Semiconducting polymer dots based l-lactate sensor by enzymatic cascade reaction system.

BACKGROUND: l-lactate detection is important for not only assessing exercise intensity, optimizing training regimens, and identifying the lactate threshold in athletes, but also for diagnosing conditions like L-lactateosis, monitoring tissue hypoxia, and guiding critical care decisions. Moreover, l-lactate has been utilized as a biomarker to represent the state of human health. However, the sensitivity of the present l-lactate detection technique is inadequate. RESULTS: Here, we reported a sensitive ratiometric fluorescent probe for l-lactate detection based on platinum octaethylporphyrin (PtOEP) doped semiconducting polymer dots (Pdots-Pt) with enzymatic cascade reaction. With the help of an enzyme cascade reaction, the l-lactate was continuously oxidized to pyruvic and then reduced back to l-lactate for the next cycle. During this process, oxygen and NADH were continuously consumed, which increased the red fluorescence of Pdots-Pt that responded to the changes of oxygen concentration and decreased the blue fluorescence of NADH at the same time. By comparing the fluorescence intensities at these two different wavelengths, the concentration of l-lactate was accurately measured. With the optimal conditions, the probes showed two linear detection ranges from 0.5 nM to 5.0 µM and 5.0 µM-50.0 µM for l-lactate detection. The limit of detection was calculated to be 0.18 nM by 3σ/slope method. Finally, the method shows good detection performance of l-lactate in both bovine serum and artificial serum samples, indicating its potential usage for the selective analysis of l-lactate for health monitoring and disease diagnosis. SIGNIFICANCE: The successful application of the sensing system in the complex biological sample (bovine serum and artificial serum samples) demonstrated that this method could be used for sensitive l-lactate detection in practical clinical applications. This detection system provided an extremely low detection limit, which was several orders of magnitude lower than methods proposed in other literatures.

Aggregation Inducing Reversible Conformational Isomerization of Surface Staple in Au18SR14 Nanoclusters.

The conformation of molecules and materials is crucial in determining their properties and applications. Here, this work explores the reversible transformation between two distinct conformational isomers in metal nanoclusters. This work demonstrates the successful manipulation of a controllable and reversible isomerization of Au18SR14 within an aqueous solution through two distinct methods: ethanol addition and pH adjustment. The initial driver is the alteration of the solution environment, leading to the aggregation of Au18SR14 protected by ligands with smaller steric hindrance. At the atomic level, the folding mode of the unique Au4SR5 staple underpins the observed structural transformation. The reversal of staple conformation leads to color shifting between green and orange-red, and tailors a second emission peak at 725 nm originating from charge transfer from the thiolate to the Au9 core. This work not only deepens the understanding of the surface structure and dual-emission of metal nanoparticles, but also enhances the comprehension of their isomerization.

Remodeling brain pathological microenvironment to lessen cerebral ischemia injury by multifunctional injectable hydrogels.

Ischemia stroke is one of the leading causes of death and disability worldwide. Owing to the limited delivery efficiency to the brain caused by the blood-brain barrier (BBB) and off-target effects of systemic treatment, it is crucial to develop an in situ drug delivery system to improve the therapeutic effect in ischemic stroke. Briefly, we report a multifunctional in situ hydrogel delivery system for the co-delivery of reactive oxygen species (ROS)-responsive nanoparticles loaded with atorvastatin calcium (DSPE-se-se-PEG@AC NPs) and ß-nerve growth factor (NGF), which is expected to remodel pathological microenvironment for improving cerebral ischemia injury. The in vitro results exhibited the multifunctional hydrogel scavenged oxygen-glucose deprivation (OGD)-induced free radical, rescued the mitochondrial function, and maintained the survival and function of neurons, hence reducing neuronal apoptosis and neuroinflammation, consequently relieving ischemia injury in hippocampal neurons cell line (HT22). In the rat ischemia stroke model, the hydrogel significantly minified cerebral infarction by regulating inflammatory response, saving apoptotic neurons, and promoting angiogenesis and neurogenesis. Besides, the hydrogel distinctly improved the rats' neurological deficits after cerebral ischemia injury over the long-term observation. In conclusion, the in-situ hydrogel platform has demonstrated promising therapeutic effects in both in vitro and in vivo studies, indicating its potential as a new and effective therapy.

CCCP inhibits DPV infection in DEF cells by attenuating DPV manipulated ROS, apoptosis, and mitochondrial stability.

Duck plague virus (DPV) is extremely infectious and lethal, so antiviral drugs are urgently needed. Our previous study shows that DPV infection with duck embryo fibroblast (DEF) induces reactive oxygen species (ROS) changes and promotes apoptosis. In this study, we tested the antiviral effect of the carbonyl cyanide m-chlorophenyl hydrazone (CCCP), a common mitochondrial autophagy inducer. Our results demonstrated a dose-dependent anti-DPV effect of CCCP, CCCP-treatment blocked the intercellular transmission of DPV after infection, and we also proved that CCCP could have an antiviral effect up to 48 hpi. The addition of CCCP reversed the DPV-induced ROS changes, CCCP can inhibit virus-induced apoptosis; meanwhile, CCCP can affect mitochondrial fusion and activate mitophagy to inhibit DPV. In conclusion, CCCP can be an effective antiviral candidate against DPV.

An injectable carrier for spatiotemporal and sequential release of therapeutic substances to treat myocardial infarction.

Myocardial infarction (MI) has become the primary cause of cardiovascular mortality, while the current treatment methods in clinical all have their shortcomings. Injectable biomaterials have emerged as a promising solution for cardiac tissue repair after MI. In this study, we designed a smart multifunctional carrier that could meet the treatment needs of different MI pathological processes by programmatically releasing different therapeutic substances. The carrier could respond to inflammatory microenvironment in the early stage of MI with rapid release of curcumin (Cur), and then sustained release recombinant humanized collagen type III (rhCol III) to treat MI. The rapid release of Cur reduced inflammation and apoptosis in the early stages, while the sustained release of rhCol III promoted angiogenesis and cardiac repair in the later stages. In vitro and in vivo results suggested that the multifunctional carrier could effectively improve cardiac function, promote the repair of infarcted tissue, and inhibit ventricular remodeling by reducing cell apoptosis and inflammation, and promoting angiogenesis in the different pathological processes of MI. Therefore, this programmed-release carrier provides a promising protocol for MI therapy.

Gibberellin signaling regulates lignin biosynthesis to modulate rice seed shattering.

The elimination of seed shattering was a key step in rice (Oryza sativa) domestication. In this paper, we show that increasing the gibberellic acid (GA) content or response in the abscission region enhanced seed shattering in rice. We demonstrate that SLENDER RICE1 (SLR1), the key repressor of GA signaling, could physically interact with the rice seed shattering-related transcription factors quantitative trait locus of seed shattering on chromosome 1 (qSH1), O. sativa HOMEOBOX 15 (OSH15), and SUPERNUMERARY BRACT (SNB). Importantly, these physical interactions interfered with the direct binding of these three regulators to the lignin biosynthesis gene 4-COUMARATE: COENZYME A LIGASE 3 (4CL3), thereby derepressing its expression. Derepression of 4CL3 led to increased lignin deposition in the abscission region, causing reduced rice seed shattering. Importantly, we also show that modulating GA content could alter the degree of seed shattering to increase harvest efficiency. Our results reveal that the "Green Revolution" phytohormone GA is important for regulating rice seed shattering, and we provide an applicable breeding strategy for high-efficiency rice harvesting.

Iron-Rich Semiconducting Polymer Dots for the Combination of Ferroptosis-Starvation and Phototherapeutic Cancer Therapy.

Chemodynamic therapy (CDT) has emerged as an outstanding antitumor therapeutic method due to its selectivity and utilization of tumor microenvironment. However, there are still unmet requirements to achieve a high antitumor efficiency, including the tumor accumulation of catalyst and enrichment of reactants of Fenton reaction. Here, an iron-loaded semiconducting polymer dot modified with glucose oxidase (Pdot@Fe@GOx) is reported to deliver iron ions into tumor tissues and in situ generation of hydrogen peroxide in tumors. On one hand, Pdot@Fe@GOx converts glucose to gluconic acid and hydrogen peroxide (H2 O2 ) in tumor, which not only consumes glucose of tumor cells, but also provides the H2 O2 for the following Fenton reaction. On the other hand, the Pdot@Fe@GOx delivers active iron ions in tumor to perform CDT with the combination of the generated H2 O2 . In addition, the Pdot@Fe@GOx has both photothermal and photodynamic effects under the irradiation of near-infrared laser, which can improve and compensate the CDT effect to kill cancer cells. This Pdot@Fe@GOx-based multiple-mode therapeutic strategy has successfully achieved a synergistic anticancer effect with minimal side effects and has the potential to be translated into preclinical setting for tumor therapy.

Biocompatibility and Biological Effects of Surface-Modified Conjugated Polymer Nanoparticles.

Semiconductiong polymer nanoparticles (Pdots) have a wide range of applications in biomedical fields including biomolecular probes, tumor imaging, and therapy. However, there are few systematic studies on the biological effects and biocompatibility of Pdots in vitro and in vivo. The physicochemical properties of Pdots, such as surface modification, are very important in biomedical applications. Focusing on the central issue of the biological effects of Pdots, we systematically investigated the biological effects and biocompatibility of Pdots with different surface modifications and revealed the interactions between Pdots and organisms at the cellular and animal levels. The surfaces of Pdots were modified with different functional groups, including thiol, carboxyl, and amino groups, named Pdots@SH, Pdots@COOH, and Pdots@NH2, respectively. Extracellular studies showed that the modification of sulfhydryl, carboxyl, and amino groups had no significant effect on the physicochemical properties of Pdots, except that the amino modification affected the stability of Pdots to a certain extent. At the cellular level, Pdots@NH2 reduced cellular uptake capacity and increased cytotoxicity due to their instability in solution. At the in vivo level, the body circulation and metabolic clearance of Pdots@SH and Pdots@COOH were superior to those of Pdots@NH2. The four kinds of Pdots had no obvious effect on the blood indexes of mice and histopathological lesions in the main tissues and organs. This study provides important data for the biological effects and safety assessment of Pdots with different surface modifications, which pave the way for their potential biomedical applications.

Advances in Injectable Hydrogel Strategies for Heart Failure Treatment.

Heart failure (HF) affects 60 million people worldwide and has developed into a global public health problem surpassing cancer and urgently needs to be solved. According to the etiological spectrum, HF due to myocardial infarction (MI) has become the dominant cause of morbidity and mortality. Possible treatments include pharmacology, medical device implantation, and cardiac transplantation, which are limited in their ability to promote long-term functional stabilization of the heart. Injectable hydrogel therapy has emerged as a minimally invasive tissue engineering treatment approach. Hydrogels can provide the necessary mechanical support for the infarcted myocardium and serve as carriers of various drugs, bioactive factors, and cells to improve the cellular microenvironment in the infarcted region and induce myocardial tissue regeneration. Herein, the pathophysiological mechanism of HF is explored and injectable hydrogels as a potential solution for current clinical trials and applications are summarized. Specifically, mechanical support hydrogels, decellularized ECM hydrogels, a variety of biotherapeutic agent-loaded hydrogels and conductive hydrogels for cardiac repair were discussed, and the mechanism of action of these hydrogel-based therapies was emphasized. Finally, the limitations and future prospects of injectable hydrogel therapy for HF post MI were proposed to inspire novel therapeutic strategies.

Ratiometric fluorescent semiconducting polymer dots for temperature sensing.

Semiconducting polymer dots (Pdots) have received much attention due to their unique characteristics, including high water solubility, good light stability, excellent biocompatibility, and low cost. Herein, we report a ratiometric nanoprobe based on Pdots-Eu for temperature sensing in vitro. The Pdots-Eu thermometer was composed of a blue temperature-insensitive semiconducting polymer, poly(9-vinylcarbazole) (PVK), a red temperature-sensitive complex tris(dibenzoylmethane)mono(5-amino-1,10-phenanthroline)europium (III) (Eu complex), and an amphiphilic polymer polystyrene graft ethylene oxide functionalized with carboxyl groups (PS-PEG-COOH). The Pdots-Eu thermometer showed two peaks at 368 nm from PVK and 611 nm from the Eu complex. The red/blue fluorescence intensity ratio of Pdots-Eu decreased with an increase in temperature, which could be used for the ratiometric monitoring of temperature change. The results showed that the red/blue fluorescence intensity ratio demonstrated a good linear relationship to the change of temperature from 25 °C to 55 °C. Impressively, the ratiometric probe featured good accuracy and high sensitivity for temperature detection in vitro, which could be used for monitoring temperature change in cells.

Responsive multifunctional hydrogels emulating the chronic wounds healing cascade for skin repair.

It remains challenging to cure chronic diabetic wounds due to its' harsh microenvironment and poor tissue regeneration ability. At present, bacteria elimination, inflammatory response suppression and angiogenesis orderly render an important paradigm for chronic diabetic wound treatment. Herein, smart-responsive multifunctional hydrogels were developed to improve chronic diabetic wound healing, which could quickly respond to the acidic environment of the diabetic wound site and mediate multistage sequential delivery of silver and curcumin-loaded polydopamine nanoparticles (PDA@Ag&Cur NPs) and vascular endothelial growth factor (VEGF). PDA@Ag&Cur NPs and VEGF endowed the hydrogels with antibacterial, anti-inflammatory and angiogenesis performances, respectively. The in vitro and in vivo experiments confirmed that our multistage drug delivery hydrogels could effectively eliminate bacteria, relieve inflammatory response, and induce angiogenesis, hence accelerating the closure of chronic diabetic wounds. In conclusion, we highlighted the importance of multistage manipulation in wound healing and offered a combinatorial therapeutic strategy to sequentially deliver drugs exactly aiming at the dynamic wound healing stages.

Regeneration of infarcted hearts by myocardial infarction-responsive injectable hydrogels with combined anti-apoptosis, anti-inflammatory and pro-angiogenesis properties.

Current treatments including drug therapy, medical device implantation, and organ transplantation have considerable shortcomings for myocardial infarction (MI), such as high invasiveness, the scarce number of donor organs, easy thrombosis, immune rejection, and poor therapeutic effects. Therefore, the development of new solutions to repair infarcted hearts is urgently needed. Smart responsive injectable hydrogels have served as a good foundation in biomedical engineering, especially for cardiac regeneration. Herein, we synthesized an injectable hydrogel that responds to the inflammatory microenvironment at the site of MI to provide the drug curcumin (Cur) and tailored recombinant humanized collagen type III (rhCol III) in a controlled manner for myocardial repair. The excellent antioxidant and anti-inflammatory properties of Cur could effectively reduce the ROS level and cell apoptosis and inhibit inflammatory reactions after MI. The tailored rhCol III promoted cell proliferation, migration, and angiogenesis. The therapeutic hydrogel resulted in the rapid recovery of cardiac function after MI by elevating the expression of the cardiac markers α-actinin and CX 43. In vitro and in vivo data showed that the combined anti-apoptosis, anti-inflammatory and pro-angiogenesis treatment strategies were an auspicious tactic for the treatment of MI, and had significant clinical application value. Furthermore, the work also demonstrated the great application potential of our tailored rhCol III in promoting the repair and regeneration of infarcted hearts.

Dissolving microneedle-encapsulated drug-loaded nanoparticles and recombinant humanized collagen type III for the treatment of chronic wound via anti-inflammation and enhanced cell proliferation and angiogenesis.

Nowadays, diabetic chronic wounds impose a heavy burden on patients and the medical system. Persistent inflammation and poor tissue remodeling severely limit the healing of chronic wounds. For these issues, the first recombinant humanized collagen type III (rhCol III) and naproxen (Nap) loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticle incorporated hyaluronic acid (HA) microneedle (MN) was fabricated for diabetic chronic wound therapy. As the tailored rhCol III was synthesized based on the Gly483-Pro512 segment, which contained the highly adhesive fragments (GER, GEK) in the human collagen type III sequence, it possessed strong cell adhesion. The mechanical strength of the prepared MN was enough to overcome the tissue barrier of necrosis/hyperkeratosis in a minimally invasive way after being applied in wounds. Subsequently, rhCol III and Nap@PLGA nanoparticles were rapidly released to the wound site within a few minutes. The prepared MN possessed favourable biocompatibility and could effectively facilitate the proliferation and migration of fibroblasts and endothelial cells. Furthermore, the regenerative efficacy of the MN was evaluated in vivo using the diabetic rat full-thickness skin wound model. These results illustrated that the prepared MN could accelerate wound closure by reducing the inflammatory response and enhancing angiogenesis or collagen deposition, indicating their significant application value in wound dressings for chronic wound repair.

A fluorescence strategy for circRNA quantification in tumor cells based on T7 nuclease-assisted cycling enzymatic amplification.

Circular Ribonucleic Acid (CircRNA) plays regulatory roles in many biological processes, such as tumors and metabolic diseases. Due to the fact that circRNA is more stable and conservative than linear RNA, circRNA has become a potential biomarker in early clinical diagnosis and biomedical research. Therefore, the quantification of circRNA expression level is of importance for understanding their functions and their applications for disease diagnosis and treatment. Nevertheless, due to the low abundance of circRNA, it is still a challenge for the analysis of circRNA in cells. Herein, we proposed a sensitive detection method for circRNA based on the T7 exonuclease-assisted cycling enzymatic amplification. The fluorescent sensor was constructed by a hairpin molecular beacon and T7 exonuclease. With the cycling enzymatic amplification process, this sensor achieved the limit of detection of 1 pM with a good linear correlation in the range of 0-100 pM (R2 = 0.9891) using circBART2.2 as a model. Furthermore, we applied the proposed method in the determination of circBART2.2 in cell lysates. The results demonstrated that this method has promising applications in early diagnosis of Epstein-Barr virus (EBV) infection-related diseases using circRNA as the biomarker.

Correction: Microenvironment-responsive multifunctional hydrogels with spatiotemporal sequential release of tailored recombinant human collagen type III for the rapid repair of infected chronic diabetic wounds.

Correction for 'Microenvironment-responsive multifunctional hydrogels with spatiotemporal sequential release of tailored recombinant human collagen type III for the rapid repair of infected chronic diabetic wounds' by Cheng Hu et al., J. Mater. Chem. B, 2021, 9, 9684-9699, DOI: 10.1039/D1TB02170B.

Microenvironment-responsive multifunctional hydrogels with spatiotemporal sequential release of tailored recombinant human collagen type III for the rapid repair of infected chronic diabetic wounds.

Recently, the incidence of chronic diabetic wounds increases continuously, and the existing clinical treatment is less effective. Thus, it is an urgent need to solve these problems for better clinical treatment effects. Herein, we prepared a brand-new tailored recombinant human collagen type III (rhCol III) and constructed a multifunctional microenvironment-responsive hydrogel carrier based on multifunctional antibacterial nanoparticles (PDA@Ag NPs) and our tailored rhCol III. The multifunctional smart hydrogel disintegrated quickly at the chronic diabetic wound sites and achieved the programed on-demand release of different therapeutic substances. The first released PDA@Ag NPs showed great antibacterial properties against S. aureus and E. coli. They could kill bacteria rapidly, and also showed antioxidant and anti-inflammatory effects at the wound site. The subsequent release of our tailored rhCol III could promote the proliferation and migration of mouse fibroblasts and endothelial cells during the proliferation and remodeling process of wound healing. Relevant results showed that the multifunctional smart hydrogel could promote the expression levels of basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF), decrease the inflammatory response, accelerate the deposition of collagen and increase cell proliferation and angiogenesis, thereby speeding up the healing of infected chronic wounds. In a word, the hydrogel, which took into consideration the complex microenvironment at the wound site and multi-stage healing process, could achieve programmed and responsive release of different therapeutic substances to meet the treatment needs in different wound healing stages. More importantly, our work illustrated the great application potential of our brand-new rhCol III in promoting chronic wound repair and regeneration.

Graphene Oxide-Template Gold Nanosheets as Highly Efficient Near-Infrared Hyperthermia Agents for Cancer Therapy.

INTRODUCTION: Near-infrared (NIR) hyperthermia agents are promising in cancer photothermal therapy due to their deeper penetration ability and less side effects. Spherical gold nanoshell and graphene-based nanomaterials are two major NIR hyperthermia agents that have been reported for photothermal therapy of cancer. Herein, we constructed a two-dimensional graphene oxide-template gold nanosheet (GO@SiO2@AuNS) hybrid that could destruct cancer cells with efficient photothermal effect. METHODS: Graphene oxide was coated with a layer of mesoporous silica, which provided binding sites for gold seeds. Then, seed-growth method was utilized to grow a layer of gold nanosheet to form the GO@SiO2@AuNS hybrid, which possessed great biocompatibility and high photothermal conversion efficiency. RESULTS: With the irradiation of NIR laser (808 nm) with low power density (0.3 W/cm2), GO@SiO2@AuNS hybrid showed a photothermal conversion efficiency of 30%, leading to a temperature increase of 16.4 °C in water. Colorectal cancer cells (KM12C) were killed with the treatment of GO@SiO2@AuNS hybrid under NIR irradiation. CONCLUSION: The GO@SiO2@AuNS hybrid may expand the library of the 2D nanostructures based on gold for cancer photothermal therapy.

Prevalence and income-related equity in hypertension in rural China from 1991 to 2011: differences between self-reported and tested measures.

BACKGROUND: Along with economic growth and living standard improvement, hypertension has become one of the most prevalent chronic diseases in China. Self-reported measures and tested measures of hypertension may differ significantly due to the low awareness of prevalence. The objective of this study is to figure out whether and how self-reported measures differ from tested measures in terms of prevalence and equity. METHOD: We have used data from the China Health and Nutrition Survey database from 1991 to 2011 and extracted the data of rural areas using hukou system. Hypertension is categorized into two groups: self-reported hypertension and tested hypertension. To evaluate the equity of self-reported hypertension and tested hypertension, we calculated their Concentration Index (C) and decomposed C based on which we have obtained the horizontal-inequity index (HI) of each year. Probit Model was deployed to analyze the key determinants of hypertension prevalence. RESULTS: We found that the prevalence of both self-reported hypertension and tested hypertension have sharply increased from 1991 to 2011 in rural China and the population of tested hypertension was significantly larger than that of self-reported hypertension. For self-reported hypertension, prevalence rate increased from 2.72 to 13.2% and for tested hypertension it increased from 11.01 to 25.05%. Both of the Concentration Index (C) and horizontal-inequity index (HI) of self-reported hypertension and tested hypertension appeared to be contradictory. The C and HI of self-reported hypertension in 2011 were 0.032 and 0.060 respectively while the C and HI of tested hypertension were - 0.024 and - 0.015 respectively. CONCLUSION: More efforts should be put into for improving the poor's health, especially in equal access to health services. Symptom-based measures such as tested hypertension should be adopted more widely in empirical studies.

circMAN1A2 could serve as a novel serum biomarker for malignant tumors.

Novel diagnostic and prognostic biomarkers of cancers are needed to improve precision medicine. Circular RNAs act as important regulators in cancers at the transcriptional and posttranscriptional levels. The circular RNA circMAN1A2 is highly expressed in nasopharyngeal carcinoma according to our previous RNA sequencing data; however, the expression and functions of circMAN1A2 in cancers are still obscure. Therefore, in this study, we evaluated the expression of circMAN1A2 in the sera of patients with nasopharyngeal carcinoma and other malignant tumors and analyzed its correlations with clinical features and diagnostic values. The expression levels of circMAN1A2 were detected by quantitative real-time PCR, and the correlations of clinical features with circMAN1A2 expression were analyzed by χ2 tests. Receiver operating characteristic curves were used to evaluate the clinical applications of circMAN1A2. The results showed that circMAN1A2 was upregulated in nasopharyngeal carcinoma, oral cancer, thyroid cancer, ovarian cancer, and lung cancer, with areas under the curves of 0.911, 0.779, 0.734, 0.694, and 0.645, respectively, indicating the good diagnostic value of circMAN1A2. Overall, our findings suggested that circMAN1A2 could be a serum biomarker for malignant tumors, providing important insights into diagnostic approaches for malignant tumors. Further studies are needed to elucidate the mechanisms of circMAN1A2 in the pathogenesis of cancer.

The phosphorylation of the N protein could affect PRRSV virulence in vivo.

The porcine respiratory and reproductive syndrome virus (PRRSV) nucleocapsid (N) protein is a multiphosphorylated protein.It has been proved that the phosphorylation of N protein could regulate the growth ability of PRRSV in Marc-145 cells. However, further investigation is needed to determine whether phosphorylation of the N protein could affect PRRSV virulence in piglets. In this study, we confirmed that the mutations could impair PRRSV replication ability in porcine primary macrophages (PAMs) as they did in Marc-145 cells. The animal experiments suggested that the pathogenicity of the mutated virus (A105-120) was significantly reduced compared with parent strain (XH-GD). Our results suggested that the phosphorylation of the N protein contributes to virus replication and virulence. This study is the first to identify a specific modification involved in PRRSV pathogenicity. Mutation of PTMs sites is also a novel way to attenuate PRRSV virulence. The mutations could be a marker in a vaccine. In conclusion, our study will improve our understanding of the molecular mechanisms of PRRSV pathogenicity.