Genetic basis of antigenic variation of SAT3 foot-and-mouth disease virus

Foot-and-mouth disease (FMD) continues to be a major burden for livestock owners in endemic countries and a threat to FMD-free countries. The epidemiology and control of FMD in Africa is complicated by the presence of five clinically indistinguishable serotypes. Of these the Southern African Territory (SAT) type 3 has received limited attention, likely due to its restricted distribution and it being less frequently detected. We investigated the intratypic genetic variation of the capsid-coding region of 22 SAT3 viruses and confirmed the geographical distribution of four topotypes. The antigenic cross-reactivity of 12 SAT3 viruses against reference antisera was assessed by performing virus neutralization assays and calculating the r1-values, which is a ratio of the heterologous neutralizing titre to the homologous neutralizing titre. Interestingly, cross-reactivity between the SAT3 reference antisera and many SAT3 viruses was notably high (r1-values > 0.3). Moreover, some of the SAT3 viruses reacted more strongly to the reference sera compared to the homologous virus (r1-values > 1). An increase in the avidity of the reference antisera to the heterologous viruses could explain some of the higher neutralization titres observed. Subsequently, we used the antigenic variability data and corresponding genetic and structural data to predict naturally occurring amino acid positions that correlate with antigenic changes. We identified four unique residues associated with a change in cross-reactivity, with two sites that change simultaneously. The analysis of antigenic differences is critical for surveillance and proper vaccine selection for effective control or the design of vaccine antigens tailored for specific geographic localities, using reverse genetics

Mapping of antigenic determinants on a SAT2 foot-and-mouth disease virus using chicken single-chain antibody fragments

Recombinant single-chain variable fragments (scFvs) of antibodies make it possible to localize antigenic and immunogenic determinants, identify protective epitopes and can be exploited for the design of improved diagnostic tests and vaccines. A neutralizing epitope, as well as other potential antigenic sites of a SAT2 foot-and-mouth disease virus (FMDV) were identified using phage-displayed scFvs. Three unique ZIM/7/83-specific scFvs, designated scFv1, scFv2 and scFv3, were isolated. Further characterization of these scFvs revealed that only scFv2 was capable of neutralizing the ZIM/7/83 virus and was used to generate neutralization-resistant virus variants. Sequence analysis of the P1 region of virus escaping neutralization revealed a residue change from His to Arg at position 159 of the VP1 protein. Residue 159 is not only surface exposed but is also located at the C-terminal base of the G–H loop, a known immunogenic region of FMDV. A synthetic peptide, of which the sequence corresponded to the predicted antigenic site of the VP1 G–H loop of ZIM/7/83, inhibited binding of scFv2 to ZIM/7/83 in a concentrationdependent manner. This region can therefore be considered in the design of SAT2 vaccine seed viruses for the regional control of FMD in Africa.The South African Department of Science and Technology (DST) and SA-UK collaborative initiative.http://www.elsevier.com/locate/virusre

Preliminary validation of a single-spot version of a solid-phase competition ELISA for the detection of southern African territories foot-and-mouth disease serotype exposure in goats

Appendix A. Supporting informationThe objective of this study was to perform a preliminary validation of a solid-phase competition ELISA (SPCE) in goats exposed to foot-and-mouth disease virus (FMDV) southern African territories (SAT) serotypes through vaccination or experimental infection. Thirty-nine goats were vaccinated with a FMDV vaccine and 37 subsequently challenged with a SAT1 virus serotype. Blood was collected every 7 days until termination at 14 days post-challenge. Single-spot SAT1 virus serotype SPCE (ss-SPCE) was performed in duplicate at two time points and a half-titration version was performed after a variable time of long-term storage. Coefficient of variation (CV) was calculated and accuracy of the ss-SPCE was estimated relative to a half-titration SPCE log10 titer of 1.6 using mixed-effect logistic regression. Additionally, sensitivity and specificity were estimated based on serological results 14-days post-challenge and at study enrolment, respectively. Three hundred and forty-two serum samples were tested in duplicate on two non-consecutive days. The median (interquartile range (IQR)) CV for the ss-SPCE for SAT1 was 2.1% (0.5, 14.3%) and 2.5% (0.6, 12.8%) for the two testing days, respectively. Median (IQR) interassay (different day) CV was 10.6% (2.5, 42.5%). Specificity and sensitivity of the ss-SPCE relative to the log10 titer using a 70% percentage inhibition positive threshold were 83.4% (95% confidence interval, 77.7–87.9) and 95.8% (90.7–98.2), respectively. Specificity was estimated as 100% (92.6, 100) and sensitivity as 97.3% (87.4, 99.9) when only considering serum tested at the beginning and end of the study, respectively. The SAT1 ss-SPCE is repeatable and accurate for determining FMDV serological status in goats.The National Research Foundation (NRF), South Africa, the Peace Parks Foundation, and MSc studies supported by South African Agricultural Sector Education and Training Authority (AgriSETA) awarded to the Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria.https://www.elsevier.com/locate/smallrumresam2024Production Animal StudiesVeterinary Tropical DiseasesNon

Impact of foot-and-mouth-disease on goat behaviour after experimental infection with serotype SAT1 virus

Infectious diseases and parasitic infestations can cause a set of non-specific clinical signs, such as increased body temperature and resting, and a decrease in food intake. These physiological and behavioural changes have an adaptive function facilitating defences against the pathogen and to support immune functions. These so-called’ sickness behaviours’ can also be used as an early detection tool for disease. Foot-and-mouth disease (FMD) still causes great economic losses in endemic countries, especially to smallholder farmers. The aim of this study was to determine if behavioural changes in goats can be used as an early indicator of FMD virus (FMDV) infection. The efficacy of a Southern African Territories (SAT) FMD vaccine was studied on forty South African indigenous goats. Changes in daily activities (resting, feeding, walking), as well as social behaviours (social resting, social feeding, dominance behaviours) were recorded and then compared over time and between clinically affected and unaffected goats. Pedometers were used to estimate average daily steps and to compare between groups of study animals. Eleven goats developed clinical signs of FMD, as well as non-FMD related sicknesses during the course of the study. Overall walking and resting behaviours were not significantly affected by the presence of FMD related clinical signs (p > 0.05). However, during the time of FMDV infection, social resting increased significantly (p < 0.001). Although goats developed FMD lesions on lips and tongues, percentage of time feeding was not affected (p = 0.762), suggesting that the study goats did not perceive the oral lesions as an important disturbance. Similarly, the number of steps did not consistently decrease in the presence of FMD-associated foot lesions. When affected by non-FMD related sicknesses, animals did not have an overall reduction in the time spent feeding (p = 0.867). However, goats affected with non-FMD conditions reduced the amount of social feeding (p = 0.002), potentially avoiding energetically costly competition at the feeding points. Overall, goats affected with FMD did not show more sickness behaviour, suggesting that FMDV infection in goats might not lead to obvious and therefore, easily detectable behavioural changes. This might have implications for farmers and animal health personnel, as individual goats infected with FMDV might be undetected within a flock due to the absence of obvious sickness behaviours, and the virus can therefore be spread more easily between herds through animal movements.The National Research Foundation (NRF), South Africa and the Peace Parks Foundation.http://www.elsevier.com/locate/prevetmedhj2021Mammal Research InstituteProduction Animal Studie

Optimization of a foot-and-mouth disease virus Southern African Territories–specific solid-phase competitive ELISA for small ruminant serum samples

We optimized and verified a single-spot solid-phase competitive ELISA (ss-SPCE) to detect antibodies against structural proteins of Southern African Territories (SAT) serotypes of foot-and-mouth disease virus (FMDV) in small ruminants. Sera from goats vaccinated and experimentally challenged with a SAT1 FMDV pool were tested in duplicate at 4 dilutions (1:10, 1:15, 1:22.5, 1:33.8) to optimize the assay. To assess the performance of the assay in naturally infected animals, we evaluated 316 goat and sheep field sera collected during active SAT2 outbreaks. Relative to results of the virus neutralization test, the optimal serum dilution and cutoff percentage inhibition (PI) were 1:15 and 50%, respectively. At these values, the Spearman rank correlation coefficient was 0.85 (p < 0.001), and the sensitivity and specificity (95% CI) were 80.3% (72.6, 87.2) and 91.1% (84.1, 95.9), respectively. Relative to the liquid-phase blocking ELISA and the nonstructural protein ELISA, the ss-SPCE exhibited divergent performance characteristics between the goat and sheep field sera. Repeatability was better for goats, but the correlation and agreement among all 3 assays were better for the sheep sera. The prevalence of SAT2 FMDV infection in the sampled sheep was 23.6%; sampled goats were seemingly FMDV-free. The ss-SPCE is an appropriate FMDV detection tool to investigate the role of small ruminants in the epidemiology of FMD in Africa.The Red Meat Research Development (RMRD) of South Africa.https://journals.sagepub.com/home/VDIhj2024Production Animal StudiesSDG-03:Good heatlh and well-bein

Improving foot-and-mouth disease control through the evaluation of goat movement patterns within the FMD protection zone of South Africa

Foot-and-mouth disease (FMD) is a transboundary animal disease that has a major impact on livestock production, regional and international trade and livelihoods of smallholder farmers in endemic settings. Many livestock diseases are transmitted through direct contact between animals, and thus between herds and flocks through animal movements. In this study, we described the pattern of goat movements among smallholder farmers within a communal farming area in South Africa. A cross-sectional survey using a semi-structured questionnaire was administered to 116 respondents, and separate 13 focus group discussions employing participatory mapping and semi-structured interviews were conducted among smallholder farmers. Overall, 22% (95% confidence interval [CI]: 16 – 31) of questionnaire respondents indicated moving new animals into their holdings during the previous 12 months while 56% (95% CI: 47 – 65) reported moving animals out of the holdings during the same timeframe. A total of 134 participants attended the focus group discussions with 68% (91/134) being male and 32% (43/134) female. Data from the study reported 37 nodes and 78 ties with an overall network density of 0.059 (SD 0.2) across the study area. Four locations within the (former) FMD-free zone of the country had connections with movement of goats from the study area. Furthermore, 60% (95% CI: 51 – 69) of farmers were ignorant of the need to obtain official veterinary movement permits for goats. These animal movements put the country at risk of future FMD outbreaks within the free zone. We recommend that the relevant authorities implement risk-based control measures to prevent the spread of infectious diseases.http://www.elsevier.com/locate/smallrumres2022-06-05hj2021Mammal Research InstituteProduction Animal Studie

Efficacy of a foot-and-mouth disease vaccine against a heterologous SAT1 virus challenge in goats

Please read abstract in the article.The National Research Foundation (NRF), South Africa and the Peace Parks Foundation.http://www.elsevier.com/locate/vaccinehj2021Production Animal Studie

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

Co-Teaching How Do General and Special Education Teachers Perceive Their Respective Roles in Various Co-Teaching Models?

Co-teaching is used in many different academic levels from elementary schools to college. Co-teaching can be both a positive and negative experience for those who participate in a co-teaching environment. Co-teaching is also known as Cooperative Teaching, Collaborative Teaching and Team-Teaching. Co-teaching is when a general and special education educators teach together in a diverse academic environment. This research focused on an online survey completed by twenty-four co-teachers (15 general and 9 special educators) in a high school located in the Midwest part of the United States. The survey was sent via email and the participants were given one week to answer all twenty questions, with the last question providing an area for co-teachers to write additional comments regarding their co-teaching experience. The questions were based on 4 point Likert scale with the following choices: strongly agree, agree, disagree and strongly disagree. The survey was divided into three major headings; general information, students and working together. Results from this study showed most of the participants have been teaching between 1-5 years and over 11 years. The majority (71 %) of the participants have co-taught between one-five years. Over half of the co-teachers felt a co-teaching classroom benefits the students. Three-quarters felt they share equal responsibilities and had a positive relationship with their co-teacher. Forty-six percent of the co-teachers felt students tend to approach one teacher more often than the other in the co-teaching classroom. Only 42% of the participants plan their lessons together and 58% disagreed as to having adequate time for planning. See chapter 4 results for more information regarding the results from the survey

Antigenic site determination on a SAT2 foot-and-mouth disease virus using a chicken antibody phage display library

Foot-and-mouth disease (FMD) is a highly contagious disease of cloven-hoofed animals. An outbreak of FMD not only severely decreases livestock productivity, but also impacts on both the local and export trade of susceptible animals and their products. This, in turn, negatively impacts the economy of affected countries. Of the seven serotypes that exist for FMD virus (FMDV), the three South African Territories (SAT) types display greater intratypic genomic and antigenic variation than the traditional “Euro-Asian” types. Although antigenic variation represents an important adaptive strategy of FMDV, especially in its maintenance host, it contributes to the decrease of vaccine cross-protection in the field, thus rendering available vaccines less effective. Knowledge of the amino acid residues that comprise the antigenic determinants will allow for the structural design of vaccine seed viruses that may provide improved protection against specific outbreak strains. The SAT2 type viruses, which are responsible for most of the FMD outbreaks in domestic animals in southern Africa, are the most variable of the SAT serotypes. In order to identify antigenic regions present on a SAT2 FMDV, two approaches were followed. In the first approach, a SAT2 vaccine strain, ZIM/7/83, was panned with a naïve chicken phagedisplayed library. Three unique SAT2/ZIM/7/83-specific phage-scFvs were obtained. Of these, phage-scFv2 was able to neutralize the SAT2/ZIM/7/83 virus and following sequencing of neutralization-resistant virus variants, an antigenic site was mapped to include residue 159 of the VP1 capsid protein. In the second approach, genetically modified viruses were generated in which known and predicted epitopes of SAT2/ZIM/7/83 were replaced with those of a disparate virus, SAT2/KNP/19/89, to determine the role of known SAT2 epitopes and to identify new potential antigenic regions. Following characterization of the epitopereplaced mutant viruses and studies with SAT2-specific monoclonal antibodies, two additional antigenic sites were mapped to include residues 71-72 of the VP2 capsid protein. The information gained from this study will not only increase the knowledge of the antigenic sites of SAT2 viruses and aid in identifying more suitable vaccine strains for SAT2 viruses, but is also the first step towards the production of a SAT2-specific epitope-based vaccine.Thesis (PhD)--University of Pretoria, 2013.South African Department of Science and TechnologyAgricultural Research CouncilUniversity of PretoriaMicrobiology and Plant PathologyPhDUnrestricte