The cytomegaloviruses: ubiquitous agents with protean clinical manifestations. I

Human cytomegalovirus harnesses host L1 retrotransposon for efficient replication

Genetic parasites, including viruses and transposons, exploit components from the host for their own replication. However, little is known about virus-transposon interactions within host cells. Here, we discover a strategy where human cytomegalovirus (HCMV) hijacks L1 retrotransposon encoded protein during its replication cycle. HCMV infection upregulates L1 expression by enhancing both the expression of L1-activating transcription factors, YY1 and RUNX3, and the chromatin accessibility of L1 promoter regions. Increased L1 expression, in turn, promotes HCMV replicative fitness. Affinity proteomics reveals UL44, HCMV DNA polymerase subunit, as the most abundant viral binding protein of the L1 ribonucleoprotein (RNP) complex. UL44 directly interacts with L1 ORF2p, inducing DNA damage responses in replicating HCMV compartments. While increased L1-induced mutagenesis is not observed in HCMV for genetic adaptation, the interplay between UL44 and ORF2p accelerates viral DNA replication by alleviating replication stress. Our findings shed light on how HCMV exploits host retrotransposons for enhanced viral fitness.

Mouse cytomegalovirus lacking sgg1 shows reduced import into the salivary glands

Cytomegaloviruses (CMVs) transmit via chronic shedding from the salivary glands. How this relates to the broad cell tropism they exhibit in vitro is unclear. Human CMV (HCMV) infection presents only after salivary gland infection is established. Murine CMV (MCMV) is therefore useful to analyse early infection events. It reaches the salivary glands via infected myeloid cells. Three adjacent spliced genes designated as m131/129 (MCK-2), sgg1 and sgg1.1, positional homologues of the HCMV UL128/130/131 tropism determinants, are implicated. We show that a sgg1 null mutant is defective in infected myeloid cell entry into the salivary glands, a phenotype distinct from MCMV lacking MCK-2. These data point to a complex, multi-step process of salivary gland colonization.

Cognitive Effects of Toxoplasma and CMV Infections: A Cross-Sectional Study of 557 Young Adults Considering Modulation by Sex and Rh Factor

One-third of humanity harbors a lifelong infection with Toxoplasma gondii, and probably about 80% are infected with human cytomegalovirus (CMV). This study aims to delineate the associations between toxoplasmosis and cognitive abilities and compare these to the associations with CMV. We evaluated the cognitive performance of 557 students, who had been examined for Toxoplasma and CMV infections, using intelligence, memory, and psychomotor tests. The results indicated cognitive impairments in seropositive individuals for both pathogens, with variations in cognitive impact related to sex and the Rh factor. Specifically, Toxoplasma infection was associated with lower IQ in men, whereas CMV was predominantly associated with worse performance by women when testing memory and reaction speeds. Analysis of the antibody concentrations indicated that certain Toxoplasma-associated cognitive detrimental effects may wane (impaired intelligence) or worsen (impaired reaction times) over time following infection. The findings imply that the cognitive impairments caused by both neurotropic pathogens are likely due to pathological changes in the brain rather than from direct manipulative action by the parasites.

Impact of Cytomegalovirus (CMV) on an Academic Pediatric Infectious Diseases Outpatient Clinic Referral Population, 2005-2020: Will the Advent of Universal Congenital CMV (cCMV) Screening Change Clinical Practice Referral Patterns?

Cytomegalovirus (CMV) infections exert a substantial impact on the practice of pediatric infectious diseases. Although most infections in children are minimally symptomatic, several populations are at risk for CMV-associated disease, including immunosuppressed children, children with HIV infection, and, most significantly, children with congenital CMV (cCMV) infection. In spite of the ubiquitous nature of CMV infection, few studies have quantified the impact of CMV-associated care in a pediatric outpatient clinic setting. We evaluated the impact of CMV on clinical care in an outpatient clinic setting over a fifteen-year period at the University of Minnesota (UMN) Masonic Children's Hospital Pediatric Infectious Diseases (PID) Clinic. A retrospective review of clinic appointments identified 253 unique patients specifically evaluated over this time period for consideration of CMV infection. Of these, 242 were pediatric patients. The majority of the pediatric patients evaluated in the PID clinic were referred for either confirmed or suspected cCMV infection, including children referred for consideration of CMV as a potential reason for a failed newborn hearing screen (NHS) and/or for evaluation of CMV as a possible etiology for documented hearing loss. In total, 116 of the children evaluated during this time period (48%) were unequivocally confirmed as having cCMV infection, with an additional 37 (15%) presenting with presumed, probable, or possible cCMV infection. A total of 16 (7%) of the pediatric CMV cases were confirmed to be post-natally acquired infections. Of the 253 total patients, 11 (4%) of the referrals were for pregnant patients seeking advice about potential therapies in the setting of a known or suspected primary maternal infection during their pregnancies, with an attendant risk of fetal CMV infection. This overview of the demographics and referral patterns for patients evaluated for known or suspected CMV infections in a tertiary care center outpatient PID clinic will serve as a useful baseline assessment, even as future patterns of outpatient care are highly likely to evolve. We predict that PID clinic referrals for newborns identified by universal cCMV screening programs will result in a shift of the CMV outpatient population to healthier infants with clinically inapparent infections, and care will need to be taken by practitioners not to over-medicalize management for these asymptomatic newborns.

Cross-Species Analysis of Innate Immune Antagonism by Cytomegalovirus IE1 Protein

The human cytomegalovirus (CMV) immediate early 1 (IE1) protein has evolved as a multifunctional antagonist of intrinsic and innate immune mechanisms. In addition, this protein serves as a transactivator and potential genome maintenance protein. Recently, the crystal structures of the human and rat CMV IE1 (hIE1, rIE1) core domain were solved. Despite low sequence identity, the respective structures display a highly similar, all alpha-helical fold with distinct variations. To elucidate which activities of IE1 are either species-specific or conserved, this study aimed at a comparative analysis of hIE1 and rIE1 functions. To facilitate the quantitative evaluation of interactions between IE1 and cellular proteins, a sensitive NanoBRET assay was established. This confirmed the species-specific interaction of IE1 with the cellular restriction factor promyelocytic leukemia protein (PML) and with the DNA replication factor flap endonuclease 1 (FEN1). To characterize the respective binding surfaces, helix exchange mutants were generated by swapping hIE1 helices with the corresponding rIE1 helices. Interestingly, while all mutants were defective for PML binding, loss of FEN1 interaction was confined to the exchange of helices 1 and 2, suggesting that FEN1 binds to the stalk region of IE1. Furthermore, our data reveal that both hIE1 and rIE1 antagonize human STAT2; however, distinct regions of the respective viral proteins mediated the interaction. Finally, while PML, FEN1, and STAT2 binding were conserved between primate and rodent proteins, we detected that rIE1 lacks a chromatin tethering function suggesting that this activity is dispensable for rat CMV. In conclusion, our study revealed conserved and distinct functions of primate and rodent IE1 proteins, further supporting the concept that IE1 proteins underwent a narrow co-evolution with their respective hosts to maximize their efficacy in antagonizing innate immune mechanisms and supporting viral replication.

Distinguishing cytomegalovirus meningoencephalitis from other viral central nervous system infections

BACKGROUND

Hallmarks of cytomegalovirus (CMV) meningoencephalitis include fever, altered mental status, or meningismus with pleocytosis, elevated protein and hypoglycorrhachia on cerebrospinal fluid (CSF) analysis. Magnetic resonance imaging may show ventriculitis, ependymitis or periventricular enhancement. Studies are limited comparing clinical and laboratory characteristics to other viral etiologies.

OBJECTIVES

This multi-center, retrospective cohort analysis reviewed patients with CMV meningitis or encephalitis and compared clinical features, laboratory findings and outcomes to the most common viral causes of meningoencephalitis.

STUDY DESIGN

Patients with encephalitis or aseptic meningitis and detectable genetic material by polymerase chain reaction were identified. Clinical characteristics, laboratory findings and neuroimaging were collected from the electronic medical record. Data analysis was performed comparing CMV to other viral etiologies.

RESULTS

485 patients were evaluated and included cases of CMV (n = 36) which were compared with herpes simplex virus (n = 114), enterovirus (n = 207), varicella zoster virus (n = 41) and West Nile virus (n = 81). Human immunodeficiency virus (HIV) infection was seen more frequently in CMV infection compared with all other viral etiologies. Clinical presentations and CSF findings of other viral etiologies differ compared with CMV. Hypoglycorrhacia occurred more often with CMV compared with other viral pathogens. Outcomes were significantly worse compared with enterovirus, herpes simplex virus and varicella zoster virus but not West Nile virus.

CONCLUSIONS

CMV meningoencephalitis occurs most often in patients with HIV and encephalitis occurs more frequently than meningitis. Clinical and laboratory findings differ compared with other viral etiologies and can support consideration of CMV in the differential diagnosis of patients with meningoencephalitis.

Herpes Simplex Virus 1 Infection of Neuronal and Non-Neuronal Cells Elicits Specific Innate Immune Responses and Immune Evasion Mechanisms

Alphaherpesviruses (α-HV) are a large family of double-stranded DNA viruses which cause many human and animal diseases. There are three human α-HVs: Herpes Simplex Viruses (HSV-1 and HSV-2) and Varicella Zoster Virus (VZV). All α-HV have evolved multiple strategies to suppress or exploit host cell innate immune signaling pathways to aid in their infections. All α-HVs initially infect epithelial cells (primary site of infection), and later spread to infect innervating sensory neurons. As with all herpesviruses, α-HVs have both a lytic (productive) and latent (dormant) stage of infection. During the lytic stage, the virus rapidly replicates in epithelial cells before it is cleared by the immune system. In contrast, latent infection in host neurons is a life-long infection. Upon infection of mucosal epithelial cells, herpesviruses immediately employ a variety of cellular mechanisms to evade host detection during active replication. Next, infectious viral progeny bud from infected cells and fuse to neuronal axonal terminals. Here, the nucleocapsid is transported via sensory neuron axons to the ganglion cell body, where latency is established until viral reactivation. This review will primarily focus on how HSV-1 induces various innate immune responses, including host cell recognition of viral constituents by pattern-recognition receptors (PRRs), induction of IFN-mediated immune responses involving toll-like receptor (TLR) signaling pathways, and cyclic GMP-AMP synthase stimulator of interferon genes (cGAS-STING). This review focuses on these pathways along with other mechanisms including autophagy and the complement system. We will summarize and discuss recent evidence which has revealed how HSV-1 is able to manipulate and evade host antiviral innate immune responses both in neuronal (sensory neurons of the trigeminal ganglia) and non-neuronal (epithelial) cells. Understanding the innate immune response mechanisms triggered by HSV-1 infection, and the mechanisms of innate immune evasion, will impact the development of future therapeutic treatments.

Association between Viral Infections and Risk of Autistic Disorder: An Overview

Autism spectrum disorder (ASD) is a neurodevelopmental condition of the central nervous system (CNS) that presents with severe communication problems, impairment of social interactions, and stereotypic behaviours. Emerging studies indicate possible associations between viral infections and neurodegenerative and neurobehavioural conditions including autism. Viral infection during critical periods of early in utero neurodevelopment may lead to increased risk of autism in the offspring. This review is aimed at highlighting the association between viral infections, including viruses similar to COVID-19, and the aetiology of autism. A literature search was conducted using Pubmed, Ovid/Medline, and Google Scholar database. Relevant search terms included "rubella and autism", "cytomegalovirus and autism", "influenza virus and autism", "Zika virus and autism", "COVID-19 and autism". Based on the search terms, a total of 141 articles were obtained and studies on infants or children with congenital or perinatal viral infection and autistic behaviour were evaluated. The possible mechanisms by which viral infections could lead to autism include direct teratogenic effects and indirect effects of inflammation or maternal immune activation on the developing brain. Brain imaging studies have shown that the ensuing immune response from these viral infections could lead to disruption of the development of brain regions and structures. Hence, long-term follow up is necessary for infants whose mothers report an inflammatory event due to viral infection at any time during pregnancy to monitor for signs of autism. Research into the role of viral infection in the development of ASD may be one avenue of improving ASD outcomes in the future. Early screening and diagnosis to detect, and maybe even prevent ASD are essential to reduce the burden of this condition.

Pathogenesis of human cytomegalovirus in the immunocompromised host

Human cytomegalovirus (HCMV) is a herpesvirus that infects ~60% of adults in developed countries and more than 90% in developing countries. Usually, it is controlled by a vigorous immune response so that infections are asymptomatic or symptoms are mild. However, if the immune system is compromised, HCMV can replicate to high levels and cause serious end organ disease. Substantial progress is being made in understanding the natural history and pathogenesis of HCMV infection and disease in the immunocompromised host. Serial measures of viral load defined the dynamics of HCMV replication and are now used routinely to allow intervention with antiviral drugs in individual patients. They are also used as pharmacodynamic read-outs to evaluate prototype vaccines that may protect against HCMV replication and to define immune correlates of this protection. This novel information is informing the design of randomized controlled trials of new antiviral drugs and vaccines currently under evaluation. In this Review, we discuss immune responses to HCMV and countermeasures deployed by the virus, the establishment of latency and reactivation from it, exogenous reinfection with additional strains, pathogenesis, development of end organ disease, indirect effects of infection, immune correlates of control of replication, current treatment strategies and the evaluation of novel vaccine candidates.

Involvement of heparan sulfate during mouse cytomegalovirus infection in murine-derived immortalized neuronal cell line

Cytomegalovirus infection cause of severe developmental disorders of the CNS. Aim: In this study, we utilized a differentiated mouse-derived hippocampal cell line (dHT22) to understand mouse CMV (MCMV) infection. Results: The expression of immediate early genes ( IE) 1 and 3 confirmed the time-dependent susceptibility of dHT22 cells to MCMV infection. MCMV infection alters the cellular distribution of heparan sulfate (HS). In addition, pretreatment with heparinase significantly reduces virus infectivity. Conclusion: The compartmentalization of HS in MCMV infected cells suggests multiple roles of HS in virus life cycle ranging from viral entry to viral transport and cellular remodeling. An enzymatic heparinase assay confirmed that HS is critical for viral entry and trafficking.

Inhibition of Human Cytomegalovirus Entry into Host Cells Through a Pleiotropic Small Molecule

Human cytomegalovirus (HCMV) infections are wide-spread among the general population with manifestations ranging from asymptomatic to severe developmental disabilities in newborns and life-threatening illnesses in individuals with a compromised immune system. Nearly all current drugs suffer from one or more limitations, which emphasizes the critical need to develop new approaches and new molecules. We reasoned that a ‘poly-pharmacy’ approach relying on simultaneous binding to multiple receptors involved in HCMV entry into host cells could pave the way to a more effective therapeutic outcome. This work presents the study of a synthetic, small molecule displaying pleiotropicity of interactions as a competitive antagonist of viral or cell surface receptors including heparan sulfate proteoglycans and heparan sulfate-binding proteins, which play important roles in HCMV entry and spread. Sulfated pentagalloylglucoside (SPGG), a functional mimetic of heparan sulfate, inhibits HCMV entry into human foreskin fibroblasts and neuroepithelioma cells with high potency. At the same time, SPGG exhibits no toxicity at levels as high as 50-fold more than its inhibition potency. Interestingly, cell-ELISA assays showed downregulation in HCMV immediate-early gene 1 and 2 (IE 1&2) expression in presence of SPGG further supporting inhibition of viral entry. Finally, HCMV foci were observed to decrease significantly in the presence of SPGG suggesting impact on viral spread too. Overall, this work offers the first evidence that pleiotropicity, such as demonstrated by SPGG, may offer a new poly-therapeutic approach toward effective inhibition of HCMV.

Cytomegalovirus Kinetics Following Primary Infection in Healthy Women

The kinetics of cytomegalovirus (CMV) DNA in infected asymptomatic hosts are largely unknown. We measured viral load (VL) in 124 fluid samples (oral, urine, vaginal, blood) collected from 21 women who acquired CMV. A quantitative real-time polymerase chain reaction assay of US17, which correlated with clinical assays, was used. VL decreased following primary infection in all fluids. The geometric mean VL of vaginal fluid was significantly higher than that of other sources: oral (3.89; 95% confidence interval [CI], 1.43-10.57), urine (6.36; 95% CI, 2.48-16.32), and whole blood (11.88; 95% CI, 4.12-34.20). Vaginal CMV shedding may provide a route for sexual and possibly perinatal transmission.

Review of cytomegalovirus coinfection in HIV-infected individuals in Africa

BACKGROUND

Cytomegalovirus (CMV) infection among HIV-infected individuals may cause end-organ disease, which is an AIDS-defining condition. Evidence from high-income countries suggests that CMV may alter the outcome of HIV infection, other than causing end-organ diseases. We reviewed literature on HIV and CMV coinfection in Africa.

METHODS

Systematic review of published studies on HIV and CMV coinfection in Africa using the PubMed database.

RESULTS

High CMV seroprevalence was found throughout Africa, exceeding 90% in most populations. Retinitis, pneumonia, and colitis were the most commonly reported CMV manifestations in HIV-infected individuals. Among patients with pulmonary symptoms, the prevalence of CMV pneumonitis varied from 20% to over 60%, whereas CMV was found in 0% to 14% of patients with gastrointestinal manifestations. Cytomegalovirus retinitis was found in 0% to 2.6% of examined HIV-infected individuals. The diagnostics of CMV end-organ diseases were found complex and difficult to interpret in African settings. Cytomegalovirus viremia was correlated with significantly lower CD4 cell count and increase in activated and apoptosis vulnerable T-lymphocytes. Also, CMV coinfection was found to be associated with increased transmission and progression of HIV infection. Moreover, detectable CMV DNA was an independent predictor of HIV transmission and mortality among HIV-infected individuals.

CONCLUSIONS

Cytomegalovirus is highly prevalent in Africa and a common cause of disease manifestations in HIV-infected individuals among all age groups. Cytomegalovirus coinfection in HIV-infected individuals in Africa is associated with increased transmission and mortality of HIV, but it is a neglected area of research.

Infection and Atherosclerosis Development

Atherosclerosis is a chronic disease hallmarked by chronic inflammation, endothelial dysfunction and lipid accumulation in the vasculature. Although lipid modification and deposition are thought to be a major source of the continuous inflammatory stimulus, a large body of evidence suggests that infectious agents may contribute to atherosclerotic processes. This could occur by either direct effects through infection of vascular cells and/or through indirect effects by induction of cytokine and acute phase reactant proteins by infection at other sites. Multiple bacterial and viral pathogens have been associated with atherosclerosis by seroepidemiological studies, identification of the infectious agent in human atherosclerotic tissue, and experimental studies demonstrating an acceleration of atherosclerosis following infection in animal models of atherosclerosis. This review will focus on those infectious agents for which biological plausibility has been demonstrated in animal models and on the challenges of proving a role of infection in human atherosclerotic disease.

The immunological underpinnings of vaccinations to prevent cytomegalovirus disease

A universal cytomegalovirus (CMV) vaccination promises to reduce the burden of the developmental damage that afflicts up to 0.5% of live births worldwide. An effective vaccination that prevents transplacental transmission would reduce CMV congenital disease and CMV-associated still births and leave populations less susceptible to opportunistic CMV disease. Thus, a vaccination against this virus has long been recognized for the potential of enormous health-care savings because congenital damage is life-long and existing anti-viral options are limited. Vaccine researchers, industry leaders, and regulatory representatives have discussed the challenges posed by clinical efficacy trials that would lead to a universal CMV vaccine, reviewing the links between infection and disease, and identifying settings where disrupting viral transmission might provide a surrogate endpoint for disease prevention. Reducing the complexity of such trials would facilitate vaccine development. Children and adolescents are the targets for universal vaccination, with the expectation of protecting the offspring of immunized women. Given that a majority of females worldwide experience CMV infection during childhood, a universal vaccine must boost natural immunity and reduce transmission due to reactivation and re-infection as well as primary infection during pregnancy. Although current vaccine strategies recognize the value of humoral and cellular immunity, the precise mechanisms that act at the placental interface remain elusive. Immunity resulting from natural infection appears to limit rather than prevent reactivation of latent viruses and susceptibility to re-infection, leaving a challenge for universal vaccination to improve upon natural immunity levels. Despite these hurdles, early phase clinical trials have achieved primary end points in CMV seronegative subjects. Efficacy studies must be expanded to mixed populations of CMV-naive and naturally infected subjects to understand the overall efficacy and potential. Together with CMV vaccine candidates currently in clinical development, additional promising preclinical strategies continue to come forward; however, these face limitations due to the insufficient understanding of host defense mechanisms that prevent transmission, as well as the age-old challenges of reaching the appropriate threshold of immunogenicity, efficacy, durability and potency. This review focuses on the current understanding of natural and CMV vaccine-induced protective immunity.

Overview of congenitally and perinatally acquired cytomegalovirus infections: recent advances in antiviral therapy

Congenital and perinatal infection with human cytomegalovirus (CMV) are commonly encountered in newborns. In recent years there has been increased awareness of the disabilities that result from congenital CMV infection, which in turn has prompted interest in examining the potential efficacy of antiviral agents to prevent or ameliorate neurodevelopmental injury. Currently, there are three licensed systemic antivirals for the treatment of CMV: ganciclovir (Cytovene, Roche] and its prodrug valganciclovir [Valcyte, Roche); foscarnet (Foscavir, AstraZeneca); and cidofovir (Vistide, Pharmacia). A CMV-specific immunoglobulin is also available. Experience with these agents in the setting of congenital and perinatal CMV infection is very limited, but there are encouraging data from a controlled clinical trial indicating that ganciclovir therapy may be of value in limiting one form of neurodevelopmental injury caused by congenital infection, that of sensorineural hearing loss. Licensed antivirals for the treatment of CMV all share the common mechanism of targeting the viral DNA polymerase, but novel therapies that employ alternative modes of action are in development. Ultimately, the problem of perinatal CMV infection may be best controlled by the development of CMV vaccines, which could be administered to young women of childbearing age to help control this important public health problem.

Cytomegalovirus protease targeted prodrug development

Human cytomegalovirus (HCMV) is a prevalent virus that infects up to 90% of the population. The goal of this research is to determine if small molecular prodrug substrates can be developed for a specific HCMV encoded protease and thus achieve site-specific activation. HCMV encodes a 256 amino acid serine protease that is responsible for capsid assembly, an essential process for herpes virus production. The esterase activity of the more stable HCMV A143T/A144T protease mutant was evaluated with model p-nitrophenol (ONp) esters, Boc-Xaa-ONp (Ala, Leu, Ile, Val, Gln, Phe at the Xaa position). We demonstrate that the A143T/A144T mutant has esterase activity toward specific small ester compounds, e.g., Boc-l-Ala-ONp. Mono amino acid and dipeptide prodrugs of ganciclovir (GCV) were also synthesized and evaluated for hydrolysis by the A143T/A144T protease mutant in solution. Hydrolysis of these prodrugs was also evaluated in Caco-2 cell homogenates, human liver microsomes (HLMs), and rat and human plasma. For the selectivity potential of the prodrugs, the hydrolysis ratio was evaluated as a percentage of prodrug hydrolyzed by the HCMV protease over the percentages of prodrug hydrolyses by Caco-2 cell homogenates, HLMs, and human/rat plasma. A dipeptide prodrug of ganciclovir, Ac-l-Gln-l-Ala-GCV, emerged as a potential selective prodrug candidate. The results of this research demonstrate that targeting prodrugs for activation by a specific protease encoded by the infectious HCMV pathogen may be achievable.

Burden of disease associated with human cytomegalovirus and prospects for elimination by universal immunisation

Cytomegalovirus is the most frequent cause of intrauterine infection and the commonest infectious agent to affect allograft recipients, yet the virus is acknowledged rarely as an occupational hazard for women of childbearing age or as a nosocomial infection. The potential role of cytomegalovirus in hastening the death of patients with AIDS, elderly people, individuals admitted to intensive-care units, and the general population is not emphasised. Development of vaccines against this important human pathogen has been delayed by reluctance to initiate proof-of-concept studies, but after recent trials, protection is a distinct possibility. Cytomegalovirus deserves to be eliminated from selected populations by means of universal immunisation as soon as suitable vaccines become licensed. This action should control disease in neonates and transplant recipients and could provide substantial additional benefits if other disease associations prove to be causal.

Seroprevalence of cytomegalovirus, Toxoplasma gondii, syphilis, and hepatitis B and C virus infections in a regional population seropositive for HIV infection

OBJECTIVE

To determine the prevalence of exposure to cytomegalovirus (CMV), Toxoplasma gondii, syphilis, hepatitis B virus (HBV) and hepatitis C virus (HCV) in a large, well characterized, regional population presenting for human immunodeficency virus (HIV) care.

DESIGN

Demographic and serological data compiled prospectively in a relational database used for routine patient care. Results were analyzed for statistically significant trends within demographic subpopulations known to be at risk of such infections.

PATIENTS AND SETTING

A total of 1274 persons with documented HIV infection in southern Alberta have sought medical care since 1985. Serological status to CMV, T gondii, syphilis, HBV and HCV infections were routinely requested as part of the initial assessment. All patients with serological results available were included in the analysis.

RESULTS

CMV infection was found in 84.1% of patients. A lower prevalence of CMV infection in those under 30 yeasr old (P<0.001), intravenous drug users (IVDUs) (P=0.001) and in patients with transfusion-acquired HIV (P<0.001) was seen. T gondii seropositivity was found in 10.6% of patients, with an increased risk of seropositivity in those born outside of Canada (P<0.001). Syphilis seropositivity was present in 5.1% of patients, with a higher prevalence in gay males (P=0.1). HBV carrier status was noted in 8.0% of patients, with males having an increased risk (P=0.025). Since 1990, there has been a 17.6% prevalence of HCV, predominantly in IVDUs (P<0.001).

CONCLUSION

Seroprevalence to common pathogens in HIV disease varies significantly among subpopulations, necessitating individual testing.

An infant case of dilated cardiomyopathy associated with congenital cytomegalovirus infection

A 2-month-old infant with congestive heart failure was referred to the authors' hospital. Echocardiography exhibited a dilated left ventricle (LV), poor LV systolic function, and intraventricular thrombus. Laboratory data showed a normal creatinine phosphokinase level and negative troponin T test results. The congestive heart failure was managed using a beta-blocker, an angiotensin receptor blocker, and diuretics. Head computed tomography performed during the treatment course showed periventricular calcifications. Congenital cytomegalovirus infection was subsequently diagnosed. Fetal echocardiography performed during pregnancy showed impaired LV function, suggesting that the cardiomyopathy was associated with cytomegalovirus infection in utero.

Design and analysis of rhesus cytomegalovirus IL-10 mutants as a model for novel vaccines against human cytomegalovirus

BACKGROUND

Human cytomegalovirus (HCMV) expresses a viral ortholog (CMVIL-10) of human cellular interleukin-10 (cIL-10). Despite only ∼26% amino acid sequence identity, CMVIL-10 exhibits comparable immunosuppressive activity with cIL-10, attenuates HCMV antiviral immune responses, and contributes to lifelong persistence within infected hosts. The low sequence identity between CMVIL-10 and cIL-10 suggests vaccination with CMVIL-10 may generate antibodies that specifically neutralize CMVIL-10 biological activity, but not the cellular cytokine, cIL-10. However, immunization with functional CMVIL-10 might be detrimental to the host because of its immunosuppressive properties.

METHODS AND FINDINGS

Structural biology was used to engineer biologically inactive mutants of CMVIL-10 that would, upon vaccination, elicit a potent immune response to the wild-type viral cytokine. To test the designed proteins, the mutations were incorporated into the rhesus cytomegalovirus (RhCMV) ortholog of CMVIL-10 (RhCMVIL-10) and used to vaccinate RhCMV-infected rhesus macaques. Immunization with the inactive RhCMVIL-10 mutants stimulated antibodies against wild-type RhCMVIL-10 that neutralized its biological activity, but did not cross-react with rhesus cellular IL-10.

CONCLUSION

This study demonstrates an immunization strategy to neutralize RhCMVIL-10 biological activity using non-functional RhCMVIL-10 antigens. The results provide the methodology for targeting CMVIL-10 in vaccine, and therapeutic strategies, to nullify HCMV's ability to (1) skew innate and adaptive immunity, (2) disseminate from the site of primary mucosal infection, and (3) establish a lifelong persistent infection.

Artemisinin-derived dimers have greatly improved anti-cytomegalovirus activity compared to artemisinin monomers

BACKGROUND

Artesunate, an artemisinin-derived monomer, was reported to inhibit Cytomegalovirus (CMV) replication. We aimed to compare the in-vitro anti-CMV activity of several artemisinin-derived monomers and newly synthesized artemisinin dimers.

METHODS

Four artemisinin monomers and two novel artemisinin-derived dimers were tested for anti-CMV activity in human fibroblasts infected with luciferase-tagged highly-passaged laboratory adapted strain (Towne), and a clinical CMV isolate. Compounds were evaluated for CMV inhibition and cytotoxicity.

RESULTS

Artemisinin dimers effectively inhibited CMV replication in human foreskin fibroblasts and human embryonic lung fibroblasts (EC(50) for dimer sulfone carbamate and dimer primary alcohol 0.06+/-0.00 microM and 0.15+/-0.02 microM respectively, in human foreskin fibroblasts) with no cytotxicity at concentrations required for complete CMV inhibition. All four artemisinin monomers (artemisinin, artesunate, artemether and artefanilide) shared a similar degree of CMV inhibition amongst themselves (in microM concentrations) which was significantly less than the inhibition achieved with artemisinin dimers (P<0.0001). Similar to monomers, inhibition of CMV with artemisinin dimers appeared early in the virus life cycle as reflected by decreased expression of the immediate early (IE1) protein.

CONCLUSIONS

Artemisinin dimers are potent and non-cytotoxic inhibitors of CMV replication. These compounds should be studied as potential therapeutic agents for the treatment of CMV infection in humans.

Neurodevelopmental outcomes following ganciclovir therapy in symptomatic congenital cytomegalovirus infections involving the central nervous system

BACKGROUND

Ganciclovir protects against hearing deterioration in infants with symptomatic congenital cytomegalovirus (CMV) disease involving the central nervous system (CNS).

OBJECTIVES

To assess the neurodevelopmental impact of ganciclovir therapy in this population.

STUDY DESIGN

100 neonates were enrolled into a controlled Phase III study of symptomatic congenital CMV involving the CNS, and were randomized to either 6 weeks of intravenous ganciclovir or no treatment. Denver developmental tests were performed at 6 weeks, 6 months, and 12 months. For each age, developmental milestones that > or =90% of normal children would be expected to have achieved were identified. The numbers of milestones not met ("delays") were determined for each subject. The average number of delays per subject was compared for each treatment group.

RESULTS

At 6 months, the average number of delays was 4.46 and 7.51, respectively, for ganciclovir recipients and "no treatment" subjects (p=0.02). At 12 months, the average number of delays was 10.06 and 17.14, respectively (p=0.007). In a multivariate regression model, the effect of ganciclovir therapy remained statistically significant at 12 months (p=0.007).

CONCLUSIONS

Infants with symptomatic congenital CMV involving the CNS receiving intravenous ganciclovir therapy have fewer developmental delays at 6 and 12 months compared with untreated infants. Based on these data as well as the previously published data regarding ganciclovir treatment and hearing outcomes, 6 weeks of intravenous ganciclovir therapy can be considered in the management of babies with symptomatic congenital CMV disease involving the CNS. If treatment is initiated, it should be started within the first month of life and patients should be monitored closely for toxicity, especially neutropenia. Since existing data only address the treatment of symptomatic congenital CMV disease involving the CNS, these data cannot be extrapolated to neonates with other manifestations of CMV disease, including asymptomatic babies and symptomatic babies who do not have CNS involvement.

Equine gammaherpesviruses: pathogenesis, epidemiology and diagnosis

Equine gammaherpesviruses (γEHV) have been widely studied over the past 45 years and many isolates have been characterised. Despite this, the diagnosis of γEHV infection remains difficult to establish as its clinical manifestations lack specificity, ranging from mild respiratory signs in a small number of animals to outbreaks in large groups of young horses. This review focuses on the epidemiology, pathogenesis, clinical manifestations and diagnosis of equine herpesvirus (EHV)-2 and -5 infections, as well as on the genetic variation of these viruses. Study of these variations has resulted in hypotheses relating to viral re-infection and re-activation. Interestingly, the viruses were found to contain genetic sequences identical to those of eukaryotic cells which are considered central to the development of viral latency through interfering with host immune and inflammatory responses. Future molecular biological studies will further elucidate the virulence mechanisms of these equine pathogens.

Mouse embryonic stem cells are not susceptible to cytomegalovirus but acquire susceptibility during differentiation

BACKGROUND

Cytomegalovirus (CMV) is the most significant infectious cause of congenital anomalies of the central nervous system caused by intrauterine infection in humans. The timing of infection and the susceptibility of cells in early gestational stages are not well understood. In this study we investigated the susceptibility of embryonic stem (ES) cells to CMV infection during differentiation.

METHODS

ES cell lines were established from transgenic mice integrated with the murine CMV (MCMV) immediate-early (IE) promoter connected with a reporter lacZ gene. The susceptibility of the ES cells was analyzed in terms of viral gene expression and viral replication after induction of differentiation.

RESULTS

ES cells were nonpermissive to MCMV infection in the undifferentiated state. Upon differentiation, permissive cells appeared approximately 2 weeks after the leukemia inhibitory factor was removed. Upon neural differentiation by retinoic acid (RA), glial cells showed specific susceptibility in terms of expression of the viral antigen. The MCMV IE promoter was not activated in ES cells from the transgenic mice. Activation of the IE promoter was detected approximately 2 weeks after induction of differentiation and observed predominantly in glial cells. Upon MCMV infection of the ES cells, viral infection was correlated with the activation of the IE promoter.

CONCLUSIONS

ES cells are nonpermissive to MCMV infection and acquire permissiveness about 2 weeks after induction of differentiation, especially in glial cells. Acquisition of permissiveness in differentiated ES cells may be associated with activation of the IE promoter.

Treatment of congenital cytomegalovirus infection: implications for future therapeutic strategies

Cytomegalovirus (CMV) infection is the most common cause of congenital infection in the developed world, occurring in approximately 1% of all liveborns. Symptomatic disease occurs in 10% of all congenitally infected infants, resulting in a spectrum of clinical manifestations that include microcephaly, chorioretinitis, hepatosplenomegaly and sensorineural hearing loss, among others. Even those children who are asymptomatic at birth have a risk of hearing loss, with approximately 8% experiencing this sequela. Overall, congenital CMV infection accounts for one-third of all cases of sensorineural hearing loss. The economic burden of disease exceeds $2 billion annually in the USA. Therefore, this infection has been the target for antiviral therapy. Studies performed by the National Institute of Allergy and Infectious Diseases Collaborative Antiviral Study Group (CASG) have evaluated ganciclovir for the treatment of symptomatic congenital CMV infection with central nervous system involvement. In a randomized, controlled clinical trial of ganciclovir treatment (6 mg/kg iv every 12 h for 6 weeks) brainstem-evoked responses were utilized as the primary endpoint and demonstrated stabilization of hearing both at 6 months and >1 year. Treatment was associated with neutropenia in over 60% of treated patients. Since ganciclovir must be given intravenously, studies with its prodrug, valganciclovir, have been performed to assess pharmacokinetics and pharmacodynamics. Currently, a clinical trial of 6 weeks versus 6 months of valganciclovir is being performed by the CASG. Notably, only intravenous ganciclovir and orally administered valganciclovir have been used to treat congenital CMV infection. Hopefully, other drugs such as maribavir will be available for evaluation in this population.

CD8+ T lymphocytes control murine cytomegalovirus replication in the central nervous system of newborn animals

Human CMV infection of the neonatal CNS results in long-term neurologic sequelae. To define the pathogenesis of fetal human CMV CNS infections, we investigated mechanisms of virus clearance from the CNS of neonatal BALB/c mice infected with murine CMV (MCMV). Virus titers peaked in the CNS between postnatal days 10-14 and infectious virus was undetectable by postnatal day 21. Congruent with virus clearance was the recruitment of CD8(+) T cells into the CNS. Depletion of CD8(+) T cells resulted in death by postnatal day 15 in MCMV-infected animals and increased viral loads in the liver, spleen, and the CNS, suggesting an important role for these cells in the control of MCMV replication in the newborn brain. Examination of brain mononuclear cells revealed that CD8(+) T cell infiltrates expressed high levels of CD69, CD44, and CD49d. IE1(168)-specific CD8(+) T cells accumulated in the CNS and produced IFN-gamma and TNF-alpha but not IL-2 following peptide stimulation. Moreover, adoptive transfer of brain mononuclear cells resulted in decreased virus burden in immunodepleted MCMV-infected syngeneic mice. Depletion of the CD8(+) cell population following transfer eliminated control of virus replication. In summary, these results show that functionally mature virus-specific CD8(+) T cells are recruited to the CNS in mice infected with MCMV as neonates.

Manifestations of human cytomegalovirus infection: proposed mechanisms of acute and chronic disease

Infections with human cytomegalovirus (HCMV) are a major cause of morbidity and mortality in humans with acquired or developmental deficits in innate and adaptive immunity. In the normal immunocompetent host, symptoms rarely accompany acute infections, although prolonged virus shedding is frequent. Virus persistence is established in all infected individuals and appears to be maintained by both a chronic productive infections as well as latency with restricted viral gene expression. The contributions of the each of these mechanisms to the persistence of this virus in the individual is unknown but frequent virus shedding into the saliva and genitourinary tract likely accounts for the near universal incidence of infection in most populations in the world. The pathogenesis of disease associated with acute HCMV infection is most readily attributable to lytic virus replication and end organ damage either secondary to virus replication and cell death or from host immunological responses that target virus-infected cells. Antiviral agents limit the severity of disease associated with acute HCMV infections, suggesting a requirement for virus replication in clinical syndromes associated with acute infection. End organ disease secondary to unchecked virus replication can be observed in infants infected in utero, allograft recipients receiving potent immunosuppressive agents, and patients with HIV infections that exhibit a loss of adaptive immune function. In contrast, diseases associated with chronic or persistent infections appear in normal individuals and in the allografts of the transplant recipient. The manifestations of these infections appear related to chronic inflammation, but it is unclear if poorly controlled virus replication is necessary for the different phenotypic expressions of disease that are reported in these patients. Although the relationship between HCMV infection and chronic allograft rejection is well known, the mechanisms that account for the role of this virus in graft loss are not well understood. However, the capacity of this virus to persist in the midst of intense inflammation suggests that its persistence could serve as a trigger for the induction of host-vs-graft responses or alternatively host responses to HCMV could contribute to the inflammatory milieu characteristic of chronic allograft rejection.

Natural history of perinatal cytomegaloviral infection

Epidemiological data presented here indicate that cytomegaloviral (CMV) infection is one of the most common perinatal infections found in human beings. Transmission to the offspring occurs in utero at birth and postnatally. Intrauterine infection results from primary or recurrent maternal involvement, the latter being more common in populations where infection is initially acquired during childhood or adolescence, such as in low socioeconomic settings. Congenital infection is usually subclinical with either type of maternal involvement but primary infection has a greater tendency to produce disease in the fetus. About 20% of the offspring infected in utero are damaged, infrequently with generalized disease, but more often with auditory involvement. The latter can develop in utero or postnatally and can be progressive. The major cause of recurrent maternal infection according to restriction enzyme analysis is reactivation of latent virus, which occurs in the face of substantial maternal humoral immunity, even with intrauterine transmission of virus. Reinfection by exogenous virus remains a lesser possibility for maternal recurrences. Even more commonly, CMV can be transmitted at birth from the infected maternal genital tract and postnatally through infected breast milk, especially in highly immune populations. With the possible exception of early pneumonia, these infections appear to be innocuous.

The use of artificial neural networks in prediction of congenital CMV outcome from sequence data

A large number of CMV strains has been reported to circulate in the human population, and the biological significance of these strains is currently an active area of research. The analysis of complex genetic information may be limited using conventional phylogenetic techniques.

We constructed artificial neural networks to determine their feasibility in predicting the outcome of congenital CMV disease (defined as presence of CMV symptoms at birth) based on two data sets: 54 sequences of CMV gene UL144 obtained from 54 amniotic fluids of women who contracted acute CMV infection during their pregnancy, and 80 sequences of 4 genes (US28, UL144, UL146 and UL147) obtained from urine, saliva or blood of 20 congenitally infected infants that displayed different outcomes at birth. When data from all four genes was used in the 20-infants’ set, the artificial neural network model accurately identified outcome in 90% of cases. While US28 and UL147 had low yield in predicting outcome, UL144 and UL146 predicted outcome in 80% and 85% respectively when used separately. The model identified specific nucleotide positions that were highly relevant to prediction of outcome. The artificial neural network classified genotypes in agreement with classic phylogenetic analysis. We suggest that artificial neural networks can accurately and efficiently analyze sequences obtained from larger cohorts to determine specific outcomes.\

The ANN training and analysis code is commercially available from Optimal Neural Informatics (Pikesville, MD).

Roles of neural stem progenitor cells in cytomegalovirus infection of the brain in mouse models

Cytomegalovirus (CMV) is the most significant infectious cause of brain disorders in humans. Although the brain is the principal target organ for CMV infection in infants with congenital infection and in immunocompromised patients, little has been known about cellular events in pathogenesis of the brain disorders. Mouse models have been developed by the authors for studying the cell tropism, infectious dynamics of CMV infection and the effects of CMV infection on proliferation, regeneration and differentiation of neural cells. It has been shown, using brain slice cultures and neurospheres, that neural stem progenitor (NSP) cells are the most susceptible to CMV infection in developing brains. The NSP cells are also susceptible to CMV infection in adult and aged brains. The susceptibility can be enhanced by stimulation of neurogenesis. It was shown that latent murine CMV infection occurs in NSP cells by demonstrating the reactivation in brain slice culture or neurospheres. It is hypothesized that CMV brain disorder such as microcephaly is caused by disturbance of cellular events in the ventricular regions, including proliferation and differentiation of the neural stem cells, whereas neurons are also targets in persistent CMV infection, presumably resulting in functional disorders such as mental retardation.

Cyclosporine inhibits mouse cytomegalovirus infection via a cyclophilin-dependent pathway specifically in neural stem/progenitor cells

The potential of neural stem and progenitor cell (NSPC) transplantation in neurodegenerative disease raises a concern about immunosuppressive agents and opportunistic neurotropic pathogens that may interfere with engraftment. Cytomegalovirus (CMV) is an important opportunistic pathogen infecting the central nervous system, where it may remain latent for life, following transplacental transmission. Cyclosporine (Cs), an immunosuppressive drug used in organ transplantation, where its use is associated with CMV reactivation, suppressed murine CMV (MCMV) infection in cultured NSPCs but not in fibroblasts. This activity of Cs appears to be mediated via cyclophilin (CyP) rather than via calcineurin. First, the calcineurin-specific inhibitor FK506 failed to suppress replication. Second, the CyP-specific inhibitor NIM811 strongly suppressed replication in NSPC. NSPCs maintained in the presence of NIM811 retained viral genomes for several weeks without detectable viral gene expression or obvious deleterious effects. The withdrawal of NIM811 reactivated viral replication, suggesting that the inhibitory mechanism was reversible. Finally, inhibition of endogenous CyP A (CyPA) by small interfering RNA also inhibited replication in NSPCs. These results show that MCMV replication depends upon cellular CyPA pathways in NSPCs (in a specific cell type-dependent fashion), that CyPA plays an important role in viral infection in this cell type, and that inhibition of viral replication via CyP leads to persistence of the viral genome without cell damage. Further, the calcineurin-signaling pathway conferring immunosuppression in T cells does not influence viral replication in a detectable fashion.

Enhancement of susceptibility of adult mouse brain to cytomegalovirus infection by infusion of epidermal growth factor

Neural precursor cells, including neural stem and progenitor cells, in the subventricular zone (SVZ) are the main targets for cytomegalovirus (CMV) infection in developing brains. The neural precursor cells in the SVZ of the adult brain have been reported to respond by proliferating after infusion with epidermal growth factor (EGF). Here we report the susceptibility of the precursor cells in the adult mouse brain to murine CMV (MCMV) infection. Adult mouse brains from 10-, 25-, and 70-week-old (W) mice were infused with either phosphate-buffered saline or EGF into the brain for 3 days, and then intracerebrally infected with MCMV for 5 days. The susceptibility of the adult brains to MCMV was significantly increased by infusion of EGF in terms of viral titers and viral antigen-positive cells. The susceptibility of the young adult brain from 10-week-old mice to MCMV was higher than that of the adult brains from 25-week-old or 70-week-old mice. Both the ependymal and the SVZ cells were susceptible to MCMV infection. The number of virus-infected cells in the SVZ was significantly increased by infusion of EGF, whereas the number of infected ependymal cells was not significantly increased. Among the virus-infected cells in the SVZ, 73% were positive for nestin, 87% were positive for Musashi, 86% were positive for GFAP, and 96% were positive for PCNA. These results indicate that the susceptibility of the adult brain to MCMV is correlated with the proliferative ability of the neural precursor cells in the SVZ of the adult brain.

The Production of a Diabetic Mouse Using Constructs Encoding Porcine Insulin Promoter-Driven Mutant Human Hepatocyte Nuclear Factor-1.ALPHA

A diabetic mouse model was produced using a mutant human hepatocyte nuclear factor-1alpha gene (HNF1alphaP291fsinsC) regulated by the porcine insulin promoter. The functionality of two different constructs containing HNF1alphaP291fsinsC, termed PD1 and PD2 (cytomegalovirus enhancer minus and plus), were examined in transgenic mice. The blood glucose levels and body weights of the PD1 transgenic mice did not differ from their non-transgenic littermates over the period from 3 to 8 weeks of age. Conversely, the PD2 transgenic mice exhibited hyperglycemia and decreased body weight. Western blot analysis demonstrated that mutant HNF-1alpha protein (HNF1alphaP291), derived from the PD2 transgene, was expressed in the PD2 mice. Morphometric studies of the pancreas of a PD2 mouse revealed that the number of pancreatic islets present was less than that in the non-transgenic mice, indicating disturbed islet neogenesis. These results suggest that impaired insulin secretion in disrupted islets causes hyperglycemia. In addition, the phenotype of PD2 transgenic mice similar to that of the HNF-1alpha gene-deficient mouse, which displays growth retardation and impaired viability. These results indicate that HNF1alphaP291 expression driven by the porcine insulin promoter, together with the cytomegalovirus enhancer, induces a diabetic phenotype in transgenic mice.

Nonhuman primate models of intrauterine cytomegalovirus infection

Congenital human cytomegalovirus (HCMV) infection has long been recognized as a threat to the developing fetus, even though studies have shown that only a subset of congenital infections results in clinical signs of disease. Among the estimated 8000 children who develop sequelae from congenital CMV infection each year in the United States alone, most suffer permanent developmental defects within the central nervous system. Because there is currently no approved vaccine for HCMV, and anti-HCMV drugs are not administered to gravid women with congenital infection because of potential toxicity to the fetus, there is a clear clinical need for effective strategies that minimize infection in the mother, transplacental transmission of the virus, and/or fetal disease. Animal models provide a method to understand the mechanisms of HCMV persistence and pathogenesis, and allow for testing of novel strategies that limit prenatal infection and disease. The rhesus macaque model is especially well suited for these tasks because monkeys and humans share strong developmental, immunological, anatomical, and biochemical similarities due to their close phylogenetic relationship. This nonhuman primate model provides an invaluable system to accelerate the clinical development of promising new therapies for the treatment of human disease. This review addresses salient findings with the macaque model as they relate to HCMV infection and potential avenues of discovery, including studies of intrauterine CMV infection. The complexity of the natural history of HCMV is discussed, along with the ethical and logistical issues associated with studies during pregnancy, the recent contributions of animal research in this field of study, and future prospects for increasing our understanding of immunity against HCMV disease.

Cytomegalovirus-induced embryopathology: mouse submandibular salivary gland epithelial-mesenchymal ontogeny as a model

BACKGROUND

Human studies suggest, and mouse models clearly demonstrate, that cytomegalovirus (CMV) is dysmorphic to early organ and tissue development. CMV has a particular tropism for embryonic salivary gland and other head mesenchyme. CMV has evolved to co-opt cell signaling networks so to optimize replication and survival, to the detriment of infected tissues. It has been postulated that mesenchymal infection is the critical step in disrupting organogenesis. If so, organogenesis dependent on epithelial-mesenchymal interactions would be particularly vulnerable. In this study, we chose to model the vulnerability by investigating the cell and molecular pathogenesis of CMV infected mouse embryonic submandibular salivary glands (SMGs).

RESULTS

We infected E15 SMG explants with mouse CMV (mCMV). Active infection for up to 12 days in vitro results in a remarkable cell and molecular pathology characterized by atypical ductal epithelial hyperplasia, apparent epitheliomesenchymal transformation, oncocytic-like stromal metaplasia, beta-catenin nuclear localization, and upregulation of Nfkb2, Relb, Il6, Stat3, and Cox2. Rescue with an antiviral nucleoside analogue indicates that mCMV replication is necessary to initiate and maintain SMG dysmorphogenesis.

CONCLUSION

mCMV infection of embryonic mouse explants results in dysplasia, metaplasia, and, possibly, anaplasia. The molecular pathogenesis appears to center around the activation of canonical and, perhaps more importantly, noncanonical NFkappaB. Further, COX-2 and IL-6 are important downstream effectors of embryopathology. At the cellular level, there appears to be a consequential interplay between the transformed SMG cells and the surrounding extracellular matrix, resulting in the nuclear translocation of beta-catenin. From these studies, a tentative framework has emerged within which additional studies may be planned and performed.

Differential expression of the immediate-early 2 and 3 proteins in developing mouse brains infected with murine cytomegalovirus

Murine cytomegalovirus (MCMV) immediate-early (IE) 2 protein has been reported to be dispensable for growth and latency in mice. Therefore, its role in viral pathogenesis and tissue tropism is not known. Here we prepared specific antibodies to the IE2 and IE3 proteins by using fusion proteins expressed in Escherichia coli as antigens. Immunostaining of MCMV-infected cultured fibroblasts revealed IE2 protein to be expressed diffusely in the nucleoplasm similar to the IE1 protein. In contrast, expression of the IE3 protein, 88 kDa, exhibited a punctate pattern in the nucleus in the early phase of infection then diminished. In the brain of neonatal mice infected with MCMV, both IE2 and IE3 proteins were detected immunohistochemically in the cells of the ventricular walls early in infection. When the infection was prolonged, the IE2 protein was expressed in neurons of the cortex and hippocampus, while the IE3 protein was preferentially expressed in glial cells in the early phase of infection, and its levels declined during the infection. These results suggest that the IE2 protein may play a role in persistent infection in neurons, whereas the IE3 protein, expressed preferentially in glial cells, may play the main role in acute infection.

Progress toward an elusive goal: current status of cytomegalovirus vaccines

Although infection with human cytomegalovirus (CMV) is ubiquitous and generally asymptomatic in most individuals, certain patient populations are at high risk for CMV-associated disease. These include HIV-infected individuals with AIDS, transplant patients, and newborn infants with congenital CMV infection. Immunity to CMV infection, both in the transplant setting and among women of childbearing age, plays a vital role in the control of CMV-induced injury and disease. Although immunity induced by CMV infection is not completely protective against reinfection, there is nevertheless a sound basis on which to believe that vaccination could help control CMV disease in high-risk patient populations. Evidence from several animal models of CMV infection indicates that a variety of vaccine strategies are capable of inducing immune responses sufficient to protect against CMV-associated illness following viral challenge. Vaccination has also proven effective in improving pregnancy outcomes following CMV challenge of pregnant guinea pigs, providing a 'proof-of-principle' relevant to human clinical trials of CMV vaccines. Although there are no licensed vaccines currently available for human CMV, progress toward this goal has been made, as evidenced by ongoing clinical trial testing of a number of immunization strategies. CMV vaccines currently in various stages of preclinical and clinical testing include: protein subunit vaccines; DNA vaccines; vectored vaccines using viral vectors, such as attenuated pox- and alphaviruses; peptide vaccines; and live attenuated vaccines. This review summarizes some of the obstacles that must be overcome in development of a CMV vaccine, and provides an overview of the current state of preclinical and clinical trial evaluation of vaccines for this important public health problem.

Colonic stricture mimicking Hirschsprung's disease: a localized cytomegalovirus infection

The diagnosis of congenital cytomegalovirus (CMV) infection is best established by isolating the virus from urine or saliva within the first 2 weeks of life. Detection beyond this point may reflect perinatal acquisition of CMV. Cytomegalovirus is usually transmitted by direct human-to-human contact through vertical or horizontal routes. Infected persons can excrete CMV in urine, saliva, semen, cervical secretions, or breast milk. Because the virus establishes latent infections, blood products and solid organs can also transmit CMV. In the surgical literature, intestinal CMV-infected cells in infants have prevalently been associated with neonatal necrotizing enterocolitis, and only very few cases of primary CMV infection of the gastrointestinal tract of surgical interest in immunocompetent neonates have been reported. We describe a neonate with congenital or perinatal CMV infection with gastrointestinal involvement who developed a colonic stricture and manifested a clinical picture simulating Hirschsprung's disease. The intestinal lesion was a localized segmental CMV infection of the colon in which inflammation dominated the histopathologic finding. Chorioretinitis was also present.

Cytomegalovirus infection inhibits the expression of N-methyl-D-aspartate receptors in the developing mouse hippocampus and primary neuronal cultures

Cytomegalovirus (CMV) is the most significant infectious cause of developmental brain disorders in humans. The infection occasionally persists and causes neurological disorders. The N-methyl-D-aspartate (NMDA) subtype of glutamate receptors is essential for the development and plasticity of synapses, but also is involved in neuronal excitotoxicity during viral infection. Here we investigated the effects of murine CMV (MCMV) infection on the expression of NMDA receptors in the hippocampal neurons of neonatal mice and primary neuronal cultures. Viral antigen was mostly found in hippocampal pyramidal neurons from the CA1 to CA3. Image analysis of immunohistochemistry demonstrated that the expression of NMDA receptor subunit 1 (NMDA-R1) protein in CA1 neurons of MCMV-infected brain was reduced to 40% of that in uninfected brain. The signal of in situ hybridization for NMDA-R1 mRNA was also decreased in CA1 neurons of MCMV-infected brain. In primary neuronal cultures, reduction of NMDA-R1 expression in MCMV-infected neurons was also detected by immunocytochemistry and Western blotting. These results suggest that reduction of NMDA receptor expression by MCMV infection may cause a decrease in the susceptibility of the neurons to excitotoxic cell death, and may be related to the establishment of viral persistence and functional disturbances in MCMV-infected neurons.

Intranasal immunization with a replication-deficient adenovirus vector expressing glycoprotein H of murine cytomegalovirus induces mucosal and systemic immunity

A vaccine vector, designated AdV-gH, was constructed by inserting the complete open reading frame of MCMV gH under control of the human CMV IE-1 promoter into the E-1 region of a replication-deficient adenovirus 5. In vitro infection of QB1-293 cells and mouse embryo cells with AdV-gH resulted in expression of MCMV gH detected by IFA. Immunization of BALB/c mice with AdV-gH (1 x 10(7) PFU) given by the intranasal route induced a humoral response with antibody detected in serum of 100% of vaccines. Antibody to MCMV gH was also detected in the bronchoalveolar lavage, fecal suspensions and vaginal washings. The viral titer of lung and salivary gland of immunized mice 10 days after intranasal challenge with MCMV (1 x 10(5) PFU) were significantly reduced compared to controls, but virus infection was not prevented. Re-exposure of mice to AdV-gH 30 days after primary immunization induced a significant boost of serum antibody response. When rechallenged with MCMV intranasally, these mice had further reduction of MCMV titers in the lung and salivary glands. Such a strategy may be important in reducing horizontal transmission of CMV infections across mucosal surfaces and in altering host immunity to CMV.

Neuropathogenesis in cytomegalovirus infection: indication of the mechanisms using mouse models

Cytomegalovirus (CMV) is the most frequent infectious cause of developmental brain disorders and also causes brain damage in immunocompromised individuals. Although the brain is one of the main targets of CMV infection, little is known about the neuropathogenesis of the brain disorders caused by CMV in humans because of the limitations in studying human subjects. Murine CMV (MCMV) is similar to human CMV (HCMV) in terms of genome structure, pattern of gene expressions, cell tropism and infectious dynamics. In mouse models, it has been shown that neural stem/progenitor cells are the most susceptible to CMV infection in developing brains. During brain development, lytic infection tends to occur in immature glial cells, presumably causing structural disorders of the brain. In the prolonged phase of infection, CMV preferentially infects neuronal cells. Infection of neurons may tend to become persistent by evasion of immune reactions, anti-apoptotic effects and neuron-specific activation of the e1-promoter, presumably causing functional neuronal disorders. It has also been shown that CMV infection in developing brains may become latent in neural immature cells. Brain disorders may occur long after infection by reactivation of the latent infection.

The UL97 protein kinase of human cytomegalovirus and homologues in other herpesviruses: impact on virus and host

The human herpesviruses, herpes simplex virus 1 (HSV-1), HSV-2, varicella zoster virus (VZV), Epstein-Barr virus (EBV), human cytomegalovirus (HCMV), human herpesvirus 6A (HHV-6A), HHV-6B, HHV-7 and HHV-8, establish persistent infections with possible recurrence during immunosuppression. HCMV replication is inhibited by the nucleoside analogue ganciclovir (GCV), the compound of choice for the treatment of HCMV diseases and preemptive treatment of infections. The viral UL97 protein (pUL97) which shares homologies with protein kinases and bacterial phosphotransferases is able to monophosphorylate GCV. Homologues of pUL97 are found in HSV (UL13), VZV (ORF47), EBV (BGLF4), HHV-6 (U69), HHV-8 (ORF36) as well as in murine CMV (M97) or rat CMV (R97). Several indolocarbazoles have been reported to be specific inhibitors of pUL97. The protein is important for efficient replication of the virus. Autophosphorylation of pUL97 was observed using different experimental systems. Most recently, it has been shown that pUL97 interacts with the DNA polymerase processivity factor pUL44. Indolocarbazole protein kinase inhibitors are promising lead compounds for the development of more specific inhibitors of HCMV.

Differential mutagen sensitivity of peripheral blood lymphocytes from smokers and nonsmokers: effect of human cytomegalovirus infection

We used the mutagen sensitivity assay to test the hypothesis that human cytomegalovirus (HCMV) infection modifies the sensitivity of cells to genetic damage from genotoxic agents. Chromosome aberration (CA) frequency in peripheral blood lymphocytes (PBLs) from 20 smokers who were matched with 20 nonsmokers by age (+/- 5 years), sex, and ethnicity was evaluated following in vitro exposure to bleomycin and/or HCMV infection. Bleomycin induced significant (P < 0.05) concentration-dependent increases in the frequency of aberrant cells, chromatid-type damage (breaks), and chromosome-type aberrations (deletions, rearrangements) in PBLs. The baseline (background) CA frequency was similar in both smokers and nonsmokers. Significantly higher frequencies of aberrant cells (P < 0.05) were observed in PBLs from smokers compared to nonsmokers at all bleomycin concentrations tested (10, 30 and 100 microg/ml). Infection of PBLs with HCMV induced a significant (P < 0.05) twofold increase in the frequency of CA (primarily chromatid breaks) in PBLs, regardless of the smoking status. PBLs from smokers and nonsmokers infected with HCMV prior to challenge with bleomycin demonstrated significant (P < 0.05) concentration-dependent increases in the levels of aberrant cells, chromatid-type damage (breaks), and chromosome-type aberrations (deletions, rearrangements) compared to noninfected cells challenged with bleomycin. The frequency of induced CA was consistently higher for PBLs derived from smokers relative to nonsmokers (P = 0.06 and 0.002). These data indicate that, individually, both smoking and HCMV infection significantly enhance the sensitivity of PBLs to bleomycin-induced genetic damage. More importantly, the data also suggest that smoking and HCMV infection interact synergistically to enhance the sensitivity of PBLs to such damage.