Nitric oxide (NO) was proposed to be an important molecule against some microorganisms. In this study, we investigated the inhibitory effect of NO on the infection by porcine reproductive and respiratory syndrome virus (PRRSV) in vitro and the role of NO in the defense against PRRSV. Our results indicated that exogenous NO did not inhibit PRRSV infection. Unexpectedly, N-acetylpenicillamine (NAP), a commonly used compound as negative control for NO-producing reagents, inhibited PRRSV replication. Thus, the inhibition effect of NAP on PRRSV replication was further explored. We found that the maximal inhibition effect of NAP on PRRSV replication was achieved upon treatment 1 h after virus infection and the virus yield was reduced by approximately 50 fold in the presence of 400 muM NAP. An obvious inhibitory effect on viral RNA and protein synthesis was also observed. However, the inhibitory effect was only achieved at early phase of virus infection. The normal virus yield could be restored upon the removal of NAP treatment. The inhibitory effect might be caused by sulfhydryl-reducing capacity and metal chelating properties of NAP. These studies suggested that (i) NO production or NO synthase (NOS) expression profiling may not be a reliable index for the immune response to PRRSV; (ii) NAP could inhibit the replication of PRRSV.

Porcine reproductive and respiratory syndrome virus (PRRSV) causes porcine reproductive and respiratory syndrome (PRRS), leading to abortion in sows and respiratory distress in breeding pigs. In China, PRRSV1 and PRRSV2 are the two circulating genotypes in swine herds, with distinct virulence. PRRSV2 further consists of classical (C-PRRSV2), highly pathogenic (HP-PRRSV2), and NADC30-Like (N-PRRSV2) subtypes. The diversity of PRRSV poses challenges for control and eradication, necessitating reliable detection assays for differentiating PRRSV genotypes.

Environmental factors, including 7,12‑dimethylbenz[a]anthracene (DMBA) exposure, and genetic predisposition, including ErbB2 overexpression/amplification, have been demonstrated to increase breast cancer susceptibility. Although DMBA‑ and ErbB2‑mediated breast cancers are well‑studied in their respective models, key interactions between environmental and genetic factors on breast cancer risk remain unclear. Therefore, the present study aimed to investigate the effect of DMBA exposure on ErbB2‑mediated mammary tumorigenesis. MMTV‑ErbB2 transgenic mice exposed to DMBA (1 mg) via weekly oral gavage for 6 weeks exhibited significantly enhanced mammary tumor development, as indicated by reduced tumor latency and increased tumor multiplicity compared with control mice. Whole mount analysis of premalignant mammary tissues from 15‑week‑old mice revealed increased ductal elongation and proliferative index in DMBA‑exposed mice. Molecular analyses of premalignant mammary tissues further indicated that DMBA exposure enhanced epidermal growth factor receptor (EGFR)/ErbB2 and estrogen receptor (ER) signaling, which was associated with increased mRNA levels of EGFR/ErbB2 family members and ER‑targeted genes. Furthermore, analysis of tumor karyotypes revealed that DMBA‑exposed tumors displayed more chromosomal alterations compared with control tumors, implicating DMBA‑induced chromosomal instability in tumor promotion in this model. Together, the data suggested that DMBA‑induced deregulation of EGFR/ErbB2‑ER pathways plays a critical role in the enhanced chromosomal instability and promotion of ErbB2‑mediated mammary tumorigenesis. The study highlighted gene‑environment interactions that may increase risk of breast cancer, which is a critical clinical issue.

Porcine reproductive and respiratory syndrome virus (PRRSV) infects mainly the porcine alveolar macrophages (PAMs) and causes porcine reproductive and respiratory syndrome (PRRS). Previous studies have analyzed the global gene expression profiles of lung tissue in vivo and PAMs in vitro following infection with PRRSV, however, transcriptome-wide understanding of the interaction between highly pathogenic PRRSV (HP-PRRSV) and PAMs in vivo has not yet been established. In this study, we employed Affymetrix microarrays to investigate the gene expression patterns of PAMs isolated from Tongcheng piglets (a Chinese indigenous breed) after infection with HP-PRRSV. During the infection, Tongcheng piglets exhibited typical clinical signs, e.g. fever, asthma, coughing, anorexia, lethargy and convulsion, but displayed mild regional lung damage at 5 and 7 dpi. Microarray analysis revealed that HP-PRRSV infection has affected PAMs in expression of the important genes involved in cytoskeleton and exocytosis organization, protein degradation and folding, intracellular calcium and zinc homeostasis. Several potential antiviral strategies might be employed in PAMs, including upregulating IFN-induced genes and increasing intracellular zinc ion concentration. And inhibition of the complement system likely attenuated the lung damage during HP-PRRSV infection. Transcriptomic analysis of PAMs in vivo could lead to a better understanding of the HP-PRRSV-host interaction, and to the identification of novel antiviral therapies and genetic components of swine tolerance/susceptibility to HP-PRRS.

Porcine reproductive and respiratory syndrome virus (PRRSV) is the cause of an economically important swine disease that has been devastating the swine industry since the late 1980s. Accumulating evidences have revealed that PRRSV infection fails to induce type I interferon (IFN-alpha/beta), which are normally induced rapidly during virus replication in virus-infected cells. However, the potential mechanisms remain largely unclear. In this study, we showed that PRRSV infection activated the signal transduction components of NF-kappaB and AP-1, but not of interferon regulatory factor 3 (IRF3), an essential IFN-beta transcription factor. Furthermore, PRRSV infection significantly blocked synthetic dsRNA-induced IFN-beta production and IRF3 nuclear translocation. To better understand the upstream signaling events that suppress IRF3 activation, we further investigated the roles of individual components of the retinoic acid-inducible gene I (RIG-I)- and Toll-like receptor 3 (TLR3)-mediated signaling pathway for IFN-beta production during PRRSV infection. We observed that PRRSV infection significantly inhibited dsRNA-induced IRF3 activation and IFN-beta generation by inactivating IFN-beta promoter stimulator 1 (IPS-1), an adaptor molecule of RIG-I. In contrast, PRRSV infection only partially reduced the activation of TIR domain-containing adaptor inducing IFN-beta (TRIF), an adaptor molecule of TLR3. Our results suggest that PRRSV infection suppresses production of IFN-beta primarily by interfering with the IPS-1 activation in the RIG-I signaling pathway.

While p73 overexpression has been associated with increased apoptosis in cancer tissues, p73 overexpressing tumors appear to be of high grade malignancy. Why this putative tumor suppressor is overexpressed in cancer cells and what the function of overexpressed p73 is in breast cancers are critical questions to be addressed. By investigating the effect of p53 inactivation on p73 expression, we found that both protein and mRNA levels of TAp73 were increased in MCF-7/p53siRNA cells, MCF-7/p53mt135 cells and HCT-116/p53-/- cells, as compared to wild type control, suggesting that p53 inactivation by various forms upregulates p73. We showed that p53 knockdown induced p73 was mainly regulated at the transcriptional level. However, although p53 has a putative binding site in the TAp73 promoter, deletion of this binding site did not affect p53 knockdown mediated activation of TAp73 promoter. Chromatin immuno-precipitation (ChIP) data demonstrated that loss of p53 results in enhanced occupancy of E2F-1 in the TAp73 promoter. The responsive sequence of p53 inactivation mediated p73 upregulation was mapped to the proximal promoter region of the TAp73 gene. To test the role of E2F-1 in p53 inactivation mediated regulation of p73 transcription, we found that p53 knockdown enhanced E2F-1 dependent p73 transcription, and mutations in E2F-1 binding sites in the TAp73 promoter abrogated p53 knockdown mediated activation of TAp73 promoter. Moreover, we demonstrated that p21 is a mediator of p53-E2F crosstalk in the regulation of p73 transcription. We concluded that p53 knockdown/inactivation may upregulate TAp73 expression through E2F-1 mediated transcriptional regulation. p53 inactivation mediated upregulation of p73 suggests an intrinsic rescuing mechanism in response to p53 mutation/inactivation. These findings support further analysis of the correlation between p53 status and p73 expression and its prognostic/predictive significance in human cancers.

Nucleotide-binding oligomerization domain 1 (NOD1) is an imperative cytoplasmic pattern recognition receptor (PRR) and considered as a key member of the NOD-like receptor (NLR) family which plays a critical role in innate immunity through sensing microbial components derived from bacterial peptidoglycan. In the current study, the full-length of duck NOD1 (duNOD1) cDNA from duck embryo fibroblasts (DEFs) was cloned. Multiple sequence alignment and phylogenetic analysis demonstrated that duNOD1 exhibited a strong evolutionary relationship with chicken and rock pigeon NOD1. Tissue-specific expression analysis showed that duNOD1 was widely distributed in various organs, with the highest expression observed in the liver. Furthermore, duNOD1 overexpression induced NF-κB activation in DEFs and the CARD domain is crucial for duNOD1-mediated NF-κB activation. In addition, silencing the duNOD1 decreased the activity of NF-κB in DEFs stimulated by iE-DAP. Overexpression of duNOD1 significantly increased the expression of TNF-α, IL-6, and RANTES in DEFs. These findings highlight the crucial role of duNOD1 as an intracellular sensor in duck innate immune system.