Ying Qi

The eukaryotic ribosome is a large ribonucleoprotein complex consisting of four types of ribosomal RNA (rRNA) and approximately 80 ribosomal proteins (RPs), forming the 40S and 60S subunits. In all living cells, its primary function is to produce proteins by converting messenger RNA (mRNA) into polypeptides. In addition to their canonical role in protein synthesis, RPs are crucial in controlling vital cellular processes such as cell cycle progression, cellular proliferation, differentiation, DNA damage repair, genome structure maintenance, and the cellular stress response. Viruses, as obligate intracellular parasites, depend completely on the machinery of the host cell for their replication and survival. During viral infection, RPs have been demonstrated to perform a variety of extra-ribosomal activities, which are especially important in viral disease processes. These functions cover a wide range of activities, ranging from controlling inflammatory responses and antiviral immunity to promoting viral replication and increasing viral pathogenicity. Deciphering the regulatory mechanisms used by RPs in response to viral infections has greatly expanded our understanding of their functions outside of the ribosome. Furthermore, these findings highlight the promising role of RPs as targets for the advancement of antiviral therapies and the development of novel antiviral approaches. This review comprehensively examines the many functions of RPs outside of the ribosome during viral infections and provides a foundation for future research on the host–virus interaction.

Human cytomegalovirus (HCMV), a herpesvirus family member, is a large, complex enveloped virus. The activation of liver X receptor (LXR) can significantly inhibit the replication of HCMV and weaken the virulence of progeny virus (unpublished data). Our results showed activated LXR affected some important viral protein expression and reduced cholesterol content in HCMV infected cells and virus particles. To further clarify the influence of activated LXR on HCMV replication, HCMV assembly and maturation processes were studied by transmission electron microscopy (TEM) in HCMV infected foreskin fibroblasts treated with LXR agonist GW3965. Results showed that activated LXR could reduce the envelope integrity of maturating virions. The functional stage of activated LXR on viral envelope integrity was mainly at virus assembly compartment (VAC) mediated envelopment but not structurally complete virus nucleocapsid formation and the egress of nucleocapsid from the nucleus to the cytoplasm mediated by nuclear egress complex. Reduced cholesterol synthesis and viral protein expression might interfere with the VAC-mediated envelopment. The nucleocapsid and tegument proteins enter the VAC area for the secondary envelope, which was interfered with and resulted in the defective particle, thereby affecting the amount and infectivity of the mature virus. The results indicate that inhibition of HCMV maturation is one mechanism of activated LXR inhibiting virus replication in infected cells.

Human cytomegalovirus (HCMV) is a ubiquitous pathogen belongs to the beta herpesvirus family. RNA2.7 is a viral long non-coding RNA accounting for more than 20% of total viral transcripts at early time of infection. By construction of RNA2.7 deleted mutant and genome transcriptomic analysis, RNA2.7 is demonstrated to repress host cellular RNA polymerase II (Pol II)-dependent transcription through inhibiting the phosphorylation of RNA polymerase II (Pol II). Co-immunoprecipitation, RNA immunoprecipitation and RNA electrophoretic mobility shift assay are followed to investigate its mechnism. A 145nt-in-length fragment in RNA2.7 is identified to bind to Pol II and block the interaction between Pol II and phosphorylated cyckin-dependent kinase 9 (phospho-CDK9). By inhibiting Pol II phosphorylation, RNA2.7 decreases the transcription and expression levels of chromatin licensing and DNA replication factor 1 (Cdt1) and cell division cycle gene 6 (Cdc6). Through above way, RNA2.7 prevents the entry of cells into S phase and facilitates viral DNA replication. Our results discover the functions of HCMV RNA2.7 in regulation of Pol II phosphorylation and cell cycle control during infection. Author summary: Human cytomegalovirus (HCMV) RNA2.7 is a viral lncRNA that is most abundant during infection. Here we show that a 145nt-in-length fragment in RNA2.7 binds to RNA polymerase II (Pol II) and blocks the interaction between Pol II and phosphorylated cyckin-dependent kinase 9 (phospho-CDK9). By inhibiting Pol II phosphorylation, RNA2.7 decreases the transcription and expression levels of chromatin licensing and DNA replication factor 1 (Cdt1) and cell division cycle gene 6 (Cdc6), and blocks host cells entering into S phase. RNA2.7 is confirmed to facilitate viral DNA replication through decreasing Cdt1 and Cdc6. Therefore, our results discover the functions of HCMV RNA2.7 in regulation of Pol II phosphorylation and cell cycle control during infection.

Human cytomegalovirus (HCMV) exists in a latent form in hematopoietic progenitors and undifferentiated cells of myeloid lineage. Protein UL138, encoded by the UL/b' region of the viral genome, serves an important role in the establishment and/or persistence of HCMV latency. However, little information about transcriptional regulation of the UL138 gene has been reported thus far. In the present study, the transcriptional regulation element (TRE) of the 1.4 kb UL138 region was identified using a series of dual‑luciferase constructs that contain 5' truncated deletion fragments located upstream of the transcription start site of the gene. The results demonstrated that the region from nucleotide 188995‑188962 of the Han strain genome exhibits promoter activity and harbors the functional binding motif for transcription factor AP‑1 (Ap‑1). Using electrophoretic mobility shift assays the physical interaction of the transcription factor to a minimal essential core sequence was demonstrated. Northern blotting revealed that deletion of the TRE in a HCMV bacterial artificial chromosome or inhibition of Ap‑1 using RNA interference eliminated or reduced the production of the UL138 1.4 kb mRNA transcript in infected human embryonic lung fibroblast cells (HELF). Deletion of the UL138 1.4 kb transcript resulted in acceleration of HCMV replication in HELF cells. To the best of the authors' knowledge, the present study is the first to analyze the transcriptional regulation of the UL138 1.4 kb transcript. Knowledge of the transcriptional regulation of the UL138 gene will enhance understanding of its mechanism in HCMV latency.

Human cytomegalovirus (HCMV) infection can cause severe illness in immunocompromised and immunodeficient individuals. As a novel HCMV‑encoded major histocompatibility complex class I‑related molecule, the UL142‑encoded protein (pUL142) is capable of suppressing natural killer (NK) cell recognition in the course of infection. However, no host factors that directly interact with HCMV pUL142 have been reported so far. In order to understand the interactions between HCMV pUL142 and host proteins, the current study used yeast two‑hybrid screening, a GST pull‑down assay and an immunofluorescence assay. A host protein, the SNARE‑associated protein Snapin, was identified to directly interact and colocalize with HCMV pUL142 in transfected human embryonic kidney‑293 cells. Snapin is abundantly expressed in the majority of cells and mediates the release of neurotransmitters through vesicular transport in the nervous system and vesicle fusion in non‑neuronal cells. It is hypothesized that HCMV pUL142 may have an impact on the neurotransmitter release process and viral dissemination via interaction with Snapin.

Background: It has been predicted that the UL31 gene originates from the positive strand of the human cytomegalovirus (HCMV) genome, whereas the UL30 and UL32 genes originate from the complementary strand. Except for the UL32 gene, the transcription of this gene region has not been investigated extensively. Methods: Northern blotting, cDNA library screening, RACE-PCR,and RT-PCR were used. Results: At least eight transcripts of the antisense orientation of UL31 were transcribed from the UL30–UL32 region during the late phase of HCMV infection. The 3^′ coterminus of these transcripts was located within the predicted UL30 gene. The longest 6.0-kb transcript was initiated upstream of the predicted UL32 gene. Other transcripts were derived from the predicted UL30 and UL31 gene region. Except for the previously predicted UL32 open reading frame (ORF), three novel ORFs, named UL31anti-1, UL31anti-2 and UL31anti-3, were located in the transcripts from the UL31anti-UL32 transcription unit. No transcription was found in UL31. Conclusion: A family of novel 3^′ coterminal transcripts was transcribed from the UL30–UL32 gene region.

Background: Interleukin-32 (IL-32) is an important factor in innate and adaptive immune responses, which activates the p38MAPK, NF-kappa B and AP-1 signaling pathways. Recent reports have highlighted that IL-32 is regulated during viral infection in humans.Methods: Enzyme-linked immunosorbent assays (ELISA) were carried out to detect IL-32 levels in serum samples. Detailed kinetics of the transcription of IL-32 mRNA and expression of IL-32 protein during human cytomegalovirus (HCMV) infection were determined by semi-quantitative RT-PCR and western blot, respectively. The expression levels of hcmv-miR-UL112-1 were detected using TaqMan® miRNA assays during a time course of 96 hours. The effects of hcmv-miR-UL112-1 on IL-32 expression were demonstrated by luciferase assay and western blot, respectively.Results: Serum levels of IL-32 in HCMV-IgM positive patients (indicating an active HCMV infection) were significantly higher than those in HCMV-IgM negative controls. HCMV infection activated cellular IL-32 transcription mainly in the immediately early (IE) phase and elevated IL-32 protein levels between 6 and 72 hours post infection (hpi) in the human embryonic lung fibroblast cell line, MRC-5. The expression of hcmv-miR-UL112-1 was detected at 24 hpi and increased gradually as the HCMV-infection process was prolonged. In addition, it was demonstrated that hcmv-miR-UL112-1 targets a sequence in the IL-32 3^′-UTR. The protein level of IL-32 in HEK293 cells could be functionally down-regulated by transfected hcmv-miR-UL112-1.Conclusions: IL-32 expression was induced by active HCMV infection and could be functionally down-regulated by ectopically expressed hcmv-miR-UL112-1. Our data may indicate a new strategy of immune evasion by HCMV through post-transcriptional regulation.

A 6-month-old girl with active human cytomegalovirus (HCMV) infection developed Reye's syndrome after vaccination. She suffered from uncommon complications of HCMV infection, including Coombs-negative hemolytic anemia and cardiac injury, but recovered after the appropriate treatment with prompt ganciclovir and symptomatic support. However, the patient died later as a result of a viral upper respiratory tract infection, which aggravated the primary disease. This case suggests that HCMV infection might be a causative agent of Reye's syndrome.

Background: To explore the relationship between enteroviruses and hospitalized children with hand, foot and mouth disease (HFMD) complicated with nervous system disease. 234 hospitalized HFMD patients treated in Shengjing Hospital, Liaoning Province were analyzed retrospectively. Based on the presence and severity of nervous system disease, the patients were grouped as follows: general patients, severely ill patients, critically ill patients and fatal patients. Based on the detected pathogen, the patients were grouped as follows: Enterovirus 71 (EV71) infection, coxsackie A16 (CA16) infection and other enterovirus (OE) infection.Results: Of the 423 hospitalized patients, most were admitted in July 2010(129/423, 30.5%). Enteroviruses were detected in 177(41.8%). 272/423 patients were male (64.3%), and fatal patients had the greatest proportion of male patients (p< 0.05). EV71 infection was found in 89/423 patients (21%). CA16 infection was detected in 8/423 patients (16.1%). Compared to group CA16, patients in group EV71 were hospitalized earlier, and the duration of hospitalization was longer (p< 0.05). Of the 92 patients with nervous system damage, 65 were infected with EV71 and 19 were infected with CA16. Among these CA16 infected patients, 2 had brainstem encephalitis and 1 had AFP. There were more patients with nervous system dysfunction in group EV71 than in groups CA16 or OE (p< 0.05). The 5 fatalities all occurred in group EV71 patients (p< 0.05). Infection with EV71 was most likely to cause neurogenic pulmonary edema (p< 0.05). Patients in group EV71 had a higher rate of suffering from coma and limb movement disorder than patients in groups CA16 or OE (p< 0.05).Conclusion: The disease progresses faster in EV71-infected HFMD patients. These patients are more likely to suffer nervous system damage, neurogenic pulmonary edema, severe sequelae or death. CA16 and other enteroviruses can also cause HFMD with severe nervous system complications.