Porcine epidemic diarrhea virus (PEDV) is a coronavirus that infects cells lining the small intestine of swine, resulting in vomiting, diarrhea, and dehydration. The amino acid sequence of the spike ...(S) protein, which is the principal target recognized by host immune cells, has multiple mutations that distinguish the two PEDV genotypes, G1 and G2. To determine whether these mutations lead to changes in antigenicity, as suggested by the failure of PEDV vaccines in China, we first optimized the codons of typical S genes of the CV777 vaccine strain (G1 subtype) and LNCT2 strain (G2 subtype) and expressed the recombinant full-length sequence of the S protein in a eukaryotic expression system. The IgG antibody levels of serum from mice immunized with purified S protein were markedly high. Antigenicity was compared by detection of polyclonal antibodies (PAbs) against the virus and S protein using an enzyme-linked immunosorbent assay (ELISA), an indirect immunofluorescence assay (IFA), and a serum cross-neutralization (SN) assay. Reactivity with the PAbs revealed significant cross-reactivity between the two PEDV subtypes, although there was a twofold difference in the antigenic responses based on PAb titers in the ELISA and IFA. Consistent with the variation in the S gene sequences, the SN titer suggested differences in the neutralization activity of the S protein between the two subtypes, which could explain the antigenic variation between the PEDV subtypes G1 and G2.
The enteric disease of swine recognized in the early 1970s in Europe was initially described as "epidemic viral diarrhea" and is now termed "porcine epidemic diarrhea (PED)". The coronavirus referred ...to as PED virus (PEDV) was determined to be the etiologic agent of this disease in the late 1970s. Since then the disease has been reported in Europe and Asia, but the most severe outbreaks have occurred predominantly in Asian swine-producing countries. Most recently, PED first emerged in early 2013 in the United States that caused high morbidity and mortality associated with PED, remarkably affecting US pig production, and spread further to Canada and Mexico. Soon thereafter, large-scale PED epidemics recurred through the pork industry in South Korea, Japan, and Taiwan. These recent outbreaks and global re-emergence of PED require urgent attention and deeper understanding of PEDV biology and pathogenic mechanisms. This paper highlights the current knowledge of molecular epidemiology, diagnosis, and pathogenesis of PEDV, as well as prevention and control measures against PEDV infection. More information about the virus and the disease is still necessary for the development of effective vaccines and control strategies. It is hoped that this review will stimulate further basic and applied studies and encourage collaboration among producers, researchers, and swine veterinarians to provide answers that improve our understanding of PEDV and PED in an effort to eliminate this economically significant viral disease, which emerged or re-emerged worldwide.
Acute diarrhea outbreaks caused by porcine epidemic diarrhea virus (PEDV) have been observed in various pig-breeding provinces of China since December 2010. Endemic strains of PEDV were isolated from ...different areas, and the complete genome sequences of 10 isolates were determined. Our objective in this study was to genetically characterize current Chinese field isolates of PEDV to better understand their epidemiology and genetic diversity. Sequence analysis showed that 10 post-2010 isolates shared high homology with each other and were always clustered together with the virulent DR13 strains (South Korea) and/or one earlier Chinese strain, CH-S, in phylogenetic analysis. All post-2010 isolates possessed common sequence changes in each gene. Our results suggest that current Chinese PEDV isolates originated from either South Korean and/or Chinese ancestors that underwent some genetic variation, thereby forming a new PEDV genotype in China.
In this paper, we propose new mathematical models with nonlinear incidence rate and double epidemic hypothesis. Then we dedicate to develop a method to obtain the threshold of the stochastic SIS ...epidemic model. To this end, first, we investigate the stability of the equilibria of the deterministic system and obtain the conditions for the extinction and the permanence of two epidemic diseases. Second, we explore and obtain the threshold of a stochastic SIS system for the extinction and the permanence in mean of two epidemic diseases. The results show that a large stochastic disturbance can cause infectious diseases to go to extinction, in other words, the persistent infectious disease of a deterministic system can become extinct due to the white noise stochastic disturbance. This implies that the stochastic disturbance is conducive to epidemic diseases control. To illustrate the performance of the theoretical results, we present a series of numerical simulations of these cases with respect to different noise disturbance coefficients.
Abstract Porcine epidemic diarrhea virus (PEDV) has two genotypes, G1 and G2. To research the immunogenicity differences of PEDV G1 and G2 genotype strains and obtain a neutralizing monoclonal ...antibody (mAb), we inoculated specific-pathogen-free BALB/c mice with a newly emerged strain, PEDV-LNCT2. After immunizations, cells from the spleen of the mice were fused with SP2/0 myeloma cells. Following culturing and subcloning, a strain, 1B9, secreting neutralizing antibody, was obtained. The 1B9 mAb neutralized new variant genotype 2 PEDV strains (LNCT2, LNSY, and Hjms), but it did not neutralize a genotype 1 PEDV strain (CV777), in vitro . Results showed that the epitope recognized by the 1B9 mAb lies in the spike protein, and that it is a conformational epitope. These findings confirm that allelic differences in the PEDV S gene between the G1 and G2 genotype strains led to changes in the S protein and, thus, differences in its immunogenicity.
Simple phenomenological growth models can be useful for estimating transmission parameters and forecasting epidemic trajectories. However, most existing phenomenological growth models only support ...single-peak outbreak dynamics whereas real epidemics often display more complex transmission trajectories.
We develop and apply a novel sub-epidemic modeling framework that supports a diversity of epidemic trajectories including stable incidence patterns with sustained or damped oscillations to better understand and forecast epidemic outbreaks. We describe how to forecast an epidemic based on the premise that the observed coarse-scale incidence can be decomposed into overlapping sub-epidemics at finer scales. We evaluate our modeling framework using three outbreak datasets: Severe Acute Respiratory Syndrome (SARS) in Singapore, plague in Madagascar, and the ongoing Ebola outbreak in the Democratic Republic of Congo (DRC) and four performance metrics.
The sub-epidemic wave model outperforms simpler growth models in short-term forecasts based on performance metrics that account for the uncertainty of the predictions namely the mean interval score (MIS) and the coverage of the 95% prediction interval. For example, we demonstrate how the sub-epidemic wave model successfully captures the 2-peak pattern of the SARS outbreak in Singapore. Moreover, in short-term sequential forecasts, the sub-epidemic model was able to forecast the second surge in case incidence for this outbreak, which was not possible using the simple growth models. Furthermore, our findings support the view that the national incidence curve of the Ebola epidemic in DRC follows a stable incidence pattern with periodic behavior that can be decomposed into overlapping sub-epidemics.
Our findings highlight how overlapping sub-epidemics can capture complex epidemic dynamics, including oscillatory behavior in the trajectory of the epidemic wave. This observation has significant implications for interpreting apparent noise in incidence data where the oscillations could be dismissed as a result of overdispersion, rather than an intrinsic part of the epidemic dynamics. Unless the oscillations are appropriately modeled, they could also give a false positive, or negative, impression of the impact from public health interventions. These preliminary results using sub-epidemic models can help guide future efforts to better understand the heterogenous spatial and social factors shaping sub-epidemic patterns for other infectious diseases.
•This study reviewed the studies on COVID-19 pandemic in supply chain disciplines.•The findings reveals that four broad themes recur in the published work.•There is a lack of empirically designed and ...theoretically grounded studies.•Based on the findings, this study provides future research opportunities.
The global spread of the novel coronavirus, also known as the COVID-19 pandemic, has had a devastating impact on supply chains. Since the pandemic started, scholars have been researching and publishing their studies on the various supply-chain-related issues raised by COVID-19. However, while the number of articles on this subject has been steadily increasing, due to the absence of any systematic literature reviews, it remains unclear what aspects of this disruption have already been studied and what aspects still need to be investigated. The present study systematically reviews existing research on the COVID-19 pandemic in supply chain disciplines. Through a rigorous and systematic search, we identify 74 relevant articles published on or before 28 September 2020. The synthesis of the findings reveals that four broad themes recur in the published work: namely, impacts of the COVID-19 pandemic, resilience strategies for managing impacts and recovery, the role of technology in implementing resilience strategies, and supply chain sustainability in the light of the pandemic. Alongside the synthesis of the findings, this study describes the methodologies, context, and theories used in each piece of research. Our analysis reveals that there is a lack of empirically designed and theoretically grounded studies in this area; hence, the generalizability of the findings, thus far, is limited. Moreover, the analysis reveals that most studies have focused on supply chains for high-demand essential goods and healthcare products, while low-demand items and SMEs have been largely ignored. We also review the literature on prior epidemic outbreaks and other disruptions in supply chain disciplines. By considering the findings of these articles alongside research on the COVID-19 pandemic, this study offers research questions and directions for further investigation. These directions can guide scholars in designing and conducting impactful research in the field.
•CH25H is not an interferon-stimulated gene (ISG) in Vero cells.•CH25H and 25HC inhibit PEDV infection through blocking viral penetration.•CH25H-M still restricts PEDV replication.•25HC has a ...broad-spectrum antiviral effect against porcine intestinal coronaviruses, including PEDV and TGEV.
Cholesterol 25-hydroxylase (CH25H) has been shown lately to be a host restriction factor that encodes an enzyme, which catalyzes the oxidized form of cholesterol to 25-hydroxycholesterol (25HC). A series of studies have shown that 25HC activity in hosts plays a vital role in inhibiting viral infection. In this study, we explored the antiviral effect of CH25H and 25HC on porcine epidemic diarrhea virus (PEDV), which causes high mortality rates in newborn piglets with severe diarrhea, and considerable financial loss in the swine industry worldwide. Our results showed that PEDV infection downregulated the expression of CH25H in Vero cells. An overexpression and knockdown assay indicated that CH25H has significant antiviral action against PEDV, and a CH25H mutant (CH25H-M) that lacks hydroxylase activity also retains antiviral activity to a lesser extent. Furthermore, 25HC had a broad-spectrum antiviral effect against different PEDV strains by blocking viral entry. In addition, CH25H and 25HC inhibited the replication of porcine transmissible gastroenteritis virus (TGEV). Taken together, CH25H as a natural host restriction factor could inhibit PEDV and TGEV infection.
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