Hongxin Li

gga-miR-375 plays a key role in tumorigenesis post subgroup J avian leukosis virus infection.

Avian leukosis is a neoplastic disease caused in part by subgroup J avian leukosis virus J (ALV-J). Micro ribonucleic acids (miRNAs) play pivotal oncogenic and tumour-suppressor roles in tumour development and progression. However, little is known about the potential role of miRNAs in avian leukosis tumours. We have found a novel tumour-suppressor miRNA, gga-miR-375, associated with avian leukosis tumorigenesis by miRNA microarray in a previous report. We have also previously studied the biological function of gga-miR-375; Overexpression of gga-miR-375 significantly inhibited DF-1 cell proliferation, and significantly reduced the expression of yes-associated protein 1 (YAP1) by repressing the activity of a luciferase reporter carrying the 3′-untranslated region of YAP1. This indicates that gga-miR-375 is frequently downregulated in avian leukosis by inhibiting cell proliferation through YAP1 oncogene targeting. Overexpression of gga-miR-375 markedly promoted serum starvation induced apoptosis, and there may be the reason why the tumour cycle is so long in the infected chickens. In vivo assays, gga-miR-375 was significantly downregulated in chicken livers 20 days after infection with ALV-J, and YAP1 was significantly upregulated 20 days after ALV-J infection (P<0.05). We also found that expression of cyclin E, an important regulator of cell cycle progression, was significantly upregulated (P<0.05). Drosophila inhibitor of apoptosis protein 1 (DIAP1), which is related to caspase-dependent apoptosis, was also significantly upregulated after infection. Our data suggests that gga-miR-375 may function as a tumour suppressor thereby regulating cancer cell proliferation and it plays a key role in avian leukosis tumorigenesis.

Effects of the thyroid hormone responsive spot 14α gene on chicken growth and fat traits

The thyroid hormone responsive spot 14alpha (THRSPalpha) gene plays important roles in chicken growth and fat deposition. The aim of this study was to identify new variations in the gene to determine their effects on growth and fat traits in chicken and to observe the effects of the THRSPalpha gene on chicken lipid profile and lipoprotein and glucose and triiodothyronine effects on the THRSPalpha expression in liver and fat cells. Two new variations, namely A197835978G and G197836086A, and a reported 9-bp insertion-deletion (indel) of the THRSPalpha gene were genotyped by single-stranded conformational polymorphism in a Xinghua x White Recessive Rock F(2) full-sib resource population. The results showed that the A197835978G was significantly associated with hatch weight and BW at 28 d of age and breast muscle weight at 90 d of age in chickens (P < 0.05). The G197836086A was significantly associated with cingular fat width (P = 0.0349) and breast muscle crude fat content (P = 0.0349). The indel was significantly associated with abdominal fat weight (P = 0.0445). The above new THRSPalpha polymorphisms were also significantly associated with the total cholesterol and low-density lipoprotein, in which the THRSPalpha GA/AG genotype was associated with lipid and lipoprotein and the THRSPalpha BB indel genotype was significantly associated with liver weight in chicken breeds. The mRNA expression analysis in vivo and in vitro culture studies suggested that the THRSPalpha gene is more responsive to glucose than triiodothyronine. In conclusion, the 3 variations of the chicken THRSPalpha gene were associated with both growth and fat traits in this study. Such effects of the THRSPalpha gene were further supported from the data of observations in association analysis of the gene with phenotypic records and plasma lipid profiles, in the THRSPalpha gene expression in chicken development, and in vivo and in vitro cell culture observation of liver and abdominal fat tissues.

Complete Genome Sequence of an Avian Leukosis Virus Isolate Associated with Hemangioma and Myeloid Leukosis in Egg-Type and Meat-Type Chickens

ABSTRACT Subgroup J avian leukosis virus (ALV-J) was first isolated from meat-type chickens that developed myeloid leukosis (ML). In recent years, field cases of hemangioma (HE) or HE and ML, rather than ML alone, have been reported in commercial layer flocks exposed to ALV-J with a high incidence in China. Here we report the complete genomic sequence of an ALV-J isolate that caused both HE and ML in egg-type and meat-type chickens in China. These findings will provide additional insights into the molecular characteristics in genomes, host range, and pathogenicity of ALV-J.

Complete Genome Sequence of a J Subgroup Avian Leukosis Virus Isolated from Local Commercial Broilers

ABSTRACT Subgroup J avian leukosis virus (ALV-J) isolate GDKP1202 was isolated from a 50-day-old local yellow commercial broiler in the Guangdong province of China in 2012. Here we report the complete genomic sequence of the GDKP1202 isolate, which caused high mortality, serious growth suppression, thymic atrophy, and liver enlargement in commercial broilers. A novel potential binding site (5′-GGCACCTCC-3′) for c-myb was identified in the GDKP1202 genome. These findings will provide additional insights into the molecular characteristics in the genomes and pathogenicity of ALV-J.

Molecular characterization of a distinct begomovirus infecting Allamanda cathartica in Guangdong, China.

Virus isolate G10 was obtained from diseased allamanda plants showing leaf curl symptoms in Guangdong, China. The full-length nucleotide sequence of a DNA-A-like molecule of G10 was cloned and sequenced; it comprises 2755 nucleotides and has a typical begomovirus genome organization with six conserved open reading frames. When compared with the DNA-A sequences of other begomoviruses, the complete nucleotide sequence of DNA-A of G10 had the highest sequence identity (81.2%) to tomato leaf curl Guangdong virus (ToLCGuV) isolate G2. This is less than the 89% identity in the complete genome that has been defined as the threshold value for demarcation of species in the genus Begomovirus. The molecular data show that isolate G10 from allamanda in Guangdong, China is a distinct Begomovirus species, for which the name Allamanda leaf curl virus (AlLCV) is proposed.

Role of gga-miR-221 and gga-miR-222 during Tumour Formation in Chickens Infected by Subgroup J Avian Leukosis Virus.

Subgroup J avian leukosis virus (ALV-J) causes a neoplastic disease in infected chickens. Differential expression patterns of microRNAs (miRNAs) are closely related to the formation and growth of tumors. (1) Background: This study was undertaken to understand how miRNAs might be related to tumor growth during ALV-J infection. We chose to characterize the effects of miR-221 and miR-222 on cell proliferation, migration, and apoptosis based on previous microarray data. (2) Methods: In vivo, the expression levels of miR-221 and miR-222 were significantly increased in the liver of ALV-J infected chickens (p < 0.01). Over-expression of gga-miR-221 and gga-miR-222 promoted the proliferation, migration, and growth of DF-1 cells, and decreased the expression of BCL-2 modifying factor (BMF) making cells more resistant to apoptosis. (3) Results: Our results suggest that gga-miR-221 and gga-miR-222 may be tumour formation relevant gene in chicken that promote proliferation, migration, and growth of cancer cells, and inhibit apoptosis. BMF expression was significantly reduced in vivo 70 days after ALV-J infection. They may also play a pivotal role in tumorigenesis during ALV-J infection.

Avian Influenza Virus Subtype H9N2 Affects Intestinal Microbiota, Barrier Structure Injury, and Inflammatory Intestinal Disease in the Chicken Ileum

Avian influenza virus subtype H9N2 (H9N2 AIV) has caused significant losses to the poultry industry due to the high mortality associated with secondary infections attributable to E. coli. This study tries to address the underlying secondary mechanisms after H9N2 AIV infection. Initially, nine day-old specific pathogen-free chickens were assigned to control (uninfected) and H9N2-infected groups, respectively. Using Illumina sequencing, histological examination, and quantitative real-time PCR, it was found that H9N2 AIV caused intestinal microbiota disorder, injury, and inflammatory damage to the intestinal mucosa. Notably, the genera Escherichia, especially E. coli, significantly increased (p < 0.01) at five days post-infection (dpi), while Lactobacillus, Enterococcus, and other probiotic organisms were significantly reduced (p < 0.01). Simultaneously, the mRNA expression of tight junction proteins (ZO-1, claudin 3, and occludin), TFF2, and Muc2 were significantly reduced (p < 0.01), indicating the destruction of the intestinal epithelial cell tight junctions and the damage of mucin layer construction. Moreover, the mRNA expression of proinflammatory cytokines IFN-γ, IL-22, IFN-α, and IL-17A in intestinal epithelial cells were significantly upregulated, resulting in the inflammatory response and intestinal injury. Our findings may provide a theoretical basis for observed gastroenteritis-like symptoms such as diarrhea and secondary E. coli infection following H9N2 AIV infection.

Effects of dietary yeast nucleotides supplementation on intestinal barrier function, intestinal microbiota, and humoral immunity in specific pathogen-free chickens

Yeast nucleotides are a fine functional additive in human and animals. The effects of dietary yeast nucleotides supplementation on intestinal development, expression of intestinal barrier-related genes, intestinal microbiota, and infectious bronchitis virus (IBV) antibody titer of specific pathogen-free (SPF) chickens were investigated. A total of 60 1-d-old chickens were divided into 4 groups, each of which included 3 replicates of 5 chickens. Group 1 served as a control that was fed a basal diet. Groups 2 to 4 were fed the basal diet supplemented with 0.1%, 0.3% and 0.5% yeast nucleotides, respectively. All chickens were inoculated intranasally with inactivated IBV vaccine at day 1 and day 10. At day 17, the intestinal development, expression of intestinal barrier-related genes and microbiota were evaluated. There was a significant increased ileal villus height and villus height to crypt depth ratio in group 2 (P < 0.05). Moreover, group 4 exhibited higher expression of zonula occludens-1 (ZO-1) and Occludin gene in ileum (P < 0.05), whereas groups 2 and 3 exhibited higher expression of Mucin 2 (MUC2) and trefoil factor 2 (TFF2) gene (P < 0.05), group 2 showed lower expression of IFN-α gene (P < 0.05). Dietary yeast nucleotides increased intestinal bacterial diversity (P < 0.05), and the abundance of Lactobacillus (P < 0.05). At day 10, 17, 24, 31, 38, and 45, the serum IBV antibody titers were tested. Group 2 exhibited higher IBV antibody titer at day 17 (P < 0.05), furthermore, groups 2 to 4 reached the effective levels 1 wk earlier than control group. In conclusion, dietary yeast nucleotides supplementation can help birds to mount a faster and stronger antibody response to IBV vaccine. In addition, dietary yeast nucleotides supplementation can also promote the intestinal development and barrier-related genes expression, and diversity and richness of intestinal microbiota.

Expression of dysregulated miRNA in vivo in DF-1 cells during the course of subgroup J avian leukosis virus infection

Aberrant expression of microRNAs (miRNAs) is known to be involved in cancer progression caused by subgroup J avian leukosis virus (ALV-J) in liver tissues. To advance our understanding of the related pathological mechanisms and virus-host interactions, seven previously reported miRNAs were selected for a comparative analysis of miRNA expression between infected and uninfected DF-1 cells, including six miRNAs related to tumorigenesis (let-7b/7i, miR-221/222, miR-125b, miR-375 and miR-2127. The results showed that six of the seven miRNAs except gga-miR-375 were upregulated in cells infected with NX0101 (caused myeloma (ML)) and GD1109 (caused hemangioma (HE)) at 1 h post infection. On day 2 post-infection, all seven miRNAs were upregulated in infected DF-1 cells. On day 6 post-infection, gga-let-7b, gga-miR-125b, and gga-miR-375 were downregulated whereas gga-miR-221 and gga-miR-222 were upregulated in DF-1 cells infected with the two ALV-J strains of different phenotypes. However, expression of gga-let-7i was reduced in DF-1 cells infected with NX0101 and was increased in those infected with GD1109; gga-miR-2127 expression showed no significant difference between infected and uninfected cells. This study is the first to report the changes in the miRNA expression levels in DF-1 cells during the course of ALV-J infection, and suggests a relationship between its pathological mechanisms and miRNAs.

Avian leukosis virus subgroup J attenuates type I interferon production through blocking IκB phosphorylation

Avian leukosis virus subgroup J (ALV-J) is an oncogenic retrovirus that causes immunosuppression and enhances susceptibility to secondary infection, resulting in great economic losses. Although ALV-J-induced immunosuppression has been well established, the underlying molecular mechanism for such induction is still unclear. Here, we report that the inhibitory effect of ALV-J infection on type I interferon expression is associated with the down-regulation of transcriptional regulator NF-κB in host cells. We found that ALV-J possess the inhibitory effect on type I interferon production in HD11 cells and that ALV-J causes the up-regulation of IκBα and down-regulation of NF-κB p65, and that ALV-J blocks the phosphorylation of IκBα on Ser32/36 amino acid residues. Collectively, our findings provide insights into the pathogenesis of ALV-J.