Nanovaccine Confers Dual Protection Against Influenza a Virus and Porcine Circovirus Type 2 [Retraction]

[This retracts the article DOI: 10.2147/IJN.S218057.].

[Mechanisms mediating the inhibitory effects of quercetin against phthalates-induced testicular oxidative damage in rats]

OBJECTIVE

To explore the mechanism underlying the inhibitory effect of quercetin against testicular oxidative damage induced by a mixture of 3 commonly used phthalates (MPEs) in rats.

METHODS

Forty male Sprague-Dawley rats were randomly divided into control group, MPEs exposure group, and MPEs with low-, median- and high-dose quercetin treatment groups. For MPEs exposure, the rats were subjected to intragastric administration of MPEs at the daily dose of 900 mg/kg for 30 consecutive days; Quercetin treatments were administered in the same manner at the daily dose of 10, 30, and 90 mg/kg. After the treatments, serum levels of testosterone, luteinizing hormone (LH), follicle stimulating hormone (FSH), and testicular malondialdeyhde (MDA), catalase (CAT) and superoxide dismutase (SOD) were detected, and testicular pathologies of the rats were observed with HE staining. The expressions of nuclear factor-E2-related factor 2 (Nrf2), Kelch-like ECH2 associated protein 1 (Keap1) and heme oxygenase 1 (HO-1) in the testis were detected using immunofluorescence assay and Western blotting.

RESULTS

Compared with the control group, the rats with MPEs exposure showed significant reductions of the anogenital distance, weight of the testis and epididymis, and the coefficients of the testis and epididymis with lowered serum testosterone, LH and FSH levels (P < 0.05). Testicular histological examination revealed atrophy of the seminiferous tubules, spermatogenic arrest, and hyperplasia of the Leydig cells in MPEs-exposed rats. MPEs exposure also caused significant increments of testicular Nrf2, MDA, SOD, CAT and HO-1 expressions and lowered testicular Keap1 expression (P < 0.05). Treatment with quercetin at the median and high doses significantly ameliorated the pathological changes induced by MPEs exposure (P < 0.05).

CONCLUSION

Quercetin treatment inhibits MPEs-induced oxidative testicular damage in rats possibly by direct scavenging of free radicals to lower testicular oxidative stress and restore the regulation of the Nrf2 signaling pathway.

[Expert consensus on measurement and clinical application of serum HBV RNA in patients with chronic HBV infection]

Since the discovery of circulating hepatitis B virus (HBV) RNA in the peripheral blood of patients with chronic hepatitis B in 1996, a growing number of studies have focused on clarifying the biological characteristics and clinical application value of serum HBV RNA. This consensus mainly summarizes the research progress of serum HBV RNA existing profiles, quantitative detection methods, and current clinical applications. In order to better apply this indicator for the clinical management of patients with chronic HBV infection, recommendations on quantitative detection target regions, detection results, and clinical applications are put forward.

[Relationship between parental reproductive age and the risk of overweight and obesity in offspring]

Objective: To explore the role of parental reproductive age on the risk of overweight and obesity in offspring. Methods: The participants were derived from physical examination data of students aged 6-18 years in seven provinces in China, and questionnaire survey was used to collect demographic characteristics and lifestyle information of the students and their parents. A total of 41 567 children with complete data were included. According to the restricted cubic spline curve, maternal reproductive age was divided into three categories, 14-23, 24-28, and 29-38 years, and paternal reproductive age was divided into 14-23, 24-30, and 31-42 years. Multivariate logistic regression model was used to analyze the association between parental reproductive age and parental nutritional status and the risk of overweight and obesity in offspring. Results: The mean age of 41 567 children was (10.6±3.2) years, and the mean paternal and maternal age were (27.9±4.4) years and (25.8±4.0) years, respectively. The detection rate of overweight and obesity was 23.4%. After adjusting factors of children diet and behaviors, the OR(95%CI)of offspring overweight and obesity in groups of fathers aged 24-30 years and mothers aged 24-28 years was 1.11 (1.04-1.18) and 1.16 (1.08-1.24), respectively. When none parents were overweight and obese, the difference of obesity risk was not statistically significant. When both parents were overweight and obese, the OR(95%CI)of offspring overweight and obesity in groups of fathers aged 24-30 years and mothers aged 14-28 years old was 1.27 (1.00-1.62) and 1.33 (1.07-1.65) respectively. Conclusion: Parental reproductive age and parental overweight and obesity status may both increase the risk of overweight and obesity in offspring, with a significant interaction effect.

Efficacy of a live attenuated highly pathogenic PRRSV vaccine against a NADC30-like strain challenge: implications for ADE of PRRSV

BACKGROUND

Porcine reproductive and respiratory syndrome virus (PRRSV) infection can cause severe reproductive failure in sows and respiratory distress in pigs of all ages, leading to major economic losses. To date, there are still no effective strategies to prevent and control PRRSV. Antibody-dependent enhancement (ADE), a phenomenon in which preexisting non-neutralizing antibodies or sub-neutralizing antibodies facilitate virus entry and replication, may be a significant obstacle in the development of effective vaccines for many viruses, including PRRSV. However, the contribution of ADE to PRRSV infection remains controversial, especially in vivo. Whether attenuated PRRSV vaccines prevent or worsen subsequent disease in pigs infected by novel PRRSV strains requires more research. In the present study, in vivo experiments were conducted to evaluate ADE under different immune statuses, which were produced by waiting different lengths of time after vaccination with a commercially available attenuated highly pathogenic PRRSV (HP-PRRSV) vaccine (JXA1-R) before challenging the pigs with a novel heterologous NADC30-like strain.

RESULTS

Piglets that were vaccinated before being challenged with PRRSV exhibited lower mortality rates, lower body temperatures, higher bodyweight gain, and lower viremia. These results demonstrate that vaccination with JXA1-R alleviated the clinical signs of PRRSV infection in all vaccinated groups.

CONCLUSIONS

The obtained data indicate that the attenuated vaccine test here provided partial protection against the NADC30-like strain HNhx. No signs of enhanced PRRSV infection were observed under the applied experimental conditions. Our results provide some insight into the molecular mechanisms underlying vaccine-induced protection or enhancement in PRRSV.

Development of an immunochromatographic strip for rapid detection of H7 subtype avian influenza viruses

BACKGROUND

H7N9 avian influenza virus (AIV) including highly and low pathogenic viruses have been detected in China since 2013. H7N9 AIV has a high mortality rate after infection in humans, and most human cases have close contacted with poultry in the live poultry market. Therefore, it is necessary to develop a rapid point-of-care testing (POCT) technique for H7N9 AIV detection.

METHODS

The H7N9 AIV was inactivated and purified, and was used as the antigen to immunize BALB/c. Twelve H7-HA specific monoclonal antibodies (McAbs) were produced through the hybridoma technique. The McAb 10A8 was conjugated with colloid gold as detecting antibody; McAb 9B6 was dispensed on the nitrocellulose membran as the capture test line and the Goat-anti mouse IgG antibody was dispensed as control line respectively. The immunochromatographic strip was prepared.

RESULTS

The analysis of ELISA and virus neutralization test showed that the obtained McAbs specifically recognized H7 HA. Based on the prepared strip, the detection of H7 AIV was achieved within 10 min. No cross-reaction occurred between H7 AIVs and other tested viruses. The detection limit of the strip for H7 was 2.4 log10EID50/0.1 mL for chicken swab samples.

CONCLUSION

The McAbs were specific for H7 and the immunochromatographic strip developed in this study was convenient, rapid and reliable for the detection of H7 AIV. The strip could provide an effective method for the rapid and early detection of H7 AIV.

Visfatin facilitates gastric cancer malignancy by targeting snai1 via the NF-κB signaling

BACKGROUND

Visfatin acts as an oncogenic factor in numerous tumors through a variety of cellular processes. Visfatin has been revealed to promote cell migration and invasion in gastric cancer (GC). Snai1 is a well-known regulator of EMT process in cancers. However, the relationship between visfatin and snai1 in GC remains unclear. The current study aimed to explore the role of visfatin in GC.

METHODS

The RT-qPCR and western blot analysis were used to measure RNA and protein levels, respectively. The cell migration and invasion were tested by Trans-well assays and western blot analysis.

RESULTS

Visfatin showed upregulation in GC cells. Additionally, Visfatin with increasing concentration facilitated epithelial-mesenchymal transition (EMT) process by increasing E-cadherin and reducing N-cadherin and Vimentin protein levels in GC cells. Moreover, endogenous overexpression and knockdown of visfatin promoted and inhibited migratory and invasive abilities of GC cells, respectively. Then, we found that snai1 protein level was positively regulated by visfatin in GC cells. In addition, visfatin activated the NF-κB signaling to modulate snai1 protein expression. Furthermore, the silencing of snai1 counteracted the promotive impact of visfatin on cell migration, invasion and EMT process in GC.

CONCLUSION

Visfatin facilitates cell migration, invasion and EMT process by targeting snai1 via the NF-κB signaling, which provides a potential insight for the treatment of GC.

An Isothermal Molecular Point of Care Testing for African Swine Fever Virus Using Recombinase-Aided Amplification and Lateral Flow Assay Without the Need to Extract Nucleic Acids in Blood

African swine fever (ASF) is a highly contagious and usually deadly porcine infectious disease listed as a notifiable disease by the World Organization for Animal Health (OIE). It has brought huge economic losses worldwide, especially since 2018, the first outbreak in China. As there are still no effective vaccines available to date, diagnosis of ASF is essential for its surveillance and control, especially in areas far from city with limited resources and poor settings. In this study, a sensitive, specific, rapid, and simple molecular point of care testing for African swine fever virus (ASFV) B646L gene in blood samples was established, including treatment of blood samples with simple dilution and boiling for 5 min, isothermal amplification with recombinase-aided amplification (RAA) at 37°C in a water bath for 10 min, and visual readout with lateral flow assay (LFA) at room temperature for 10–15 min. Without the need to extract viral DNA in blood samples, the intact workflow from sampling to final diagnostic decision can be completed with minimal equipment requirement in 30 min. The detection limit of RAA-LFA for synthesized B646L gene-containing plasmid was 10 copies/μl, which was 10-fold more sensitive than OIE-recommended PCR and quantitative PCR. In addition, no positive readout of RAA-LFA was observed in testing classical swine fever virus, porcine reproductive and respiratory syndrome virus, porcine epidemic diarrhea virus, pseudorabies virus and porcine circovirus 2, exhibiting good specificity. Evaluation of clinical blood samples of RAA-LFA showed 100% coincident rate with OIE-recommended PCR, in testing both extracted DNAs and treated bloods. We also found that some components in blood samples greatly inhibited PCR performance, but had little effect on RAA. Inhibitory effect can be eliminated when blood was diluted at least 32–64-fold for direct PCR, while only a 2–4 fold dilution of blood was suitable for direct RAA, indicating RAA is a better choice than PCR when blood is used as detecting sample. Taken together, we established an sensitive, specific, rapid, and simple RAA-LFA for ASFV molecular detection without the need to extract viral DNA, providing a good choice for point of care testing of ASF diagnosis in the future.

Generation and immunogenicity analysis of recombinant classical swine fever virus glycoprotein E2 and Erns expressed in baculovirus expression system

Classical swine fever (CSF) caused by the classical swine fever virus (CSFV) is a highly contagious swine disease resulting in large economical losses worldwide. The viral envelope glycoprotein E2 and E^rns are major targets for eliciting antibodies against CSFV in infected animals. In this report, the glycoprotein E2 and E^rns were expressed using the baculovirus system and their protective immunity in rabbits were tested. Twenty CSFV seronegative rabbits were randomly divided into five groups. Each rabbit was intramuscularly immunized with CSFV-E2, CSFV-E^rns, or their combination (CSFV-E2 + E^rns). Besides, a commercial CSFV vaccine (C-strain) and PBS were used as positive or negative controls, respectively. Four weeks after the second immunization, all the rabbits were challenged with 100 RID₅₀ of CSFV C-strain. High levels of CSFV E2-specific antibody, neutralizing antibody and cellular immune responses to CSFV were elicited in the rabbits inoculated with C-strain, CSFV-E2, and CSFV-E2 + E^rns. And the rabbits inoculated with the three vaccines received complete protection against CSFV C-strain. However, no neutralizing antibody was detected in the E^rns vaccinated rabbits and the rabbits exhibited fever typical of CSFV, suggesting the E^rns alone is not able to induce a protective immune response. Taken together, while the E^rns could not confer protection against CSFV, E2 and E2 + E^rns could not only elicit humoral and cell-mediated immune responses but also confer complete protection against CSFV C-strain in rabbits.

Maintenance treatment in advanced HER2-negative gastric cancer

Survival for patients with advanced gastric cancer (GC) remains poor. Systemic chemotherapy which has reached a plateau stays the standard first-line (1L) treatment for advanced human epidermal growth-factor receptor 2 (HER2)-negative GC. To maximize the benefit of 1L treatment, the concept of maintenance treatment is constantly being explored. In advanced HER2-negative GC, current clinical guidelines do not recommend a standard maintenance therapy strategy. In addition to the monotherapy maintenance with fluorouracil after 4-6 cycles of 1L chemotherapy, some agents that are active against novel targets have been evaluated in clinical trials for maintenance treatment. Whereas most of these trials do not reach their primary endpoints, they open new horizons for the 1L treatment of advanced HER2-negative GC. Therefore, we reviewed the clinical trials in the field of maintenance treatment in advanced HER2-negative GC and discussed some of the problems in clinical trials.

Development and evaluation of duplex TaqMan real-time PCR assay for detection and differentiation of wide-type and MGF505-2R gene-deleted African swine fever viruses

Background

African swine fever (ASF) is the most important disease to the pigs and cause serious economic losses to the countries with large-scale swine production. Vaccines are recognized as the most useful tool to prevent and control ASF virus (ASFV) infection. Currently, the MGF505 and MGF360 gene-deleted ASFVs or combined with CD2v deletion were confirmed to be the most promising vaccine candidates. Thus, it is essential to develop a diagnosis method to discriminate wide-type strain from the vaccines used.

Results

In this study, we established a duplex TaqMan real-time PCR based on the B646L gene and MGF505-2R gene. The sequence alignment showed that the targeted regions of primers and probes are highly conserved in the genotype II ASFVs. The duplex real-time assay can specifically detect B646L and MGF505-2R gene single or simultaneously without cross-reaction with other porcine viruses tested. The limit of detection was 5.8 copies and 3.0 copies for the standard plasmids containing B646L and MGF505-2R genes, respectively. Clinical samples were tested in parallel by duplex real-time PCR and a commercial ASFV detection kit. The detection results of these two assays against B646L gene were well consistent.

Conclusion

We successfully developed and evaluated a duplex TaqMan real-time PCR method which can effectively distinguish the wide type and MGF505 gene-deleted ASFVs. It would be a useful tool for the clinical diagnosis and control of ASF.

PCV cap proteins fused with calreticulin expressed into polymers in Escherichia coli with high immunogenicity in mice

BACKGROUND

Porcine circovirus type 2 (PCV2) is the main causative agent of porcine circovirus diseases (PCVDs) which causes huge yearly economic losses in the swine industry. Capsid protein (Cap) is the major structural protein of PCV2 that can induce a protective immune response. Therefore, developing a novel and safe subunit vaccine against PCV2 infection is needed.

RESULTS

In this study, the Cap gene was bound to the truncated calreticulin (CRT) (120-250 aa/120-308 aa) at the N/C terminal, and then the CRT-Cap fusion genes were expressed in Escherichia coli (E.coli). The size-exclusion chromatography and dynamic light scattering (DLS) data showed that the purified recombinant CRT-Cap fusion protein (rP5F) existed in the form of polymers. Immunization with rP5F stimulated high levels of PCV2 specific antibody and neutralization antibody in mice, which were almost identical to those induced by the commercial subunit and inactivated vaccines. The lymphocyte proliferation and cytokine secretion were also detected in rP5F immunized mice. According to the results of PCV2-challenge experiment, the virus loads significantly decreased in mice immunized with rP5F. The data obtained in the current study revealed that rP5F had the potential to be a subunit vaccine candidate against PCV2 in the future.

CONCLUSIONS

We have successfully expressed Cap-CRT fusion proteins in E.coli and optimized rP5F could form into immunogenic polymers. Mice immunized with rP5F efficiently induced humoral and part of cellular immune responses and decreased the virus content against PCV2-challenge, which suggested that rF5P could be a potential subunit vaccine candidate.

Genetic characterization and recombination analysis of atypical porcine pestivirus

Atypical porcine pestivirus (APPV) is recognised as the etiology of congenital tremor (CT) Type A-II and poses a challenge to pig production. Here, we described a CT case in piglets caused by APPV infection in central China in 2017. Interestingly, different from a previous report, more CT litters were observed in the second and third parity sows compared to the first and fourth parity. Evolutionary analysis and recombination evaluation were conducted for the isolate and 61 APPV genomes were available in GenBank. Phylogenetic analysis revealed a high level of genetic variation of APPV and the coexistence of three clades (Clades I-III) in China. The isolate was clustered into Clade I, which seemed to be prevalent worldwide and displayed higher genetic variability (Subgroups 1-4) compared with Clade II and Clade III, both of which were only reported in China. Notably, three putative recombinants were identified and characterized in APPV. The recombination events occurred in inter-clades (Clade II and III) or intra-clades (Clade I). To the best of our knowledge, this study presents the first evidence of homologous recombination within Pestivirus K. These results provide new clinical presentations of APPV infection and may be helpful in better understanding the large amount of genetic variations in this genus.

A strip test for the optical determination of influenza virus H3 subtype using gold nanoparticle coated polystyrene latex microspheres

A strip test is described for the optical determination of influenza virus H3 subtype. It utilizes gold nanoparticle (AuNP) coated polystyrene latex microspheres (PS) as the label and a sandwich format. The AuNP and PS particles were linked using monoclonal antibodies against influenza virus as the bridge. Under the optimal conditions, the visual detection limit of the AuNP-PS-based strip test was as low as 1/16 hemagglutination unit (HAU). It was 64 times higher than that of 10 nm (4 HAU) AuNP-based strip tests. Quantitative analysis showed that the detection limit of the AuNP-PS-based strip is 0.016 HAU. The AuNP-PS-based strip test showed no cross-reactivity to the other subtypes (H1, H5, H7, or H9) of influenza viruses. Graphical abstract .

Broad-spectrum detection of zeranol and its analogues by a colloidal gold-based lateral flow immunochromatographic assay in milk

Based on colloidal gold and broad-spectrum monoclonal antibody that binds to zeranol and its five analogues with high sensitivity, a lateral flow immunochromatographic assay (LFIA) in a competitive format was developed to specifically determine residues of zeranol, an illegal growth promoter in livestock. In this study, the assay had high sensitivity and was broad-spectrum only for zeranol and its five analogues, and the results were obtained within 10 min without needing sophisticated procedures. The cutoff values for zeranol and its five analogues were 10 ng/mL, and the IC₅₀ values for zeranol, β-zearalanol, zearalanone, α-zearalenol, β-zearalenol and zearalenone were 1.250, 1.800, 1.775, 1.225, 1.709 and 1.319 ng/mL, respectively. The recovery rates were ranged from 85.6 to 93.9%, with the coefficient of variations less than 12.4%. The results demonstrated that the LFIA could be used for rapid, simultaneous, semi-quantitative and quantitative detection of residues of zeranol and its five analogous in milk.

Porcine sialoadhesin suppresses type I interferon production to support porcine reproductive and respiratory syndrome virus infection

Porcine reproductive and respiratory syndrome virus (PRRSV) is a significant threat to the global swine industry. Porcine sialoadhesin (poSn) has been previously shown to mediate PRRSV attachment and internalization. In the current study, we report its unidentified role in antagonism of type I interferon (IFN) production during PRRSV infection. We determined that poSn facilitated PRRSV infection via inhibition of type I IFN transcription. Mechanistically, poSn interacted with a 12 kDa DNAX-activation protein (DAP12), which was dependent on residues 51–57 within DAP12 transmembrane domain (TMD). PRRSV exploited the poSn-DAP12 pathway to attenuate activation of nuclear factor-kappa B (NF-κB). More importantly, the poSn-DAP12 pathway was involved in inhibiting poly (I:C)-triggered IFN production. All these results reveal a novel role of poSn in suppressing host antiviral responses, which deepens our understanding of PRRSV pathogenesis.

miR-382-5p promotes porcine reproductive and respiratory syndrome virus (PRRSV) replication by negatively regulating the induction of type I interferon

Previous studies have indicated that inhibition of type I interferon production may be an important reason for porcine reproductive and respiratory syndrome virus (PRRSV) to achieve immune escape, revealing the mechanism of inhibiting the production of type I interferon will help design novel strategies for controlling PRRS. Here, we found that PRRSV infection upregulated the expression of miR-382-5p, which in turn inhibited polyI:C-induced the production of type I interferon by targeting heat shock protein 60 (HSP60), thus facilitating PRRSV replication in MARC-145 cells. Furthermore, we found that HSP60 could interact with mitochondrial antiviral signaling protein (MAVS), an important signal transduction protein for inducing production of type I interferon, and promote polyI:C-mediated the production of type I interferon in a MAVS-dependent manner. Finally, we also found that HSP60 could inhibit PRRSV replication in a MAVS-dependent manner, which indicated that HSP60 was a novel antiviral protein against PRRSV replication. In conclusion, the study demonstrated that miR-382-5p was upregulated during PRRSV infection and may promote PRRSV replication by negatively regulating the production of type I interferon, which also indicated that miR-382-5p and HSP60 might be the potential therapeutic targets for anti-PRRSV.

Co-infection status of porcine circoviruses (PCV2 and PCV3) and porcine epidemic diarrhea virus (PEDV) in pigs with watery diarrhea in Henan province, central China

Porcine circoviruses (PCV2 and PCV3) and porcine epidemic diarrhea virus (PEDV) are important swine viruses that threaten the swine industry worldwide. Here, we evaluated the co-infection status of PCV2, PCV3 and PEDV in 76 enteric samples from piglets with severe diarrhea disease in Henan, China. All samples were tested by PCR/RT-PCR. Our results showed that the infection rate of PCV2, PCV3 and PEDV was 82.89%, 76.32% and 68.42%, respectively. Interestingly, most of these samples exhibited mixed infections. The co-infection rates of PCV2 and PCV3, PCV2 and PEDV, PCV3 and PEDV were 69.74%, 57.89% and 53.95%, respectively. And the triple infection rate was 48.68%. Furthermore, the genetic characteristics of PCV2 and PCV3 were analyzed based on the cap genes. Two PCV2 genotypes, PCV2b and PCV2d, were circulating in the fields. The cap gene of PCV2b and PCV2d isolates only shared 94.6%-95.0% nucleotide identities. The PCV3 isolates together with the reference strains could be divided into four clades (clade1-4), and the cap genes of these isolates have 98.6%-100% nucleotide identities to each other. Distinctive amino acid substitutions were also characterized on the cap protein of PCV2 and PCV3 isolates. Our studies provide the new knowledge on the co-infectious status of PCV2, PCV3 and PEDV in China. The results also provide insight into the genetic diversity and molecular epidemiology of PCV2 and PCV3.

Isolation of Three Novel Senecavirus A Strains and Recombination Analysis Among Senecaviruses in China

Senecavirus A (SVA), an emerging swine picornavirus of swine, is one of the causative agents of vesicular disease which is clinically indistinguishable from foot-and-mouth disease in pigs. Here, 3 cases of vesicular disease were reported which was caused by SVA in November 2018 in Henan, China. Three new SVA strains were identified and conducted a genetically evolutionary analysis. The isolates shared 98.1–99.0% genomic pairwise identity to each other and had the highest similarity, of 98.3–98.7%, with the American strain KS15-01, respectively. Phylogenetic analysis indicated that the Chinese prevalent strains could be clearly divided into cluster 1, cluster 2, and cluster 3. Furthermore, one isolate (HeNNY-1/2018) and two previously reported strains (HB-CH-2016 and SVA/CHN/10/2017) were identified as recombinants using several algorithms. It revealed that the recombination among SVA strains has occurred in China since 2016 or earlier. The findings of studies updated the prevalent status of SVA in China. Besides, the genetic evolution and recombinant events of SVA should be attracted more attentions in the future.

Phylogenetic analysis of porcine circovirus type 2 (PCV2) between 2015 and 2018 in Henan Province, China

Background

Porcine circovirus type 2 (PCV2) is the pathogen of porcine circovirus associated diseases (PCVAD) and one of the main pathogens in the global pig industry, which has brought huge economic losses to the pig industry. In recent years, there has been limited research on the prevalence of PCV2 in Henan Province. This study investigated the genotype and evolution of PCV2 in this area.

Results

We collected 117 clinical samples from different regions of Henan Province from 2015 to 2018. Here, we found that the PCV2 infection rate of PCV2 was 62.4%. Thirty-seven positive clinical samples were selected to amplify the complete genome of PCV2 and were sequenced. Based on the phylogenetic analysis of PCV2 ORF2 and complete genome, it was found that the 37 newly detected strains belonged to PCV2a (3 of 37), PCV2b (21 of 37) and PCV2d (13 of 37), indicating the predominant prevalence of PCV2b and PCV2d strains. In addition, we compared the amino acid sequences and found several amino acid mutation sites among different genotypes. Furthermore, the results of selective pressure analysis showed that there were 5 positive selection sites.

Conclusions

This study indicated the genetic diversity, molecular epidemiology and evolution of PCV2 genotypes in Henan Province during 2015–2018.

The broad-spectrum and ultra-sensitive detection of zeranol and its analogues by an enzyme-linked immunosorbent assay in cattle origin samples

Zeranol (α-zearalanol) has been used as a growth promoter in livestock since 1969 in some non-EU countries; the residues of zeranol and its five analogues in animal origin foods may endanger human health due to their strong estrogenic and anabolic activities. Therefore, it is urgent to establish simple, rapid, real-time, broad-spectrum and high-sensitivity detection methods for the residues of zeranol and its analogues. In this study, an ultrasensitive indirect-competition enzyme-linked immunosorbent assay (ic-ELISA) was established for the rapid multi-residue detection of zeranol and its five analogues in cattle origin samples, which was based on a broad-spectrum monoclonal antibody (mAb) that specifically bound to zeranol and its analogues with high sensitivity. The half maximal inhibitory concentration (IC₅₀) values for zeranol, β-zearalanol, zearalanone, α-zearalenol, β-zearalenol, and zearalenone were 0.103, 0.080, 0.161, 0.177, 0.254, and 0.194 ng mL⁻¹, respectively, the recovery rates of cattle origin samples spiked with zeranol ranged from 79.2–104.2%, and the coefficient of variation (CV) values were less than 11.4%. Excellent correlation (R² = 0.9845) was obtained between the results of HPLC-MS/MS and ic-ELISA. In conclusion, the developed ic-ELISA could be employed as an ultrasensitive and broad-spectrum detection method for monitoring trace ZEN residues in cattle origin foods.

This paper presents a broad-spectrum and ultra-sensitive ic-ELISA method for the rapid detection of zeranol and its analogues in cattle origin samples.

IFI16 Inhibits Porcine Reproductive and Respiratory Syndrome Virus 2 Replication in a MAVS-Dependent Manner in MARC-145 Cells

Porcine reproductive and respiratory syndrome virus (PRRSV) is a single-stranded positive-sense RNA virus, and the current strategies for controlling PRRSV are limited. Interferon gamma-inducible protein 16 (IFI16) has been reported to have a broader role in the regulation of the type I interferons (IFNs) response to RNA and DNA viruses. However, the function of IFI16 in PRRSV infection is unclear. Here, we revealed that IFI16 acts as a novel antiviral protein against PRRSV-2. IFI16 could be induced by interferon-beta (IFN-β). Overexpression of IFI16 could significantly suppress PRRSV-2 replication, and silencing the expression of endogenous IFI16 by small interfering RNAs led to the promotion of PRRSV-2 replication in MARC-145 cells. Additionally, IFI16 could promote mitochondrial antiviral signaling protein (MAVS)-mediated production of type I interferon and interact with MAVS. More importantly, IFI16 exerted anti-PRRSV effects in a MAVS-dependent manner. In conclusion, our data demonstrated that IFI16 has an inhibitory effect on PRRSV-2, and these findings contribute to understanding the role of cellular proteins in regulating PRRSV replication and may have implications for the future antiviral strategies.

Porcine Reproductive and Respiratory Syndrome Virus Enhances Self-Replication via AP-1-Dependent Induction of SOCS1

Porcine reproductive and respiratory syndrome virus (PRRSV) has caused tremendous economic losses in the swine industry since its emergence in the late 1980s. PRRSV exploits various strategies to evade immune responses and establish chronic persistent infections. Suppressor of cytokine signaling (SOCS) 1, a member of the SOCS family, is a crucial intracellular negative regulator of innate immunity. In this study, it was shown that SOCS1 can be co-opted by PRRSV to evade host immune responses, facilitating viral replication. It was observed that PRRSV induced SOCS1 production in porcine alveolar macrophages, monkey-derived Marc-145 cells, and porcine-derived CRL2843-CD163 cells. SOCS1 inhibited the expression of IFN-β and IFN-stimulated genes, thereby markedly enhancing PRRSV replication. It was observed that the PRRSV N protein has the ability to upregulate SOCS1 production and that nuclear localization signal-2 (NLS-2) is essential for SOCS1 induction. Moreover, SOCS1 upregulation was dependent on p38/AP-1 and JNK/AP-1 signaling pathways rather than classical type I IFN signaling pathways. In summary, to our knowledge, the findings of this study uncovered the molecular mechanism that underlay SOCS1 induction during PRRSV infection, providing new insights into viral immune evasion and persistent infection.

Design and preliminary application of affinity peptide based on the structure of the porcine circovirus type II Capsid (PCV2 Cap)

Background

Affinity peptides, as a core part of affinity chromatography, play an important role in the purification of target molecules.

Methods

Here we describe the use of molecular docking technology for virtual screening of affinity peptides that specifically recognize the PCV2 Cap protein for the first time. Thirteen candidate peptides with high scores were obtained and then further characterized. Experimentally, the affinity and sensitivity of the peptides studied were identified by ELISA and LSPR, respectively. In order to investigate the purification effect of a selected peptide (L11) for the recombinant PCV2 Cap protein, it was coupled to NHS agarose magnetic beads as an affinity adsorbent (NaMB-L11); and the ligand density of the affinity adsorbent and pH value in the purification of the recombinant PCV2 Cap protein were optimized.

Results

Our data showed that the peptide L11- DYWWQSWE has the smallest K_D = 103 nM with higher specificity for PCV2 Cap protein recognition. The NaMB-L11 affinity adsorbent yielded a purified Cap sample with 98% purity at 90% recovery in a single step.

Conclusion

Based on the structure, we obtained a high affinity peptide L11 binding to the PCV2 Cap protein by molecular docking technology. It not only provides a theoretical basis for the design of PCV2 Cap affinity peptide, but a new method for the purification of the PCV2 Cap protein.

Nanovaccine Confers Dual Protection Against Influenza A Virus And Porcine Circovirus Type 2

BACKGROUND

The influenza A virus (IAV) is known for its high variability and poses a huge threat to the health of humans and animals. Pigs play a central role in the cross-species reassortment of IAV. Ectodomain of matrix protein 2 (M2e) is the most conserved protective antigen in IAV and can be used to develop nanovaccines through nanoparticles displaying to increase its immunogenicity. However, the high immunogenicity of nanoparticles can cause the risk of off-target immune response, and excess unwanted antibodies may interfere with the protective efficacy of M2e-specific antibodies. Therefore, it is necessary to select reasonable nanoparticles to make full use of antibodies against nanoparticles while increasing the level of M2e-specific antibodies. Porcine circovirus type 2 (PCV2) is the most susceptible virus in pigs and can promote IAV infection. It is meaningful to develop a vaccine that can simultaneously control swine influenza virus (SIV) and PCV2.

METHODS

In the present study, M2e of different copy numbers were inserted into the capsid (Cap) protein of PCV2 and expressed in Escherichia coli to form self-assembled chimeric virus-like particles (VLPs) nanovaccine. BALB/c mice and pigs were immunized with these nanovaccines to explore optimal anti-IAV and anti-PCV2 immunity.

RESULTS

Cap is capable of carrying at least 81 amino acid residues (three copies of M2e) at its C-terminal without impairing VLPs formation. Cap-3M2e VLPs induced the highest levels of M2e-specific immune responses, conferring protection against lethal challenge of IAVs from different species and induced specific immune responses consistent with PCV2 commercial vaccines in mice. In addition, Cap-3M2e VLPs induced high levels of M2e-specific antibodies and PCV2-specific neutralizing antibodies in pigs.

CONCLUSION

Cap-3M2e VLP is an economical and promising bivalent nanovaccine, which provides dual protection against IAV and PCV2.

Development of novel subunit vaccine based on truncated fiber protein of egg drop syndrome virus and its immunogenicity in chickens

Egg-drop syndrome virus (EDSV) is an avian adenovirus that causes markedly decrease in egg production and in the quality of the eggs when it infects chickens. In this report, we engineered truncated fiber protein containing the entire knob domain and part of the shaft region as a vaccine candidate. The protein was obtained in the soluble fraction in Escherichia coli (E. coli), and expression level after nickel-affinity purification was 126 mg/L. By means of multiple characterization methods, it is demonstrated that the recombinant protein retains the native trimeric structure. A single inoculation with the structure-stabilized recombinant protein, even at the lowest dose of 2 μg, stimulated hemagglutination inhibition (HI) antibody responses in chickens, for at least 16 weeks. Neutralizing titers in sera from the protein immunized groups was similar to that of inactivated vaccine immunized group. The lymphocyte proliferation response and cytokine secretion were also induced in immunized SPF chickens. In addition, immunization with the fiber protein also significantly reduced the viral load in the liver. Taken together, these results suggest the truncated fiber protein as an effective single dose, long lasting and rapidly effective vaccine to protect against EDSV.

Prevalence and genetic characteristics of porcine reproductive and respiratory syndrome virus in central China during 2016-2017: NADC30-like PRRSVs are predominant

NADC30-like strains of porcine reproductive and respiratory syndrome virus (PRRSV) were firstly reported in China in 2013. Since then, these strains have been epidemic in more than 13 provinces/regions. During 2016-2017, a total of 18 PRRSV isolates were obtained from 52 clinical samples in Henan province. Based on comparative and phylogenetic analyses of ORF5 and partial Nsp2 genes, 83.3% (15/18) isolates belonged to NADC30-like strains, and the ORF5 shared 87.4%-95.5% nucleotide identity with NADC30/JL580 and 84.2%-89.9% with JXA1/CH-1a, respectively. The genetic variation analysis showed that extensive amino acid substitutions happened in the significant regions of ORF5 including major linear antigenic epitopes (27-30aa, 37-45aa, 52-61aa) and the potential N-glycosylation sites (32-35aa). 16.7% (3/18) isolates were very close to HP-PRRSV derived attenuated strains. Moreover, these three isolates shared common residues at the positions 33D, 59 N, 164R, 196R in ORF5 and 303D, 399T, 575V, 598R, 604G in Nsp2, which were thought to be unique to modified live vaccines (MLVs) or their derivatives. Therefore, they were probably the revertants from MLVs. Our studies showed that the HP-PRRSV strains seemed to be gradually disappearing and NADC30-like strains had become the main causative agents of PRRS in central China. Comparing with HP-PRRSVs, the ORF5 of NADC30-like PRRSV strains displayed extensive amino acid mutations which may be related with immune evasion. Furthermore, the circulation of MLV derivatives in the fields made the diagnosis and control of PRRSV more complicated.

Unravelling the receptor binding property of egg drop syndrome virus (EDSV) from the crystal structure of EDSV fiber head

Egg drop syndrome virus (EDSV) is an avian adenovirus that causes markedly decrease in egg production, and in the quality of the eggs when it infects chickens. Until now, EDSV virus-cell interactions are poorly understood, and the cellular receptor is still unknown. In the present study, we determined the atomic structure of the fiber head of EDSV (residues 377-644) at 2.74 Å resolution. Structure comparison with the (chick embryo lethal orphan) CELO long fiber head and human adenovirus fiber heads reveals that the avian adenovirus may interact with the same attachment factor in a unique fashion. Based on the previous studies of CELO virus, we assumed that the chicken coxsackievirus and adenovirus receptor (CAR) may be the attachment factor. We then demonstrate that the chicken CAR serves as a cellular attachment factor for EDSV based on three lines of evidences. Taken together, the results presented here are helpful for further exploring the pathogenesis related to the interaction between EDSV and host cells, and may be used for vaccine development and intervention strategies against EDSV infection.

A Universal Influenza Nanovaccine for "Mixing Vessel" Hosts Confers Potential Ability to Block Cross-Species Transmission

Influenza A virus (IAV), a deadly zoonotic pathogen, poses a tremendous threat and burden to global health systems. Pigs act as "mixing vessel" hosts to support and generate new pandemic viruses. Preventing the spread of IAV in pigs effectively can delay or even block cross-species transmission. Universal vaccines based on the highly conserved ectodomain of influenza matrix protein 2 (M2e) have been widely reported, but have not been applied due to inadequate protection. Porcine circovirus type 2 (PCV2) causes immunosuppression and promotes swine influenza virus (SIV) infection. Here, M2e is inserted into capsid protein of PCV2 without burying the neutralizing epitopes and self-assembles to form a bivalent nanovaccine. Inoculation with the nanovaccine induces robust M2e- and PCV2-specific immune responses. The nanovaccine confers protection against lethal challenges of IAV from different species in mice, and significantly reduces SIV titers in pigs' respiratory tract and blocks SIV transmission. These results indicate that the nanovaccine is an economical and promising PCV2 and universal IAV bivalent vaccine, and it will synergistically and powerfully offer potential ability to block IAV cross-species reassortment and transmission.

Competitive electrochemical immunosensor for maduramicin detection by multiple signal amplification strategy via hemin@Fe-MIL-88NH2/AuPt

Maduramicin (MD) is a type of monoglycoside polyether ionophore antibiotic that can effectively treat coccidiosis and facilitate animal growth. However, its extensive and excessive use brings potential risk to human health. Herein, an electrochemical immunosensor based on indirect competitive format was fabricated for analysis of MD residue in eggs by a multiple signal amplification system. Initially, Au nanoparticles were deposited onto glassy carbon electrode surface to load the coating antigen MD-BSA and to improve conductivity. Then the signal amplification platform was constructed by encapsulating hemin into Fe-MIL-88 NH₂ metal-organic frameworks (hemin@MOFs), and then the obtained composites were decorated with AuPt nanoparticles. The synthesized hemin@MOFs/AuPt was not only used as a signal amplification mediator, but also utilized as a carrier for immobilization of horseradish peroxidase-conjugated affinipure goat anti-mouse antibody (Ab₂-HRP) and horseradish peroxidase (HRP). The constructed hemin@MOFs/AuPt-Ab₂-HRP bioconjugates could effectively amplify the current signal since hemin@MOFs, AuPt and HRP all exhibited high catalytic activity towards the hydrogen peroxide. Moreover, the established immunosensor showed high sensitivity and stability during the detection procedure. With the synergistic catalytic effect of hemin@MOFs, AuPt and HRP, a wide detection range of 0.1-50 ng mL^-1 and a low detection limit of 0.045 ng mL^-1 were achieved (S/N = 3), respectively. Ultimately, the developed method displayed excellent performance in practical applications, providing a promising probability to detect other veterinary drug residues to guarantee food safety.

Identification of a linear B-cell epitope on glycoprotein (GP) 2a of porcine reproductive and respiratory syndrome virus (PRRSV)

Glycoprotein (GP) 2a was a minor structural protein of porcine reproductive and respiratory syndrome virus (PRRSV) and was one of crucial proteins for PRRSV to bind cell receptor, which indicated that there were neutralizing epitopes on GP2a. In the present work, we used mouse anti-GP2a_41-208aa serum and one GP2a_41-208aa specific monoclonal antibody (McAb) to identify B-cell epitopes of GP2a by peptide-based ELISA. A liner B-cell epitope F¹⁹⁴PTPGSRPKLHDFQQ²⁰⁸ was identified. However, the results of virus neutralization experiment showed that the McAb could not reduce the titers of PRRSV, which indicated that the identified epitope was not the neutralizing epitope of PRRSV. While the amino acid sequence of this epitope was conserved in North American (type 2) PRRSV, which suggested that this epitope might be diagnostic potential for type 2 PRRSV strains. In conclusion, our present work identified a new epitope on GP2a and this epitope might be diagnostic potential for type 2 PRRSV strains.

Detection and genetic characteristics of porcine circovirus 3 based on oral fluids from asymptomatic pigs in central China

Background

Porcine circovirus 3 (PCV3) is an emerging etiological agent to the swine industry. However, its circulating status and genetic characteristics were still unclear in Henan, central China. Here, 318 porcine oral fluid specimens were collected from asymptomatic pigs in five farms and tested by PCR .

Results

The results showed that the positive rate of PCV3 was 12.3% (39/318) for the total samples, and 15.06% (25/166) in the stall-based samples, 9.21% (14/152) in the pen-based samples. Of the PCV3-positive samples, 41.0% were also positive for porcine circovirus 2 (PCV2). Nucleotide sequence comparison indicated that the 10 complete genomes and 34 capsid (cap) genes in this study shared 98.7–99.9% and 98–100% pairwise identities to each other, respectively. According to phylogenetic analysis and sequence alignment of cap gene, all the isolated sequences were clustered into 3 clades, including subgroup 1 (21/39, 61.8%), subgroup 2 (5/39, 14.7%) and subgroup 3 (8/39, 23.5%). Similar to previous reports, four amino acids (V24A, K27R, S77 T and I150L) in cap protein were identified as a conserved subgroup specific molecular marker.

Conclusion

Our research provided new insights into the epidemiology surveillance and genetic characteristics of PCV3 in China.

Electronic supplementary material

The online version of this article (10.1186/s12917-019-1952-3) contains supplementary material, which is available to authorized users.

Evaluation of an immunochromatographic strip for detection of avian avulavirus 1 (Newcastle disease virus)

We evaluated an immunochromatographic strip for the detection of avian avulavirus 1 (Newcastle disease virus, NDV) based on a high-affinity monoclonal antibody (mAb) that specifically recognizes the hemagglutinin-neuraminidase (HN) protein. The anti-HN mAb was labeled with colloidal gold as the detector. A chicken anti-NDV polyclonal antibody and staphylococcal protein A (SPA) were blotted on the nitrocellulose membrane for the test and control lines, respectively. The strip specifically recognized the NDV antigen with no cross-reactivity to other viruses that were examined. Furthermore, it specifically recognized a variety of NDV isolates, including virulent and attenuated strains. These results were confirmed using hemagglutination (HA) and RT-PCR assays. The NDV detection strip detected 10^4.9 EID₅₀ viruses/0.1 mL in the NDV-infected sample, which is comparable to the classical HA test (10^5.2 EID₅₀/0.1 mL). Following experimental infection, NDV was detected using the detection strip in infected tissues as early as 36 h after experimental infection and prior to development of clinical signs and appearance of gross anatomic lesions. The diagnostic sensitivity and specificity of the NDV detection strip for NDV infection were 83.3% and 100%, respectively, as confirmed by RT-PCR.

Porcine reproductive and respiratory syndrome virus induces interleukin-1β through MyD88/ERK/AP-1 and NLRP3 inflammasome in microglia

Porcine reproductive and respiratory syndrome virus (PRRSV) infection which caused severe reproductive failure and respiratory disorders in swine is accompanied with severe nervous symptoms. Our previous studies demonstrated that microglia, the resident innate immune cells in central nervous system (CNS), could support PRRSV infection and replication in vitro. And PRRSV infection led to the increased expressions of large amounts of proinflammatory cytokines and chemokines which contributed to neuropathogenesis of PRRSV. Interleukin-1β (IL-1β) is one of the increased proinflammatory cytokines, which possesses diverse functions in immune response upon virus infection, including activation of innate immune and modulation of adaptive immune responses. Importantly, considerable evidences indicated that 1L-1β is involved in neuronal injury. Here, we demonstrated that PRRSV infection up-regulated IL-1β expression at both the mRNA and protein levels in microglia in a dose-dependent manner. Myeloid differentiation primary response gene 88 (MyD88), extracellular signal-regulated kinase1/2 (ERK) and activator protein 1 (AP-1) were involved in PRRSV induced IL-1β production in microglia. Moreover, NOD-like receptor protein 3 (NLRP3) inflammasome is activated by PRRSV in microglia, which is required for IL-1β secretion. Taken together, our data indicated that PRRSV infection could induce IL-1β up-regulation, which was likely mediated by MyD88/ERK/AP-1 and NLRP3 inflammasome. These findings will provide new insights into the molecular mechanisms of IL-1β production and some implications for neuropathogenesis of PRRSV.

Vacuum Sealing Drainage Therapy for Refractory Infectious Wound on 16 Renal Transplant Recipients

BACKGROUND

Refractory infectious wounds on renal transplantation (RT) recipients significantly prolong hospital stay, increase medical costs, and threaten allograft survival. Vacuum sealing drainage (VSD) therapy is a new technique for managing wounds based on the principle of application of controlled negative pressure. The aim of this study was to summarize the efficacy and safety of VSD therapy in the management of refractory infectious wounds following RT.

MATERIALS AND METHODS

This is a retrospective study of a cohort of 661 consecutive patients who received renal transplants over a period of 3 years in which the data were collected and analyzed retrospectively.

RESULTS

Out of the 661 patients, 16 (2.4%) developed refractory wound infection following RT. Nineteen organisms were identified by culture from all patients, including 10 patients infected with 1 or more bacteria, 2 patients with fungal infection, and 4 patients with both. Specifically, mucormycosis was demonstrated in 4 patients, pan-resistant Klebsiella pneumoniae in 2 patients, and Acinetobacter baumannii in 2 patients. All 16 patients were treated with VSD therapy for a median of 37 days (range, 6-111 days). The number of VSD sets used ranged from 4 to 28 sets (mean, 11.1 sets). A combination of antibiotics, debridement, and VSD therapy lead to 100% (16 of 16) wound healing. No VSD-relevant adverse events were observed.

CONCLUSIONS

VSD therapy is an effective and safe adjunct to conventional treatment modalities for the management of refractory wound infection following RT.

Characterization of the interaction between recombinant porcine aminopeptidase N and spike glycoprotein of porcine epidemic diarrhea virus

Porcine epidemic diarrhea (PED) has caused huge economic losses to the global pork industry. Infection by its causative agent PED virus (PEDV), an Alpha-coronavirus, was previously proven to be mediated by its spike (S) glycoprotein and a cellular receptor porcine aminopeptidase N (pAPN). Interestingly, some recent studies have indicated that pAPN is not a functional receptor for PEDV. To date, there is a lack of a direct evidence for the interaction between pAPN and PEDV S protein in vitro. Here, we prepared pAPN ectodomain and the truncated variants of PEDV S protein in Drosophila S2 cells. These recombinant proteins were homogeneous after purification by metal-affinity and size-exclusion chromatography. We then assayed the purified target proteins through immunogenicity tests, PEDV binding interference assays, circular dichroism (CD) measurements, pAPN activity assay and structural determination, demonstrating that they were biologically functional. Finally, we characterized their interactions by gel filtration chromatography, native-polyacrylamide gel electrophoresis (PAGE) and surface plasmon resonance (SPR) analyses. The results showed that their affinities were too low to form complexes, which suggest that pAPN may be controversial as the genuine receptor for PEDV. Therefore, further research needs to be carried out to elucidate the interaction between PEDV and its genuine receptor.

Comparison of two docking methods for peptide-protein interactions

BACKGROUND

The importance of peptides in regulatory interactions has caused peptide-protein docking to attract the attention of many researchers. A variety of methods for molecular modeling of peptide-protein docking, such as local search and global search, are currently used.

RESULTS

The interactions of 11 peptides and CSFV E2 protein were evaluated by the GalaxyPepDock and FlexX/ SYBYL programs, respectively. The assessment scores of all the peptides were correlated with their K_D values. The final results showed that a moderate correlation coefficient was represented between K_D values and CScores of predicted models by FlexX/ SYBYL.

CONCLUSION

Our results demonstrate that considering the flexibility of the peptide is better than searching for more potential binding sites on the target protein surface while performing peptide-protein molecular docking. These data provide reasonable evidence for the molecular design of peptides and guidance for the functional assignment of target proteins. © 2018 Society of Chemical Industry.

The CD163 long-range scavenger receptor cysteine-rich repeat: expression, purification and X-ray crystallographic characterization

Scavenger receptors (SRs) play critical roles in various physiological and pathological pathways. One of them, CD163, is a multifunctional endocytic receptor and is characterized by a long-range scavenger receptor cysteine-rich (SRCR) repeat. However, the structural and functional details of this long-range SRCR repeat have not yet been elucidated. In this study, the CD163 long-range SRCR repeat was expressed in Drosophila Schneider 2 cells. The recombinant protein was homogeneous after purification by metal-affinity, cation-exchange and size-exclusion chromatography. Single crystals were obtained using 20% PEG 4000, 0.15 M potassium sodium tartrate tetrahydrate pH 8.5 and diffracted to 3.30 Å resolution. As the first view of a long-range SRCR repeat, this work lays the structural basis for a deep understanding of SRs and their multiple functions.

Effect of Early Immunosuppression Therapy on De Novo Anti-Human-Leukocyte-Antigen Antibody After Kidney Transplantation

The aim of the study was to investigate the effect of immunosuppression therapy early after kidney transplantation, particularly exposure of mycophenolic acid (MPA) and calcineurin inhibitor (CNI), on posttransplantation de novo HLA antibody production.

METHODS

A single-center retrospective cohort study was performed at the First Affiliated Hospital of Sun Yat-sen University, enrolling the kidney transplant or pancreas-kidney transplant recipients who had surgery between January 2010 and February 2016.

RESULTS

A total of 214 recipients were included in the study with a median follow-up period of 1.06 years. A total of 30 recipients (14.0%) were positive in HLA antibody detection posttransplant with a median follow-up period of 1.46 years. Ten recipients (4.7%) lost their allograft function during follow-up, and 6 of them (60%) developed de novo HLA antibody after graft failure. Multivariate analysis showed that acute rejection significantly increased the risk of de novo HLA antibody (hazard ratio [HR], 2.732). Intensified MPA dosing therapy reduced the risk by 59.8% (HR, 0.402); low-dose CNI therapy increased the risk by 33.3% (HR, 1.333), and the effect of extremely low-dose CNI therapy was even larger (HR, 2.242).

CONCLUSION

The risk of de novo HLA antibody can be decreased by reducing the risk of acute rejection. A tendency was seen in low-dose CNI therapy to increase the risk of de novo HLA antibody, but intensified MPA dosing therapy may provide an umbrella protection effect by reducing the risk. Prospective study was required to confirm the effects.

Higher Incidence of Renal Allograft Glomerulonephritis in Living-Related Donor Kidney Transplantation

Glomerulonephritis recurrence has emerged as one of the leading causes of allograft loss. We aimed to investigate the effect of living-related and deceased donation on the incidence of renal allograft glomerulonephritis and its effect on renal allograft survival.

METHODS

Adult renal allograft recipients with primary glomerulonephritis were enrolled. Transplantation date was from Feb 2004 to Dec 2015. Exclusion criteria included combined organ transplantation, structural abnormality, diabetic nephropathy, hypertension nephropathy, obstructive nephropathy, and primary uric acid nephropathy. The incidence of biopsy-proven allograft glomerulonephritis was compared between the living-related donor group and the deceased donor group. Graft survival was assessed with Kaplan-Meier method, and Cox proportional hazard model was used to evaluate the effect of posttransplant glomerulonephritis on graft outcome.

RESULTS

There were 525 living-related donor kidney transplant recipients (LRKTx) and 456 deceased donor kidney transplant recipients (DDKTx) enrolled. The incidence of IgA nephropathy was 8.8% in the LRKTx group and 1.3% in the DDKTx group (P < .001); the incidence of focal segmental glomerulosclerosis (FSGS) was 3.8% in the LRKTx group and 1.5% in the DDKTx group (P = .03). FSGS increased the risk of graft failure compared with non-FSGS (hazard ratio [HR], 3.703 [1.459-9.397]; P = .006). IgA nephropathy increased the risk of graft failure by over 5 times 5 years after kidney transplantation compared with non-IgA nephropathy, but it did not affect early allograft survival (HR for ≥5 years, 6.139; 95% CI, 1.766-21.345; P = .004; HR for <5 years, 0.385 [0.053-2.814]; P = .35).

CONCLUSIONS

Higher incidence of IgA nephropathy and FSGS in renal allograft was observed in living-related donor kidney transplantation compared with deceased donor kidney transplantation. De novo or recurrent IgA nephropathy and FSGS impaired long-term renal allograft survival.

Development of an immunochromatographic lateral flow strip for the simultaneous detection of aminoglycoside residues in milk

A colloidal gold-based immunochromatographic strip with a competitive format has been developed for the rapid, simultaneous, semi-quantitative and quantitative detection of several aminoglycoside residues in milk, including gentamicin sulfate (GM), neomycin sulfate (NEO) and kanamycin sulfate (KN). Three monoclonal antibodies against the three corresponding aminoglycosides were conjugated to colloidal gold particles and applied to the conjugate pads of the strip. The competitors [GM-bovine serum albumin (GM-BSA), NEO-BSA and KN-BSA conjugates] of GM, NEO and KN were immobilized onto a nitrocellulose (NC) membrane at three detection zones, T1, T2, and T3, respectively. The minimal cut-off values of the strip were 10 ng mL⁻¹ for GM, and 100 ng mL⁻¹ for NEO and KN, which are lower than the maximum residue levels (MRLs) established for aminoglycosides. The IC₅₀ values of the strip were 0.737 ng mL⁻¹, 8.971 ng mL⁻¹ and 11.110 ng mL⁻¹ for GM, NEO and KN respectively. In conclusion, the immunochromatographic lateral flow strip could be used for rapid, simultaneous, semi-quantitative and quantitative detection of GM, NEO and KN residues in milk.

A colloidal gold-based immunochromatographic strip has been developed for the rapid, simultaneous, semi-quantitative and quantitative detection of several aminoglycoside residues in milk, including gentamicin sulfate (GM), neomycin sulfate (NEO) and kanamycin sulfate (KN).

A novel duplex TaqMan probe-based real-time RT-qPCR for detecting and differentiating classical and variant porcine epidemic diarrhea viruses

Two different genotypes of porcine epidemic diarrhea virus (PEDV), the classical and variant strains, are classified by multiple insertions and deletions in their S genes. It is critical to detect and differentiate two genotypes in the pork industry to prevent PEDV outbreaks. In the present study, a novel duplex TaqMan RT-PCR was developed for detecting and differentiating PEDV strains in China. There was no cross-amplification between the two probes when using standard recombinant plasmids, and the specificity was further confirmed by using other seven non-PEDV swine pathogens. The minimum copies required for the detection of both classical and variant PEDV were 4.8 × 10² DNA copies/reaction. The repeatability of TaqMan RT-PCR was evaluated using standard recombinant plasmids and gave coefficients of variation 0.19-4.93. In recent 5 years, 79 clinical samples were collected from piglets with severe diarrhea in the Central China. Among these clinical samples, 51 were confirmed as PEDV positive by conventional RT-PCR, whereas 63 variant PEDV, 3 co-infections and 1 classical PEDV were confirmed by this duplex TaqMan RT-PCR, with viral loads of 10²-10⁸, 10²-10³, and 10⁴ copies/reaction, respectively. Therefore, the duplex TaqMan RT-PCR could be a useful method for detecting and differentiating variant and classical PEDV strains. The results showed that variant PEDV was prevalent in clinical samples in central China. Moreover, in this study, co-infection by PEDV strains was detected for the first time and might help explain the emergence of the novel recombinant PEDV in recent years.