Ling Lian

Introduction: Marek’s disease, caused by the oncogenic Marek’s disease virus (MDV), remains a major threat to poultry production. Host immune responses and apoptosis pathways play critical roles in MDV pathogenesis, yet the underlying mechanisms are not fully understood. Methods: Chicken embryo fibroblasts (CEF) were treated with poly I:C to assess its effect on MDV infection, followed by transcriptome profiling to identify differentially expressed genes. Functional assays using siRNA knockdown and overexpression of TNFRSF11B were performed to evaluate its impact on viral infection and apoptosis. Results: Poly I:C treatment significantly reduced MDV infection in CEF. Transcriptome analysis identified 274 DEGs, among which TNFRSF11B was notably downregulated. Consistently, MDV infection suppressed TNFRSF11B expression in both CEF and spleen tissues. Functional assays revealed that knockdown of TNFRSF11B enhanced MDV infection, whereas its overexpression suppressed MDV infection. Furthermore, MDV infection induced substantial cell apoptosis, and TNFRSF11B knockdown further exacerbated this effect, as demonstrated by elevated CASP3 expression and higher apoptosis rates. A strong positive correlation was observed between MDV infection levels and apoptosis rates ( R ² = 0.9895, p < 0.0001). Discussion: Our findings indicated TNFRSF11B could modulate MDV infection through collaborating with MDV to modulate cell apoptosis. This study provides new insights into the pathogenesis of MDV and potential antiviral strategies targeting MDV/TNFRSF11b—cell apoptosis.

Blood and meat spots in egg white and yolk are regarded as defects affecting egg internal quality. The presence of blood and meat spots in egg directly reflects the health status of the hen’s ovary and oviduct. In this study, we analyzed mRNA and lncRNA profiles from 36 samples (ovary, magnum/isthmus, and uterus) collected from 12 Rhode Island Red hens with higher and lower incidence of blood and meat spots (BMS) in eggs, to elucidate the factors associated with BMS incidence. There were 398, 359, 548 differentially expressed genes (DEGs) and 194, 34, 170 differentially expressed lncRNAs (DElncRNAs) across the ovary, magnum/isthmus and uterus identified between high and low BMS incidence groups. Through WGCNA analysis, we identified phenotype-associated gene modules in the ovary, the key tissues where egg yolk formed, which indicated DEGs in the ovary was associated with BMS formation. Further analysis revealed 36, 28, 353 DEGs were co-expressed with DElncRNAs in the ovary, magnum/isthmus tissues, and uterus, respectively. Functional enrichment analysis indicated that co-expressed genes in ovary and magnum/isthmus were predominantly associated with inflammatory responses and immune regulation, which indicated inflammation response occurred in ovary tissue. Our study provided the transcriptome profiles of chickens with high and low BMS, which was helpful for in-depth research on molecular mechanisms underlying BMS formation.

Introduction: The blood and meat spots in eggs are recognized as defects for egg quality. The frequency of blood and meat spots in brown-shell eggs is much higher than that in white-shell eggs in previous studies. However, the actual occurrence frequency and their effects on the microbial composition in eggs remain poorly understood.Methods: In this study, we examined the frequency of blood and meat spots in brown-shell and white-shell eggs, respectively, from Rhode Island Red and White Leghorn chickens at seven ages.Results: The results showed that blood and meat spots in brown-shell eggs exhibit much higher average frequency (63.99%) than that in white-shell eggs (1.37%). Furthermore, we analyzed the relationship between the presence of blood and meat spots and the microbial community distribution in the egg albumen and yolk. Briefly, we selected brown-shell eggs (n = 112) from Rhode Island Red, among which 51 eggs showing blood/meat spots were classified as RIR_CASE, and 61 normal eggs without blood/meat spot were classified as RIR_CON. Additional white-eggshell eggs (n = 124) without blood/meat spots from White Leghorn were selected as WL_CON. 16S rRNA sequencing was performed in both egg white and yolk. The results indicated that neither egg white nor yolk is sterile, with Proteobacteria identified as the dominant bacterial phyla. The microbial alpha diversity in both egg white and yolk of RIR_CASE was significantly lower compared to RIR_CON and WL_CON. Beta diversity analysis showed that the Weighted UniFrac Distance between RIR_CASE and RIR_CON in the egg yolk group was significantly larger than the distance between WL_CON and RIR_CON. It suggested that the difference of microbial diversity was mainly caused by blood and meat spots other than by chicken breeds. LEfSe analysis identified eight microbial taxa closely linked to the presence of blood and meat spots in egg white or yolk. Moreover, through the combination of random forest analysis, we identified the unique microbial biomarkers Comamonas_F and Chryseobacterium in the egg white of the RIR_CASE group.Discussion: Our study indicates that eggs with blood and meat spots occur at a higher frequency in brown-shell chickens and are accompanied by a distinct microbial community distribution.

Marek’s disease (MD), an immunosuppressive disease induced by the Marek’s disease virus (MDV), is regarded as an ideal model for lymphoma research to elucidate oncogenic and anti-oncogene genes. Using this model, we found that circRUNX2.2, derived from exon 6 of RUNX2, was significantly upregulated in MDV-infected tumorous spleens. In this study, we deeply analyzed the potential role of circRUNX2.2 in lymphoma cells. An open reading frame (ORF) in circRUNX2.2 with no stop codon was predicted, and small peptides (named circRUNX2.2-rt) presenting multiple ladder-like bands with different molecular weights encoded by circRUNX2.2 were detected via Western blotting assay. The polysome fraction assay reconfirmed the translation ability of circRUNX2.2, which could be detected in polysome fractions. Subsequent analysis verified that it translated in a rolling circle manner, rather than being assisted by the internal ribosome entry site (IRES) or m6A-mediated mechanism. Furthermore, we found that circRUNX2.2-rt was potently induced in MSB1 cells treated with sodium butyrate (NaB), which reactivated MDV and forced the MDV transition from the latent to reactivation phase. During this phase, MDV particles were clearly observed by electron microscopy, and the viral gene pp38 was also significantly upregulated. A biological function study showed that circRUNX2.2-rt promoted cell proliferation and cell cycle transition from the S to G2 phase and inhibited the apoptosis of MSB1. Further immunoprecipitation and mass spectrometry assays showed that 168 proteins potentially interacting with circRUNX2.2-rt were involved in multiple pathways related to cell cycle regulation, which proved that circRUNX2.2-rt could bind or recruit proteins to mediate the cell cycle.

Avian leukosis virus subgroup E (ALVE) as a kind of endogenous retroviruses extensively exists in chicken genome. The insertion of ALVE has some effects on chicken production traits and appearance. Most of the work on ALVEs has been done with commercial breeds. We present here an investigation of ALVE elements in seven Chinese domestic breeds and four standard breeds. Firstly, we established an ALVE insertion site dataset by using the obsERVer pipeline to identify ALVEs from whole-genome sequence data of eleven chicken breeds, seven Chinese domestic breeds, including Beijing You (BY), Dongxiang (DX), Luxi Game (LX), Shouguang (SG), Silkie (SK), Tibetan (TB) and Wenchang (WC), four standard breeds, including White Leghorn (WL), White Plymouth Rock (WR), Cornish (CS), and Rhode Island Red (RIR). A total of 37 ALVE insertion sites were identified and 23 of them were novel. Most of these insertion sites were distributed in intergenic regions and introns. We then used locus-specific PCR to validate the insertion sites in an expanded population with 18~60 individuals in each breed. The results showed that all predicted integration sites in 11 breeds were verified by PCR. Some ALVE insertion sites were breeds specific, and 16 out of 23 novel ALVEs were found in only one Chinese domestic chicken breed. We randomly selected three ALVE insertions including ALVE_CAU005, ALVE_ros127, and ALVE_ros276, and obtained their insertion sequences by long-range PCR and Sanger sequencing. The insertion sequences were all 7525 bp, which were full-length ALVE insertion and all of them were highly homologous to ALVE1 with similarity of 99%. Our study identified the distribution of ALVE in 11 chicken breeds, which expands the current research on ALVE in Chinese domestic breeds.