FAT10 induces immune suppression by upregulating PD-L1 expression in hepatocellular carcinoma.

The upregulation of programmed death ligand 1 (PD-L1) plays a crucial role in facilitating cancer cells to evade immune surveillance through immunosuppression. However, the precise regulatory mechanisms of PD-L1 in hepatocellular carcinoma (HCC) remain undefined. The correlation between PD-L1 and ubiquitin-like molecules (UBLs) was studied using sequencing data from 20 HCC patients in our center, combined with TCGA data. Specifically, the association between FAT10 and PD-L1 was further validated at both the protein and mRNA levels in HCC tissues from our center. Subsequently, the effect of FAT10 on tumor progression and immune suppression was examined through both in vivo and in vitro experiments. Utilizing sequencing data, qPCR, and Western blotting assays, we confirmed that FAT10 was highly expressed in HCC tissues and positively correlated with PD-L1 expression. Additionally, in vitro experiments demonstrated that the overexpression of FAT10 fostered the proliferation, migration, and invasion of HCC cells. Furthermore, the overexpression of FAT10 in HCC cells led to an increase in PD-L1 expression, resulting in the inhibition of T cell proliferation and the enhancement of HCC cell resistance to T cell-mediated cytotoxicity. Moreover, in vivo experiments utilizing the C57BL/6 mouse model revealed that overexpression of FAT10 effectively suppressed the infiltration of CD8 + GZMB + and CD8 + Ki67 + T cells, as well as reduced serum levels of TNF-α and IFN-γ. Mechanistically, we further identified that FAT10 upregulates PD-L1 expression via activating the PI3K/AKT/mTOR pathway, but not in a ubiquitin-like modification. In conclusion, our findings indicate that FAT10 promotes immune evasion of HCC via upregulating PD-L1 expression, suggesting its potential as a novel target to enhance the efficiency of immunotherapy in HCC.

Time trends in the incidence of interstitial lung disease across Brazil, Russia, India, China and South Africa (BRICS) from 1990 to 2019: An age-period-cohort analysis.

BACKGROUND AND OBJECTIVE: The global incidence of interstitial lung disease (ILD) has risen over the past few decades. However, few studies have evaluated the status and incidence trends of ILD in Brazil, Russia, India, China and South Africa (BRICS). This study assesses the trends of ILD incidence across the BRICS with an emphasis on ILD changes from 1990 to 2019. METHODS: Incidence rates were estimated by the data obtained from the Global Burden of Disease Study 2019 (GBD 2019). Age-period-cohort modelling was used to estimate the effects on ILD from 1990 to 2019, and the net drift and local drift were calculated. RESULTS: In 2019, a total of 11.4 million cases of ILD were reported in the BRICS countries. From 1990 to 2019, the incidence rate of ILD in BRICS showed an upward trend. India consistently reported the highest incidence rate, while China showed the fastest growth rate (107.6%). Russia reported a similar incidence rates for men and women, with a lower age of peak incidence compared to the other four countries. We found the time effect was unfavourable for BRICS in the first decade, especially for Brazil; in China and Brazil, the risk of people born after 1960 has rapidly decreased. CONCLUSION: ILD shows a rising incidence in BRICS. with the trends varying based on age and other environmental factors. BRICS should strengthen specific public health approaches and policies for different stages and populations.

Deoxynivalenol triggers mitotic catastrophe and apoptosis in C2C12 myoblasts.

Deoxynivalenol (DON), commonly known as vomitoxin, is a mycotoxin produced by fungi and is frequently found as a contaminant in various cereal-based food worldwide. While the harmful effects of DON have been extensively studied in different tissues, its specific impact on the proliferation of skeletal muscle cells remains unclear. In this study, we utilized murine C2C12 myoblasts as a model to explore the influence of DON on their proliferation. Our observations indicated that DON exhibits dose-dependent toxicity, significantly inhibiting the proliferation of C2C12 cells. Through the application of RNA-seq analysis combined with gene set enrichment analysis, we identified a noteworthy downregulation of genes linked to the extracellular matrix (ECM) and condensed chromosome. Concurrently with the reduced expression of ECM genes, immunostaining analysis revealed notable changes in the distribution of fibronectin, a vital ECM component, condensing into clusters and punctate formations. Remarkably, the exposure to DON induced the formation of multipolar spindles, leading to the disruption of the normal cell cycle. This, in turn, activated the p53-p21 signaling pathway and ultimately resulted in apoptosis. These findings contribute significant insights into the mechanisms through which DON induces toxicity within skeletal muscle cells.

Global, regional, and national time trends in incidence for depressive disorders, from 1990 to 2019: an age-period-cohort analysis for the GBD 2019.

BACKGROUND: Even with advances in primary health care, depressive disorders remain a major global public health problem. We conducted an in-depth analysis of global, regional and national trends in depressive disorders incidence over the past 30 years. METHODS: Data on the incidence of depressive disorders were obtained by sex (female, male, and both), location (204 countries), age (5-84 years), year (1990-2019) from the Global Burden of Disease Study (GBD) 2019. Further, age-period-cohort modeling was used to estimate the net drift, local drift, age, period and cohort effects between 1990 and 2019. RESULTS: In 2019, although the incidence of depressive disorders has increased by 59.3% to 290 million (95% UI: 256, 328), the age-standardized incidence rate has decreased by 2.35% to 3588.25 per 100,000 people (3152.71, 4060.42) compared to 1990. There was an emerging transition of incidences from the young and middle-aged population to the old population. From 1990 to 2019, the net drift of incidence rate ranged from -0.54% (-0.61%, -0.47%) in low-middle Socio-demographic Index (SDI) regions to 0.52% (0.25%, 0.79%) in high SDI regions. Globally, the incidence rate of depressive disorders increases with age, period effects showing a decreasing risk and cohort effects beginning to decline after the 1960s. CONCLUSIONS: Our current findings reflect substantial health disparities and potential priority-setting of depressive disorders incidence in the three dimensions of age, period and cohort across SDI regions, countries. The scope of healthcare to improve the progression of depressive disorders events can be expanded to include males, females of all ages.

A multiplex fluorescence-based loop-mediated isothermal amplification assay for identifying chicken parvovirus, chicken infectious anaemia virus, and fowl aviadenovirus serotype 4.

Chicken parvovirus (ChPV), chicken infectious anaemia virus (CIAV) and fowl adenovirus serotype 4 (FAdV-4) are avian viruses that have emerged in recent years and have endangered the global poultry industry, causing great economic loss. In this study, a multiplex fluorescence-based loop-mediated isothermal amplification (mLAMP) assay for detecting ChPV, CIAV and FAdV-4 was developed to simultaneously diagnose single and mixed infections in chickens. Three primer sets and composite probes were designed according to the conserved regions of the NS gene of ChPV, VP1 gene of CIAV and hexon gene of FAdV-4. Each composite probe was labelled with a different fluorophore, which was detached to release the fluorescence signal after amplification. The target viruses were distinguished based on the colour of the mLAMP products. The mLAMP assay was shown to be sensitive, with detection limits of 307 copies of recombinant plasmids containing the ChPV target genes, 749 copies of CIAV and 648 copies of FAdV-4. The assay exhibited good specificity and no cross-reactivity with other symptomatically related avian viruses. When used on field materials, the results of the mLAMP assay were in 100% agreement with those of the previously published PCR assay. The mLAMP assay is rapid, economical, sensitive and specific, and the results of amplification are directly observable by eye. Therefore, the mLAMP assay is a useful tool for the clinical detection of ChPV, CIAV and FAdV-4 and can be applied in rural areas.

Exclusion of NUMB Exon12 Controls Cancer Cell Migration through Regulation of Notch1-SMAD3 Crosstalk.

NUMB is an endocytic adaptor protein that contains four isoforms (p65, p66, p71 and p72) due to alternative splicing regulation. Here, we show that NUMB exon12 (E12)-skipping isoforms p65/p66 promote epithelial to mesenchymal transition (EMT) and cancer cell migration in vitro, and facilitate cancer metastasis in mice, whereas E12-included p71/p72 isoforms attenuate these effects. Mechanistically, p65/p66 isoforms significantly increase the sorting of Notch1 through early endosomes (EEs) for enhanced Notch1 activity. In contrast, p71/p72 isoforms act as negative regulators of Notch1 by ubiquitylating the Notch1 intracellular domain (N1ICD) and promoting its degradation. Moreover, we observed that the interaction between N1ICD and SMAD3 is important for their own stabilization, and for NUMB-mediated EMT response and cell migration. Either N1ICD or SMAD3 overexpression could significantly recuse the migration reduction seen in the p65/p66 knockdown, and Notch1 or SMAD3 knockdown rescued the migration advantage seen in the overexpression of p66. Taken all together, our study provides mechanistic insights into the opposite regulation of Notch1-SMAD3 crosstalk by NUMB isoforms and identifies them as critical regulators of EMT and cancer cell migration.

Co-Infection with Common Respiratory Pathogens and SARS-CoV-2 in Patients with COVID-19 Pneumonia and Laboratory Biochemistry Findings: A Retrospective Cross-Sectional Study of 78 Patients from a Single Center in China.

BACKGROUND This retrospective study aimed to investigate co-infections with common respiratory pathogens and SARS-CoV-2 and laboratory biochemistry findings in patients with COVID-19 in the Zhuzhou area of China, in order to provide a reference for the disease assessment and clinical treatment of COVID-19. MATERIAL AND METHODS The clinical data of COVID-19 patients admitted to the hospital of Zhuzhou City from January 28 to March 15, 2020, as well as laboratory test results for respiratory pathogens and biochemical indicators, were collected to conduct correlation analyses. All patients were diagnosed based on fluorescence-based PCR assay for SARS-CoV-2. RESULTS Eleven of the 78 patients (14.1%) were co-infected with other respiratory pathogens, among which Mycoplasma pneumoniae (n=5, 45.5%) and respiratory syncytial virus (n=4, 36.4%) were the most frequent. There were 8 patients co-infected with 1 other pathogen and 3 patients co-infected with 2 other pathogens. Compared with mono-infected COVID-19 patients, patients with co-infections had significantly higher levels of procalcitonin (P=0.002). CONCLUSIONS The findings showed that Mycoplasma pneumonia and respiratory syncytial virus were the most common co-infections in patients with COVID-19 pneumonia. Increased levels of PCT in patients with COVID-19 pneumonia were associated with co-infection.

U2-related proteins CHERP and SR140 contribute to colorectal tumorigenesis via alternative splicing regulation.

Dysregulation of calcium homeostasis endoplasmic reticulum protein (CHERP) has been implicated in several cancers, but it remains elusive how CHERP contributes to cancer cell proliferation and cancer development. Here, we observed that CHERP and its binding partner SR140 are significantly upregulated in human clinical colorectal cancer tissues (CRC). CHERP and SR140 could form a protein complex to stabilize each other. Knockdown of CHERP or SR140 triggers double-stranded DNA breaks and cell death. Furthermore, UPF3A, the RNA surveillance factor, was identified as a splicing target of CHERP and SR140, which bind specifically to the regulated exon4 and modulate UPF3A splicing. UPF3A knockdown recapitulates CHERP/SR140 depletion both in vitro and in mice. Importantly, overexpression of UPF3A significantly rescues proliferation defect of CHERP/SR140-depleted cells. These results confirmed that the effect of CHERP/SR140 in promoting tumorigenesis was partially mediated by UPF3A. Extending these results, upregulation of CHERP/SR140 observed in CRC remarkably parallels increased inclusion of UPF3A exon4. Together, our study clarifies how CHERP/SR140 exert an oncogenic role in CRC development partially through regulating expression of UPF3A variants.

Altered gene expression profiles of the MDA5 signaling pathway in peripheral blood lymphocytes of chickens infected with avian reovirus.

Avian reovirus (ARV) is a member of the genus Orthoreovirus in the family Reoviridae and causes a severe syndrome including viral arthritis that leads to considerable losses in the poultry industry. Innate immunity plays a significant role in host defense against ARV. Here, we explored the interaction between ARV and the host innate immune system by measuring mRNA expression levels of several genes associated with the MDA5 signaling pathway. The results showed that expression peaks for MDA5, MAVS, TRAF3, TRAF6, IRF7, IKKɛ, TBK1 and NF-κB occurred at 3 days postinfection (dpi). Moreover, type I IFN (IFN-α, IFN-ß) and IL-12 expression levels peaked at 3 dpi, while type II IFN (IFN-γ), IL-6, IL-17 and IL-18 expression reached a maximum level at 1 dpi. IL-8 changed at 5 dpi, and IL-1ß and TNF-α changed at 7 dpi. Interestingly, several key IFN-stimulated genes (ISGs), including IFITM1, IFITM2, IFITM5, Mx1 and OASL, were simultaneously upregulated and reached maximum values at 3 dpi. These data indicate that the MDA5 signaling pathway and innate immune cytokines were induced after ARV infection, which would contribute to the ARV-host interaction, especially at the early infection stage.

Avian reovirus σA and σNS proteins activate the phosphatidylinositol 3-kinase-dependent Akt signalling pathway.

The present study was conducted to identify avian reovirus (ARV) proteins that can activate the phosphatidylinositol 3-kinase (PI3K)-dependent Akt pathway. Based on ARV protein amino acid sequence analysis, σA, σNS, µA, µB and µNS were identified as putative proteins capable of mediating PI3K/Akt pathway activation. The recombinant plasmids σA-pcAGEN, σNS-pcAGEN, µA-pcAGEN, µB-pcAGEN and µNS-pcAGEN were constructed and used to transfect Vero cells, and the expression levels of the corresponding genes were quantified by immunofluorescence and Western blot analysis. Phosphorylated Akt (P-Akt) levels in the transfected cells were measured by flow cytometry and Western blot analysis. The results showed that the σA, σNS, µA, µB and µNS genes were expressed in Vero cells. σA-expressing and σNS-expressing cells had higher P-Akt levels than negative control cells, pcAGEN-expressing cells and cells designed to express other proteins (i.e., µA, µB and µNS). Pre-treatment with the PI3K inhibitor LY294002 inhibited Akt phosphorylation in σA- and σNS-expressing cells. These results indicate that the σA and σNS proteins can activate the PI3K/Akt pathway.

Genetic and phylogenetic analysis of a novel parvovirus isolated from chickens in Guangxi, China.

A previously unidentified chicken parvovirus (ChPV) strain, associated with runting-stunting syndrome (RSS), is now endemic among chickens in China. To explore the genetic diversity of ChPV strains, we determined the first complete genome sequence of a novel ChPV isolate (GX-CH-PV-7) identified in chickens in Guang Xi, China, and showed moderate genome sequence similarity to reference strains. Analysis showed that the viral genome sequence is 86.4 %-93.9 % identical to those of other ChPVs. Genetic and phylogenetic analyses showed that this newly emergent GX-CH-PV-7 is closely related to Gallus gallus enteric parvovirus isolate ChPV 798 from the USA, indicating that they may share a common ancestor. The complete DNA sequence is 4612 bp long with an A+T content of 56.66 %. We determined the first complete genome sequence of a previously unidentified ChPV strain to elucidate its origin and evolutionary status.

Transcriptome analysis of alternative splicing events regulated by SRSF10 reveals position-dependent splicing modulation.

Splicing factor SRSF10 is known to function as a sequence-specific splicing activator. Here, we used RNA-seq coupled with bioinformatics analysis to identify the extensive splicing network regulated by SRSF10 in chicken cells. We found that SRSF10 promoted both exon inclusion and exclusion. Motif analysis revealed that SRSF10 binding to cassette exons was associated with exon inclusion, whereas the binding of SRSF10 within downstream constitutive exons was associated with exon exclusion. This positional effect was further demonstrated by the mutagenesis of potential SRSF10 binding motifs in two minigene constructs. Functionally, many of SRSF10-verified alternative exons are linked to pathways of stress and apoptosis. Consistent with this observation, cells depleted of SRSF10 expression were far more susceptible to endoplasmic reticulum stress-induced apoptosis than control cells. Importantly, reconstituted SRSF10 in knockout cells recovered wild-type splicing patterns and considerably rescued the stress-related defects. Together, our results provide mechanistic insight into SRSF10-regulated alternative splicing events in vivo and demonstrate that SRSF10 plays a crucial role in cell survival under stress conditions.

Far upstream element-binding protein 1 and RNA secondary structure both mediate second-step splicing repression.

Splicing of mRNA precursors consists of two steps that are almost invariably tightly coupled to facilitate efficient generation of spliced mRNA. However, we described previously a splicing substrate that is completely blocked after the first step. We have now investigated the basis for this unusual second-step inhibition and unexpectedly elucidated two independent mechanisms. One involves a stem-loop structure located downstream of the 3'splice site, and the other involves an exonic splicing silencer (ESS) situated 3' to the structure. Both elements contribute to the second-step block in vitro and also cause exon skipping in vivo. Importantly, we identified far upstream element-binding protein 1 (FUBP1), a single-stranded DNA- and RNA-binding protein not previously implicated in splicing, as a strong ESS binding protein, and several assays implicate it in ESS function. We demonstrate using depletion/add-back experiments that FUBP1 acts as a second-step repressor in vitro and show by siRNA-mediated knockdown and overexpression assays that it modulates exon inclusion in vivo. Together, our results provide additional insights into splicing control, and identify FUBP1 as a splicing regulator.

GeXP analyzer-based multiplex reverse-transcription PCR assay for the simultaneous detection and differentiation of eleven duck viruses.

BACKGROUND: Duck viral pathogens primarily include the avian influenza virus (AIV) subtypes H5, H7, and H9; duck hepatitis virus (DHV); duck tembusu virus (DTMUV); egg drop syndrome virus (EDSV); duck enteritis virus (DEV); Newcastle disease virus (NDV); duck circovirus (DuCV); muscovy duck reovirus (MDRV); and muscovy duck parvovirus (MDPV). These pathogens cause great economic losses to China's duck breeding industry. RESULT: A rapid, specific, sensitive and high-throughput GeXP-based multiplex PCR assay consisting of chimeric primer-based PCR amplification with fluorescent labeling and capillary electrophoresis separation was developed and optimized to simultaneously detect these eleven viral pathogens. Single and mixed pathogen cDNA/DNA templates were used to evaluate the specificity of the GeXP-multiplex assay. Corresponding specific DNA products were amplified from each pathogen. Other pathogens, including duck Escherichia coli, duck Salmonella, duck Staphylococcus aureus, Pasteurella multocida, infectious bronchitis virus, and Mycoplasma gallisepticum, did not result in amplification products. The detection limit of GeXP was 10(3)copies when all twelve pre-mixed plasmids containing the target genes of eleven types of duck viruses were present. To further evaluate the reliability of GeXP, 150 clinical field samples were evaluated. Comparison with the results of conventional PCR methods for the field samples, the GeXP-multiplex PCR method was more sensitive and accurate. CONCLUSION: This GeXP-based multiplex PCR method can be utilized for the rapid differential diagnosis of clinical samples as an effective tool to prevent and control duck viruses with similar clinical symptoms.

Simultaneous detection of eight immunosuppressive chicken viruses using a GeXP analyser-based multiplex PCR assay.

BACKGROUND: Immunosuppressive viruses are frequently found as co-infections in the chicken industry, potentially causing serious economic losses. Because traditional molecular biology methods have limited detection ability, a rapid, high-throughput method for the differential diagnosis of these viruses is needed. The objective of this study is to develop a GenomeLab Gene Expression Profiler Analyser-based multiplex PCR method (GeXP-multiplex PCR) for simultaneous detection of eight immunosuppressive chicken viruses. RESULTS: Using chimeric primers, eight such viruses, including Marek's disease virus (MDV), three subgroups of avian leucosis virus (ALV-A/B/J), reticuloendotheliosis virus (REV), infectious bursal disease virus (IBDV), chicken infectious anaemia virus (CIAV) and avian reovirus (ARV), were amplified and identified by their respective amplicon sizes. The specificity and sensitivity of the optimised GeXP-multiplex PCR assay were evaluated, and the data demonstrated that this technique could selectively amplify these eight viruses at a sensitivity of 100 copies/20 µl when all eight viruses were present. Among 300 examined clinical specimens, 190 were found to be positive for immunosuppressive viruses according to this novel assay. CONCLUSION: The GeXP-multiplex PCR assay is a high-throughput, sensitive and specific method for the detection of eight immunosuppressive viruses and can be used for differential diagnosis and molecular epidemiological surveys.

A duplex real-time PCR assay for the detection and quantification of avian reovirus and Mycoplasma synoviae.

BACKGROUND: Infectious arthritis in broilers represents an economic and health problem, resulting in severe losses due to retarded growth and downgrading at the slaughterhouse. The most common agents associated with cases of infectious arthritis in poultry are avian reovirus (ARV) and Mycoplasma synoviae (MS). The accurate differentiation and rapid diagnosis of ARV and MS are essential prerequisites for the effective control and prevention of these avian pathogens in poultry flocks. This study thus aimed to develop and validate a duplex real-time PCR assay for the simultaneous detection and quantification of ARV and MS. METHODS: Specific primers and probes for each pathogen were designed to target the special sequence of the ARV σC gene or the MS phase-variable surface lipoprotein hemagglutinin (vlhA) gene. A duplex real-time PCR assay was developed, and the reaction conditions were optimized for the rapid detection and quantification of ARV and MS. RESULTS: The duplex real-time PCR assay was capable of ARV- and MS-specific detection without cross-reaction with other non-targeted avian pathogens. The sensitivity of this assay was 2 × 10(1) copies for a recombinant plasmid containing ARV σC or MS vlhA gene, and 100 times higher than that of conventional PCR. This newly developed PCR assay was also reproducible and stable. All tested field samples of ARV and/or MS were detectable with this duplex real-time PCR assay compared with pathogen isolation and identification as well as serological tests. CONCLUSION: This duplex real-time PCR assay is highly specific, sensitive and reproducible and thus could provide a rapid, specific and sensitive diagnostic tool for the simultaneous detection of ARV and MS in poultry flocks. The assay will be useful not only for clinical diagnostics and disease surveillance but also for the efficient control and prevention of ARV and MS infections.

Reverse-transcription, loop-mediated isothermal amplification assay for the sensitive and rapid detection of H10 subtype avian influenza viruses.

BACKGROUND: The H10 subtype avian influenza viruses (H10N4, H10N5 and H10N7) have been reported to cause disease in mammals, and the first human case of H10N8 subtype avian influenza virus was reported in 2013. Recently, H10 subtype avian influenza viruses (AIVs) have been followed more closely, but routine diagnostic tests are tedious, less sensitive and time consuming, rapid molecular detection assays for H10 AIVs are not available. METHODS: Based on conserved sequences within the HA gene of the H10 subtype AIVs, specific primer sets of H10 subtype of AIVs were designed and assay reaction conditions were optimized. A reverse-transcription loop-mediated isothermal amplification (RT-LAMP) assay was established for the rapid detection of H10 subtype AIVs. The specificity was validated using multiple subtypes of AIVs and other avian respiratory pathogens, and the limit of detection (LOD) was tested using concentration gradient of in vitro-transcribed RNA. RESULTS: The established assay was performed in a water bath at 63 °C for 40 min, and the amplification result was visualized directly as well as under daylight reflections. The H10-RT-LAMP assay can specifically amplify H10 subtype AIVs and has no cross-reactivity with other subtypes AIVs or avian pathogens. The LOD of the H10-RT-LAMP assay was 10 copies per µL of in vitro-transcribed RNA. CONCLUSIONS: The RT-LAMP method reported here is demonstrated to be a potentially valuable means for the detection of H10 subtype AIV and rapid clinical diagnosis, being fast, simple, and low in cost. Consequently, it will be a very useful screening assay for the surveillance of H10 subtype AIVs in underequipped laboratories as well as in field conditions.

A loop-mediated isothermal amplification assay for the visual detection of duck circovirus.

BACKGROUND: Duck circovirus (DuCV) infection in farmed ducks is associated with growth problems or retardation syndromes. Rapid identification of DuCV infected ducks is essential to control DuCV effectively. Therefore, this study aims to develop of an assay for DuCV to be highly specific, sensitive, and simple without any specialized equipment. METHODS: A set of six specific primers was designed to target the sequences of the Rep gene of DuCV, and A loop-mediated isothermal amplification (LAMP) assay were developed and the reaction conditions were optimized for rapid detection of DuCV. RESULTS: The LAMP assay reaction was conducted in a 62°C water bath condition for 50 min. Then the amplification products were visualized directly for color changes. This LAMP assay is highly sensitive and able to detect twenty copies of DuCV DNA. The specificity of this LAMP assay was supported by no cross-reaction with other duck pathogens. CONCLUSION: This LAMP method for DuCV is highly specific and sensitive and can be used as a rapid and direct diagnostic assay for testing clinical samples.

Sequencing and phylogenetic analysis of an avian reovirus genome.

Avian reovirus infection causes considerable economic loss to the commercial poultry industry. Live-attenuated vaccine strain S1133 (v-S1133, derived from parent strain S1133) is considered the safest and most effective vaccine and is currently used worldwide. To identify the genes responsible for its attenuation, DNA sequences of open reading frames (ORF) of S1133 and its parent strains S1133, 1733, 526, and C78 along with three field isolates (GuangxiR1, GuangxiR2, and GX110058) and one isolate (GX110116) from a vaccinated chicken were performed. The sequence data were compared with available sequences in nucleotide sequence databases of American (AVS-B, 138, 176) and Chinese (C-98 and T-98) origin. Sequence analysis identified that several v-S1133 specific nucleotide substitutions existed in the ORFs of λA, λB, λC, µA, µB, µNS, σA, σB, and σNS genes. The v-S1133 strain could be differentiated from the field-isolated strains based on single nucleotide polymorphisms. Phylogenetic analysis revealed that v-S1133 shared the highest sequence homologies with S1133 and reovirus isolates from China, grouped together in one cluster. Chinese isolates were clearly more distinct from the American reovirus AVS-B strain, which is associated with runting-stunting syndrome in broilers.