Porcine endemic diarrhea virus infection regulates long noncoding RNA expression

RNA-Seq analysis of long non-coding RNA in human intestinal epithelial cells infected by Shiga toxin-producing Escherichia coli

BACKGROUND

The Shiga toxin-producing Escherichia coli (STEC) infects animals and induces acute intestinal inflammation. Long non-coding RNAs (lncRNAs) are known to play crucial roles in modulating inflammation response. However, it is not clear whether lncRNAs are involved in STEC-induced inflammation.

METHODS AND RESULTS

To understand the association of lncRNAs with STEC infection, we used RNA-seq technology to analyze the profiles of lncRNAs in Mock-infected and STEC-infected human intestinal epithelial cells (HIECs). We detected a total of 702 lncRNAs differentially expressed by STEC infection. 583 differentially expressed lncRNAs acted as competitive microRNAs (miRNAs) binding elements in regulating the gene expression involved in TNF signaling pathway, IL-17 signaling pathway, PI3K-Akt signaling pathway, and apoptosis pathways. We analyzed 3 targeted genes, TRADD, TRAF1 and TGFB2, which were differentially regulated by mRNA-miRNA-lncRNA interaction network, potentially involved in the inflammatory and apoptotic response to STEC infection. Functional analysis of up/downstream genes associated with differentially expressed lncRNAs revealed their role in adheres junction and endocytosis. We also used the qRT-PCR technique to validate 8 randomly selected differentially expressed lncRNAs and mRNAs in STEC-infected HIECs.

CONCLUSION

Our results, for the first time, revealed differentially expressed lncRNAs induced by STEC infection of HIECs. The results will help investigate the molecular mechanisms for the inflammatory responses induced by STEC.

Transcriptomics yields valuable information regarding the response mechanisms of Chinese Min pigs infected with PEDV

Porcine epidemic diarrhea virus (PEDV) causes porcine epidemic diarrhea (PED), a highly infectious disease, which has resulted in huge economic losses for the pig industry. To date, the pathogenic and immune response mechanism was not particularly clear. The purpose of this study was to investigate the pathogenic and immune responses of pigs infected with PEDV.In this study, 12 Min pigs were randomly selected without taking colostrum. At 3 days old, eight piglets were infected with 1 mL of PEDV solution (10 TCID50/ml), and the remaining four piglets were handled by 1 mL of 0.9% normal saline. Within the age of 7 days old, four piglets died and were considered as the death group. Correspondingly, four alive individuals were classified into the resistance group. Tissues of the duodenum, jejunum, ileum, colon, cecum, and rectum of piglets in the three groups were collected to measure the PEDV content. Additionally, the jejunum was used for the measurements and analyses of Hematoxylin-eosinstaining (HE), immunohistochemical sections, and transcriptomics. The phenotypes of Min piglets infected with PEDV showed that the viral copy numbers and jejunal damage had significant differences between the death and resistance groups. We also observed the transcriptome of the jejunum, and the differentially expressed (DE) analysis observed 6,585 DE protein-coding genes (PCGs), 3,188 DE long non-coding RNAs (lncRNAs), and 350 DE microRNAs (miRNAs), which were mainly involved in immune response and metabolic pathways. Furthermore, the specific expressed molecules for each group were identified, and 97 PCGs,108 lncRNAs, and 51 miRNAs were included in the ceRNA-regulated networks. By weighted gene co-expression network analysis (WGCNA) and transcription factor (TF) prediction, 27 significant modules and 32 significant motifs (E-value < 0.05) annotated with 519 TFs were detected. Of these TFs, 53 were DE PCGs. In summary, the promising key PCGs, lncRNAs, and miRNAs related to the pathogenic and immunological response of pigs infected with PEDV were detected and provided new insights into the pathogenesis of PEDV.

Long non-coding RNA LOC103222771 promotes infection of porcine reproductive and respiratory syndrome virus in Marc-145 cells by downregulating Claudin-4

Porcine reproductive and respiratory syndrome (PRRS) is an important swine disease caused by infection of porcine reproductive and respiratory syndrome virus (PRRSV), which leads to huge loss in swine industry. How to effectively control PRRS is challenging. Long non-coding RNA (lncRNA) are key regulator of viral infections and anti-virus immunological responses, therefore, further understanding of lncRNAs will aid to identification of novel regulators of viral infections and better design of prevention and control strategies to viral infection related diseases and immune disorders. We demonstrated that PRRSV infection upregulated the expression of lncRNA LOC103222771 in Marc-145 cells and porcine alveolar macrophage cells (PAMs) and that LOC103222771 is mainly located in cytoplasm. Knockdown of LOC103222771 could inhibit the PRRSV infection in Marc-145 cells. RNA-seq analysis and subsequent validation revealed increased expression of Claudin-4 (CLDN4) in Marc-145 when LOC103222771 was specifically downregulated，suggesting that LOC103222771 might be an upstream regulator of CLDN4, an important component of tight junctions for establishment of the paracellular barrier that controls the flow of molecules in the intercellular space between epithelial cells. We and others showed that Downregulation of CLDN4 could boost the infection of PRRSV. Collectively, LOC103222771/CLDN4 signal axis might be a novel mechanism of PRRSV pathogenesis, implying a potential therapeutic target against PRRSV infection.

Emerging role of microRNAs and long non-coding RNAs in COVID-19 with implications to therapeutics

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection which is commonly known as COVID-19 (COronaVIrus Disease 2019) has creeped into the human population taking tolls of life and causing tremendous economic crisis. It is indeed crucial to gain knowledge about their characteristics and interactions with human host cells. It has been shown that the majority of our genome consists of non-coding RNAs. Non-coding RNAs including micro RNAs (miRNAs) and long non-coding RNAs (lncRNAs) display significant roles in regulating gene expression in almost all cancers and viral diseases. It is intriguing that miRNAs and lncRNAs remarkably regulate the function and expression of major immune components of SARS-CoV-2. MiRNAs act via RNA interference mechanism in which they bind to the complementary sequences of the viral RNA strand, inducing the formation of silencing complex that eventually degrades or inhibits the viral RNA and viral protein expression. LncRNAs have been extensively shown to regulate gene expression in cytokine storm and thus emerges as a critical target for COVID-19 treatment. These lncRNAs also act as competing endogenous RNAs (ceRNAs) by sponging miRNAs and thus affecting the expression of downstream targets during SARS-CoV-2 infection. In this review, we extensively discuss the role of miRNAs and lncRNAs, describe their mechanism of action and their different interacting human targets cells during SARS-CoV-2 infection. Finally, we discuss possible ways how an interference with their molecular function could be exploited for new therapies against SARS-CoV-2.

METTL3-Mediated LncRNA EN_42575 m6A Modification Alleviates CPB2 Toxin-Induced Damage in IPEC-J2 Cells

Long non-coding RNAs (lncRNAs) modified by n6-methyladenosine (m6A) have been implicated in the development and progression of several diseases. However, the mechanism responsible for the role of m6A-modified lncRNAs in Clostridium perfringens type C piglet diarrhea has remained largely unknown. We previously developed an in vitro model of CPB2 toxin-induced piglet diarrhea in IPEC-J2 cells. In addition, we previously performed RNA immunoprecipitation sequencing (MeRIP-seq), which demonstrated lncRNA EN_42575 as one of the most regulated m6A-modified lncRNAs in CPB2 toxin-exposed IPEC-J2 cells. In this study, we used MeRIP-qPCR, FISH, EdU, and RNA pull-down assays to determine the function of lncRNA EN_42575 in CPB2 toxin-exposed IPEC-J2 cells. LncRNA EN_42575 was significantly downregulated at different time points in CPB2 toxin-treated cells. Functionally, lncRNA EN_42575 overexpression reduced cytotoxicity, promoted cell proliferation, and inhibited apoptosis and oxidative damage, whereas the knockdown of lncRNA EN_42575 reversed these results. Furthermore, the dual-luciferase analysis revealed that METTL3 regulated lncRNA EN_42575 expression in an m6A-dependent manner. In conclusion, METTL3-mediated lncRNA EN_42575 exerted a regulatory effect on IPEC-J2 cells exposed to CPB2 toxins. These findings offer novel perspectives to further investigate the function of m6A-modified lncRNAs in piglet diarrhea.

Genome-Wide Analysis of Long Noncoding RNAs in Porcine Intestine during Weaning Stress

Long noncoding RNAs (lncRNAs) play crucial roles in various biological processes, and they are considered to be closely associated with the pathogenesis of intestinal diseases. However, the role and expression of lncRNAs in intestinal damage during weaning stress remain unknown. Herein, we investigated the expression profiles of jejunal tissue from weaning piglets at 4 and 7 d after weaning (groups W4 and W7, respectively) and from suckling piglets on the same days (groups S4 and S7, respectively). Genome-wide analysis of lncRNAs was also performed using RNA sequencing technology. A total of 1809 annotated lncRNAs and 1612 novel lncRNAs were obtained from the jejunum of piglets. In W4 vs. S4, a total of 331 lncRNAs showed significant differential expression, and a total of 163 significantly differentially expressed lncRNAs (DElncRNAs) was identified in W7 vs. S7. Biological analysis indicated that DElncRNAs were involved in intestinal diseases, inflammation, and immune functions, and were mainly enriched in the Jak-STAT signaling pathway, inflammatory bowel disease, T cell receptor signaling pathway, B cell receptor signaling pathway and intestinal immune network for IgA production. Moreover, we found that lnc_000884 and target gene KLF5 were significantly upregulated in the intestine of weaning piglets. The overexpression of lnc_000884 also significantly promoted the proliferation and depressed apoptosis of IPEC-J2 cells. This result suggested that lnc_000884 may contribute to repairing intestinal damage. Our study identified the characterization and expression profile of lncRNAs in the small intestine of weaning piglets and provided new insights into the molecular regulation of intestinal damage during weaning stress.

LncRNA EN-90756 promotes CPB2-induced proliferation and inhibits apoptosis in IPEC-J2 cells by affecting the JAK-STAT signaling pathway activation

Background

Long non-coding RNAs (lncRNAs), as key regulators, are closely associated with the development of a variety of disease. However, the mechanisms by which lncRNAs regulate Clostridium perfringens type C induced piglet diarrhea are unclear.

Methods

In the present study, we explored the expression and characterization of lncRNAs in a C. perfringens beta2 (CPB2) toxin-treated intestinal porcine epithelial cell line-J2 (IPEC-J2) using RNA-sequencing (RNA-seq).

Results

A total of 6,558 lncRNAs were identified, of which 49 lncRNAs were significantly differentially expressed between the control and CPB2 groups. Functional enrichment analysis showed that the target genes of differentially expressed lncRNA EN-90756 were mainly associated with defense response to virus, and negative regulation of apoptotic process. LncRNA EN-90756 was significantly up-regulated in IPEC-J2 cells at different time points after CPB2 treatment. Functionally, knockdown of lncRNA EN-90756 might regulate the proliferation and apoptosis of IPEC-J2 cells by affecting the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling pathway. LncRNA EN-90756 may be involved in CPB2 toxin-induced piglet diarrhea by regulating the expression of its target gene MX1 (encoding MX dynamin like GTPase 1).

Conclusion

Long non-coding RNA EN-90756 affected the antiviral ability of IPEC-J2 cells by regulating the expression of MX1. Meanwhile, lncRNA EN-90756 might regulate cell proliferation and apoptosis by affecting JAK-STAT signaling pathway activation. These findings provide novel perspectives and directions for further exploration of the regulatory mechanisms of lncRNAs on CPB2 toxin-induced diarrhea in piglets.

Integrated analysis of lncRNA-mediated ceRNA network involved in immune regulation in the spleen of Meishan piglets

Meishan pigs are a famous local pig breed in China, with high fertility and early sexual maturity, and stronger immunity compared to other breeds. The spleen is the largest lymphoid organ in pigs and performs essential functions, such as those relating to immunity and haematopoiesis. The invasion of many pathogenic microorganisms in pigs is associated with spleen damage. Long non-coding RNAs participate in a broad range of biological processes and have been demonstrated to be associated with splenic immune regulation. However, the expression network of mRNAs and lncRNAs in the spleen of Meishan pigs remains unclear. This study collected spleen tissues from Meishan piglets at three different ages as a model, and mRNA and lncRNA transcripts were profiled for each sample. Additionally, 1,806 differential mRNAs and 319 differential lncRNAs were identified. A complicated interaction between mRNAs and lncRNAs was identified via WGCNA, demonstrating that lncRNAs are a crucial regulatory component in mRNA. The results show that the modules black and red have similar mRNA and lncRNA transcription patterns and are mainly involved in the process of the immune defense response. The core genes (DHX58 and IFIT1) and key lncRNAs (TCONS-00002102 and TCONS-00012474) of piglet spleen tissue were screened using the ceRNA network. The expression of these genes is related to the immune response of pigs. Our research may contribute to a further understanding of mRNA and lncRNA expression in the spleen of piglets, and provide new ideas to improve the disease resistance of piglets.

RNA-seq reveals a novel porcine lncRNA MPHOSPH9-OT1 induces CXCL8/IL-8 expression in ETEC infected IPEC-J2 cells

Enterotoxigenic Escherichia coli (ETEC) is a major cause of bacterial diarrhea in piglets, leading to economic losses in the pig industry. In past decades, long non-coding RNAs (lncRNAs) have shown to be widely involved in the regulation of host immunity in porcine infection diseases. In this study, we explored the lncRNAs associated with ETEC F41 infection in IPEC-J2 cells by high-throughput sequencing and bioinformatic analysis. A total of 10150 novel porcine lncRNAs were identified. There were 161 differentially expressed (DE) lncRNAs associated with ETEC F41 infection, of which 65 DE lncRNAs were up-regulated and 96 DE lncRNAs were down-regulated. Functional and KEGG enrichment analysis of predicted target genes of DE lncRNAs indicated they are enriched in cell growth and inflammation-related pathways, such as endocytosis, focal adhesion, TGF-β signaling pathway, and adherens junctions. We revealed a novel candidate lncRNA MPHOSPH9-OT1 that was up-regulated after ETEC infection. The qRT-PCR validation and ELISA assessment showed the knockdown and overexpression of MPHOSPH9-OT1 resulted in significantly down- and up-regulation of cellular mRNA levels and secreted cytokine levels of CXCL8/IL-8, respectively. Meanwhile, MPHOSPH9-OT1 equilibrium is important to maintain the transepithelial electric resistance value and tight junction protein expression of IPEC-J2 cells. This study provides insights into the functionality of novel porcine lncRNAs in host immune responses to ETEC infection.

The Effects of Swine Coronaviruses on ER Stress, Autophagy, Apoptosis, and Alterations in Cell Morphology

Swine coronaviruses include the following six members, namely porcine epidemic diarrhea virus (PEDV), transmissible gastroenteritis virus (TGEV), porcine delta coronavirus (PDCoV), swine acute diarrhea syndrome coronavirus (SADS-CoV), porcine hemagglutinating encephalomyelitis virus (PHEV), and porcine respiratory coronavirus (PRCV). Clinically, PEDV, TGEV, PDCoV, and SADS-CoV cause enteritis, whereas PHEV induces encephalomyelitis, and PRCV causes respiratory disease. Years of studies reveal that swine coronaviruses replicate in the cellular cytoplasm exerting a wide variety of effects on cells. Some of these effects are particularly pertinent to cell pathology, including endoplasmic reticulum (ER) stress, unfolded protein response (UPR), autophagy, and apoptosis. In addition, swine coronaviruses are able to induce cellular changes, such as cytoskeletal rearrangement, alterations of junctional complexes, and epithelial-mesenchymal transition (EMT), that render enterocytes unable to absorb nutrients normally, resulting in the loss of water, ions, and protein into the intestinal lumen. This review aims to describe the cellular changes in swine coronavirus-infected cells and to aid in understanding the pathogenesis of swine coronavirus infections. This review also explores how the virus exerted subcellular and molecular changes culminating in the clinical and pathological findings observed in the field.

Differential expression analysis of mRNAs, lncRNAs, and miRNAs expression profiles and construction of ceRNA networks in PEDV infection

BACKGROUND

Porcine Epidemic Diarrhea Virus (PEDV) is a coronavirus that seriously affects the swine industry. MicroRNAs and long noncoding RNAs are two relevant non-coding RNAs (ncRNAs) class and play crucial roles in a variety of physiological processes. Increased evidence indicates a complex interaction between mRNA and ncRNA. However, our understanding of the function of ncRNA involved in host-PEDV interaction is limited.

RESULTS

A total of 1,197 mRNA transcripts, 539 lncRNA transcripts, and 208 miRNA transcripts were differentially regulated at 24 h and 48 h post-infection. Gene ontology (GO) and KEGG pathway enrichment analysis showed that DE mRNAs and DE lncRNAs were mainly involved in biosynthesis, innate immunity, and lipid metabolism. Moreover, we constructed a miRNA-mRNA-pathway network using bioinformatics, including 12 DE mRNAs, 120 DE miRNAs, and 11 pathways. Finally, the target genes of DE miRNAs were screened by bioinformatics, and we constructed immune-related lncRNA-miRNA-mRNA ceRNA networks. Then, the selected DE genes were validated by qRT-PCR, which were consistent with the results from RNA-Seq data.

CONCLUSIONS

This study provides the comprehensive analysis of the expression profiles of mRNAs, lncRNAs, and miRNAs during PEDV infection. We characterize the ceRNA networks which can provide new insights into the pathogenesis of PEDV.

Comparative transcriptomic analysis of porcine epidemic diarrhea virus epidemic and classical strains in IPEC-J2 cells

In recent years, porcine epidemic diarrhea (PED) has become widespread and caused huge economic losses for the global pig industry. There is growing evidence that frequent outbreaks of diarrhea are caused by the variants of porcine epidemic diarrhea virus (PEDV) with high pathogenicity. Herein, an epidemic strain of PEDV HLJ strain was isolated and characterized from Heilongjiang Province of China, and the whole genomic expression profile of intestinal porcine epithelial cells (IPEC-J2) infected with HLJ strain was investigated in comparison with classical CV777 strain. A total of 26,851 genes were identified, of these, 25,880 were known genes and 971 were novel genes. There were 258 differentially expressed genes (DEGs) identified between PEDV HLJ-infected and uninfected cells at 24 h post infection (hpi), and 201 DEGs between PEDV HLJ and CV777 infection. A comparative analysis revealed that 258 DEGs were enriched in 468 gene ontology (GO) terms and mapped to 179 KEGG pathways, and 201 DEGs in 1120 GO terms and mapped to 115 KEGG pathways for HLJ-infected cells in contrast to the uninfected and CV777-infected cells, respectively. Specifically, PEDV HLJ strain could activate anti-viral innate immune response and inflammation more intensively than CV777, in which mRNA levels of interferon (IFN-β), chemokines (CCL5 and CXCL10) and pro-inflammatory cytokines (IL-8 and TNF-α) were induced earlier and more strongly. Subsequently, 20 DEGs and 5 proteins were selected and validated by real-time fluorescence quantitative PCR (RT-qPCR) and western blot, and the results were consistent with the transcriptomic analysis. Overall, this study may be helpful for understanding the pathogenesis mechanism of PEDV variants, and contribute to the effective prevention and control of PEDV infection.

Amachawadi R, Dash AP, Yadav MP, Prasad KS, P S, Jain AS, Shivamallu C. COVID-19 PANDEMIC: A SYSTEMATIC REVIEW ON THE CORONAVIRUSES OF ANIMALS AND SARS-CoV-2

Coronaviruses (CoVs), classified into four genera, viz., alpha-, beta-, gamma-, and Delta- CoV, represent an important group of diverse transboundary pathogens that can infect a variety of mammalian and avian species including humans, animals, poultry, and non-poultry birds. CoVs primarily infect lung and gut epithelial cells, besides monocytes and macrophages. CoVs have high mutation rates causing changes in host specificity, tissue tropism, and mode of virus excretion and transmissions. The recent CoV zoonoses are SARS, MERS, and COVID-19 that are caused by the transmission of beta-CoVs of bats to humans. Recently, reverse zoonoses of the COVID-19 virus have been detected in dogs, tigers, and minks. Beta-CoV strains also infect bovine (BCoV) and canine species (CRCoV); both these beta-CoVs might have originated from a common ancestor. Despite the high genetic similarity between BCoV, CRCoV, and HCoV-OC43, these differ in species specificity. Alpha-CoV strains infect canine (CCoV), feline (FIPV), swine (TGEV and PEDV), and humans (HCoV229E and NL63). Six coronavirus species are known to infect and cause disease in pigs, seven in human beings, and two in dogs. The high mutation rate in CoVs is attributed to error-prone 3′-5′ exoribonuclease (NSP 14), and genetic recombination to template shift by the polymerase. The present compilation describes the important features of the CoVs and diseases caused in humans, animals, and birds that are essential in surveillance of diverse pool of CoVs circulating in nature, and monitoring interspecies transmission, zoonoses, and reverse zoonoses.

Intestinal Viral Loads and Inactivation Kinetics of Livestock Viruses Relevant for Natural Casing Production: a Systematic Review and Meta-Analysis

Animal intestines are the source of edible sausage casings, which are traded worldwide and may come from areas where notifiable infectious animal diseases are prevalent. To estimate the risks of virus contamination, knowledge about the quantity of virus and decimal reduction values of the standard preservation method by salting is of great importance. A literature search, based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, was performed in search engine CAB Abstracts to determine the viral load of 14 relevant animal viruses in natural casings or intestines. Only a very limited number of scientific publications per virus were found and viral loads in the intestines varied from high for ASFV (five publications), BVDV (3), CSFV (6), PPRV (3), RPV (2) and TGEV (3) to moderate for PEDV (2) and SVDV (3), low for HEV (2) and FMDV (5), very low for VESV (1) and negative for PrV (2) and VSV (1). PRRSV was found in intestines, however, viral titers were not published. Three viruses (BVDV, CSFV and PPRV) with high viral loads were selected to search for their inactivation kinetics. For casings, no inactivation data were found, however, thermal inactivation data of these viruses were available, but differed in quantity, quality and matrices. In conclusion, important data gaps still exist when it comes to the quantitative inactivation of viruses in sausage casings or livestock intestines.

Identification and characterization of PEDV infection in rat crypt epithelial cells

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The rat crypt epithelial cells (IEC-6) were highly susceptible to different subtypes of PEDV.

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The PEDV replication capacity in IEC-6 cells was similar to Vero cells and superior to that in IPEC-J2 cells.

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PEDV infection activated a robust immune response in IEC-6 cells.

Porcine epidemic diarrhea (PED) is a devastating enteric disease to the world's swine production. Porcine epidemic diarrhea virus (PEDV), as the PED causative agent, has been commonly propagated and investigated in Vero cells, as well as in IPEC-J2, a porcine epithelial cell-jejunum 2. However, Vero cells, which are defective in interferon production, cannot represent the host response in enteric cells while PEDV replicates poorly in IPEC-J2 cells. In this study, we observed that rat crypt epithelial cells (IEC-6) were highly susceptible to different subtypes of PEDV. The replication kinetics of PEDV in IEC-6 cells is similar to that in Vero cells, but it is much higher than in IPEC-J2 cells. Besides that, PEDV infection in IEC-6 cells can induce the production of inflammatory cytokines and interferon, especially the type III IFNs. Collectively, our findings suggest that IEC-6 is an ideal cell line for PEDV replication and immune response studies.

Identification and analysis of long non-coding RNAs that are involved in inflammatory process in response to transmissible gastroenteritis virus infection

Background

Transmissible gastroenteritis virus (TGEV) infection can cause acute inflammation. Long noncoding RNAs (lncRNAs) play important roles in a number of biological process including inflammation response. However, whether lncRNAs participate in TGEV-induced inflammation in porcine intestinal epithelial cells (IPECs) is largely unknown.

Results

In this study, the next-generation sequencing (NGS) technology was used to analyze the profiles of lncRNAs in Mock and TGEV-infected porcine intestinal epithelial cell-jejunum 2 (IPEC-J2) cell line. A total of 106 lncRNAs were differentially expressed. Many differentially expressed lncRNAs act as elements to competitively attach microRNAs (miRNAs) which target to messenger RNA (mRNAs) to mediate expression of genes that related to toll-like receptors (TLRs), NOD-like receptors (NLRs), tumor necrosis factor (TNF), and RIG-I-like receptors (RLRs) pathways. Functional analysis of the binding proteins and the up/down-stream genes of the differentially expressed lncRNAs revealed that lncRNAs were principally related to inflammatory response. Meanwhile, we found that the differentially expressed lncRNA TCONS_00058367 might lead to a reduction of phosphorylation of transcription factor p65 (p-p65) in TGEV-infected IPEC-J2 cells by negatively regulating its antisense gene promyelocytic leukemia (PML).

Conclusions

The data showed that differentially expressed lncRNAs might be involved in inflammatory response induced by TGEV through acting as miRNA sponges, regulating their up/down-stream genes, or directly binding proteins.

Resistance to ETEC F4/F18-mediated piglet diarrhoea: opening the gene black box

Diarrhoea, a significant problem in pig rearing industry affecting pre- and post-weaning piglets is caused by enterotoxigenic Escherichia coli (ETEC). The ETEC are classified as per the fimbriae types which are responsible for bacterial attachment with enterocytes and release of toxins causing diarrhoea. However, genetic difference exists for susceptibility to ETEC infection in piglets. The different phenotypes found in pigs determine their (pigs') susceptibility or resistance towards fimbrial subtypes/variants (F4ab, F4ac, F4ad and F18). Specific receptors are present on intestinal epithelium for attachment of these fimbriae, which do not express to same level in all animals. This differential expression is genetically determined and thus their genetic causes (may be putative candidate gene or mutations) render some animals resistant or susceptible to one or more fimbrial subtypes. Genetic linkage studies have revealed the mapping location of the receptor loci for the two most frequent variants F4ab and F4ac to SSC13q41 (i.e. q arm of 13th chromosome of Sus scrofa). Some SNPs have been identified in mucin gene family, transferring receptor gene, fucosyltransferase 1 gene and swine leucocyte antigen locus that are proposed to be linked mutations for resistance/susceptibility towards ETEC diarrhoea. However, owing to the variety of fimbrial types and subtypes, it would be difficult to identify a single causative mutation and the candidate loci may involve more number of genes/regions. In this review, we focus on the genetic mutations in genes involved in imparting resistance/susceptibility to F4 or F18 ETEC diarrhoea and possibilities to use them as marker for selection against susceptible animals.