Development of an indirect ELISA method based on the VP1 protein for detection of IgG antibodies against porcine sapelovirus.

Porcine sapelovirus (PSV) is a newly emerging enterovirus that is widely prevalent in China. Since there is no clinical serological testing for PSV, the objective of this study was to develop an indirect enzyme-linked immunosorbent assay (i-ELISA) for detection of PSV immunoglobulin G (IgG) antibody in pigs. A PSV strain, named SHPD202148, was first isolated from the fecal samples of piglets. Its structural protein, VP1, was prokaryotic-expressed in the pET expression system, followed by purification. Using the recombinant protein with reactogenicity as coating antigen, an i-ELISA, characterized by high sensitivity and specificity, had a detection limit at 1:12 800 dilution with a determined cutoff value of 0.352. Finally, field sera collected from different pig herds were tested in parallel by the serum neutralization (SN) test. The result showed that 126 samples were positive and 36 were negative, with an agreement of 97.0% in both cases. This i-ELISA can be used as an alternative serological test for detecting antibodies against PSV in blood serum.

Le sapelovirus porcin (PSV) est un entérovirus nouvellement émergent largement répandu en Chine. Puisqu'il n'y a pas de test sérologique clinique pour le PSV, l'objectif de cette étude était de développer un test immuno-enzymatique indirect (i-ELISA) pour la détection d'immunoglobuline G (IgG) anti-PSV chez les porcs. Une souche de PSV, nommée SHPD202148, a d'abord été isolée à partir d'échantillons fécaux de porcelets. Sa protéine structurale, VP1, a été exprimée par un procaryote dans le système d'expression pET, suivie d'une purification. Utilisant la protéine recombinante à réactogénicité comme antigène de revêtement, un i-ELISA, caractérisé par une sensibilité et une spécificité élevées, avait une limite de détection à une dilution de 1:12 800 avec une valeur seuil déterminée de 0,352. Enfin, des sérums de terrain collectés dans différents troupeaux de porcs ont été testés en parallèle par le test de neutralisation sérique (SN). Le résultat a montré que 126 échantillons étaient positifs et 36 étaient négatifs, avec un accord de 97,0 % dans les deux cas. Cet i-ELISA peut être utilisé comme test sérologique alternatif pour détecter les anticorps anti-PSV dans le sérum sanguin.(Traduit par Docteur Serge Messier).

Genomic Divergence Characterization and Quantitative Proteomics Exploration of Type 4 Porcine Astrovirus.

Porcine astrovirus (PAstV) has been identified as an important diarrheic pathogen with a broad global distribution. The PAstV is a potential pathogen to human beings and plays a role in public health. Until now, the divergence characteristics and pathogenesis of the PAstV are still not well known. In this study, the PAstV-4 strain PAstV/CH/2022/CM1 was isolated from the diarrheal feces of a piglet in Shanghai, which was identified to be a recombination of PAstV4/JPN (LC201612) and PAstV4/CHN (JX060808). A time tree based on the ORF2 protein of the astrovirus demonstrated that type 2-5 PAstV (PAstV-2 to 5) diverged from type 1 PAstV (PAstV-1) at a point from 1992 to 2000. To better understand the molecular basis of the virus, we sought to explore the host cell response to the PAstV/CH/2022/CM1 infection using proteomics. The results demonstrate that viral infection elicits global protein changes, and that the mitochondria seems to be a primary and an important target in viral infection. Importantly, there was crosstalk between autophagy and apoptosis, in which ATG7 might be the key mediator. In addition, the NOD-like receptor X1 (NLRX1) in the mitochondria was activated and participated in several important antiviral signaling pathways after the PAstV/CH/2022/CM1 infection, which was closely related to mitophagy. The NLRX1 may be a crucial protein for antagonizing a viral infection through autophagy, but this has yet to be validated. In conclusion, the data in this study provides more information for understanding the virus genomic characterization and the potential antiviral targets in a PAstV infection.

NDV entry into dendritic cells through macropinocytosis and suppression of T lymphocyte proliferation.

Newcastle disease virus (NDV) causes major economic losses in the poultry industry. Previous studies have shown that NDV utilizes different pathways to infect various cells, including dendritic cells (DCs). Here, we demonstrate that NDV gains entry into DCs mainly via macropinocytosis and clathrin-mediated endocytosis. The detection of cytokines interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), interleukin-12 (IL-12), interleukin-4 (IL-4) and interleukin-10 (IL-10) indicates that NDV significantly induces Th1 responses and lowers Th2 responses. Furthermore, NDV entry into DCs resulted in the upregulation of TNF-related apoptosis-inducing ligand (TRAIL) and cleaved caspase-3 proteins, which in turn activated the extrinsic apoptosis pathway and induced DCs apoptosis. Transwell® co-culture demonstrated that direct contact between live NDV-stimulated DCs and T cells, rather than heated-inactivated NDV, inhibited CD4+ T cell proliferation. Taken together, these findings provide new insights into the mechanism underlying NDV infections, particularly in relation to antigen presentation cells and suppression of T cell proliferation.