Marek's disease (MD) is a lymphoproliferative disease of chickens induced by a highly cell-associated oncogenic α-herpesvirus, Marek's disease virus (MDV). MDV replicates in chicken lymphocytes and establishes a latency infection within CD4⁺ T cells. Host-virus interaction, immune responses to infection, and transcriptional profiling of chicken gene expression in MD are poorly understood. In this study we conducted a global host gene expression analysis in the splenocytes of MDV-infected chickens using oligonucleotide-based Affymetrix GeneChip Chicken Genome Arrays. These arrays contain probes for more than 32,000 chicken transcripts and most of the known MDV genes and open reading frames. Two-week-old MD-susceptible chickens were inoculated with an oncogenic strain of MDV, and spleen samples were collected 5 and 15 days post-infection (dpi) for RNA isolation and microarray analysis. Array results displayed a significant differential pattern of immune response transcriptome between the two phases of MDV infection. The expression levels of more than 22 immune-response and related genes were downregulated, while the expression levels of at least 58 genes were increased at 5 dpi (cytolytic infection), compared to age-matched control birds. In comparison, out of 73 immune-response and related genes, 67 genes were downregulated, with only 6 genes having higher expression levels at 15 dpi (latency infection). Cytokines, chemokines, MHC molecules and related receptors, and adhesion molecules were among the many MDV-induced downregulated genes that are critical for an effective antiviral immune response. In addition, several apoptosis-associated genes were decreased in expression during latent infection, suggesting an MDV-induced blocking of initiation or progression of programmed cell death processes. These chicken arrays are valuable tools in understanding the molecular mechanisms behind viral pathogenesis and chicken gene expression patterns, and associated biological pathways in response to MDV infection.

Background: Friedreich's ataxia (FRDA) is an inherited recessive disorder characterized by progressive neurological disability and heart abnormalities. A deficiency in the protein frataxin causes this disease. Frataxin deficiency leads to progressive iron accumulation in mitochondria, excessive free radical production and dysfunction of respiratory chain complexes. The expansion (GAA) repeat in the first intron causes decreased frataxin expression by interfering with transcription.Methods: Activity of mitochondrial respiratory chain complex I (measured as NADH ferricyanide reductase) and intracellular ATP measurement was performed on lymphocyte of FRDA patients (n=12) and control subjects (n=25).Results: Our findings showed that complex I activity and intracellular ATP were significantly reduced (P=0.001) in patients compared with controls and we found strong correlation between complex I activity and intracellular ATP content in FRDA patients (r = 0.93; P<0.002). 8.6 and 9.0 kb deletion in mtDNA was detected in 9 patients out of 12 (75%) by multiplex polymerase chain reaction (PCR) and Southern blot analysis.Conclusions: This study suggested that a biochemical defect in complex I activity and ATP production, which may be due to iron accumulation in mitochondria, can be involved in age of onset of FRDA.

Marek's disease (MD) is a lymphoproliferative disease of chickens that is caused by a highly cell-associated oncogenic alpha-herpesvirus, Marek's disease virus (MDV). The role of cytokines and other related proteins in MD pathogenesis and immunity is poorly understood. The aim of this study was to examine the transcriptional profiling of a panel of cytokines and other immune-related genes in the splenic tissues of chickens infected with a highly oncogenic strain of MDV during cytolytic infection and latency. Real-time polymerase chain reaction analysis revealed significant upregulation in the expression levels of interleukins (IL)-1beta, IL-4, IL-6, IL-10, IL-12p35, and IL-13, interferons (IFN)-1alpha, IFN-1beta, and IFN-gamma, chicken myelomonocytic growth factor (cMGF), granulocyte-macrophage colony-stimulating factor (GM-CSF), and inducible nitric oxide synthase (iNOS) in the infected chickens at 5 d post-inoculation (lytic infection). The changes in the mRNA levels of IL-18 and MHC I were minimal in comparison to those of the control birds. There was no significant difference in the expression levels of IL-2, IL-8, MHC II, Bcl-2, Bcl-x, and Nr-13 between the two groups. With the exception of IL-10, which showed high transcriptional activity beyond the lytic phase, the expression patterns of all the tested genes were similar between the infected and age-matched control birds at 15 d post-inoculation (latency infection). Of the genes examined, in addition to the high transcriptional activities of IL-1beta, IL-6, IL-12, iNOS, and type 1 and 2 IFNs, the relative expression levels of IL-4, IL-10, and IL-13 were significantly upregulated in the infected chickens during the lytic phase of infection compared to uninfected controls (a 9- to 50-fold difference). This observation suggests that (1) an immune response with a Th-2 characteristic is induced by a very virulent plus MDV strain during the lytic phase of infection; and (2) there is no significant MDV-specific immune response in the latent phase of infection.