Role Of Human Cytomegalovirus Infection Research Articles

THU-257 - Characterizing the role of human cytomegalovirus infection associated with biliary atresia

THU-257 - Characterizing the role of human cytomegalovirus infection associated with biliary atresia

Human Cytomegalovirus Induced Aberrant Expression of Non-coding RNAs.

Human cytomegalovirus (HCMV) is a β-herpesvirus whose genome consists of double stranded linear DNA. HCMV genome can generate non-coding RNAs (ncRNAs) through transcription in its host cells. Besides that, HCMV infection also changes the ncRNAs expression profile of the host cells. ncRNAs play a key role in maintaining the normal physiological activity of cells, and the disorder of ncRNAs expression has numerous adverse effects on cells. However, until now, the relationship between ncRNAs and HCMV-induced adverse effects are not summarized in detail. This review aims to give a systematic summary of the role of HCMV infection in ncRNAs expression while providing insights into the molecular mechanism of unnormal cellular events caused by ncRNAs disorder. ncRNAs disorder induced by HCMV infection is highly associated with cell proliferation, apoptosis, tumorigenesis, and immune regulation, as well as the development of cardiovascular diseases, and the potential role of biomarker. We summarize the studies on HCMV associated ncRNAs disorder and suggest innovative strategies for eliminating the adverse effects caused by HCMV infection.

Congenital Human Cytomegalovirus Infection Inducing Sensorineural Hearing Loss.

Human cytomegalovirus (HCMV) is the primary cause of congenital infections. Despite its clinical significance, congenital HCMV infection is frequently overlooked clinically since most affected infants are asymptomatic. Sensorineural hearing loss (SNHL) is one of the most widely known disorders caused by congenital HCMV infection. The potential mechanism, however, remains unknown to date. The mechanism by which congenital HCMV infection induces sensorineural deafness has been partly characterized, leading to advancements in diagnosis, therapy, and prevention strategies. HCMV-induced hearing loss primarily involves immune responses, the release of inflammatory factors by natural killer (NK) cells, apoptosis of cochlear spiral ganglion, and potential changes due to vascular dysfunction. The diagnosis of HCMV induced SNHL includes serological examination to mothers, imaging, and amniotic fluid examination. Ganciclovir, mainly used for antiviral therapy and behavioral prevention, can, to some degree, prevent congenital HCMV infection. The role of HCMV infection in hearing loss needs further investigation since the mechanism of hearing loss caused by cytomegalovirus infection is not well understood. Although some advancement has been made in diagnosing and treating SNHL, more improvement is needed. A comprehensive understanding of cytomegalovirus’s pathogenesis is of key importance for preventing, diagnosing, and treating SNHL.

Detection of human cytomegalovirus in patients with epithelial ovarian cancer and its impacts on survival

BackgroundThe cause of epithelial ovarian cancer (EOC) is not elucidated. Viral infection may induce chronic inflammatory infection and play a role in the pathogenesis of cancers. Some viruses are considered to be oncomodulatory, modulating cellular pathways such as cell proliferation, tumor progression, vascular disease development, and immune evasion. Human cytomegalovirus (HCMV) has been detected in several types of cancers including ovarian cancer. However, the role of HCMV in ovarian carcinogenesis remains controversial.ObjectiveTo investigate the potential role of HCMV infection in EOC, we evaluated the prevalence of HCMV proteins in EOC tissue and its impacts on patients’ survival.MethodsFormalin-fixed paraffin-embedded tissues from 66 patients with EOC and 30 patients with benign ovarian cystadenoma were studied. Specimens were analyzed for expression of HCMV immediate early protein (IE) and HCMV tegument protein (pp65) by immunohistochemistry.ResultsHCMV-IE protein expression was detected in 82% of EOC and 36% of benign tumors; pp65 was detected in 97% of EOC and 63% of benign tumors. Extensive HCMV-IE protein expression was associated with higher stage of EOC. Reactivation of latent HCMV within the tumor at interval debulking surgery may be induced by neoadjuvant chemotherapy before surgery. Extensive HCMV-IE expression was associated with shorter median overall survival than focal or negative expression (39 versus 41 months, P = 0.03). Multivariate analysis indicated that HCMV-IE expression was an independent prognostic factor for overall survival (P = 0.034).ConclusionsThis study demonstrate a high prevalence of HCMV proteins in tissue sections from patients with EOC. HCMV infection can be potential risk factor for EOC development. Extensive HCMV-IE expression indicated a poor prognosis. The relationship between HCMV and clinical outcomes highlight the need for further researches on the oncomodulatory role of HCMV in ovarian cancer.

The emerging role of human cytomegalovirus infection in human carcinogenesis: a review of current evidence and potential therapeutic implications.

It is well-established that infections with viruses harboring oncogenic potential increase the cancer risk. Virus induced oncogenic processes are influenced by a complex and unique combination of host and environmental risk factors that are currently not fully understood. Many of the oncogenic viruses exhibit a prolonged, asymptomatic latency after a primary infection, and cause cancer in only a minority of carriers. From an epidemiologic point of view, it is therefore difficult to determine their role in cancer development. However, recent evidence suggests a neoplastic potential of one additional ubiquitous virus; human Cytomegalovirus (HCMV). Emerging data presents HCMV as a plausible cancer-causing virus by demonstrating its presence in >90% of common tumor types, while being absent in normal tissue surrounding the tumor. HCMV targets many cell types in tumor tissues, and can cause all the ten proposed hallmarks of cancer. This virus exhibits cellular tumor-promoting and immune-evasive strategies, hijacks proangiogenic and anti-apoptotic mechanisms and induces immunosuppressive effects in the tumor micro-environment. Recognizing new cancer-causing mechanisms may increase the therapeutic potential and prophylactic options for virus associated cancer forms. Such approaches could limit viral spread, and promote anti-viral and immune controlling strategies if given as add on to standard therapy to potentially improve the prognosis of cancer patients. This review will focus on HCMV-related onco-viral mechanisms and the potential of HCMV as a new therapeutic target in HCMV positive cancer forms.

High Human Cytomegalovirus IgG Level is Associated with Increased Incidence of Diabetic Atherosclerosis in Type 2 Diabetes Mellitus Patients.

BackgroundAt present, whether human cytomegalovirus (HCMV) infection is associated with type 2 diabetes mellitus (T2DM) is debatable. The effect of active HCMV infection on glucose regulation has been poorly studied. Although HCMV infection is correlated with atherosclerosis in cardiovascular disease, the role of HCMV infection in the development of diabetic atherosclerosis in T2DM is unclear and is usually neglected by endocrinologists. The aim of this study was to assess the effects of HCMV infection on glucose regulation and the development of diabetic atherosclerosis in T2DM patients.Material/MethodsA total of 222 hospitalized T2DM patients were enrolled. Nested polymerase chain reactions were used to detect HCMV DNA extracted from peripheral blood leukocytes. Quantitative real-time PCR was used to determine viral load. HCMV IgG antibody concentrations were analyzed by chemiluminescence immunoassay.ResultsHCMV active infection, viral load, and HCMV IgG titers were not correlated with glucose regulation. Binary logistic regression demonstrated that the highest quartile of HCMV IgG concentration (>500 U/ml) was correlated with the incidence of diabetic atherosclerosis (OR: 8.0, 95%CI: 2.3–27.2), and that titer >127U/ml of HCMV IgG is an independent predictor for the development of diabetic atherosclerosis in T2DM patients (OR: 4.6, 95%CI: 1.9–11.3) after adjustment for all potential confounding factors.ConclusionsActive HCMV infection is unlikely to influence glucose regulation in T2DM. However, HCMV IgG titers are associated with the incidence of diabetic atherosclerosis, and titer >127U/ml of HCMV IgG might be an independent risk factor for the development of diabetic atherosclerosis in T2DM patients.

5(th) International Workshop on CMV and Immunosenescence - A shadow of cytomegalovirus infection on immunological memory.

Human cytomegalovirus (HCMV), a member of the betaherpesvirus family, is an omnipresent pathogen worldwide. Primary HCMV infection elicits robust responses from both the innate and adaptive branches of the immune system. The T-cell response is extraordinary large; on average 10% of the total circulating memory compartment of both the CD4 and CD8 T-cell subsets is specific for HCMV, which makes this virus possibly the most immunogenic microbe for the human immune system. However, despite the extensive immune response, HCMV is not cleared and persists in the host due to its numerous immune evasion mechanisms. Both, primary infection and long-term persistence of HCMV are largely subclinical for the majority of individuals, but HCMV virus is linked to considerable morbidity in immunologically immature and immunocompromised individuals. The role of HCMV infection in immunocompetent hosts has gained considerable interest, and has led to insights that favor a neutral or even beneficial co-existence, but also HCMV-driven detrimental consequences have been reported especially in the elderly. This differential outcome of HCMV infection might be related to the huge variability in the size and phenotype of HCMV-specific T-cell responses among individuals, caused by the differences in infectious dose and the immunocompetence of the host. The interactions between CMV and the immune system were discussed at the 5th International Workshop on CMV and Immunosenescence. Here, we highlight some of the key findings discussed in the meeting, with an emphasis on the particular role of HCMV in memory T-cell formation.

Characteristics and functions of human cytomegalovirus UL128 gene/protein.

Human cytomegalovirus (HCMV) ORF UL128 protein is highly conserved among viral field isolates and functions in two different molecular forms, monomeric UL128 protein and in a complex with glycoproteins gH, gL, UL130, and UL131A protein. Monomeric UL128 protein works as soluble chemokine analogue to attract peripheral blood mononuclear cells (PBMCs) and selectively induces expression of interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α) in PBMCs. The gH/gL/UL128/UL130/UL131A complex is indispensable for entry into both endothelial and epithelial cells. In conclusion, UL128 plays an important role in HCMV infection.

The Smallest Capsid Protein Mediates Binding of the Essential Tegument Protein pp150 to Stabilize DNA-Containing Capsids in Human Cytomegalovirus

Human cytomegalovirus (HCMV) is a ubiquitous herpesvirus that causes birth defects in newborns and life-threatening complications in immunocompromised individuals. Among all human herpesviruses, HCMV contains a much larger dsDNA genome within a similarly-sized capsid compared to the others, and it was proposed to require pp150, a tegument protein only found in cytomegaloviruses, to stabilize its genome-containing capsid. However, little is known about how pp150 interacts with the underlying capsid. Moreover, the smallest capsid protein (SCP), while dispensable in herpes simplex virus type 1, was shown to play essential, yet undefined, role in HCMV infection. Here, by cryo electron microscopy (cryoEM), we determine three-dimensional structures of HCMV capsid (no pp150) and virion (with pp150) at sub-nanometer resolution. Comparison of these two structures reveals that each pp150 tegument density is composed of two helix bundles connected by a long central helix. Correlation between the resolved helices and sequence-based secondary structure prediction maps the tegument density to the N-terminal half of pp150. The structures also show that SCP mediates interactions between the capsid and pp150 at the upper helix bundle of pp150. Consistent with this structural observation, ribozyme inhibition of SCP expression in HCMV-infected cells impairs the formation of DNA-containing viral particles and reduces viral yield by 10,000 fold. By cryoEM reconstruction of the resulting “SCP-deficient” viral particles, we further demonstrate that SCP is required for pp150 functionally binding to the capsid. Together, our structural and biochemical results point to a mechanism whereby SCP recruits pp150 to stabilize genome-containing capsid for the production of infectious HCMV virion.

Is human cytomegalovirus associated with breast cancer progression?

BackgroundIt has been hypothesized that human cytomegalovirus (HCMV) may be associated with breast cancer progression. However, the role of HCMV infection in breast cancer remains controversial. We aimed to assess whether HCMV genes (UL122 and UL83) could be detected in breast carcinomas and reinvestigated their possible association with breast cancer progression. DNA from paraffin-embedded tissues was analyzed by real-time PCR. We investigated 20 fibroadenomas and 27 primary breast carcinomas (stages II, III, and IV).FindingsTwo carcinomas were positive for HCMV, one was positive for two TaqMan viral detection probes, and one was positive for a sole TaqMan viral detection probe (UL83), whereas the remainder of the samples was negative.ConclusionsSamples studied showed no association between HCMV infection and breast cancer progression.

Human Cytomegalovirus Gene UL21a Encodes a Short-Lived Cytoplasmic Protein and Facilitates Virus Replication in Fibroblasts

The human cytomegalovirus (HCMV) gene UL21a was recently annotated by its conservation in chimpanzee cytomegalovirus. Two large-scale mutagenic analyses showed that mutations in overlapping UL21a/UL21 resulted in a severe defect of virus growth in fibroblasts. Here, we characterized UL21a and demonstrated its role in HCMV infection. We mapped a UL21a-specific transcript of approximately 600 bp that was expressed with early kinetics. UL21a encoded pUL21a, a protein of approximately 15 kDa, which was unstable and localized predominantly to the cytoplasm during HCMV infection or when expressed alone. Interestingly, pUL21a was drastically stabilized in the presence of proteasome inhibitor MG132, but its instability was independent of a functional ubiquitin-mediated pathway, suggesting that pUL21a underwent proteasome-dependent, ubiquitin-independent degradation. A UL21a deletion virus was attenuated in primary human newborn foreskin fibroblasts (HFFs) and embryonic lung fibroblasts (MRC-5), whereas a marker-rescued virus and mutant viruses lacking the neighboring or overlapping genes UL20, UL21, or UL21.5-UL23 replicated at wild-type levels. The growth defect of UL21a-deficient virus in MRC-5 cells was more pronounced than that in HFFs. At a high multiplicity of infection, the UL21a deletion virus synthesized viral proteins with wild-type kinetics but had a two- to threefold defect in viral DNA replication. More importantly, although pUL21a was not detected in the virion, progeny virions produced by the mutant virus were approximately 10 times less infectious than wild-type virus, suggesting that UL21a is required for HCMV to establish efficient productive infection. We conclude that UL21a encodes a short-lived cytoplasmic protein and facilitates HCMV replication in fibroblasts.

276: Investigations into the Pathogenesis of Cytomegalovirus-Induced Transplant-Arteriosclerosis Using a Humanized Mouse Model

Recent findings have emphasised an important role of human cytomegalovirus infection (HCMV) in the development of transplant arteriosclerosis. Therefore, the aim of this study was to investigate the immunological mechanisms of HCMV in the progression of transplant arteriosclerosis in a human peripheral blood lymphocyte (hu-PBL)/RAG-2(-/-) gc(-/-) mouse-xenograft-model.

Investigations into the pathogenesis of cytomegalovirus-induced transplant-arteriosclerosis using a humanized mouse model

Introduction: Recent findings have emphasised an important role of human cytomegalovirus infection (HCMV) in the development of transplant arteriosclerosis. Therefore, the aim of this study was to develop a human peripheral blood lymphocyte (hu-PBL)/RAG-2(–/–)yc(–/–) mouse-xenograft-model to investigate the immunological mechanisms of HCMV in the progression of transplant arteriosclerosis.

Sequence Conservation of Human Cytomegalovirus UL140 Open Reading Frame in Clinical Strains

To investigate the variability of human cytomegalovirus (HCMV) UL140 open reading frame (ORF) in clinical strains, and to explore the relationship between the variability of UL140 ORF and different symptoms of HC-MV infection. HCMV UL140 ORF was amplified by polymerase chain reaction and sequenced selectedly in 30 clinical strains. UL140 ORF of all clinical strains was amplified successfully. Compared with that of Toledo strain, the nucleotide and amino acid sequence identities among all strains were 96.5%-100.0% and 95.2%-100.0%, respectively. All of the nucleotide changes were substitutions. The post-translational modification sites were conserved. The result of phylogenetic tree showed that the strains did not cluster according to different clinical symptoms. HCMV UL140 ORF in clinical strains is highly conserved, which may play an important role in HC-MV infection.

Investigations into the pathogenesis of cytomegalovirus-induced transplant-arteriosclerosis using a humanized mouse model

Introduction: Recent findings have emphasised an important role of human cytomegalovirus infection (HCMV) in the development of transplant arteriosclerosis. Therefore, the aim of this study was to develop a human peripheral blood lymphocyte (hu-PBL)/RAG-2(–/–)gc(–/–) mouse-xenograft-model to investigate the immunological mechanisms of HCMV in the progression of transplant arteriosclerosis.

Structure and variability of the UL149 open reading frame from low-passage clinical isolates of human cytomegalovirus

Human cytomegalovirus (HCMV), a ubiquitous herpesvirus, causes a lifelong subclinical infection in healthy adults but leads to significant morbidity and mortality in neonates and immunocompromised individuals. A region (referred to as UL/b′) present in the Toledo strain of HCMV and low passage clinical isolates contains 19 additional genes, which are absent in the highly passage laboratory strain AD169. One of these genes, UL149 open reading frame, was amplified by PCR and sequenced from isolates obtained from infants with congenital HCMV infection, to determine whether genetic variation of this gene could influence the signs of the virus infection. The major finding is that the UL149 is a variable gene in all 26 clinical isolates, and the sequences from clinical isolates were classified into three major groups. It is concluded that the HCMV UL149 sequence is variable at the nucleotide level and it might play an important role in HCMV infection.

Cytomegalovirus is not associated with progression and metastasis of colorectal cancer

Recently, it was hypothesized that human cytomegalovirus (HCMV) might be associated with colorectal cancer progression. However, the role of HCMV infection in colorectal cancer remains controversial. We aimed to assess whether nucleic acids and/or gene products of HCMV could be detected in primary and metastatic colorectal carcinomas. Fresh-frozen biopsy specimens from 77 primary and metastatic colorectal carcinomas of randomly selected patients were analyzed by PCR and immunohistochemistry. We investigated 57 primary tumors and 20 metastases, comprising 13 tumor pairs from the same patient. In PCR, four primary tumors showed a positive CMV result whereas all investigated metastases were negative including three paired samples from positive primaries. In immunohistochemistry, no specific staining could be determined in all neoplastic epithelial cells. In summary, we think that there is no association between CMV infection and tumor progression or metastasis formation of colorectal cancer.

Binding of human cytomegalovirus to sulfated glucuronyl glycosphingolipids and their inhibitory effects on the infection.

Interactions between human cytomegalovirus (HCMV) and various carbohydrate structures were analysed using sulfated glucuronyl glycosphingolipids (SGGLs) and the structurally related glycosphingolipids (GLs). A thin-layer chromatography-overlay assay and a solid-phase binding assay revealed that HCMV strongly bound to sulfated glucuronyl lactosaminylparagloboside, one of the SGGLs having the repeating lactosamine structure (3Gal beta1-4GlcNAc1-)2 in addition to the 3-O-sulfated glucuronyl moiety. The virus bound less strongly to other 3-O-sulfated GLs, which included sulfated glucuronyl paragloboside and cerebroside sulfate ester, and also to (3Gal beta1-4GlcNAc1-)2-containing GLs that included nLc6Cer. Thus, a (3Gal beta1-4GlcNAc1-)2 and a 3-O-sulfated saccharide seem to be important structures for the binding by HCMV. When virus particles were preincubated with these GLs, inhibitory effects were observed both on expression of the viral immediate-early gene and on plaque formation by HCMV. These effects were very well correlated with the abilities of the GLs to bind to the virus. Pretreatment of host cells with HNK-1 monoclonal antibody, which specifically recognizes SGGLs, resulted in partial inhibition of plaque formation by HCMV. These results clearly show that HCMV recognizes and binds to the sulfated carbohydrate structure in SGGL and also suggest that binding of HCMV to the specific sugar structure may play an important role in HCMV infection.

Evidence for the role of cell protein phosphorylation in human cytomegalovirus/host cell fusion.

The mechanism by which human cytomegalovirus (HCMV) enters cells is unknown. We sought evidence that protein phosphorylation plays a role in HCMV infection in two ways: (1) by determining whether the degree of phosphorylation of a constitutively phosphorylated 92.5 kDa putative cell membrane receptor for HCMV gH is changed following exposure to HCMV or monoclonal anti-idiotype antibodies (MAb2) that antigenically mimic HCMV gH, and (2) by studying the effects of protein kinase inhibition on receptor phosphorylation and HCMV adsorption or fusion. Phosphorylation of the 92.5 kDa cell membrane protein was specifically increased within 10 min of incubation with HCMV or MAb2 that had been crosslinked by goat anti-mouse antibodies. In addition, fusion of viral envelope with the cell membrane was inhibited by certain protein kinase inhibitors which also inhibited receptor phosphorylation, while the adsorption of [3H]HCMV to human embryonic lung cells was not affected. Tyrosine kinase inhibitors inhibited virus/cell fusion to a greater extent than protein kinase C (PKC) inhibitors, and an inhibitor which primarily affects cAMP and cGMP kinases had little effect. In addition, fusion was stimulated by preincubating cells with agents that stimulated receptor phosphorylation including a phorbol ester, tyrosine phosphatase inhibitor and serine/threonine phosphatase inhibitor. These data indicate that increased phosphorylation of a 92.5 kDa putative cell membrane protein receptor for gH is an early event in response to HCMV, and that cell protein phosphorylation by tyrosine kinase(s) and PKC may facilitate HCMV/cell membrane fusion.

Identification and molecular characterization of the murine cytomegalovirus homolog of the human cytomegalovirus UL100 gene

The UL100 gene of human cytomegalovirus (HCMV) has been shown to encode an envelope glycoprotein that might play an important role in HCMV infection. Using the HCMV UL100 gene as a probe in low stringency hybridization studies, we were able to identify the putative UL100 homologous gene of murine cytomegalovirus (MCMV), strain Smith. The MCMV gene was sequenced and localized to the left end of the EcoRI fragment H on the MCMV physical map. This genomic location is similar to that found for the HCMV UL100 gene. The MCMV UL100 mRNA is 1.6 kb in size and is expressed exclusively in the late stages of infection. The 5′ and 3′ boundaries of the transcript were determined. The open reading frame (ORF) of the UL100 gene could encode a protein of 371 amino acid residues with a calculated molecular mass of 42 kDa. Computer analysis of the deduced amino acid sequence of this gene predicted the presence of eight transmembrane domains and four N-linked glycosylation sites in the protein. Sequence comparison revealed that this putative protein shares similarity with the predicted UL100 homologs of several other herpesviruses, and is most similar to the HCMV UL100 protein (47% identity).