scholarly journals Host Factors Affecting Generation of Immunity Against Porcine Epidemic Diarrhea Virus in Pregnant and Lactating Swine and Passive Protection of Neonates

Pathogens ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 130 ◽  
Author(s):  
Stephanie N. Langel ◽  
Qiuhong Wang ◽  
Anastasia N. Vlasova ◽  
Linda J. Saif

Porcine epidemic diarrhea virus (PEDV) is a highly virulent re-emerging enteric coronavirus that causes acute diarrhea, dehydration, and up to 100% mortality in neonatal suckling piglets. Despite this, a safe and effective PEDV vaccine against highly virulent strains is unavailable, making PEDV prevention and control challenging. Lactogenic immunity induced via the gut-mammary gland-secretory IgA (sIgA) axis, remains the most promising and effective way to protect suckling piglets from PEDV. Therefore, a successful PEDV vaccine must induce protective maternal IgA antibodies that passively transfer into colostrum and milk. Identifying variables that influence lymphocyte migration and IgA secretion during gestation and lactation is imperative for designing maternal immunization strategies that generate the highest amount of lactogenic immune protection against PEDV in suckling piglets. Because pregnancy-associated immune alterations influence viral pathogenesis and adaptive immune responses in many different species, a better understanding of host immune responses to PEDV in pregnant swine may translate into improved maternal immunization strategies against enteric pathogens for multiple species. In this review, we discuss the role of host factors during pregnancy on antiviral immunity and their implications for generating protective lactogenic immunity in suckling neonates.

2021 ◽  
Author(s):  
Shengchao Deng ◽  
Juan Wang ◽  
Mudassar Mohiuddin ◽  
Lisai Zhu ◽  
Guiping Wang ◽  
...  

Abstract Background: Porcine epidemic diarrhea virus belongs to family of coronaviruses which are notorious for rapid spread of severe diarrhea among suckling piglets. The virus mainly replicates in the epithelial cells of duodenum, jejunum, ileum and colon and is a life threatening condition in pigs. A highly virulent strain “CHYJ130330” having high mortality rate was isolated from a field outbreak, identified as a new virulent genotype II/G2-b strain and adapted successfully to vero cells was used to prepare inactivated vaccine against PEDV. This newly prepared vaccine was given through intranasal route and is compared with the commercially available bi-combined (PEDV and TGEV) vaccine given by intramuscular injection. In this study milk or mucosal IgA and IgG antibody levels have been used to predict vaccine efficacy and the level of protective immunity against PED virus. Antibody titers in the milk of sows and intestines of suckling piglets were compared by enzyme-linked immunosorbent assay (ELISA). Results: It was shown that CHYJ vaccine induced significantly higher levels of PEDV IgA antibody in milk of sows and intestines of piglets as compared to commercial bi-combined vaccine. Both CHYJ and commercial vaccines were not able to induce detectable IgG levels in the intestines of piglets; the later however induced higher IgG levels when detected in the sow’s milk. Protective efficacy of vaccines was determined against a highly virulent PEDV strain. CHYJ intranasal vaccine gives a better protection 80% (4/5) rate as compared to commercial i.m. vaccine conferring 60% (3/5) immunity in suckling piglets. Conclusions: It is therefore concluded that PEDV inactivated CHYJ vaccine confer better lactogenic immunity and gives more protection to suckling piglets than available bi-combined TGEV and PEDV vaccine through passive immunization.


Pathogens ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1115
Author(s):  
SeEun Choe ◽  
Gyu-Nam Park ◽  
Sok Song ◽  
Jihye Shin ◽  
Van Phan Le ◽  
...  

To prevent diarrhea in suckling piglets infected by porcine epidemic diarrhea virus (PEDV), porcine epidemic diarrhea (PED) vaccines are administered mainly through intramuscular (IM) or oral routes. We found that growing pigs vaccinated with an inactivated PEDV vaccine via the intradermal (ID) route had higher neutralizing antibody titers and cytokine (IFN-γ, IL-4, and IL-10) levels than non-vaccinated pigs. In addition, suckling piglets acquired lactogenic immunity from pregnant sows inoculated with an ID PED vaccine. We evaluated the efficacy of vaccination via this route, along with subsequent protection against virulent PEDV. At six days post-challenge, the survival rate of suckling piglets exposed to virulent PEDV was 70% for the ID group and 0% for the mock group (no vaccine). At necropsy, villi length in the duodenum and ileum of piglets with lactogenic immunity provided by ID-vaccinated sows proved to be significant (p < 0.05) when compared with those in piglets from mock group sows. Thus, vaccination using an inactivated PED vaccine via the ID route provides partial protection against infection by virulent PEDV.


Vaccines ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1084
Author(s):  
Fengsai Li ◽  
Xiaona Wang ◽  
Xiaolong Fan ◽  
Ling Sui ◽  
Hailin Zhang ◽  
...  

Porcine epidemic diarrhea (PED), which is caused by the porcine epidemic diarrhea virus (PEDV), has occurred worldwide and poses a serious threat to the pig industry. Intestine is the main function site of PEDV; therefore, it is important to develop an oral mucosal immunity vaccine against this virus infection. Most traditional plasmid delivery vectors use antibiotic genes as a selective marker, easily leading to antibiotic accumulation and gene contamination. In this study, to explore whether the alanine racemase gene (Alr) could be used as a screening marker and develop an efficient oral vaccine against PEDV infection, a recombinant strain was constructed using Lactobacillus casei with Alr deletion (L. casei ΔAlr W56) to deliver the Alr gene and a core-neutralizing epitope (COE) antigen. This recombinant bacterium efficiently induced secretory immunoglobulin A (SIgA)-based mucosal and immunoglobulin G (IgG)-based humoral immune responses via oral vaccination in mice. Compared to the other strains, the recombinant bacteria were able to grow without the addition of D-alanine, revealing that Alr in the plasmid could function normally in defective bacteria. This oral mucosal vaccine would provide a useful strategy to substitute the application of antibiotics in the future and induce efficient immune responses against PEDV infection.


Viruses ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 41 ◽  
Author(s):  
Chi-Fei Kao ◽  
Hui-Wen Chang

Porcine epidemic diarrhea virus (PEDV) has continuously caused severe economic losses to the global swine industries; however, no successful vaccine against PEDV has been developed. In this study, we generated four autologous recombinant viruses, including the highly virulent iPEDVPT-P5, attenuated iPEDVPT-P96, and two chimeric viruses (iPEDVPT-P5-96S and iPEDVPT-P96-5S) with the reciprocally exchanged spike (S) gene, to study the role of the S gene in PEDV pathogenesis. A deeper understanding of PEDV attenuation will aid in the rational design of a live attenuated vaccine (LAV) using reverse genetics system. Our results showed that replacing the S gene from the highly virulent iPEDVPT-P5 led to complete restoration of virulence of the attenuated iPEDVPT-P96, with nearly identical viral shedding, diarrhea pattern, and mortality rate as the parental iPEDVPT-P5. In contrast, substitution of the S gene with that from the attenuated iPEDVPT-P96 resulted in partial attenuation of iPEDVPT-P5, exhibiting similar viral shedding and diarrhea patterns as the parental iPEDVPT-P96 with slightly severe histological lesions and higher mortality rate. Collectively, our data confirmed that the attenuation of the PEDVPT-P96 virus is primarily attributed to mutations in the S gene. However, mutation in S gene alone could not fully attenuate the virulence of iPEDVPT-P5. Gene (s) other than S gene might also play a role in determining virulence.


2021 ◽  
Vol 12 ◽  
Author(s):  
Yi Hu ◽  
Xiaohong Xie ◽  
Lingchen Yang ◽  
Aibing Wang

Porcine epidemic diarrhea virus (PEDV), a coronavirus pathogen of the pig intestinal tract, can cause fatal watery diarrhea in piglets, thereby causing huge economic losses to swine industries around the world. The pathogenesis of PEDV has intensively been studied; however, the viral proteins of PEDV and the host factors in target cells, as well as their interactions, which are the foundation of the molecular mechanisms of viral infection, remain to be summarized and updated. PEDV has multiple important structural and functional proteins, which play various roles in the process of virus infection. Among them, the S and N proteins play vital roles in biological processes related to PEDV survival via interacting with the host cell proteins. Meanwhile, a number of host factors including receptors are required for the infection of PEDV via interacting with the viral proteins, thereby affecting the reproduction of PEDV and contributing to its life cycle. In this review, we provide an updated understanding of viral proteins and host factors, as well as their interactions in terms of PEDV infection. Additionally, the effects of cellular factors, events, and signaling pathways on PEDV infection are also discussed. Thus, these comprehensive and profound insights should facilitate for the further investigations, control, and prevention of PEDV infection.


2019 ◽  
Vol 8 (12) ◽  
Author(s):  
Fei Su ◽  
Bin Yu ◽  
Junxing Li ◽  
Lihua Xu ◽  
Xiufang Yuan

We report here the complete genome sequence of porcine epidemic diarrhea virus (PEDV) strain ZJ/ZX2018-C10, isolated from infected piglets in Zhejiang Province, China. The genome sequence was highly similar to AH2012, a highly virulent Chinese PEDV strain.


2017 ◽  
Vol 91 (14) ◽  
Author(s):  
Yixuan Hou ◽  
Chun-Ming Lin ◽  
Masaru Yokoyama ◽  
Boyd L. Yount ◽  
Douglas Marthaler ◽  
...  

ABSTRACT We previously isolated a porcine epidemic diarrhea virus (PEDV) strain, PC177, by blind serial passaging of the intestinal contents of a diarrheic piglet in Vero cell culture. Compared with the highly virulent U.S. PEDV strain PC21A, the tissue culture-adapted PC177 (TC-PC177) contains a 197-amino-acid (aa) deletion in the N-terminal domain of the spike (S) protein. We orally inoculated neonatal, conventional suckling piglets with TC-PC177 or PC21A to compare their pathogenicities. Within 7 days postinoculation, TC-PC177 caused mild diarrhea and lower fecal viral RNA shedding, with no mortality, whereas PC21A caused severe clinical signs and 55% mortality. To investigate whether infection with TC-PC177 can induce cross-protection against challenge with a highly virulent PEDV strain, all the surviving piglets were challenged with PC21A at 3 weeks postinoculation. Compared with 100% protection in piglets initially inoculated with PC21A, 88% and 100% TC-PC177- and mock-inoculated piglets had diarrhea following challenge, respectively, indicating incomplete cross-protection. To investigate whether this 197-aa deletion was the determinant for the attenuation of TC-PC177, we generated a mutant (icPC22A-S1Δ197) bearing the 197-aa deletion from an infectious cDNA clone of the highly virulent PEDV PC22A strain (infectious clone PC22A, icPC22A). In neonatal gnotobiotic pigs, the icPC22A-S1Δ197 virus caused mild to moderate diarrhea, lower titers of viral shedding, and no mortality, whereas the icPC22A virus caused severe diarrhea and 100% mortality. Our data indicate that deletion of this 197-aa fragment in the spike protein can attenuate a highly virulent PEDV, but the virus may lose important epitopes for inducing robust protective immunity. IMPORTANCE The emerging, highly virulent PEDV strains have caused substantial economic losses worldwide. However, the virulence determinants are not established. In this study, we found that a 197-aa deletion in the N-terminal region of the S protein did not alter virus (TC-PC177) tissue tropism but reduced the virulence of the highly virulent PEDV strain PC22A in neonatal piglets. We also demonstrated that the primary infection with TC-PC177 failed to induce complete cross-protection against challenge by the highly virulent PEDV PC21A, suggesting that the 197-aa region may contain important epitopes for inducing protective immunity. Our results provide an insight into the role of this large deletion in virus propagation and pathogenicity. In addition, the reverse genetics platform of the PC22A strain was further optimized for the rescue of recombinant PEDV viruses in vitro. This breakthrough allows us to investigate other virulence determinants of PEDV strains and will provide knowledge leading to better control PEDV infections.


2016 ◽  
Vol 4 (4) ◽  
Author(s):  
Xiang Gao ◽  
Dongliang Li ◽  
Jingyi Zhao ◽  
Farong Xu ◽  
Xinna Ge ◽  
...  

Porcine epidemic diarrhea virus, a member of the family Coronaviridae , is an economically important pathogen that causes severe enteritis, vomiting, dehydration, and a high mortality rate, especially among suckling piglets. Here, we report the complete genome sequence (28,036 nucleotides [nt]) of a porcine epidemic diarrhea virus (PEDV) strain isolated in a novel outbreak in Shandong, China.


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