The detection of long-lasting memory foot-and-mouth disease (FMD) virus serotype O-specific CD4+ T cells from FMD-vaccinated cattle by bovine major histocompatibility complex class II tetramer.

Foot-and-mouth disease (FMD) is a highly contagious, economically devastating disease of cloven-hooved animals. The development of long-lasting effective FMD vaccines would greatly benefit the global FMD control programme. Deep analysis of adaptive immunity in cattle vaccinated against FMD is technically challenging due to the lack of species-specific tools. In this study, we aimed to identify CD4+ T-cell epitopes in the FMD virus (FMDV) capsid and to phenotype the CD4+ T cells that recognize them using bovine major histocompatibility complex (BoLA) class II tetramer. A BoLA class II tetramer based on the DRA/DRB3*020:02 allele and FMDV antigen-stimulated PBMCs from bovine vaccinates were used to successfully identify four epitopes in the FMDV capsid, three of which have not been previously reported; two epitopes were identified in the structural protein VP1, one in VP3 and one in VP4. Specificity of the three novel epitopes was confirmed by proliferation assay. All epitope-expanded T-cell populations produced IFN-γ in vitro, indicating a long-lasting Th1 cell phenotype after FMD vaccination. VP3-specific CD4+ T cells exhibited the highest frequency amongst the identified epitopes, comprising >0·004% of the CD4+ T-cell population. CD45RO+ CCR7+ defined central memory CD4+ T-cell subpopulations were present in higher frequency in FMDV-specific CD4+ T-cell populations from FMD-vaccinated cattle ex vivo. This indicates an important role in maintaining cell adaptive immunity after FMD vaccination. Notably, FMDV epitope-loaded tetramers detected the presence of FMDV-specific CD4+ T cells in bovine PBMC more than four years after vaccination. This work contributes to our understanding of vaccine efficacy.

Real-time decision-making during emergency disease outbreaks.

In the event of a new infectious disease outbreak, mathematical and simulation models are commonly used to inform policy by evaluating which control strategies will minimize the impact of the epidemic. In the early stages of such outbreaks, substantial parameter uncertainty may limit the ability of models to provide accurate predictions, and policymakers do not have the luxury of waiting for data to alleviate this state of uncertainty. For policymakers, however, it is the selection of the optimal control intervention in the face of uncertainty, rather than accuracy of model predictions, that is the measure of success that counts. We simulate the process of real-time decision-making by fitting an epidemic model to observed, spatially-explicit, infection data at weekly intervals throughout two historical outbreaks of foot-and-mouth disease, UK in 2001 and Miyazaki, Japan in 2010, and compare forward simulations of the impact of switching to an alternative control intervention at the time point in question. These are compared to policy recommendations generated in hindsight using data from the entire outbreak, thereby comparing the best we could have done at the time with the best we could have done in retrospect. Our results show that the control policy that would have been chosen using all the data is also identified from an early stage in an outbreak using only the available data, despite high variability in projections of epidemic size. Critically, we find that it is an improved understanding of the locations of infected farms, rather than improved estimates of transmission parameters, that drives improved prediction of the relative performance of control interventions. However, the ability to estimate undetected infectious premises is a function of uncertainty in the transmission parameters. Here, we demonstrate the need for both real-time model fitting and generating projections to evaluate alternative control interventions throughout an outbreak. Our results highlight the use of using models at outbreak onset to inform policy and the importance of state-dependent interventions that adapt in response to additional information throughout an outbreak.

Effects of polyethylene glycol on bovine intestine alkaline phosphatase activity and stability.

In this study, we evaluated the effects of polyethylene glycol (PEG) on bovine intestine alkaline phosphatase (BIALP) activity and stability. In the hydrolysis of p-nitrophenylphosphate (pNPP) at pH 9.8 at 20 °C, the k(cat)/K(m) values of BIALP plus 5-15% w/v free PEG with molecular masses of 1, 2, 6, and 20 kDa (PEG1000, PEG2000, PEG6000, and PEG20000 respectively) were 120-140%, 180-300%, 130-170%, and 110-140% respectively of that of BIALP without free PEG (1.8 µM(-1) s(-1)), indicating that activation by PEG2000 was the highest. Unmodified BIALP plus 5% PEG2000 and BIALP pegylated with 2,4-bis(O-methoxypolyethylene glycol)-6-chloro-s-triazine exhibited 1.3-fold higher activity on average than that of BIALP without free PEG under various conditions, including pH 7.0-10.0 and 20-65 °C. The temperatures reducing initial activity by 50% in 30-min incubation of unmodified BIALP plus 5% PEG2000 and pegylated BIALP were 51 and 47 °C respectively, similar to that of BIALP without free PEG (49 °C). These results indicate that the addition of PEG2000 and pegylation increase BIALP activity without affecting its stability, suggesting that they can be used in enzyme immunoassay with BIALP to increase sensitivity and rapidity.

FMD-VS: A virtual sensor to index FMD virus scattering.

Foot-and-mouth disease (FMD) models-analytical models for tracking and analyzing FMD outbreaks-are known as dominant tools for examining the spread of the disease under various conditions and assessing the effectiveness of countermeasures. There has been some remarkable progress in modeling research since the UK epidemic in 2001. Several modeling methods have been introduced, developed, and are still growing. However, in 2010 when a FMD outbreak occurred in the Miyazaki prefecture, a crucial problem reported: Once a regional FMD outbreak occurs, municipal officials in the region must make various day-to-day decisions throughout this period of vulnerability. The deliverables of FMD modeling research in its current state appear insufficient to support the daily judgments required in such cases. FMD model can be an efficient support tool for prevention decisions. It requires being conversant with modeling and its preconditions. Therefore, most municipal officials with no knowledge or experience found full use of the model difficult. Given this limitation, the authors consider methods and systems to support users of FMD models who must make real-time epidemic-related judgments in the infected areas. We propose a virtual sensor, designated "FMD-VS," to index FMD virus scattering in conditions where there is once a notion of FMD; and (2) shows how we apply the developed FMD-VS technique during an outbreak. In (1), we show our approach to constructing FMD-VS based on the existing FMD model and offer an analysis and evaluation method to assess its performance. We again present the results produced when the technique applied to 2010 infection data from the Miyazaki Prefecture. For (2), we outline the concept of a method that supports the prevention judgment of municipal officials and show how to use FMD-VS.

The implementation of cattle market closure strategies to mitigate the foot-and-mouth disease epidemics: A contact modeling approach.

Foot-and-mouth disease (FMD) is one of the most endemic diseases in livestock worldwide. The disease occurrence generally results in a huge economic impact. The virus may distribute across countries or even continents along the contact network of animal movements. The present study, therefore, aimed to explore a cattle movement network originated in Tak, a Thailand-Myanmar bordered province and to demonstrate how FMDV spread among the nodes of market, source and destination. Subsequently, we examined the effectiveness of market closure intervention. The market-market (M-M) network was constructed to highlight the inter-market connections and the FMDV was modeled to spread along the trade chain. Four market closure scenarios based on rapidness and duration of implementation were examined. Our results indicate that two of the three major markets located in the province were highly connected and a strongly connected component was identified. The intra-provincial animal movements, which were currently overlooked, should be moved into sights as most of the high-risk sources for FMD epidemics were recognized in a close proximity to the cattle markets. Simultaneously, remote destinations across the country were identified. The inter-provincial animal movement control must be strengthened once FMD outbreak is notified. Based on our simulations, closing markets with low inter-market connectivity may not prevent the spread of FMDV. A selective market closure strategy targeting highly connected markets together with cattle trader tracking system was an alternative approach. However, socio-economic consequences regarding this intervention must be considered.

The effect of depopulation and restocking on reproductive and growth performances on Japanese commercial swine farms.

This study compared the reproductive and growth performances of pigs before and after depopulation and restocking after a foot-and-mouth disease outbreak in Japan. Data for the time period before and after depopulation and restocking were obtained from three farrow-to-finish farms. As a result of depopulation and restocking, hygiene levels were improved, and common infectious diseases, such as porcine reproductive and respiratory syndrome and Aujeszky's disease, remained undetected on the farms. Compared with before depopulation, reproductive and growth performances improved after depopulation; the number of total pigs born was higher, the postweaning mortality rate was lower, and the age at slaughter was lower (P<0.05). In summary, depopulation and restocking improved the reproductive and growth performances of pigs.