RESUMO
Marek's disease virus (MDV) integrates its genome into the telomeres of host chromosomes and causes fatal lymphomas in chickens. This integration is facilitated by telomeric repeat sequences (TMRs) at the ends of the viral genome, and is crucial for MDV-induced lymphomagenesis. The SB-1 vaccine virus is commonly used in commercial bivalent vaccines against MDV and also contains TMRs at its ends. Here, we demonstrate that SB-1 efficiently integrates its genome into the chromosomes of latently infected T cells. Deletion of the TMRs from the SB-1 genome did not affect virus replication, but severely impaired virus integration and genome maintenance in latently infected T cells and in chickens. Strikingly, the reduced integration and maintenance of latent SB-1 significantly impaired vaccine protection. Taken together, our data revealed that the TMRs facilitate SB-1 integration and that integration and/or maintenance of the latent viral genome is critical for vaccine protection.
RESUMO
Oncogenic viruses contribute to 15% of global human cancers. To achieve that, virus-encoded oncoproteins deregulate cellular transcription, antagonize common cellular pathways, and thus drive cell transformation. Notably, adenoviruses were the first human viruses proven to induce cancers in diverse animal models. Over the past decades, human adenovirus (HAdV)-mediated oncogenic transformation has been pivotal in deciphering underlying molecular mechanisms. Key adenovirus oncoproteins, encoded in early regions 1 (E1) and 4 (E4), co-ordinate these processes. Among the different adenovirus species, the most extensively studied HAdV-C5 displays lower oncogenicity than HAdV-A12. A complete understanding of the different HAdV-A12 and HAdV-C5 oncoproteins in virus-mediated cell transformation, as summarized here, is relevant for adenovirus research and offers broader insights into viral transformation and oncogenesis.
Assuntos
Adenovírus Humanos , Humanos , Adenovírus Humanos/genética , Adenovírus Humanos/fisiologia , Animais , Oncogenes , Transformação Celular Viral , Neoplasias/virologia , Neoplasias/genética , Proteínas Oncogênicas/metabolismo , Proteínas Oncogênicas/genética , Carcinogênese/genéticaRESUMO
Marek's disease virus (MDV) vaccines were the first vaccines that protected against cancer. The avirulent turkey herpesvirus (HVT) was widely employed and protected billions of chickens from a deadly MDV infection. It is also among the most common vaccine vectors providing protection against a plethora of pathogens. HVT establishes latency in T-cells, allowing the vaccine virus to persist in the host for life. Intriguingly, the HVT genome contains telomeric repeat arrays (TMRs) at both ends; however, their role in the HVT life cycle remains elusive. We have previously shown that similar TMRs in the MDV genome facilitate its integration into host telomeres, which ensures efficient maintenance of the virus genome during latency and tumorigenesis. In this study, we investigated the role of the TMRs in HVT genome integration, latency, and reactivation in vitro and in vivo. Additionally, we examined HVT infection of feather follicles. We generated an HVT mutant lacking both TMRs (vΔTMR) that efficiently replicated in cell culture. We could demonstrate that wild type HVT integrates at the ends of chromosomes containing the telomeres in T-cells, while integration was severely impaired in the absence of the TMRs. To assess the role of TMRs in vivo, we infected one-day-old chickens with HVT or vΔTMR. vΔTMR loads were significantly reduced in the blood and hardly any virus was transported to the feather follicle epithelium where the virus is commonly shed. Strikingly, latency in the spleen and reactivation of the virus were severely impaired in the absence of the TMRs, indicating that the TMRs are crucial for the establishment of latency and reactivation of HVT. Our findings revealed that the TMRs facilitate integration of the HVT genome into host chromosomes, which ensures efficient persistence in the host, reactivation, and transport of the virus to the skin.
Assuntos
Galinhas , Doença de Marek , Telômero , Integração Viral , Latência Viral , Animais , Galinhas/virologia , Telômero/genética , Telômero/virologia , Doença de Marek/virologia , Doença de Marek/imunologia , Doença de Marek/prevenção & controle , Vetores Genéticos , Herpesvirus Meleagrídeo 1/genética , Herpesvirus Meleagrídeo 1/imunologia , Vacinas contra Doença de Marek/imunologia , Vacinas contra Doença de Marek/genética , Genoma Viral , Herpesvirus Galináceo 2/genética , Herpesvirus Galináceo 2/imunologia , Sequências Repetitivas de Ácido Nucleico , Doenças das Aves Domésticas/virologia , Doenças das Aves Domésticas/imunologia , Doenças das Aves Domésticas/prevenção & controleRESUMO
Adenoviruses are a group of double-stranded DNA viruses that can mainly cause respiratory, gastrointestinal, and eye infections in humans. In addition, adenoviruses are employed as vector vaccines for combatting viral infections, including SARS-CoV-2, and serve as excellent gene therapy vectors. These viruses have the ability to modulate the host cell machinery to their advantage and trigger significant restructuring of the nuclei of infected cells through the activity of viral proteins. One of those, the adenovirus DNA-binding protein (DBP), is a multifunctional non-structural protein that is integral to the reorganization processes. DBP is encoded in the E2A transcriptional unit and is highly abundant in infected cells. Its activity is unequivocally linked to the formation, structure, and integrity of virus-induced replication compartments, molecular hubs for the regulation of viral processes, and control of the infected cell. DBP also plays key roles in viral DNA replication, transcription, viral gene expression, and even host range specificity. Notably, post-translational modifications of DBP, such as SUMOylation and extensive phosphorylation, regulate its biological functions. DBP was first investigated in the 1970s, pioneering research on viral DNA-binding proteins. In this literature review, we provide an overview of DBP and specifically summarize key findings related to its complex structure, diverse functions, and significant role in the context of viral replication. Finally, we address novel insights and perspectives for future research.
Assuntos
Adenoviridae , Replicação do DNA , Proteínas de Ligação a DNA , Proteínas Virais , Humanos , Adenoviridae/fisiologia , Adenovírus Humanos/fisiologia , DNA Viral/genética , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Proteínas Virais/genética , Proteínas Virais/metabolismo , Replicação ViralRESUMO
The adenovirus C5 E1B-55K protein is crucial for viral replication and is expressed early during infection. It can interact with E4orf6 to form a complex that functions as a ubiquitin E3 ligase. This complex targets specific cellular proteins and marks them for ubiquitination and, predominantly, subsequent proteasomal degradation. E1B-55K interacts with various proteins, with p53 being the most extensively studied, although identifying binding sites has been challenging. To explain the diverse range of proteins associated with E1B-55K, we hypothesized that other binding partners might recognize the simple p53 binding motif (xWxxxPx). In silico analyses showed that many known E1B-55K binding proteins possess this amino acid sequence; therefore, we investigated whether other xWxxxPx-containing proteins also bind to E1B-55K. Our findings revealed that many cellular proteins, including ATR, CHK1, USP9, and USP34, co-immunoprecipitate with E1B-55K. During adenovirus infection, several well-characterized E1B-55K binding proteins and newly identified interactors, including CSB, CHK1, and USP9, are degraded in a cullin-dependent manner. Notably, certain binding proteins, such as ATR and USP34, remain undegraded during infection. Structural predictions indicate no conservation of structure around the proposed binding motif, suggesting that the interaction relies on the correct arrangement of tryptophan and proline residues.