Epidemiological investigation of swine Japanese encephalitis virus based on RT-RAA detection method.

JEV is one of the zoonotic pathogens that cause serious diseases in humans. JEV infection can cause abortion, mummified foetus and stillbirth in sows, orchitis and semen quality decline in boars, causing huge economic losses to pig industry. In order to investigate the epidemiology of JEV in pigs in Sichuan province, a rapid and efficient fluorescent Reverse transcription recombinase-aided amplification (RT-RAA) detection method was established. Aborted fetuses and testicular swollen boar samples were detected by RT-RAA in pigs in the mountain areas around Sichuan Basin, and the detection rate of JEV was 6.49%. The positive samples were identified as JEV GI strain and GIIIstrain by sequencing analysis. We analyzed the whole gene sequence of a positive sample for the GI virus. The Envelope Protein (E protein) phylogenetic tree analysis was far related to the Chinese vaccine strain SA14-14-2, and was most closely related to the JEV GI strains SH17M-07 and SD0810 isolated from China. The results showed that we established an efficient, accurate and sensitive method for clinical detection of JEV, and JEV GI strains were prevalent in Sichuan area. It provides reference for the prevention and control of JEV in Sichuan.

Getah Virus Infection Rapidly Causes Testicular Damage and Decreases Sperm Quality in Male Mice.

Getah virus (GETV) is a zoonotic arbovirus that can cause infection in many animals. It can cause pyrexia and reproductive losses in animals. The objective of the study was to explore the effects of GETV on male reproductive ability. Male mice were injected with 100 × TCID50/0.1 ml in a volume of 100-µL GETV in their hindquarter muscle, resulting in decreased semen quality and testicular histopathological changes, and the virus was detected in the testes. At 0.5 dpi (day post-infection), male mice showed decreased sperm density, motility, and decreased serum testosterone concentration, an increased sperm malformation rate, vacuoles in spermatogonial cells/spermatocytes in spermatogenic tubules, and the highest virus copies in testis. At 2 dpi, the sperm density and motility reached the lowest value of 3.99 × 106/ml and 62.03%, and the malformation rate reached 43.67%. At 28 dpi, the sperm indexes of the experimental group gradually approached that of the control group, but there were still significant differences. Since then, histopathological changes have worsened, with the most severe histopathological changes at 7 dpi and gradual recovery. Up to 14 dpi, the virus was detected by qRT-PCR and immunohistochemistry, which showed that the virus was only present in the testicular interstitium. GETV infection can rapidly enter the testis of mice and reduce the semen quality of mice, which needs to be paid attention to in the prevention and control of GETV.

Transcriptome Analyses of Senecavirus A-Infected PK-15 Cells: RIG-I and IRF7 Are the Important Factors in Inducing Type III Interferons.

Senecavirus A (SVA) is a new type of virus related to swine vesicular disease, which results in enormous economic losses worldwide. At present, the host transcriptional responses to SVA infection, host-SVA interactions, and the mechanism of SVA in innate immune modulation are not well understood. This study explores the gene expression profiles of PK-15 cells at 0, 6, 12, 18, 24, 36 h SVA post-infection by RNA sequencing. Our analysis identified 61, 510, 1,584, 2,460, and 2,359 differentially expressed genes (DEGs) in the comparison groups S6 vs. Control, S12 vs. Control, S18 vs. Control, S24 vs. Control, S36 vs. Control, respectively. The reproducibility and repeatability of the results were validated by RT-qPCR, and all DEGs exhibited expression patterns consistent with the RNA-seq results. According to GO enrichment analysis and KEGG pathway analysis of DEGs in different periods after SVA infection, we found that SVA infection significantly modified the host cell gene-expression patterns and the host cells responded in highly specific manners, including response to signal reception and transmission, external biotic stimulus, response to the virus and host immune defense response. Notably, we observed the specific induction of type III interferon IFN-λ1 and IFN-λ3, which indicated that type III interferon plays an important antiviral function in PK-15 cells. Furthermore, our results showed that SVA might be recognized by RIG-I/MDA-5 receptors first after infecting PK-15 cells and then activates downstream IRF7-mediated signaling pathways, causing an increase in the expression of type III interferon. This study could provide important insights into the modulation of host metabolism during SVA infection and provide a strong theoretical basis for a better understanding of the pathogenic mechanism and immune escape mechanism of SVA.

Genetic variations in S gene of porcine epidemic diarrhoea virus from 2018 in Sichuan Province, China.

Porcine epidemic diarrhoea virus (PEDV) belongs to the family Coronavirus, a genus of coronavirus, a highly contact-infectious intestinal disease pathogen. In this study, we downloaded 62 PEDV S gene sequences uploaded to GenBank, including 10 uploaded by our laboratory from 2018, and constructed a PEDV S gene evolution tree using MEGA V7.0 software. Phylogenetic tree analysis indicated that the genogroup of PEDV in Sichuan Province was divided into three coexisting genogroups (GII-a, GII-b and GI-a), of them, GII-a has become the main genogroup in the province due to its prevalence and range of spread. Amino acid sequence analysis showed that there were amino acid insertions and deletions in the S protein encoded by the amplified S gene, and there were amino acid mutations in the COE and SS6 of the epitope in the amplified S protein. These results provide a basic research theory for understanding the prevalence of PEDV variation and controlling PED in Sichuan.

Isolation and phylogenomic analysis of two Senecavirus A isolates in Sichuan Province, 2018.

In our study, we isolated and characterised two new Senecavirus A (SVA) isolates in Sichuan Province, China. Phylogenetic analysis of both the SVA full-length genomes and the VP1 genes revealed that the two new SVA isolates are more closely related to previous Chinese strains and US strains. The most variable isolate, SVV-SC-01, showed a significant difference from previous SVA strains, and it was identified as a recombinant using several algorithms. Study findings indicate that the SVA virus in China is constantly evolving and new SVA variants may have emerged. Hence, we must take effective measures to prevent further spread of SVA. This report provides evidence that SVA infection of pigs has occurred in Sichuan Province, and the results will contribute to our understanding of the genetic characteristics and recombinant events of SVA in China.