Porcine epidemic diarrhea virus (PEDV) causes a severe clinical enteric disease in suckling neonates with up to 100% mortality, resulting in devastating economic losses to the pork industry in recent years. Maternal immunity via colostrum and milk is a vital source to neonates of passive protection against diarrhea, dehydration and death caused by PEDV. Comprehensive information on neutralizing activity (NA) against PEDV in mammary secretions is critically important for assessing the protective capacity of sows. Therefore, the objectives of this study were to characterize anti-PEDV neutralizing activity in mammary secretions. Anti-PEDV NA was present in colostrum, milk and serum from PEDV-infected sows as determined both by immunofluorescence and ELISA-based neutralizing assays, with neutralization levels higher in colostrum and milk than in serum. The highest NA was observed in colostrum on day 1, and decreased rapidly in milk at day 3, then gradually declined from day 3 to day 19 post-farrowing. Notably, the NA in mammary secretions showed various patterns of decline over time of lactation that may contribute to variation in sow protective capacities. The kinetics of NA decline were associated with total IgA and IgG antibody levels. Neutralizing activity significantly correlated with specific IgA primarily to spike domain 1 (S1) and domain 2 (S2) proteins of PEDV rather than to specific IgG in colostrum. Subsequently, the NA in milk was mainly related to specific IgA to S1 and S2 during lactation.

Porcine epidemic diarrhea virus (PEDV) is an important pig pathogen that can cause vomiting, diarrhea, and dehydration, leading to serious damage to the swine industry worldwide. In this study, a nanoparticle-assisted polymerase chain reaction (nanoPCR) assay targeting the N gene of PEDV was developed and the sensitivity and specificity were investigated. Under the optimized conditions for detection of PEDV RNA, the nanoPCR assay was 100-fold more sensitive than a conventional RT-PCR assay. The lower detection limit of the nanoPCR assay was 2.7 × 10(-6) ng/μL of PEDV RNA and no cross-reaction was observed with other viruses. This is the first report to demonstrate the application of a nanoPCR assay for the detection of PEDV. The sensitive and specific nanoPCR assay developed in this study can be applied widely in clinical diagnosis and field surveillance of PEDV-infection.

Porcine epidemic diarrhea virus (PEDV) causes acute diarrhea, dehydration in pigs, and high mortality rates in piglets <3 weeks of age. Maternal immunity protects piglets, but information on vaccination before or after natural infection in endemically exposed sow herds is limited. Currently, the recovery goal in sow units infected with PEDV is to become fully naive again or use natural virus infection to develop immune gilts through a feedback program before introduction into the sow herd. Since neutralizing antibodies in the gut are critical for protection against enteric viral infections such as PEDV, we evaluated the effect of a conditionally licensed, adjuvanted inactivated PEDV vaccine on neutralizing antibody levels in milk and colostrum in both naive and previously naturally exposed sow herds. The results illustrate that intramuscular vaccination increased neutralizing antibody titers, and anti-PEDV IgA and IgG in milk and colostrum of sows that were previously infected. Thus, inactivated PEDV vaccines may provide increased protection to piglets nursing on previously infected sows against exposure to PEDV through increased delivery of lactogenic neutralizing antibodies to the enteric site of infection.

Porcine circovirus-associated disease (PCVAD) caused by porcine circovirus type 2 (PCV2) is an important disease in the global pig industry. Dendritic cells (DCs) are the primary immune cells capable of initiating adaptive immune responses as well as major target cells of PCV2. To determine whether PCV2 affects the immune functions of DCs, we evaluated the expression of endocytosis and co-stimulatory molecules on DCs (CD11c) from PCV2-infected mouse spleen by flow cytometry (FCM). We also analyzed the main cytokines secreted by DCs (CD11c) and activation of CD4 and CD8 T cells by DCs (CD11c) through measurement of cytokine secretion, using ELISA. Compared with control mice, PCV2 did not affect the endocytic activity of DCs but it significantly enhanced TNF-α secretion and markedly decreased IFN-α secretion. Subsets of CD40, MHCII CD40 and CD137L CD86 DCs did not increase obviously, but MHCII CD40 and CD137L CD80/CD86 DCs increased significantly in PCV2-infected mouse spleen. Under the stimulation of DCs from PCV2-infected mouse, secretion of IFN-γ by CD4 and CD8 T cells and of IL-12 by CD8 T cells was significantly lower than in control mice, while secretion of IL-4 by CD4 T cells was remarkably higher. These results indicate that PCV2 modulates cytokine secretion and co-stimulatory molecule expression of DCs, and alters activation of CD4 and CD8 T cells by DCs. The immunomodulatory effects of PCV2 on DCs might be related to the host's immune dysfunction and persistent infection with this virus.

Background: Sow endometritis is a common disease in pig breeding farms after artificial insemination, which leads to gray-green vaginal secretions and decreased conception rates. It is important to perform an etiologic diagnosis for effective treatments and control of diseases. The aim of this study was to carry out a pathogenic detection in five specimens of vaginal secretions collected from sick pigs with endometritis, implement identification of the pathogens by phenotypic detection and 16 s rDNA sequence and phylogeny analysis, and determinate antibiotic susceptibility of the isolates. Results: A Streptococcus strain was isolated and identified from all of the five specimens. The isolate was positive for Voges-Proskauer (V-P) and for the hydrolysis of arginine, esculin and myelin-associated glycoprotein (MAG). Acid formation was observed for sorbitol, mushroom sugar, sucrose, and glucose. The 16S rDNA sequence of the isolate possessed 99.93% similarity to that of Streptococcus porcinus. The phylogenetic analysis of 16S rDNA sequence showed that the isolate belonged to the same clade as the S. porcinus strains from humans, pigs, and other animals. The isolate exhibited multi-drug resistance to aminoglycosides, quinolones, macrolides and tetracyclines except being sensitive to some βlactams such as penicillin G, cephalothin, cefazolin, cephradine and cefuroxime. Conclusions: A S. porcinus isolate with multi-drug resistance was identified from vaginal secretions of sows with endometritis in one pig breeding farm, which suggests that the sow endometritis was caused by S. porcinus infection during artificial insemination. This study indicates that sensitive antibiotics such as penicillin G or some cephalosporins could be used for treatment of the diseases. In addition, the study hints that bacterial multi-drug resistance is a tough problem for disease treatment in pig farms.