Emerging Hypervirulent Marek's Disease Virus Variants Significantly Overcome Protection Conferred by Commercial Vaccines

Novel lncRNA 803 related to Marek's disease inhibits apoptosis of DF-1 cells

Marek's disease (MD) is a neoplastic disease that significantly affects the poultry industry. Long non-coding RNAs (lncRNAs) are crucial regulatory factors in various biological processes, including tumourigenesis. However, the involvement of novel lncRNAs in the course of MD virus (MDV) infection is still underexplored. Here, we present the first comprehensive characterization of differentially expressed lncRNAs in chicken spleen at different stages of MDV infection. A series of differentially expressed lncRNAs was identified at each stage of MDV infection through screening. Notably, our investigation revealed a novel lncRNA, lncRNA 803, which exhibited significant differential expression at different stages of MDV infection and was likely to be associated with the p53 pathway. Further analyses demonstrated that the overexpression of lncRNA 803 positively regulated the expression of p53 and TP53BP1 in DF-1 cells, leading to the inhibition of apoptosis. This is the first study to focus on the lncRNA expression profiles in chicken spleens during MDV pathogenesis. Our findings highlight the potential role of the p53-related novel lncRNA 803 in MD pathogenesis and provide valuable insights for decoding the molecular mechanism of MD pathogenesis involving non-coding RNA.RESEARCH HIGHLIGHTS Differentially expressed lncRNAs in spleens of chickens infected with Marek's disease virus at different stages were identified for the first time.The effects of novel lncRNA 803 on p53 pathway and apoptosis of DF-1 cells were reported for the first time.

Immunopotentiating effect of lentinan on chicks and its inhibitory effect on Marek's disease virus infection

Marek's disease virus (MDV) is a significant tumorigenic virus that causes severe immunosuppression in chickens. Lentinan (LNT) is an immunomodulator containing β-glucans and is widely used in areas such as antiviral, anticancer, and immune regulation. To investigate the immunomodulatory effects of LNT on specific pathogen-free (SPF) chicks and its potential to inhibit MDV infection, we conducted an MDV challenge experiment and observed the immune-enhancing effect of LNT on SPF chicks. The results showed that LNT promoted the growth and development of SPF chicks and induced the upregulation of cytokines such as Mx protein, interferon-γ (INF-γ), tumor necrosis factor-α (TNF-α), and interleukin-2 (IL-2). The specific gravity of CD4+ T-lymphocytes and CD8+ T-lymphocytes and their ratios were also significantly upregulated. Prophylactic use of LNT inhibited MDV replication in lymphocytes, liver, and spleen. It also alleviated MDV-induced weight loss and hepatosplenomegaly in SPF chicks. The present study confirms that LNT can enhance the levels of innate and cellular immunity in SPF chicks and contributes to the inhibition of MDV replication in vivo and mitigation of immune organ damage in chicks due to MDV infection. This provides an adjunctive measure for better control of MDV infection.

Immune escape of avian oncogenic Marek's disease herpesvirus and antagonistic host immune responses

Marek's disease virus (MDV) is a highly pathogenic and oncogenic alpha herpesvirus that causes Marek's disease (MD), which is one of the most important immunosuppressive and rapid-onset neoplastic diseases in poultry. The onset of MD lymphomas and other clinical diseases can be efficiently prevented by vaccination; these vaccines are heralded as the first demonstration of a successful vaccination strategy against a cancer. However, the persistent evolution of epidemic MDV strains towards greater virulence has recently resulted in frequent outbreaks of MD in vaccinated chicken flocks worldwide. Herein, we provide an overall review focusing on the discovery and identification of the strategies by which MDV evades host immunity and attacks the immune system. We have also highlighted the decrease in the immune efficacy of current MD vaccines. The prospects, strategies and new techniques for the development of efficient MD vaccines, together with the possibilities of antiviral therapy in MD, are also discussed.

The novel lncRNA-9802/miR-1646 axis affects cell proliferation of DF-1 by regulating Bax/Bcl-2 signaling pathway

Marek's disease (MD) is a severe infectious and immunosuppressive neoplastic condition that significantly impacts the global poultry industry. Investigating the role of non-coding RNA in pathogenic mechanisms of MD virus (MDV) offers valuable insights for the effective prevention and management of MD. A higher expression of the novel lncRNA-9802 can be found in spleen tissues of MDV-infected chickens from our prior research, and there is a potential association between lncRNA-9802 and cell proliferation. In this study, we further demonstrated that over-expression of lncRNA-9802 could promote the proliferation of DF-1 cells. It has been established that lncRNA-9802 mediated its effects by binding to miR-1646, and further modulated the expression of the Bax and Bcl-2 genes. Deciphering the role of the recently discovered MD-associated lncRNA-9802/miR-1646 axis provides valuable theoretical basis for decoding the molecular mechanisms underlying MDV pathogenesis.