Astragalus polysaccharide enhances immunity and inhibits H9N2 avian influenza virus in vitro and in vivo

This study investigated the humoral immunization of Astragalus polysaccharide （APS） against HgN2 avian influenza virus （H9N2 AIV） infection in chickens. The effects of APS treatment on H9N2 infection was evaluated by an Mqq- [3（4, 5-dimethylthiazol-2-yl）-2, 3-diphenyl tetrazolium bromide] assay and analysis of MFIC and cytokine mRNA expression. The effect on lymphocyte and serum antibody titers in vivo was also investigated. IL-4, IL-6, IL-10, LITAF, IL-12 and antibody titers to H9N2 AIV wet enhanced in the first week after APS treatment. The results indicated that APS treatment reduces H9N2 AIV replication and promotes early humoral immune responses in young chickens.This study investigated the humoral immunization of Astragalus polysaccharide （APS） against HgN2 avian influenza virus （H9N2 AIV） infection in chickens. The effects of APS treatment on HgN2 infection was evaluated by an M]q- [3（4, 5-dimethylthiazol-2-yl）-2, 3-diphenyl tetrazolium bromide] assay and analysis of MHC and cytokine mRNA expression. The effect on lymphocyte and serum antibody titers in vivo was also investigated. IL-4, IL-6, IL-10, LITAF, IL-12 and antibody titers to PIgN2 AIV were enhanced in the first week after APS treatment. The results indicated that APS treatment reduces HgN2 AIV replication and promotes early humoral immune responses in young chickens.

A Highly Pathogenic Strain of Porcine Deltacoronavirus Caused Watery Diarrhea in Newborn Piglets

Porcine deltacoronavirus(PDCoV) is a newly identified virus that causes watery diarrhea in newborn piglets and results in significant economic losses to the pig industry. Since first reported in Hong Kong in 2012, PDCoV has been subsequently detected in USA, South Korea, Thailand, and China's Mainland. Here we isolated a strain of PDCoV, named CHN-GD-2016,from the intestinal content of a diseased newborn piglet with severe diarrhea in a pig farm in Guangdong, China. PDCoV CHN-GD-2016 could be identified by immunofluorescence with PDCoV specific rabbit antisera, and typical crown-shaped particles with spiky surface projections of this PDCoV were observed with electron microscopy. Genomic analysis showed that the PDCoV CHN-GD-2016 was closely related to other Chinese PDCoV strains, with the highest sequence similarity with the strain CHN/Tianjin/2016. Importantly, inoculation of newborn piglets with 1×10~5 TCID_(50) of CHN-GD-2016 by oral feeding successfully reproduced clear clinical symptoms, including vomiting, dehydration, and severe diarrhea in piglets. In addition, the virus RNA in rectal swabs from 1 to 7 days post inoculation was detected, macroscopic and microscopic lesions in small intestine were observed, and viral antigen was also detected in the small intestines with immunohistochemical staining. Collectively, the data show in this study confirms that PDCoV is present in Guangdong,China and is highly pathogenic in newborn piglets.

Evaluation of purified recombinant spike fragments forassessment of the presence of serum neutralizing antibodiesagainst a variant strain of porcine epidemic diarrhea virus

Since 2010, variant strains of porcine epidemic diarrhea virus(PEDV) have caused disasters in the pork industry. The spike(S) protein, as the major immunity-eliciting antigen, has previously been used for serological testing and has been found to correlate significantly with the results of the serum neutralization(SN) test. However, further evaluation of this method is needed as new epidemic strains of PEDV emerge. Hence, the main objective of this study was to assess sow sera and determine the correlation between enzyme-linked immunosorbent assay(ELISA) results(involving a newly isolated GDS01 virus-based ELISA and ELISAs based on seven recombinant fragments comprising overlapping S1 and partial S2 sequences) and SN titers. Furthermore, we determined the reliability of the ELISAs based on receiver operating characteristics(ROC) curve analyses. For the most promising ELISA, i.e., the SP4 ELISA, the correlation coefficient(r) and the area under curve(AUC) were determined to be 0.6113 and 0.8538, respectively. In addition, we analyzed the homology of the SP4 sequences obtained from different strains(including vaccine strains) and found that various strains showed a high degree of homology in this region. Thus, we conclude that SP4 is a promising serological testing protein for use in the field.

Isolation and Characterization of A Novel Fowl Adenovirus Serotype 8a Strain from China

Since 2012,the clinical cases of inclusion body hepatitis showed an increasing trend in China,causing considerable economic losses to the poultry industry.In this study,a fowl adenovirus strain CH/GDLZ/201801 was isolated from a chicken flock experiencing inclusion body hepatitis and analyzed by complete genome sequencing.The pathogenicity of the new virus strain was examined by experimental infection of specific pathogen free chickens.The isolate was identified by immunofluorescence and the virions presented typical icosahedral particles under transmission electron microscopy.The full genome of the isolate was 44,329 nucleotides in length with 58%G+C content.Phylogenetic analysis,based on the whole genome,revealed that the new isolate was closest to serotype 8a from the species Fowl aviadenovirus E(FAdVE).Recombination analysis and phylogenetic analysis showed that the new isolate is a recombinant strain between FAdV-8a and FAdV-8b.In infection experiments,three infected chickens showed clinical signs and one chicken died on day 7 post infection,corresponding to 5%mortality.Macroscopic and microscopic lesions in the liver were observed,and viral antigen could be detected in the livers by immunohistochemical staining and TEM.Taken together,our study describes the genomic characteristics and pathogenicity of a FAdV-8a strain in China.It would lay a solid foundation for further study of the pathogenic mechanism and vaccine development of the virus.

Genome-wide transcriptome analysis of porcine epidemic diarrhea virus virulent or avirulent strain-infected porcine small intestinal epithelial cells

Porcine epidemic diarrhea virus(PEDV)is the main cause of diarrhea,vomiting,and mortality in pigs,which results in devastating economic loss to the pig industry around the globe.In recent years,the advent of RNAsequencing technologies has led to delineate host responses at late stages of PEDV infection;however,the comparative analysis of host responses to early-stage infection of virulent and avirulent PEDV strains is currently unknown.Here,using the BGI DNBSEQ RNA-sequencing,we performed global gene expression profiles of pig intestinal epithelial cells infected with virulent(GDS01)or avirulent(HX)PEDV strains for 3,6,and 12 h.It was observed that over half of all significantly dysregulated genes in both infection groups exhibited a down-regulated expression pattern.Functional enrichment analyses indicated that the differentially expressed genes(DEGs)in the GDS01 group were predominantly related to autophagy and apoptosis,whereas the genes showing the differential expression in the HX group were strongly enriched in immune responses/inflammation.Among the DEGs,the functional association of TLR3 and IFIT2 genes with the HX and GDS01 strains replication was experimentally validated by TLR3 inhibition and IFIT2 overexpression systems in cultured cells.TLR3 expression was found to inhibit HX strain,but not GDS01 strain,replication by enhancing the IFIT2 expression in infected cells.In conclusion,our study highlights similarities and differences in gene expression patterns and cellular processes/pathways altered at the early-stage infection of PEDV virulent and avirulent strains.These findings may provide a foundation for establishing novel therapies to control PEDV infection.

Tandem 3'UTR Patterns and Gene Expression Profiles of Marc-145 Cells During PRRSV Infection

Porcine reproductive and respiratory syndrome virus(PRRSV) causes substantial economic losses to the global pig industry. Alternative polyadenylation(APA) is a mechanism that diversifies gene expression, which is important for tumorigenesis, development, and cell differentiation. However, it is unclear whether APA plays a role in the course of PRRSV infection. To address this issue, in this study we carried out a whole-genome transcriptome analysis of PRRSVinfected Marc-145 African green monkey kidney cells and identified 185 APA switching genes and 393 differentially expressed genes(DEGs). Most of these genes were involved in cellular process, metabolism, and biological regulation, and there was some overlap between the two gene sets. DEGs were found to be more directly involved in the antiviral response than APA genes. These findings provide insight into the dynamics of host gene regulation during PRRSV infection and a basis for elucidating the pathogenesis of PRRSV.