Changes in apoptosis, proliferation and T lymphocyte subtype on thymic cells of SPF chickens infected with reticuloendotheliosis virus

Rho-GTPases subfamily: cellular defectors orchestrating viral infection

Ras homolog gene family-guanosine triphosphatases (Rho-GTPases), key molecular switches regulating cytoskeletal dynamics and cellular signaling, play a pivotal role in viral infections by modulating critical processes such as viral entry, replication, and release. This review elucidates the intricate mechanisms through which Rho-GTPases, via interactions with guanine nucleotide exchange factors (GEFs), GTPase-activating proteins (GAPs), and other signaling pathways, including the phosphoinositide 3-kinase/protein kinase B (PI3K/Akt), rat sarcoma (Ras), and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathways, facilitate viral pathogenesis. Specific viruses, such as influenza A virus (IAV), herpesviruses, human immunodeficiency virus (HIV), and respiratory syncytial virus (RSV), exploit Rho-GTPase-mediated cytoskeletal reorganization to enhance infectivity. For example, Rho-GTPases promote actin remodeling and membrane fusion, which are essential for viral entry and intracellular transport. Furthermore, Rho-GTPases modulate immune responses, often suppressing antiviral defenses to favor viral replication. Despite these insights, the molecular mechanisms underlying Rho-GTPase regulation during viral infections remain incompletely understood. Future research should focus on delineating the precise roles of Rho-GTPases in distinct viral life cycles, uncovering novel regulatory mechanisms, and developing targeted antiviral therapies that selectively inhibit Rho-GTPase signaling without compromising host cell functions. Such advancements could pave the way for broad-spectrum antiviral strategies, particularly against viruses that heavily rely on cytoskeletal manipulation for infection.

Expression characteristics of miR-222b-5p/MAPK10 in major immune organs of SPF chickens infected with avian reticuloendotheliosis virus strain SNV (REV-SNV)

Reticuloendotheliosis virus (REV) is a retrovirus in poultry that can atrophy immune organs and cause immunosuppression and tumor diseases. Our previous results revealed that, in the spleen of SPF chickens infected with REV-SNV, gga-miR-222b-5p expression was upregulated at 7, 14 and 21 dpi, and MAPK10 expression was downregulated, both of which were negatively correlated, with a targeted relationship between the two at 28, 35 and 42 dpi. To understand and analyze the expression patterns of MAPK10 and gga-miR-222b-5p in infected chickens at different times and in different immune organs, qRT-PCR was used to analyze the spleen, bursa of Fabricius and thymus samples of SPF chickens at 7, 14, 21, 28, 35 and 42 dpi. The results revealed that, in the spleen, MAPK10 gene expression was highly significantly downregulated at 7, 14, 21, 35 and 42 dpi, and gga-miR-222b-5p expression was significantly upregulated at six-time points. In the bursa of Fabricius, MAPK10 expression was significantly downregulated at six-time points, and gga-miR-222b-5p expression was upregulated at 7, 21, 28, 35 and 42 dpi. In the thymus, MAPK10 and gga-miR-222b-5p expression was upregulated at six-time points. A negative regulatory relationship was evident in the spleen and bursa of Fabricius but not in the thymus. This study suggested that gga-miR-222b-5p may induce the downregulation of MAPK10 in the spleen and bursa of Fabricius and promote tumor formation.

Delivery of dendritic cells targeting 3M2e-HA2 nanoparticles with a CpG adjuvant via lysosomal escape of Salmonella enhances protection against H9N2 avian influenza virus

Avian influenza virus (AIV) subtype H9N2 still poses a great threat to the poultry farming industry and public health worldwide, and the development of a new influenza vaccine that is safe and conservative and able to address influenza virus mutations is highly promising for application. HA2, the neck of the HA protein, and M2e, the extracellular N-terminal structural domain of the M2 protein, are conserved and effective protective antigens. In this study, the HA2 sequences were fused with three M2e copies (H9N2, H1N1 and H5N1) to the norovirus VP1 protein via the SpyTag-SpyCatcher platform to form self-assembled nanoparticles and display antigenic proteins on its surface, yielding pYL262. The chicken dendritic cells (DCs) targeting the nanobody phage-54 were then fused to HA2-3M2e to yield pYL327. Finally, a synthesized 20-repeat CpG adjuvant gene fragment was inserted into pYL327, resulting in the plasmid pYL331. All the constructed plasmids were then transformed into the sifA gene-deficient Salmonella vector χYL56 for oral immunization. The results showed that sifA-deficient Salmonella could efficiently increase antigen-specific mucosal sIgA antibody titers, especially in alveolar lavage samples, whereas the presence of the phage-54 nanobody could dramatically increase intracellular IFN-γ mRNA levels, indicating its ability to enhance the Th1-type immune response. Finally, the presence of the CpG adjuvant clearly increased T-cell proliferation and promoted DC activation, with elevated splenic TLR21 levels observed. Strikingly, after oral immunization with χYL56 (pYL331), chickens were protected against challenge with the G57 genotype H9N2 virus, which presented similar or even better levels of virus shedding and body weight gain compared with the commercial inactivated vaccine, providing a new option for controlling H9N2 virus infection in the future.

Septin11 promotes hepatocellular carcinoma cell motility by activating RhoA to regulate cytoskeleton and cell adhesion

Septins as GTPases in the cytoskeleton, are linked to a broad spectrum of cellular functions, including cell migration and the progression of hepatocellular carcinoma (HCC). However, roles of SEPT11, the new member of septin, have been hardly understood in HCC. In the study, the clinical significance and biological function of SEPT11 in HCC was explored. SEPT11 was screened out by combining ATAC-seq with mRNA-seq. Role of SEPT11 in HCC was further investigated by using overexpression, shRNA and CRISPR/Cas9-mediated SEPT11-knockout cells or in vivo models. We found RNA-seq and ATAC-seq highlights LncRNA AY927503 (AY) induced SEPT11 transcription, resulting in Rho GTPase activation and cytoskeleton actin aggregation. The GTP-binding protein SEPT11 is thus considered, as a downstream factor of AY, highly expressed in various tumors, including HCC, and associated with poor prognosis of the patients. In vitro, SEPT11 overexpression promotes the migration and invasion of HCC cells, while SEPT11-knockout inhibits migration and invasion. In vivo, SEPT11-overexpressed HCC cells show high metastasis incidents but don't significantly affect proliferation. Meanwhile, we found SEPT11 targets RhoA, thereby regulating cytoskeleton rearrangement and abnormal cell adhesion through ROCK1/cofilin and FAK/paxillin signaling pathways, promoting invasion and migration of HCC. Further, we found SEPT11 facilitates the binding of GEF-H1 to RhoA, which enhances the activity of RhoA. Overall, our study confirmed function of SEPT11 in promoting metastasis in HCC, and preliminarily explored its related molecular mechanism. SEPT11 acts as an oncogene in HCC, also draws further interest regarding its clinical application as a potential therapeutic target.

Effects of Reticuloendotheliosis virus on TLR-3/IFN-Β pathway in specific pathogen-free chickens

Birds infected by Reticuloendotheliosis virus (REV) are vulnerable to other microorganisms. This immunosuppression is related to the immune organs (thymus, bursa of Fabricius, and spleen) damaged by REV. The regulation of IFN-β greatly depends on pattern recognition receptor TLR-3 and nuclear factors IRF-7, NF-κB. To address if and how the TLR-3/IFN-β pathway is disturbed by REV, 60 one-day-old specific-pathogen-free chickens were intraperitoneally injected with RE virus dilution (n = 30) or stroke-physiological saline solution (n = 30). At 1, 3, 7, 21, and 28 days post-infection, after collecting thymuses, bursas, and spleens, we monitor the kinetics of TLR-3, IFN-β, NF-κB p65, and IRF-7 at transcriptional and translational levels using qPCR, Western blotting, and ELISA separately. As a result, compared with control chickens, the mRNA levels of TLR-3, IRF-7, and NF-κB p65 showed increasingly differences in the early period of REV infection. Synchronal changes occurred at translation levels. In the latter infection period, a decrease of NF-κB p65 was contemporaneous with a fall in IFN-β at both transcriptional and translational levels in the thymuses and bursas. These data suggest that the changes of IFN-β content are closely related to NF-κB p65 when REV invades chicken central immune organs. That reveals new insights into the immunosuppression mechanism of REV in avian.

Glycyrrhiza polysaccharides can improve and prolong the response of chickens to the Newcastle disease vaccine

Licorice is a medicinal and food plant widely used to treat diseases and produce food additives, because of its unique chemical constituents like polysaccharides, flavones, and saponins. Glycyrrhiza Polysaccharides (GPS-1) are water-soluble neutral polysaccharides extracted from licorice. Currently, GPS-1 is administrated to chickens by gavage every d for 14 d to observe the impact of GPS-1 on the Newcastle disease vaccine. To determine the immunity of these chickens to NDV, blood serum levels of hemagglutinin-inhibition (HI) antibody, and immunoglobulins IgA and IgG were measured. Meanwhile, the expression levels of cytokines IL-2, IL-4, IL-17, and IFN-γ were measured to evaluate the degree of immune booster activity. The chickens' spleen and peripheral blood lymphocytes displayed a significant increase in the proportion of CD4+ and CD8+ T cells after booster treatments with GPS-1. The results indicated that GPS-1 had a significant, dose-dependent, immune-boosting effect which could enhance NDV vaccine immunity in chickens.

Poly (I: C) inhibits reticuloendothelial virus replication in chicken macrophage-like cells through the activation of toll-like receptor-3 signaling

Reticuloendothelial virus (REV) is widely found in many domestic poultry areas and results in severe immunosuppression of infected chickens. This increases the susceptibility to other pathogens, which causes economic losses to the poultry industry. The aim of our study was to determine whether polyinosinic-polycytidylic acid [Poly (I: C)] treatment could inhibit REV replication in chicken macrophage-like cell line, HD11. We found that Poly (I: C) treatment could markedly inhibit REV replication in HD11 from 24 to 48 h post infection (hpi). Additionally, Poly (I: C) treatment could switch HD11 from an inactive type into M1-like polarization from 24 to 48 hpi. Furthermore, Poly (I: C) treatment promoted interferon-β secretion from HD11 post REV infection. Moreover, Toll-like receptor-3 (TLR-3) mRNA and protein levels in HD11 treated with Poly (I: C) were markedly increased compared to those of HD11 not treated with Poly (I: C). The above results suggested that Poly (I: C) treatment switches HD11 into M1-like polarization to secret more interferon-β and activate TLR-3 signaling, which contributes to block REV replication. Our findings provide a theoretical reference for further studying the underlying pathogenic mechanism of REV and Poly (I: C) as a potential therapeutic intervention against REV infection.

Changes in oxidation-antioxidation function on the thymus of chickens infected with reticuloendotheliosis virus

Background

Reticuloendotheliosis virus (REV) is a retrovirus that causes severe immunosuppression in poultry. Animals grow slowly under conditions of oxidative stress. In addition, long-term oxidative stress can impair immune function, as well as accelerate aging and death. This study aimed to elucidate the pathogenesis of REV from the perspective of changes in oxidative-antioxidative function following REV infection.

Methods

A total of 80 one-day-old specific pathogen free (SPF) chickens were randomly divided into a control group (Group C) and an REV-infected group (Group I). The chickens in Group I received intraperitoneal injections of REV with 10^4.62/0.1 mL TCID₅₀. Thymus was collected on day 1, 3, 7, 14, 21, 28, 35, and 49 for histopathology and assessed the status of oxidative stress.

Results

In chickens infected with REV, the levels of H₂O₂ and MDA in the thymus increased, the levels of TAC, SOD, CAT, and GPx1 decreased, and there was a reduction in CAT and Gpx1 mRNA expression compared with the control group. The thymus index was also significantly reduced. Morphological analysis showed that REV infection caused an increase in the thymic reticular endothelial cells, inflammatory cell infiltration, mitochondrial swelling, and nuclear damage.

Conclusions

These results indicate that an increase in oxidative stress enhanced lipid peroxidation, markedly decreased antioxidant function, caused thymus atrophy, and immunosuppression in REV-infected chickens.

Comparative analysis of key immune protection factors in H9N2 avian influenza viruses infected and immunized specific pathogen-free chicken

H9N2 avian influenza viruses (AIV) continue to circulate in vaccinated chicken flocks in China, which prompted us to investigate the differential immune protection factors induced by H9N2 AIV infection and immunization for analyzing the reason of protection deficiency of H9N2 AIV inactivated vaccine. In this study, we firstly explored virus-induced optimal immune responses in chicken after H9N2 AIV infection. And, we found that H9N2 hemagglutination inhibition (HI) antibody level, antiviral interferon-stimulated genes including 2′,5’-oligoadenylate synthetase-like and myxovirus resistance 1, CD8⁺ T cell response in peripheral blood lymphocytes (PBL) accompanied by the cytotoxicity-associated genes, including poly (ADP-ribose) polymerase and IFN-r play important roles in defending against H9N2 infection. Besides, we observed that vaccine immunization triggered the similar H9N2 HI antibody level as viral infection, the increase of CD4⁺ T cell percentage instead of CD8⁺ T cell percentage in PBL. Moreover, we further made a comparative analysis of immune-related gene expression profile in PBL and lung after H9N2 AIV infection and immunization, respectively. The results showed that vaccine immunization contributed to the up-regulation of Th2 cytokine. But the deficiency of cytotoxicity-associated genes induced by H9N2 AIV inactivated vaccine may be the potential key reason of protection deficiency. These findings provide evidence and direction for developing effective H9N2 AIV vaccines.

Feed-borne Bacillus cereus exacerbates respiratory distress in chickens infected with Chlamydia psittaci by inducing haemorrhagic pneumonia

Chlamydia psittaci is an important zoonotic pathogen and its oral route of infection plays an important role in the transmission and persistence. Bacillus cereus (B. cereus) strain, a common contaminant of animal feed and feedstuffs, can cause severe diarrhoea and malnutrition in poultry. In our previous study, a B. cereus strain (Dawu C), isolated from the haemorrhagic lungs of infected chickens, was shown to harbour two virulence genes (hblC and cytk) and was able to induce haemorrhagic lesions in the lungs, as well as gizzard erosion and ulceration (GEU) syndrome in broilers. In the present study, we tested the hypothesis that B. cereus-induced GEU would aggravate C. psittaci infection. Our results showed that SPF chickens exposed to B. cereus developed a severe GEU syndrome. More interestingly, prior infection with B. cereus facilitated C. psittaci infection, and aggravated GEU and respiratory distress, which were accompanied by high chlamydial loads in the lungs and severe lesions in respiratory organs. Moreover, levels of local inflammatory cytokines were elevated and T cell responses were impaired in the infected birds. In conclusion, GEU caused by B. cereus may facilitate chlamydial transmission from the ventriculus to the lungs.RESEARCH HIGHLIGHTS Bacillus cereus contributes to the gizzard erosion and ulceration syndrome in chickens.Exposure to Bacillus cereus exacerbates pneumonia in birds following chlamydial infection.Bacillus cereus facilitates persistent chlamydial infection and exacerbates immune responses.

Systematic Identification of Host Immune Key Factors Influencing Viral Infection in PBL of ALV-J Infected SPF Chicken

Although research related to avian leukosis virus subgroup J (ALV-J) has lasted for more than a century, the systematic identification of host immune key factors against ALV-J infection has not been reported. In this study, we establish an infection model in which four-week-old SPF chickens are infected with ALV-J strain CHN06, after which the host immune response is detected. We found that the expression of two antiviral interferon-stimulated genes (ISGs) (Mx1 and IFIT5) were increased in ALV-J infected peripheral blood lymphocytes (PBL). A significant CD8⁺ T cell response induced by ALV-J appeared as early as seven days post-infection (DPI), and humoral immunity starting from 21 DPI differed greatly in the time scale of induction level. Meanwhile, the ALV-J viremia was significantly decreased before antibody production at 14 DPI, and eliminated at 21 DPI under a very low antibody level. The up-regulated CD8⁺ T cell in the thymus (14DPI) and PBL (7 DPI and 21 DPI) was detected, indicating that the thymus may provide the output of CD8⁺ T cell to PBL, which was related to virus clearance. Besides, up-regulated chemokine CXCLi1 at 7 DPI in PBL was observed, which may be related to the migration of the CD8⁺ T cell from the thymus to PBL. More importantly, the CD8 ^high+ T cell response of the CD8αβ phenotype may produce granzyme K, NK lysin, or IFN-γ for clearing viruses. These findings provide novel insights and direction for developing effective ALV-J vaccines.