Poly(A)-Binding Protein Cytoplasmic 1 Inhibits Porcine Epidemic Diarrhea Virus Replication by Interacting with Nucleocapsid Protein.

Porcine epidemic diarrhea virus (PEDV) is the etiological agent of porcine epidemic diarrhea (PED) characterized by vomit, watery diarrhea, dehydration and high mortality. Outbreaks of highly pathogenic variant strains of PEDV have resulted in extreme economic losses to the swine industry all over the world. The study of host-virus interaction can help to better understand the viral pathogenicity. Many studies have shown that poly(A)-binding proteins are involved in the replication process of various viruses. Here, we found that the infection of PEDV downregulated the expression of poly(A)-binding protein cytoplasmic 1 (PABPC1) at the later infection stage in Vero cells. The overexpression of PABPC1 inhibited the proliferation of PEDV at transcription and translation level, and siRNA-mediated depletion of PABPC1 promoted the replication of PEDV. Furthermore, mass spectrometry analysis and immunoprecipitation assay confirmed that PABPC1 interacted with the nucleocapsid (N) protein of PEDV. Confocal microscopy revealed the co-localizations of PABPC1 with N protein in the cytoplasm. Taken together, these results demonstrate the antiviral effect of PABPC1 against PEDV replication by interacting with N protein, which increases understanding of the interaction between PEDV and host.

A novel low virulent respiratory infectious bronchitis virus originating from the recombination of QX, TW and 4/91 genotype strains in China.

In China, variants of infectious bronchitis virus (IBV) evolve continually and diverse recombinant strains have been reported. Here, an IBV strain, designated as ck/CH/LJX/2017/07 (referred as JX17) was isolated from chicken vaccinated with H120 and 4/91 in Jiangxi, China, in 2017. Sequence analysis reveals of the S1 gene of JX17 the highest nucleotide identity of 98.15% with that of GI-7 genotype TW2575/98 strain. Furthermore, whole genome analysis among JX17 and other 18 IBV strains demonstrates that JX17 has the highest nucleotide identity of 95.94% with GI-19 genotype YX10 strain. Among all genes of JX17 except the S1 gene, the N gene and 3' UTR have the highest identity to GI-13 genotype 4/91 strain and the rest genes are the most identical to GI-19 genotype YX10 strain. Analyzed by the RDP and SimPlot, the recombination of JX17 strain was shown to occur in regions which include 5'-terminal S1 gene (20,344 to 22,447 nt), most N gene and 3' UTR (26,163 to 27,648 nt). The pathogenicity study shows that JX17 is a natural low virulent IBV variant which caused respiratory symptoms but no death. Taken together, these results indicate that IBV strains continue to evolve through genetic recombination and three prevalent genotypes in China including QX, TW and 4/91 have started to recombine.