Interaction between the human cytomegalovirus-encoded UL142 and cellular Snapin proteins

Proteomic Analysis of Differentially Expressed Proteins in A549 Cells Infected with H9N2 Avian Influenza Virus

Influenza A viruses (IAVs) are highly contagious pathogens that cause zoonotic disease with limited availability of antiviral therapies, presenting ongoing challenges to both public health and the livestock industry. Unveiling host proteins that are crucial to the IAV life cycle can help clarify mechanisms of viral replication and identify potential targets for developing alternative host-directed therapies. Using a four-dimensional (4D), label-free methodology coupled with bioinformatics analysis, we analyzed the expression patterns of cellular proteins that changed following H9N2 virus infection. Compared to the control group, the H9N2 infected group displayed 732 differentially expressed proteins (DEPs), with 298 proteins showing upregulation and 434 proteins showing downregulation. Gene Ontology (GO) functional analysis showed that DEPs were catalog in 11 biological processes, three cellular components, and eight molecular functions. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that DEPs were involved in processes including cytokine signaling pathways induced by virus infection and protein digestion and absorption. Proteins including TP53, DDX58, and STAT3 were among the top hub proteins in the protein-protein interaction (PPI) analysis, suggesting that these signaling cascades could be essential for the propagation of IAVs. Furthermore, the host protein SNAPIN was chosen to ascertain the accuracy of expression changes identified through a proteomic analysis. The results indicated that SNAPIN was downregulated following infection with IAVs both in vitro and in vivo, which is consistent with the proteomics results, suggesting that SNAPIN may serve as a key regulatory factor in the viral life cycle of IAVs. Our research delineates an extensive interaction map of IAV infection within the A549 cells, facilitating the discovery of pivotal proteins that contribute to the virus's propagation, potentially offering target candidates to screen for antiviral therapeutics.

Insights into the Transcriptome of Human Cytomegalovirus: A Comprehensive Review

Human cytomegalovirus (HCMV) is a widespread pathogen that poses significant risks to immunocompromised individuals. Its genome spans over 230 kbp and potentially encodes over 200 open-reading frames. The HCMV transcriptome consists of various types of RNAs, including messenger RNAs (mRNAs), long non-coding RNAs (lncRNAs), circular RNAs (circRNAs), and microRNAs (miRNAs), with emerging insights into their biological functions. HCMV mRNAs are involved in crucial viral processes, such as viral replication, transcription, and translation regulation, as well as immune modulation and other effects on host cells. Additionally, four lncRNAs (RNA1.2, RNA2.7, RNA4.9, and RNA5.0) have been identified in HCMV, which play important roles in lytic replication like bypassing acute antiviral responses, promoting cell movement and viral spread, and maintaining HCMV latency. CircRNAs have gained attention for their important and diverse biological functions, including association with different diseases, acting as microRNA sponges, regulating parental gene expression, and serving as translation templates. Remarkably, HCMV encodes miRNAs which play critical roles in silencing human genes and other functions. This review gives an overview of human cytomegalovirus and current research on the HCMV transcriptome during lytic and latent infection.

Interaction between the VP2 protein of deformed wing virus and host snapin protein and its effect on viral replication

Introduction

Deformed wing virus (DWV) is one of the causative agents of colony collapse disorder. The structural protein of DWV plays a vital role in the process of viral invasion and host infection; however, there is limited research on DWV.

Methods and Results

In this study, we screened the host protein snapin, which can interact with the VP2 protein of DWV, using the yeast two-hybrid system. Through computer simulation and GST pull-down and CO-IP assays, an interaction between snapin and VP2 was confirmed. Furthermore, immunofluorescence and co-localization experiments revealed that VP2 and snapin primarily co-localized in the cytoplasm. Consequently, RNAi was used to interfere with the expression of snapin in worker bees to examine the replication of DWV after the interference. After silencing of snapin, the replication of DWV in worker bees was significantly downregulated. Hence, we speculated that snapin was associated with DWV infection and involved in at least one stage of the viral life cycle. Finally, we used an online server to predict the interaction domains between VP2 and snapin, and the results indicate that the interaction domain of VP2 was approximately located at 56-90, 136-145, 184-190, and 239-242 aa and the snapin interaction domain was approximately located at 31-54 and 115-136 aa.

Conclusion

This research confirmed that DWV VP2 protein could interacts with the snapin of host protein, which provides a theoretical basis for further investigation of its pathogenesis and development of targeted therapeutic drugs.

Deciphering the human cellular interactors of alphavirus unique domain of chikungunya virus

The life-threatening re-emerged chikungunya virus (CHIKV) can cause an epidemic outbreak and still has no vaccine available so far. Alphavirus unique domain (AUD) of CHIKV nsP3 is a multifunctional domain that remains conserved among alphaviruses and is critical for CHIKV replication. The understanding of AUD-host protein-protein interactions and their association with the cellular processes concerning CHIKV infection are not well studied. In the current study, the protein-protein interactions of AUD and its human host were elucidated by screening of universal human cDNA library using yeast two-hybrid system. The chosen interactions were further validated by GST pull-down assay, and their network mapping was analyzed. The study revealed that the identified interactors are linked with the vesicle trafficking and transcription corepressor activities. Further, the interfacial residues of interactions between viral and host proteins were predicted, which will further provide the new platform to develop novel antivirals.

HCMV-Encoded NK Modulators: Lessons From in vitro and in vivo Genetic Variation

Human cytomegalovirus (HCMV) is under constant selective pressure from the immune system in vivo. Study of HCMV genes that have been lost in the absence of, or genetically altered by, such selection can focus research toward findings of in vivo significance. We have been particularly interested in the most pronounced change in the highly passaged laboratory strains AD169 and Towne—the deletion of 13–15 kb of sequence (designated the U_L/b′ region) that encodes up to 22 canonical genes, UL133-UL150. At least 5 genes have been identified in U_L/b′ that inhibit NK cell function. UL135 suppresses formation of the immunological synapse (IS) by remodeling the actin cytoskeleton, thereby illustrating target cell cooperation in IS formation. UL141 inhibits expression of two activating ligands (CD155, CD112) for the activating receptor CD226 (DNAM-1), and two receptors (TRAIL-R1, R2) for the apoptosis-inducing TRAIL. UL142, ectopically expressed in isolation, and UL148A, target specific MICA allotypes that are ligands for NKG2D. UL148 impairs expression of CD58 (LFA-3), the co-stimulatory cell adhesion molecule for CD2 found on T and NK cells. Outside U_L/b′, studies on natural variants have shown UL18 mutants change affinity for their inhibitory ligand LIR-1, while mutations in UL40's HLA-E binding peptide differentially drive NKG2C⁺ NK expansions. Research into HCMV genomic stability and its effect on NK function has provided important insights into virus:host interactions, but future studies will require consideration of genetic variability and the effect of genes expressed in the context of infection to fully understand their in vivo impact.

Interaction of porcine reproductive and respiratory syndrome virus major envelope proteins GP5 and M with the cellular protein Snapin

BACKGROUND

Porcine reproductive and respiratory syndrome (PRRS) is characterized by abortions in pregnant sows and respiratory disease, particularly in young pigs. The causative agent is porcine reproductive and respiratory syndrome virus (PRRSV), a member of the arterivirus family. GP5 and M are the major envelope proteins encoded by PRRSV. To further characterize these two viral proteins, a yeast two-hybrid approach was utilized to identify interacting partners of PRRSV GP5 and M proteins.

METHODS

Interacting partners of PRRSV GP5 and M were identified using a porcine macrophage cDNA library yeast two-hybrid screen. Subsequently, the interactions between PRRSV GP5/M and the cellular protein Snapin were mapped using truncated versions of the GP5 and M proteins in a yeast two-hybrid assay to localize the interactions. The Snapin gene from the African green monkey kidney cell line MARC-145, which is permissive to PRRSV, was cloned and sequenced, and compared to porcine Snapin. Cellular Snapin expression was reduced in PRRSV-infected cells via Snapin-specific siRNA targeting.

RESULTS

Here we show that the cellular Snap-Associated Protein (Snapin), an accessory protein of the SNARE membrane fusion network and also a member of the BLOC-1 complex, specifically interacts with GP5 and M. Inhibition of Snapin expression via siRNA targeting of Snapin results in the reduction of PRRSV replication.

CONCLUSIONS

The PRRSV GP5 and M proteins are known to form a heterodimeric complex which is important for viral structure and infectivity, and both PRRSV proteins can interact with cellular Snapin. Snapin knock-down suggests these interactions could be important in the PRRSV lifecycle. GP5 and M proteins may interact with Snapin to exploit its roles in intracellular transport and membrane fusion.