection or vaccination.

Endoscopic stent suture fixation for prevention of esophageal stent migration during prolonged dilatation for achalasia treatment

The aim of this study is to compare endoscopic stent suture fixation with endoscopic clip attachment or the use of partially covered stents (PCS) regarding their capability to prevent stent migration during prolonged dilatation in achalasia. Large-diameter self-expanding metal stents (30 mm × 80 mm) were placed across the gastroesophageal junction in 11 patients with achalasia. Stent removal was scheduled after 4 to 7 days. To prevent stent dislocation, endoscopic clip attachment, endoscopic stent suture fixation, or PCS were used. The Eckardt score was evaluated before and 6 months after prolonged dilatation. After endoscopic stent suture fixation, no (0/4) sutured stent migrated. When endoscopic clips were used, 80% (4/5) clipped stents migrated (p = 0.02). Of two PCS (n = 2), one migrated and one became embedded leading to difficult stent removal. Technical adverse events were not seen in endoscopic stent suture fixation but were significantly correlated with the use of clips or PCS (r = 0.828, p = 0.02). Overall, 72% of patients were in remission regarding their achalasia symptoms 6 months after prolonged dilatation. Endoscopic suture fixation of esophageal stents but not clip attachment appears to be the best method of preventing early migration of esophageal stents placed at difficult locations such as at the naive gastroesophageal junction.

Insights into Jumonji C-domain containing protein 6 (JMJD6): a multifactorial role in foot-and-mouth disease virus replication in cells

The Jumonji C-domain containing protein 6 (JMJD6) has had a convoluted history, and recent reports indicating a multifactorial role in foot-and-mouth disease virus (FMDV) infection have further complicated the functionality of this protein. It was first identified as the phosphatidylserine receptor on the cell surface responsible for recognizing phosphatidylserine on the surface of apoptotic cells resulting in their engulfment by phagocytic cells. Subsequent study revealed a nuclear subcellular localization, where JMJD6 participated in lysine hydroxylation and arginine demethylation of histone proteins and other non-histone proteins. Interestingly, to date, JMDJ6 remains the only known arginine demethylase with a growing list of known substrate molecules. These conflicting associations rendered the subcellular localization of JMJD6 to be quite nebulous. Further muddying this area, two different groups illustrated that JMJD6 could be induced to redistribute from the cell surface to the nucleus of a cell. More recently, JMJD6 was demonstrated to be a host factor contributing to the FMDV life cycle, where it was not only exploited for its arginine demethylase activity, but also served as an alternative virus receptor. This review attempts to coalesce these divergent roles for a single protein into one cohesive account. Given the diverse functionalities already characterized for JMJD6, it is likely to continue to be a confounding protein resulting in much contention going into the near future.

Interaction between FMDV Lpro and transcription factor ADNP is required for optimal viral replication

The foot-and-mouth disease virus (FMDV) leader protease (L^pro) inhibits host translation and transcription affecting the expression of several factors involved in innate immunity. In this study, we have identified the host transcription factor ADNP (activity dependent neuroprotective protein) as an L^pro interacting protein by mass spectrometry. We show that L^pro can bind to ADNP in vitro and in cell culture. RNAi of ADNP negatively affected virus replication and higher levels of interferon (IFN) and IFN-stimulated gene expression were detected. Importantly, infection with FMDV wild type but not with a virus lacking Lpro (leaderless), induced recruitment of ADNP to IFN-α promoter sites early during infection. Furthermore, we found that L^pro and ADNP are in a protein complex with the ubiquitous chromatin remodeling factor Brg-1. Our results uncover a novel role of FMDV L^pro in targeting ADNP and modulation of its transcription repressive function to decrease the expression of IFN and ISGs.

Impact of sarcopenia on outcome in patients with esophageal resection following neoadjuvant chemotherapy for esophageal cancer

BACKGROUND

Nutritional status and body composition parameters such as sarcopenia are important risk factors for impaired outcome in patients with esophageal cancer. This study was conducted to evaluate the effect of sarcopenia on long-term outcome after esophageal resection following neoadjuvant treatment.

METHODS

Skeletal muscle index (SMI) and body composition parameters were measured in patients receiving neoadjuvant treatment for locally advanced esophageal cancer. Endpoints included relapse-free survival (RFS) and overall survival (OS).

RESULTS

The study included 130 patients. Sarcopenia was found in 80 patients (61.5%). Patients with squamous-cell cancer (SCC) showed a decreased median SMI of 48 (range 28.4-60.8) cm/m² compared with that of patients with adenocarcinoma (AC) of 52 (range 34.4-74.2) cm/m², P < 0.001. The presence of sarcopenia had a significant impact on patient outcome: HR 1.69 (1.04-2.75), P = 0.036. Median OS was 20.5 (7.36-33.64) versus 52.1 (13.55-90.65) months in sarcopenic and non-sarcopenic patients, respectively. Sarcopenia was identified as an independent risk factor: HR 1.72 (1.049-2.83), P = 0.032.

CONCLUSION

Our data provide evidence that sarcopenia impacts long-term outcome after esophageal resection in patients who have undergone neoadjuvant therapy. Assessment of the body composition parameter can be a reasonable part of patient selection and may influence treatment methods.

Pathogenesis and micro-anatomic characterization of a cell-adapted mutant foot-and-mouth disease virus in cattle: Impact of the Jumonji C-domain containing protein 6 (JMJD6) and route of inoculation

A companion study reported Jumonji-C domain containing protein 6 (JMJD6) is involved in an integrin- and HS-independent pathway of FMDV infection in CHO cells. JMJD6 localization was investigated in animal tissues from cattle infected with either wild type A24-FMDV (A24-WT) or mutant FMDV (JMJD6-FMDV) carrying E95K/S96L and RGD to KGE mutations in VP1. Additionally, pathogenesis of mutant JMJD6-FMDV was investigated in cattle through aerosol and intraepithelial lingual (IEL) inoculation. Interestingly, JMJD6-FMDV pathogenesis was equivalent to A24-WT administered by IEL route. In contrast, JMJD6-FMDV aerosol-infected cattle did not manifest signs of FMD and animals showed no detectable viremia. Immunofluorescent microscopy of post-mortem tissue revealed JMJD6-FMDV exclusively co-localized with JMJD6(+) cells while A24-WT was occasionally found in JMJD6(+) cells. In vitro, chemical uptake inhibitors demonstrated JMJD6-FMDV entered cells via clathrin-coated pit endocytosis. In vivo, JMJD6-FMDV exhibited preference for JMJD6(+) cells, but availability of this alternative receptor likely depends on route of inoculation.

Role of Jumonji C-domain containing protein 6 (JMJD6) in infectivity of foot-and-mouth disease virus

Foot-and-mouth disease virus (FMDV) utilizes four integrins (αvβ1, αvβ3, αvβ6, and αvβ8) as its primary cell receptor. During cell culture propagation, FMDV frequently adapts to use heparan sulfate (HS), and rarely utilizes an unidentified third receptor. Capsid mutations acquired by a soluble integrin resistant FMDV cause (i) adaptation to CHO-677 cells (ii) increased affinity to membrane-bound Jumonji C-domain containing protein 6 (JMJD6) (iii) induced JMJD6 re-localization from the cell surface and cytoplasm to the nucleus. Interestingly, pre-treatment of cells with N- and C-terminal JMJD6 antibodies or by simultaneous incubation of mutant virus with soluble JMJD6 (but not by treatment with HS or αvβ6) impaired virus infectivity in cultured cells. JMJD6 and mutant virus co-purified by reciprocal co-immunoprecipitation. Molecular docking predictions suggested JMJD6 C-terminus interacts with mutated VP1 capsid protein. We conclude when specific VP1 mutations are displayed, JMJD6 contributes to FMDV infectivity and may be a previously unidentified FMDV receptor.

Analysis of the interaction between host factor Sam68 and viral elements during foot-and-mouth disease virus infections

BACKGROUND

The nuclear protein Src-associated protein of 68 kDa in mitosis (Sam68) is known to bind RNA and be involved in cellular processes triggered in response to environmental stresses, including virus infection. Interestingly, Sam68 is a multi-functional protein implicated in the life cycle of retroviruses and picornaviruses and is also considered a marker of virus-induced stress granules (SGs). Recently, we demonstrated the partial redistribution of Sam68 to the cytoplasm in FMDV infected cells, its interaction with viral protease 3C(pro), and found a significant reduction in viral titers as consequence of Sam68-specific siRNA knockdowns. Despite of that, details of how it benefits FMDV remains to be elucidated.

METHODS

Sam68 cytoplasmic localization was examined by immunofluorescent microscopy, counterstaining with antibodies against Sam68, a viral capsid protein and markers of SGs. The relevance of RAAA motifs in the IRES was investigated using electromobility shift assays with Sam68 protein and parental and mutant FMDV RNAs. In addition, full genome WT and mutant or G-luc replicon RNAs were tested following transfection in mammalian cells. The impact of Sam68 depletion to virus protein and RNA synthesis was investigated in a cell-free system. Lastly, through co-immunoprecipitation, structural modeling, and subcellular fractionation, viral protein interactions with Sam68 were explored.

RESULTS

FMDV-induced cytoplasmic redistribution of Sam68 resulted in it temporarily co-localizing with SG marker: TIA-1. Mutations that disrupted FMDV IRES RAAA motifs, with putative affinity to Sam68 in domain 3 and 4 cause a reduction on the formation of ribonucleoprotein complexes with this protein and resulted in non-viable progeny viruses and replication-impaired replicons. Furthermore, depletion of Sam68 in cell-free extracts greatly diminished FMDV RNA replication, which was restored by addition of recombinant Sam68. The results here demonstrated that Sam68 specifically co-precipitates with both FMDV 3D(pol) and 3C(pro) consistent with early observations of FMDV 3C(pro)-induced cleavage of Sam68.

CONCLUSION

We have found that Sam68 is a specific binding partner for FMDV non-structural proteins 3C(pro) and 3D(pol) and showed that mutations at RAAA motifs in IRES domains 3 and 4 cause a decrease in Sam68 affinity to these RNA elements and rendered the mutant RNA non-viable. Interestingly, in FMDV infected cells re-localized Sam68 was transiently detected along with SG markers in the cytoplasm. These results support the importance of Sam68 as a host factor co-opted by FMDV during infection and demonstrate that Sam68 interact with both, FMDV RNA motifs in the IRES and viral non-structural proteins 3C(pro) and 3D(pol).

Treatment of Barrett's esophagus: update on new endoscopic surgical modalities

Barrett's esophagus represents a premalignant condition, which is strongly associated with the incidence of esophageal adenocarcinoma. Currently, there are no validated markers to extract exactly that certain patient that will proceed to neoplastic progression. Therefore, therapeutic options have to include a larger population to provide prophylaxis for affected patients. Recently developed endoscopic therapeutic approaches offer treatment options for prevention or even treatment of limited esophageal adenocarcinoma. At present, high eradication rates of intestinal metaplasia as well as dysplasia are observed, whereas low complication rates offer a convenient safety profile. These striking new methods symbolize a changing paradigm in a field, where minimal-invasive tissue ablating methods and tissue preserving techniques have led to modified regimens. This review will focus on current standards and newly emerging methods to treat Barrett's esophagus and its progression to cancer and will highlight their evolution, potential benefits and their limitations.

Bioinformatics and Molecular Analysis of the Evolutionary Relationship between Bovine Rhinitis A Viruses and Foot-And-Mouth Disease Virus

Bovine rhinitis viruses (BRVs) cause mild respiratory disease of cattle. In this study, a near full-length genome sequence of a virus named RS3X (formerly classified as bovine rhinovirus type 1), isolated from infected cattle from the UK in the 1960s, was obtained and analyzed. Compared to other closely related Aphthoviruses, major differences were detected in the leader protease (L^pro), P1, 2B, and 3A proteins. Phylogenetic analysis revealed that RS3X was a member of the species bovine rhinitis A virus (BRAV). Using different codon-based and branch-site selection models for Aphthoviruses, including BRAV RS3X and foot-and-mouth disease virus, we observed no clear evidence for genomic regions undergoing positive selection. However, within each of the BRV species, multiple sites under positive selection were detected. The results also suggest that the probability (determined by Recombination Detection Program) for recombination events between BRVs and other Aphthoviruses, including foot-and-mouth disease virus was not significant. In contrast, within BRVs, the probability of recombination increases. The data reported here provide genetic information to assist in the identification of diagnostic signatures and research tools for BRAV.

Cell culture adaptation mutations in foot-and-mouth disease virus serotype A capsid proteins: implications for receptor interactions

In this study we describe the adaptive changes fixed on the capsid of several foot-and-mouth disease virus serotype A strains during propagation in cell monolayers. Viruses passaged extensively in three cell lines (BHK-21, LFBK and IB-RS-2) consistently gained positively charged amino acids in the putative heparin-sulfate-binding pocket (VP2 βE-βF loop, VP1 C-terminus and VP3 β-B knob) surrounding the fivefold symmetry axis (VP1 βF-βG loop) and at other discrete sites on the capsid (VP3 βG-βH loop, VP1 C-terminus, VP2 βC strand and VP1 βG-βH loop). A lysine insertion in the VP1 βF-βG loop of two of the BHK-21-adapted viruses supports the biological advantage of positively charged residues acquired in cell culture. The charge transitions occurred irrespective of cell line, suggesting their possible role in ionic interaction with ubiquitous negatively charged cell-surface molecules such as glycosaminoglycans (GAG). This was supported by the ability of the cell-culture-adapted variants to replicate in the integrin-deficient, GAG-positive CHO-K1 cells and their superior fitness in competition assays compared with the lower passage viruses with WT genotypes. Substitutions fixed in the VP1 βG-βH loop (-3, -2 and +2 'RGD' positions) or in the structural element known to be juxtaposed against that loop (VP1 βB-βC loop) suggest their possible role in modulating the efficiency and specificity of interaction of the 'RGD' motif with αv-integrin receptors. The nature and location of the substitutions described in this study could be applied in the rapid cell culture adaptation of viral strains for vaccine production.

Redistribution of demethylated RNA helicase A during foot-and-mouth disease virus infection: role of Jumonji C-domain containing protein 6 in RHA demethylation

Previously, RNA helicase A (RHA) re-localization from the nucleus to the cytoplasm in foot-and-mouth disease virus (FMDV) infected cells was shown to coincide with loss of RHA methylated arginine residues at its C-terminus. The potential interaction between RHA and Jumonji C-domain (JmjC) protein 6 (JMJD6) arginine demethylase in infected cells was investigated. Treatment with N-oxalylglycine (NOG) inhibitor of JmjC demethylases prevented FMDV-induced RHA demethylation and re-localization, and also decreased viral protein synthesis and virus titers. Physical interaction between JMJD6 and RHA was demonstrated via reciprocal co-immunoprecipitation, where RHA preferentially bound JMJD6 monomers. Nuclear efflux of demethylated RHA (DM-RHA) coincided with nuclear influx of JMJD6, which was not observed using another picornavirus. A modified biochemical assay demonstrated JMJD6 induced dose-dependent demethylation of RHA and two RHA-derived isoforms, which could be inhibited by NOG. We propose a role for JMJD6 in RHA demethylation stimulated by FMDV, that appears to facilitate virus replication.

Analysis of SAT type foot-and-mouth disease virus capsid proteins and the identification of putative amino acid residues affecting virus stability

Foot-and-mouth disease virus (FMDV) initiates infection by adhering to integrin receptors on target cells, followed by cell entry and disassembly of the virion through acidification within endosomes. Mild heating of the virions also leads to irreversible dissociation into pentamers, a characteristic linked to reduced vaccine efficacy. In this study, the structural stability of intra- and inter-serotype chimeric SAT2 and SAT3 virus particles to various conditions including low pH, mild temperatures or high ionic strength, was compared. Our results demonstrated that while both the SAT2 and SAT3 infectious capsids displayed different sensitivities in a series of low pH buffers, their stability profiles were comparable at high temperatures or high ionic strength conditions. Recombinant vSAT2 and intra-serotype chimeric viruses were used to map the amino acid differences in the capsid proteins of viruses with disparate low pH stabilities. Four His residues at the inter-pentamer interface were identified that change protonation states at pH 6.0. Of these, the H145 of VP3 appears to be involved in interactions with A141 in VP3 and K63 in VP2, and may be involved in orientating H142 of VP3 for interaction at the inter-pentamer interfaces.

Examination of soluble integrin resistant mutants of foot-and-mouth disease virus

Background

Foot-and-mouth disease virus (FMDV) initiates infection via recognition of one of at least four cell-surface integrin molecules α_vβ₁, α_vβ₃, α_vβ₆, or α_vβ₈ by a highly conserved Arg-Gly-Asp (RGD) amino acid sequence motif located in the G-H loop of VP1. Within the animal host, the α_vβ₆ interaction is believed to be the most relevant. Sub-neutralizing levels of soluble secreted α_vβ₆ (ssα_vβ₆) was used as a selective pressure during passages in vitro to explore the plasticity of that interaction.

Results

Genetically stable soluble integrin resistant (SIR) FMDV mutants derived from A24 Cruzeiro were selected after just 3 passages in cell culture in the presence of sub-neutralizing levels of ssα_vβ₆. SIR mutants were characterized by: replication on selective cell lines, plaque morphology, relative sensitivity to ssα_vβ₆ neutralization, relative ability to utilize α_vβ₆ for infection, as well as sequence and structural changes. All SIR mutants maintained an affinity for α_vβ₆. Some developed the ability to attach to cells expressing heparan sulfate (HS) proteoglycan, while others appear to have developed affinity for a still unknown third receptor. Two classes of SIR mutants were selected that were highly or moderately resistant to neutralization by ssα_vβ₆. Highly resistant mutants displayed a G145D substitution (RGD to RDD), while moderately resistant viruses exhibited a L150P/R substitution at the conserved RGD + 4 position. VP1 G-H loop homology models for the A-type SIR mutants illustrated potential structural changes within the integrin-binding motif by these 2 groups of mutations. Treatment of O1 Campos with ssα_vβ₆ resulted in 3 SIR mutants with a positively charged VP3 mutation allowing for HS binding.

Conclusions

These findings illustrate how FMDV particles rapidly gain resistance to soluble receptor prophylactic measures in vitro. Two different serotypes developed distinct capsid mutations to circumvent the presence of sub-neutralizing levels of the soluble cognate receptor, all of which resulted in a modified receptor tropism that expanded the cell types susceptible to FMDV. The identification of some of these adaptive mutations in known FMDV isolates suggests these findings have implications beyond the cell culture system explored in these studies.

Endoscopic suture fixation of gastrointestinal stents: proof of biomechanical principles and early clinical experience

BACKGROUND AND STUDY AIMS

Gastrointestinal stents have become an important therapeutic option for several indications. However, migration in up to 40 % of cases represents a significant drawback, especially when covered prostheses are used. We hypothesized that a novel endoscopic suturing device could enable endoluminal stent fixation, which might increase attachment and thereby potentially reduce migration.

PATIENTS AND METHODS

In an initial ex vivo porcine model, stents were attached to the esophageal wall with either endoscopic hemoclips or by endoscopic suture stent fixation (ESSF). The distal tension force required to induce dislocation was measured in Newtons (N) by a digital force gauge and was compared with conventional stent placement. ESSF was then performed clinically in five patients, in whom self-expanding metal stents were sutured in place for endoscopic treatment of gastrointestinal fistulas or strictures.

RESULTS

Esophageal ESSF was achieved in all experiments and significantly increased the force needed to displace the stent (n = 12; mean force 20.4 N; 95 % confidence interval [CI]: 15.4 - 25.4; P < 0.01) compared with clip fixation (n = 8; mean 6.1 N; 95 %CI 4.7 - 7.6) or stent placement without fixation (n = 16; mean 4.8 N; 95 %CI 4.0 - 5.6). All clinical cases of ESSF were performed successfully (5 /5) and took a median of 15 minutes. Elective stent removal was achieved without complications. One stent migration (1 /5) due to sutures being placed too superficially was observed. More loosely tied sutures remained intact, with the stent attached in place.

CONCLUSION

Endoscopic suture fixation of gastrointestinal stents provided significantly enhanced migration resistance in an ex vivo setting. In addition, early clinical experience found ESSF to be technically feasible and easy to accomplish.

Theiler's murine encephalomyelitis virus contrasts with encephalomyocarditis and foot-and-mouth disease viruses in its functional utilization of the StopGo non-standard translation mechanism

The picornaviruses' genome consists of a positive-sense ssRNA. Like many picornaviruses, cardioviruses synthesize two distinct polyprotein precursors from adjacent but non-overlapping genome segments. Both the [L-1ABCD-2A] and the [2BC-3ABCD] polyproteins are proteolytically processed to yield mature capsid and non-structural proteins, respectively. An unusual translational event, known as 'StopGo' or 'Stop-Carry on', is responsible for the release of the [L-1ABCD-2A] polyprotein from the ribosome and synthesis of the N-terminal amino acid of the [2BC-3ABCD] polyprotein. A common feature of these viruses is the presence of a highly conserved signature sequence for StopGo: -D(V/I)ExNPG(↓)P-, where -D(V/I)ExNPG are the last 7 aa of 2A, and the last P- is the first amino acid of 2B. Here, we report that, in contrast to encephalomyocarditis virus and foot-and-mouth disease virus, a functional StopGo does not appear to be essential for Theiler's murine encephalomyelitis virus viability when tested in vitro and in vivo.

The nuclear protein Sam68 is cleaved by the FMDV 3C protease redistributing Sam68 to the cytoplasm during FMDV infection of host cells

Picornavirus infection can lead to disruption of nuclear pore traffic, shut-off of cell translation machinery, and cleavage of proteins involved in cellular signal transduction and the innate response to infection. Here, we demonstrated that the FMDV 3C(pro) induced the cleavage of nuclear RNA-binding protein Sam68 C-terminus containing the nuclear localization sequence (NLS). Consequently, it stimulated the redistribution of Sam68 to the cytoplasm. The siRNA knockdown of Sam68 resulted in a 1000-fold reduction in viral titers, which prompted us to study the effect of Sam68 on FMDV post-entry events. Interestingly, Sam68 interacts with the internal ribosomal entry site within the 5' non-translated region of the FMDV genome, and Sam68 knockdown decreased FMDV IRES-driven activity in vitro suggesting that it could modulate translation of the viral genome. The results uncover a novel role for Sam68 in the context of picornaviruses and the proteolysis of a new cellular target of the FMDV 3C(pro).

Transrectal natural orifice translumenal endoscopic surgery (NOTES) for colorectal resection

Natural orifice translumenal endoscopic surgery (NOTES) is a new surgical paradigm involving performance of intra-abdominal surgery via a natural orifice and thereafter peritoneal access through an intentionally created hole in a hollow viscus. The vast majority of research in this rapidly evolving field had involved access via an oral or vaginal route. Access via a transanal route, other than the obvious concern over contamination, has many appealing attributes. In addition, transanal surgery has long been a common procedure lending a valuable clinical experience to the foundation of this field of research. Examples of preclinical and clinical research on transanal NOTES colorectal resections are here presented and discussed.

Predicting antigenic sites on the foot-and-mouth disease virus capsid of the South African Territories types using virus neutralization data

Foot-and-mouth disease virus (FMDV) outer capsid proteins 1B, 1C and 1D contribute to the virus serotype distribution and antigenic variants that exist within each of the seven serotypes. This study presents phylogenetic, genetic and antigenic analyses of South African Territories (SAT) serotypes prevalent in sub-Saharan Africa. Here, we show that the high levels of genetic diversity in the P1-coding region within the SAT serotypes are reflected in the antigenic properties of these viruses and therefore have implications for the selection of vaccine strains that would provide the best vaccine match against emerging viruses. Interestingly, although SAT1 and SAT2 viruses displayed similar genetic variation within each serotype (32 % variable amino acids), antigenic disparity, as measured by r(1)-values, was less pronounced for SAT1 viruses compared with SAT2 viruses within our dataset, emphasizing the high antigenic variation within the SAT2 serotype. Furthermore, we combined amino acid variation and the r(1)-values with crystallographic structural data and were able to predict areas on the surface of the FMD virion as antigenically relevant. These sites were mostly consistent with antigenic sites previously determined for types A, O and C using mAbs and escape mutant studies. Our methodology offers a quick alternative to determine antigenic relevant sites for FMDV field strains.

Custom-engineered chimeric foot-and-mouth disease vaccine elicits protective immune responses in pigs

Chimeric foot-and-mouth disease viruses (FMDV) of which the antigenic properties can be readily manipulated is a potentially powerful approach in the control of foot-and-mouth disease (FMD) in sub-Saharan Africa. FMD vaccine application is complicated by the extensive variability of the South African Territories (SAT) type viruses, which exist as distinct genetic and antigenic variants in different geographical regions. A cross-serotype chimeric virus, vKNP/SAT2, was engineered by replacing the external capsid-encoding region (1B-1D/2A) of an infectious cDNA clone of the SAT2 vaccine strain, ZIM/7/83, with that of SAT1 virus KNP/196/91. The vKNP/SAT2 virus exhibited comparable infection kinetics, virion stability and antigenic profiles to the KNP/196/91 parental virus, thus indicating that the functions provided by the capsid can be readily exchanged between serotypes. As these qualities are necessary for vaccine manufacturing, high titres of stable chimeric virus were obtained. Chemically inactivated vaccines, formulated as double-oil-in-water emulsions, were produced from intact 146S virion particles of both the chimeric and parental viruses. Inoculation of guinea pigs with the respective vaccines induced similar antibody responses. In order to show compliance with commercial vaccine requirements, the vaccines were evaluated in a full potency test. Pigs vaccinated with the chimeric vaccine produced neutralizing antibodies and showed protection against homologous FMDV challenge, albeit not to the same extent as for the vaccine prepared from the parental virus. These results provide support that chimeric vaccines containing the external capsid of field isolates can be successfully produced and that they induce protective immune responses in FMD host species.

Inhibitors of foot and mouth disease virus targeting a novel pocket of the RNA-dependent RNA polymerase

Background

Foot-and-Mouth Disease Virus (FMDV) is a picornavirus that infects cloven-hoofed animals and leads to severe losses in livestock production. In the case of an FMD outbreak, emergency vaccination requires at least 7 days to trigger an effective immune response. There are currently no approved inhibitors for the treatment or prevention of FMDV infections.

Methodology/Principal Findings

Using a luciferase-based assay we screened a library of compounds and identified seven novel inhibitors of 3Dpol, the RNA-dependent RNA polymerase of FMDV. The compounds inhibited specifically 3Dpol (IC₅₀s from 2-17 µM) and not other viral or bacterial polymerases. Enzyme kinetic studies on the inhibition mechanism by compounds 5D9 and 7F8 showed that they are non-competitive inhibitors with respect to NTP and nucleic acid substrates. Molecular modeling and docking studies into the 3Dpol structure revealed an inhibitor binding pocket proximal to, but distinct from the 3Dpol catalytic site. Residues surrounding this pocket are conserved among all 60 FMDV subtypes. Site directed mutagenesis of two residues located at either side of the pocket caused distinct resistance to the compounds, demonstrating that they indeed bind at this site. Several compounds inhibited viral replication with 5D9 suppressing virus production in FMDV-infected cells with EC₅₀ = 12 µM and EC₉₀ = 20 µM).

Significance

We identified several non-competitive inhibitors of FMDV 3Dpol that target a novel binding pocket, which can be used for future structure-based drug design studies. Such studies can lead to the discovery of even more potent antivirals that could provide alternative or supplementary options to contain future outbreaks of FMD.

Sequence-based prediction for vaccine strain selection and identification of antigenic variability in foot-and-mouth disease virus

Identifying when past exposure to an infectious disease will protect against newly emerging strains is central to understanding the spread and the severity of epidemics, but the prediction of viral cross-protection remains an important unsolved problem. For foot-and-mouth disease virus (FMDV) research in particular, improved methods for predicting this cross-protection are critical for predicting the severity of outbreaks within endemic settings where multiple serotypes and subtypes commonly co-circulate, as well as for deciding whether appropriate vaccine(s) exist and how much they could mitigate the effects of any outbreak. To identify antigenic relationships and their predictors, we used linear mixed effects models to account for variation in pairwise cross-neutralization titres using only viral sequences and structural data. We identified those substitutions in surface-exposed structural proteins that are correlates of loss of cross-reactivity. These allowed prediction of both the best vaccine match for any single virus and the breadth of coverage of new vaccine candidates from their capsid sequences as effectively as or better than serology. Sub-sequences chosen by the model-building process all contained sites that are known epitopes on other serotypes. Furthermore, for the SAT1 serotype, for which epitopes have never previously been identified, we provide strong evidence – by controlling for phylogenetic structure – for the presence of three epitopes across a panel of viruses and quantify the relative significance of some individual residues in determining cross-neutralization. Identifying and quantifying the importance of sites that predict viral strain cross-reactivity not just for single viruses but across entire serotypes can help in the design of vaccines with better targeting and broader coverage. These techniques can be generalized to any infectious agents where cross-reactivity assays have been carried out. As the parameterization uses pre-existing datasets, this approach quickly and cheaply increases both our understanding of antigenic relationships and our power to control disease.

New strains of viruses arise continually. Consequently, predicting when past exposure to closely related strains will protect against infection by novel strains is central to understanding the dynamics of a broad range of the world's most important infectious diseases. While previous research has developed valuable tools for describing the observed antigenic landscapes, our ability to predict cross-protection between different viral strains depends almost entirely on cumbersome and expensive live animal work, often restricted to model species rather than the natural host. The development of computer-based approaches to the estimation of cross-protection from viral sequence data would be hugely valuable, and our study represents a significant step towards this research goal.