Ning Li

Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) poses a serious threat to the swine industry in China. As a major pig-producing province, Shandong requires continuous epidemiological monitoring of PRRSV. To elucidate the molecular epidemiology of the virus, 1621 clinical samples were collected from suspected cases across different regions of Shandong Province between 2023 and 2025, primarily from Tai’an, Linyi, Jining, and Liaocheng. RT-qPCR detection showed that the positive rate for PRRSV-2 was 20.05% (325/1621). Genetic analysis based on ORF5 and NSP2 genes indicated that Sublineage L1C (NADC30-like) was the dominant strain for 38.38% of ORF5 gene and 72.73% of NSP2 sequencing results. This was followed by Sublineage L8E and L1A and L5A strains. Key virulence-related mutations were identified at residues R13 and R151 in the GP5 protein, which are associated with enhanced pathogenicity. Additionally, variations in neutralizing epitope and the number of N-glycosylation sites (ranging from 2 to 5 per strain) suggested potential immune evasion. Notably, 26.79% (15/56) of sequenced samples showed discordant ORF5 and NSP2 genotyping results, indicating widespread recombination among PRRSV strains in Shandong Province. These finding demonstrated that the genetic diversity, high recombination frequency, and key amino acid variations in circulating PRRSV strains collectively undermine vaccine effectiveness. This study highlights the need to optimize vaccination strategies, enhance biosecurity measures, and implement effective disease control and elimination programs to reduce the impact of PRRSV in Shandong Province.

Although particulate matter (PM) is strongly associated with allergic reactions, the potential risk of the ability of PM derived from poultry houses to induce allergic reactions remains unclear. This study investigated the effects of duck housing PM on allergic reactions in mice. PM samples and fungi were collected from a duck farm. Ovalbumin (OVA) was used as a positive control, with ambient-level concentrations of PM, high-concentration PM (HPM), and fungal experimental groups. Aerosol exposure was performed on the mice. Serum IgE, allergic mediators (histamines and leukotrienes), cytokines, and pulmonary histopathology were analyzed. Furthermore, HPM-induced metabolic profiles in bronchoalveolar lavage fluid were measured. The results revealed that all the treatment groups of mice presented allergic symptoms, including sneezing and coughing; higher concentrations of IgE, His, and LTs in the serum; upregulation of allergic reaction-related cytokines, such as IL4, IL5, and IL33; and microscopic lesions of the lungs characterized by inflammatory cell infiltration were observed in all the treatment groups, indicating that PM and fungi can cause allergic reactions. Notably, allergic reactions were more pronounced in the HPM and fungal groups than in the PM group. In addition, metabolomics analyses revealed that HPM exposure caused metabolic disorders in mouse lungs. The key pathway with the highest correlation to metabolite differences was pyrimidine metabolism, which is associated with allergic reactions. In conclusion, this study demonstrated that exposure to PM in duck houses can cause allergic reactions in mice and significant metabolomic changes in the lungs, especially HPM. Moreover, the contribution of fungal components in the PM cannot be ignored. These findings highlight the potential health risks associated with PM from the poultry industry.

Porcine epidemic diarrhea virus (PEDV), a member of the genus Alpha coronavirus, is one of the main pathogens causing piglet diarrhea. PEDV can enhance its replication by regulating host protein function. The tyrosine phosphatase src homology 2 domain-containing PTP (SHP-1) acts as a host natural immune protein capable of influencing viral replication, but there are no studies on the regulation of virus replication by pig SHP-1. In this study, we expressed porcine SHP-1 protein and examined its interaction with PEDV as well as its potential role in PEDV infection. The results showed that SHP-1 overexpression in porcine kidney cells (PK15) significantly increased the mRNA level of viral S protein in a dose-dependent manner. In contrast, SHP-1 knockdown reduced S gene expression, indicating that SHP-1 promoted PEDV replication. Overexpression of SHP-1 had an inhibitory effect on IFN-β, TNF-α, ISG15, and CXCL10, while this inhibition was reduced as SHP-1 expression decreased. Furthermore, we found that SHP-1 interacted with TNF receptor-associated factor 3 (TRAF3) and inhibited its K63-linked ubiquitination, suppressing the expression of IFN-β and ISGs and facilitating PEDV replication. The study provided new insights for the prevention and control of porcine epidemic diarrhea.

African swine fever (ASF) is a devastating swine infectious disease that poses a serious threat to the global swine industry. Since ASF was first reported in China in 2018, this disease has caused significant economic losses in China. To characterize the histopathological changes induced by ASF virus (ASFV) in pigs and elucidate its pathogenic mechanism, this study used the ASFV HLJ/18 strain to infect specific pathogen-free piglets. The thymus, bone marrow, spleen, tonsil, lymph node, heart, liver, lung, and kidney were collected within the tenth day post-infection for histopathology, immunohistochemistry (IHC), TdT-mediated dUTP nick-end labeling, and Martius Scarlet Blue staining tests. The results showed that ASFV was widely distributed in various organs. Hemorrhage, cellular degeneration, and necrosis were observed in all examined organs, accompanied by a significant loss of lymphocytes in the immune organs, along with a large number of necrotic and apoptotic cells. Indirect immunofluorescence assay and IHC further showed that ASFV can infect monocytes and macrophages, epithelial cells, and hepatocytes. Apoptosis was prominently observed, particularly in lymphocytes within the immune organs, but it is worth noting that ASFV induced apoptosis in many different cell types in addition to lymphocytes. Furthermore, fibrin was observed in the blood vessels of multiple tissues, which may be associated with disseminated intravascular coagulation. These results demonstrate that the ASFV HLJ/18 strain was highly pathogenic to piglets, leading to severe pathological damage. This study provides valuable insights for deeply analyzing the pathogenicity mechanisms of ASFV. IMPORTANCE: Since African swine fever (ASF) first appeared in China in 2018, it has seriously jeopardized the healthy development of China's swine industry and caused huge economic losses. The characteristic of ASF is extensive hemorrhage in the organs, accompanied by immune suppression in the infected pigs. This study examined the damage caused by the virus and related mechanisms in histopathology and immunopathology. ASFV targets the macrophages, induces massive cell necrosis, and the formation of vascular microthrombi in multiple systems, leading to severe tissue damage and high mortality. Additionally, apoptosis and necrosis occurring in immune organs lead to an imbalance in the number and proportion of lymphocytes, further developing immune suppression. In conclusion, this study provides comprehensive insight into the immunopathology of ASFV infection.

Porcine reproductive and respiratory syndrome (PRRS) is one of the most serious diseases threatening the swine industry worldwide. However, no satisfactory control strategy has existed until now. In this study, the effectiveness of tylvalosin against PRRSV and the underlying mechanism was investigated. The results showed that in porcine alveolar macrophages (PAMs), tylvalosin can inhibit the replication of the NADC30-like and NADC34-like strains in a dose-dependent manner. It is worth noting that pre-incubation with tylvalosin had no significant inhibitory effect on the NADC30-like strain but did inhibit the NADC34-like strain. Co-incubation of both viruses and tylvalosin or post-incubation with tylvalosin after viral infection inhibited PRRSV. We further analyzed the effect of tylvalosin on different stages of PRRSV replication and found that the stages in the PRRSV life cycle could be blocked by tylvalosin. Tylvalosin has an antiviral effect on all four stages of the NADC34-like strain’s infectious cycle but has no effect against the adsorption phase of the NADC30-like strain. These results demonstrated that tylvalosin suppressed PRRSV infection in PAMs and inhibited PRRSV infection at multiple steps of the viral life cycle. This study will contribute to the clinical prevention and control of PRRS and provide a basis for further exploration of the anti-PRRSV effects of tylvalosin.

Particulate matter (PM) and the microorganisms of duck houses may have negative impacts on animal and human health. During 2021‐2022, PM2.5 and PM10 inside and outside the duck house were sampled with a built‐in air sampler in Tai’an City, Shandong Province, and the diversity and abundance of microorganisms within the PM were analyzed by macrogenomic and absolute sequence analysis. The results showed that PM2.5 and PM10 concentrations in the house and at downwind points exceeded the short‐term (24 h) guideline of the global air quality guidelines (AQG). Macrogenome sequencing showed that the microbial composition of the PM2.5 samples was dominated by bacteria (exceed 85%); a total of 1316 bacterial genera and 110 fungal genera were identified in PM2.5 samples from duck house 1 in winter, which were much higher than the results of amplicon sequencing method reported before, and relatively high levels of the pathogenic bacteria (Coccidioides immitis, etc.) and the conditionally pathogenic bacterium (Rothia nasimurium) were identified at the species level. Absolute quantitative sequencing detected conditionally pathogenic bacteria and allergens at high levels in PM10 samples: Corynebacterium (5.6 × 10⁷ copies/g), Aerococcus (9.9 × 10⁶ copies/g), Alternaria (3.3 × 10⁶ copies/g), and Aspergillus (8.3 × 10⁵ copies/g). Moreover, Corynebacterium was the highest content of PM10 in summer and PM2.5 samples in winter, and its pathogenicity and potential threat should be noted. The diversity and relative abundance of microorganisms were similar in the duck house and at the downwind point. The results showed that the microorganisms in the house environment have a greater influence on the air environment around the downwind point and may pose a public health risk to the staff and the surrounding area.

Heat stress is one of the major stressors affecting dairy cow production, which causes great losses in animal husbandry production and economic development. This study combined 16S rDNA sequencing, metagenomic sequencing, and metabolomic analysis to investigate the effects of heat stress on the rumen microbiome and metabolism of cows. To achieve this, 10 cows each of growing heifers, heifers, and lactating cows were selected for sample collection in April and August (a total of 60 cows). Ruminal fluid was collected, filtered through gauze, and immediately transferred to liquid nitrogen prior to metagenomic, 16S rDNA sequencing, and metabolomic analyses. Heat stress increased the abundance of pathogenic bacteria, such as Treponema_2 , Sphingobacterium , and Streptococcus , in cattle at all growth stages, with the structure and composition of rumen microbial communities being the most affected by heat stress in growing heifers and the least affected by heat stress in lactating cows. Heat stress led to a significant decrease in carbohydrate metabolic function in growing heifers and heifers, whereas microbial function was the most stable in lactating cows, suggesting that changes in microbial function are not only more conserved than microbial composition but are also affected by age. Heat stress led to significant enrichment of fatty acyl metabolites in growing heifers, heifers, and lactating cows, and the heat stress indicator species Bacillus , Lactococcus , Streptococcus , and Enterococcus were significantly associated with fatty acyl compounds in growing heifers and heifers. Therefore, heat stress alters the metabolic status of cows by modulating fatty acid biosynthesis, the PPAR signaling pathway, and arachidonic acid metabolism through the regulation of long-chain fatty acids and other biomarkers in cows at three growth stages. IMPORTANCE: Heat stress is one of the main causes of economic losses in the dairy industry worldwide; however, the mechanisms associated with the metabolic and microbial changes in heat stress remain unclear. Here, we characterized both the changes in metabolites, rumen microbial communities, and their functional potential indices derived from rumen fluid and serum samples from cows at different growth stages and under different climates. This study highlights that the rumen microbe may be involved in the regulation of lipid metabolism by modulating the fatty acyl metabolites. Under heat stress, the changes in the metabolic status of growing heifers, heifers, and lactating cows were closely related to arachidonic acid metabolism, fatty acid biosynthesis, and energy metabolism. Moreover, this study provides new markers for further research to understand the effects of heat stress on the physiological metabolism of Holstein cows and the time-dependent changes associated with growth stages.