Constitutive TRIM22 Expression in the Respiratory Tract Confers a Pre-Existing Defence Against Influenza A Virus Infection

TRIMming down Flavivirus Infections

Flaviviruses comprise a large number of arthropod-borne viruses, some of which are associated with life-threatening diseases. Flavivirus infections are rising worldwide, mainly due to the proliferation and geographical expansion of their vectors. The main human pathogens are mosquito-borne flaviviruses, including dengue virus, Zika virus, and West Nile virus, but tick-borne flaviviruses are also emerging. As with any viral infection, the body's first line of defense against flavivirus infections is the innate immune defense, of which type I interferon is the armed wing. This cytokine exerts its antiviral activity by triggering the synthesis of hundreds of interferon-induced genes (ISGs), whose products can prevent infection. Among the ISGs that inhibit flavivirus replication, certain tripartite motif (TRIM) proteins have been identified. Although involved in other biological processes, TRIMs constitute a large family of antiviral proteins active on a wide range of viruses. Furthermore, whereas some TRIM proteins directly block viral replication, others are positive regulators of the IFN response. Therefore, viruses have developed strategies to evade or counteract TRIM proteins, and some even hijack certain TRIM proteins to their advantage. In this review, we summarize the current state of knowledge on the interactions between flaviviruses and TRIM proteins, covering both direct and indirect antiviral mechanisms.

Exploring TRIM proteins' role in antiviral defense against influenza A virus and respiratory coronaviruses

Numerous tripartite motif (TRIM) proteins, identified as E3 ubiquitin ligases, participate in various viral infections through ubiquitylation, ISGylation, and SUMOylation processes. Respiratory viruses, particularly influenza A virus (IAV) and respiratory coronaviruses (CoVs), have severely threatened public health with high morbidity and mortality, causing incalculable losses. Research on the regulation of TRIM proteins in respiratory virus infections is crucial for disease prevention and control. This review introduces TRIM proteins, summarizes recent discoveries regarding their roles and molecular mechanisms in IAV and CoVs infections, discusses current research gaps, and explores potential future trends in this rapidly developing field. It aims to enhance understanding of virus-host interactions and inform the development of new molecularly targeted therapies.

Multi-Directional Mechanisms of Participation of the TRIM Gene Family in Response of Innate Immune System to Bacterial Infections

The multigene TRIM family is an important component of the innate immune system. For a long time, the main function of the genes belonging to this family was believed to be an antiviral defense of the host organism. The issue of their participation in the immune system response to bacterial invasion has been less studied. This review is the first comprehensive analysis of the mechanisms of functioning of the TRIM family genes in response to bacterial infections, which expands our knowledge about the role of TRIM in the innate immune system. When infected with different types of bacteria, individual TRIM proteins regulate inflammatory, interferon, and other responses of the immune system in the cells, and also affect autophagy and apoptosis. Functioning of TRIM proteins in response to bacterial infection, as well as viral infection, often includes ubiquitination and various protein-protein interactions with both bacterial proteins and host cell proteins. At the same time, some TRIM proteins, on the contrary, contribute to the infection development. Different members of the TRIM family possess similar mechanisms of response to viral and bacterial infection, and the final impact of these proteins could vary significantly. New data on the effect of TRIM proteins on bacterial infections make an important contribution to a more detailed understanding of the innate immune system functioning in animals and humans when interacting with pathogens. This data could also be used for the search of new targets for antibacterial defense.

Transcriptome Analysis in Air-Liquid Interface Porcine Respiratory Epithelial Cell Cultures Reveals That the Betacoronavirus Porcine Encephalomyelitis Hemagglutinating Virus Induces a Robust Interferon Response to Infection

Porcine hemagglutinating encephalomyelitis virus (PHEV) replicates in the upper respiratory tract and tonsils of pigs. Using an air-liquid interface porcine respiratory epithelial cells (ALI-PRECs) culture system, we demonstrated that PHEV disrupts respiratory epithelia homeostasis by impairing ciliary function and inducing antiviral, pro-inflammatory cytokine, and chemokine responses. This study explores the mechanisms driving early innate immune responses during PHEV infection through host transcriptome analysis. Total RNA was collected from ALI-PRECs at 24, 36, and 48 h post inoculation (hpi). RNA-seq analysis was performed using an Illumina Hiseq 600 to generate 100 bp paired-end reads. Differential gene expression was analyzed using DeSeq2. PHEV replicated actively in ALI-PRECs, causing cytopathic changes and progressive mucociliary disruption. Transcriptome analysis revealed downregulation of cilia-associated genes such as CILK1, DNAH11, LRRC-23, -49, and -51, and acidic sialomucin CD164L2. PHEV also activated antiviral signaling pathways, significantly increasing the expression of interferon-stimulated genes (RSAD2, MX1, IFIT, and ISG15) and chemokine genes (CCL5 and CXCL10), highlighting inflammatory regulation. This study contributes to elucidating the molecular mechanisms of the innate immune response to PHEV infection of the airway epithelium, emphasizing the critical roles of the mucociliary, interferon, and chemokine responses.

Influenza Virus Host Restriction Factors: The ISGs and Non-ISGs

Influenza virus has been one of the most prevalent and researched viruses globally. Consequently, there is ample information available about influenza virus lifecycle and pathogenesis. However, there is plenty yet to be known about the determinants of influenza virus pathogenesis and disease severity. Influenza virus exploits host factors to promote each step of its lifecycle. In turn, the host deploys antiviral or restriction factors that inhibit or restrict the influenza virus lifecycle at each of those steps. Two broad categories of host restriction factors can exist in virus-infected cells: (1) encoded by the interferon-stimulated genes (ISGs) and (2) encoded by the constitutively expressed genes that are not stimulated by interferons (non-ISGs). There are hundreds of ISGs known, and many, e.g., Mx, IFITMs, and TRIMs, have been characterized to restrict influenza virus infection at different stages of its lifecycle by (1) blocking viral entry or progeny release, (2) sequestering or degrading viral components and interfering with viral synthesis and assembly, or (3) bolstering host innate defenses. Also, many non-ISGs, e.g., cyclophilins, ncRNAs, and HDACs, have been identified and characterized to restrict influenza virus infection at different lifecycle stages by similar mechanisms. This review provides an overview of those ISGs and non-ISGs and how the influenza virus escapes the restriction imposed by them and aims to improve our understanding of the host restriction mechanisms of the influenza virus.

Integrated analysis of miRNA-mRNA expression of newly emerging swine H3N2 influenza virus cross-species infection with tree shrews

BACKGROUND

Cross-species transmission of zoonotic IAVs to humans is potentially widespread and lethal, posing a great threat to human health, and their cross-species transmission mechanism has attracted much attention. miRNAs have been shown to be involved in the regulation of IAVs infection and immunity, however, few studies have focused on the molecular mechanisms underlying miRNAs and mRNAs expression after IAVs cross-species infection.

METHODS

We used tree shrews, a close relative of primates, as a model and used RNA-Seq and bioinformatics tools to analyze the expression profiles of DEMs and DEGs in the nasal turbinate tissue at different time points after the newly emerged swine influenza A virus SW2783 cross-species infection with tree shrews, and miRNA-mRNA interaction maps were constructed and verified by RT-qPCR, miRNA transfection and luciferase reporter assay.

RESULTS

14 DEMs were screened based on functional analysis and interaction map, miR-760-3p, miR-449b-2, miR-30e-3p, and miR-429 were involved in the signal transduction process of replication and proliferation after infection, miR-324-3p, miR-1301-1, miR-103-1, miR-134-5p, miR-29a, miR-31, miR-16b, miR-34a, and miR-125b participate in negative feedback regulation of genes related to the immune function of the body to activate the antiviral immune response, and miR-106b-3p may be related to the cross-species infection potential of SW2783, and the expression level of these miRNAs varies in different days after infection.

CONCLUSIONS

The miRNA regulatory networks were constructed and 14 DEMs were identified, some of them can affect the replication and proliferation of viruses by regulating signal transduction, while others can play an antiviral role by regulating the immune response. It indicates that abnormal expression of miRNAs plays a crucial role in the regulation of cross-species IAVs infection, which lays a solid foundation for further exploration of the molecular regulatory mechanism of miRNAs in IAVs cross-species infection and anti-influenza virus targets.

The Timing and Magnitude of the Type I Interferon Response Are Correlated with Disease Tolerance in Arbovirus Infection

Infected hosts possess two alternative strategies to protect themselves against the negative impact of virus infections: resistance, used to abrogate virus replication, and disease tolerance, used to avoid tissue damage without controlling viral burden. The principles governing pathogen resistance are well understood, while less is known about those involved in disease tolerance. Here, we studied bluetongue virus (BTV), the cause of bluetongue disease of ruminants, as a model system to investigate the mechanisms of virus-host interactions correlating with disease tolerance. BTV induces clinical disease mainly in sheep, while cattle are considered reservoirs of infection, rarely exhibiting clinical symptoms despite sustained viremia. Using primary cells from multiple donors, we show that BTV consistently reaches higher titers in ovine cells than cells from cattle. The variable replication kinetics of BTV in sheep and cow cells were mostly abolished by abrogating the cell type I interferon (IFN) response. We identified restriction factors blocking BTV replication, but both the sheep and cow orthologues of these antiviral genes possess anti-BTV properties. Importantly, we demonstrate that BTV induces a faster host cell protein synthesis shutoff in primary sheep cells than cow cells, which results in an earlier downregulation of antiviral proteins. Moreover, by using RNA sequencing (RNA-seq), we also show a more pronounced expression of interferon-stimulated genes (ISGs) in BTV-infected cow cells than sheep cells. Our data provide a new perspective on how the type I IFN response in reservoir species can have overall positive effects on both virus and host evolution. IMPORTANCE The host immune response usually aims to inhibit virus replication in order to avoid cell damage and disease. In some cases, however, the infected host avoids the deleterious effects of infection despite high levels of viral replication. This strategy is known as disease tolerance, and it is used by animal reservoirs of some zoonotic viruses. Here, using a virus of ruminants (bluetongue virus [BTV]) as an experimental system, we dissected virus-host interactions in cells collected from species that are susceptible (sheep) or tolerant (cow) to disease. We show that (i) virus modulation of the host antiviral type I interferon (IFN) responses, (ii) viral replication kinetics, and (iii) virus-induced cell damage differ in tolerant and susceptible BTV-infected cells. Understanding the complex virus-host interactions in disease tolerance can allow us to disentangle the critical balance between protective and damaging host immune responses.

Impact of TRIM5α and TRIM22 Genes Expression on the Clinical Course of Coronavirus Disease 2019

OBJECTIVE

The innate immune response in humans involves a wide variety of factors, including the tripartite motif-containing 5α (TRIM5α) and 22 (TRIM22) as a cluster of genes on chromosome 11 that have exhibited antiviral activity in several viral infections. We analyzed the correlation of the expression of TRIM5α and TRIM22 with the severity of Coronavirus Disease 2019 (COVID-19) in blood samples of 330 patients, divided into two groups of severe and mild disease, versus the healthy individuals who never had contact with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2).

METHODS

The transcription level of TRIM5α and TRIM22 was determined by quantitative real-time polymerase chain reaction (qPCR). The laboratory values were collected from the patients' records.

RESULTS

The expression of both genes was significantly lower in the severe group containing the hospitalized patients than in both the mild group and the control group. However, in the mild group, TRIM22 expression was significantly higher (p <0.0001) than in the control group while TRIM5α expression was not significantly different between these two groups. We found a relationship between the cycle threshold (Ct) value of patients and the expression of the aforementioned genes.

CONCLUSION

The results of our study indicated that lower Ct values or higher RNA viral load might be associated with the downregulation of TRIM5α and TRIM22 and the severity of COVID-19. Additional studies are needed to confirm the results of this study.

On the relationship between tripartite motif-containing 22 single-nucleotide polymorphisms and COVID-19 infection severity

Background

The tripartite motif containing (TRIM)-22 participates in innate immune responses and exhibits antiviral activities. The present study aimed to assess of the relationship between TRIM22 single-nucleotide polymorphisms and clinical parameters with the coronavirus disease 2019 (COVID-19) infection severity.

Methods

TRIM22 polymorphisms (rs7113258, rs7935564, and rs1063303) were genotyped using TaqMan polymerase chain reaction (PCR) assay in 495 dead and 497 improved severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-positive patients.

Results

In this study, the frequencies of TRIM22 rs1063303 GG, rs7935564 GG, and rs7113258 TT were significantly higher in dead patients than in improved patients, and higher viral load with low PCR Ct value was noticed in dead patients. The multivariate logistic regression analysis revealed that the lower levels of low-density lipoprotein (LDL), cholesterol, PCR Ct value, and lower 25-hydroxyvitamin D, and also higher levels of erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and TRIM22 rs1063303 GG, rs7113258 TT, and rs3824949 GG genotypes were related to the COVID-19 infection severity.

Conclusion

Our finding proved the probable relationship between the COVID-19 infection severity with the genotypes of TRIM22 SNPs and clinical parameters. More research is required worldwide to show the association between the COVID-19 infection severity and host genetic factors.