A newly emerging porcine circovirus, designated PCV3, has been reported in various countries (USA, Poland, South Korea and China) since 2017. Its presence may be associated with porcine dermatitis and nephropathy syndrome (PDNS), reproductive failure, and multisystem inflammation. In this study, we report identification of PCV3 in cases of reproductive failure in various regions in Hunan, China. From January 2015 to December 2016, sera were collected from 190 sows from seven farms with reproductive problems. Specifically, 85 samples were from sows with a history of reproductive failure, whereas the remaining 105 were from healthy sows. The PCV3-positive rate was significantly higher in sows with reproductive failure (45.9%) than in healthy sows (21.9%), based on quantitative PCR (qPCR) assays. Although phylogenetic analysis based on the cap gene suggested that these PCV3 isolates belonged to the clade PCV3a, amino acid sequence variations in the Cap protein still occurred among these isolates, and these might have contributed to antigenic alterations of the Cap protein, based on the Jameson-Wolf antigenic index. Finally, we concluded that PCV3 was circulating in sows in Hunan province, China. However, the association of PCV3 with reproductive failure in sows and its potential for vertical transmission need to be studied further.

Background Porcine circovirus type 3 (PCV3), recently widely isolated from pigs with various clinical conditions, is likely globally epidemic. However, development of serological diagnosis for PCV3 in pigs is ongoing. Our objectives were to: 1) establish an indirect ELISA, using PCV3 capsid protein (Cap) prepared by Baculovirus Expression Vector System (BEVS) as a high-quality coating antigen for detection of PCV3-associated antibodies in serum samples; and 2) use this ELISA to conduct a serological survey for PCV3 in various regions of Hunan province, China. Results The PCV3 positive rate to the ELISA assay (total of 190 serum samples) was higher in sows with reproductive failure compared to healthy sows (34/85, 40.0% versus 30/105, 28.6%), with similar results using qPCR assays. Further, in an additional 1038 serum samples collected from January 2016 to May 2018 in various regions of Hunan province and tested with this established ELISA, 20 to 84% were positive for PCV3 (according to region of sera collection), with high PCV3 seroprevalence (> 50%) in herds in Changde, Hengyang and Yueyang. Moreover, among serum samples from herds in Shaoyang and Changde, PCV3 seroprevalence was higher in sows than in other classes of pigs (i.e., suckling piglets, nursery pigs, gilts, growing-finishing pigs and boars). Conclusions We developed a full-length PCV3 Cap-based ELISA using a eukaryotic expression system with excellent potential to elucidate PCV3 epidemiology. Based on this assay, PCV3 has been circulating in Hunan province. PCV3 prevalence was lower in healthy sows than in those with reproductive failure. Further studies are warranted to identify the PCV3 responsible for high seroprevalence in sows and determine pathogenesis of PCV3 in sows with reproductive failure. Electronic supplementary material The online version of this article (10.1186/s12917-019-1810-3) contains supplementary material, which is available to authorized users.

Porcine parvoviruses (PPVs) and porcine circoviruses (PCVs) infect pigs worldwide, with PPV1–7 and PCV2 infections common in pigs. Although PPV7 was only identified in 2016, co-infection of PPV7 and PCV2 is already common, and PPV7 may stimulate PCV2 replication. PCV3, a novel type of circovirus, is prevalent in pig populations worldwide and considered to cause reproductive disorders and dermatitis nephrotic syndrome. In recent studies, pigs were commonly infected with both PCV3 and PPV7. Our objective was to investigate the co-infections between PPV7 and PCV3 in samples from swine on farms in Hunan, China, and assess the potential impacts of PPV7 on PCV3 viremia. A total of 209 samples, known to be positive (105) or negative (104) for PCV3, were randomly selected from serum samples that were collected from commercial swine herds in seven regions from 2016 to 2018 in our previous studies; these samples were subjected to real-time PCR to detect PPV7. Of these samples, 23% (48/209) were positive for PPV7. Furthermore, the PPV7 positive rate was significantly higher in PCV3 positive serum (31.4%, 33/105) than in PCV3 negative serum (14.4%, 15/104). Another 62 PCV3 positive sow serum samples and 20 PCV3 positive aborted fetuses were selected from 2015 to 2016 in our other previous study. These samples were designated as being from farms with or without long-standing histories of reproductive failure (RF or non-RF), respectively, and they were also subjected to real-time PCR to detect PPV7 and to determine whether PPV7 affected PCV3 viremia. Among the 62 serum samples (39 PCV3 positive RF-serum and 23 PCV3 positive non-RF-serum), 45.1% (28/62) were positive for PPV7 and PCV3, and the PPV7 positive rate was significantly higher in PCV3 positive RF-serum (51.2%, 20/39) than in PCV3 positive non-RF-serum (34.8%, 8/23). In addition, there was a higher positive rate of PPV7 (55%, 11/20) in PCV3 positive aborted fetus samples. In addition, the copy number of PCV3 in PPV7 positive samples was significantly higher than that in PPV7 negative serum samples. Based on these findings, we concluded that PPV7 may stimulate PCV3 replication.

Although porcine circovirus-like particles can function as a vector to carry foreign peptides into host cells, displaying foreign peptides on the surface of virus-like particles (VLPs) remains challenging. In this study, a plateau, consisting of the middle portion of Loop CD (MP-Lcd) from two neighboring subunits of PCV2 capsid protein (Cap), was identified as an ideal site to insert various foreign peptides or epitopes and display them on the surface of PCV2 VLPs. One of the goals of this work is to determine if the surface pattern of this plateau can be altered without compromising the neutralizing activity against PCV2 infections. Therefore, biological roles of MP-Lcd regarding VLPs assembly, cell entry, and antigenicity were investigated to determine whether this was a universal site for insertion of foreign functional peptides. Three-dimensional (3D) structure simulations and mutation assays revealed MP-Lcd was dispensable for PCV2 Cap assembly into VLPs and their entry into host cells. Notably, substitution of MP-Lcd with a foreign peptide, caused surface pattern changes around two-fold axes of PCV2 VLPs based on 3D structure simulation, but was not detrimental to VLPs assembly and cell entry. Moreover, this substitution had no adverse effect on eliciting neutralizing antibodies (NAbs) against PCV2 infection in pigs. In conclusion, MP-Lcd of the PCV2 Cap was a promising site to accommodate and display foreign epitopes or functional peptides on the surface of PCV2 VLPs. Furthermore, chimeric VLPs (cVLPs) would have potential as bivalent or multivalent vaccines and carriers to deliver functional peptides to target cells.

Purpose This study assessed the prognostic value of red blood cell distribution width (RDW) and cancer antigen 125 (CA125) in predicting the prognosis of endometrial cancer (EC) patients. Patients and Methods In this study, we included 525 patients with EC between January 2013 and January 2019. Demographic and clinical indicators were collected, and the receiver operating characteristics curve (ROC) and cutoff values were calculated between the early and advanced stages of EC. Independent risk factors associated with EC prognosis were assessed using Cox regression analyses and the Kaplan–Meier method. Results Compared to women in the early stage of EC, women with advanced stage had significantly elevated RDW coefficient of variation (RDW-CV) and CA125 levels and lower mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) (both P < 0.05). Consequently, RDW-CV and CA125 were found to be independent risk factors for EC by using ROC curve and multivariate logistic regression analysis. The survival analysis curve was used to assess the diagnostic value of RDW-CV, CA125, and their combination in the prognosis of EC. The results showed that patients with high expression of RDW-CV and CA125 had worse overall survival than those with low expression. Moreover, multivariate Cox regression analysis indicated that RDW-CV+CA125=2 was an independent prognostic factor. Conclusion These findings suggest that CA125 combined with RDW-CV has a good prognostic value for EC. Thus, the RDW-CV+CA125 score is a promising prognostic marker for the clinical decision-making process regarding EC outcomes.