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Biomedical subjects

V C Emery

Publications and source records attributed to V C Emery.

At least 37 records · Page 2Linked to original sources
PubMed2000

Changes in the natural history of cytomegalovirus retinitis following the introduction of highly active antiretroviral therapy.

OBJECTIVE: To determine the effect of highly active antiretroviral therapy (HAART) on the natural history of cytomegalovirus (CMV) retinitis. DESIGN AND PARTICIPANTS: Retrospective analysis of 103 consecutive patients diagnosed with CMV retinitis between 1990 and 1998. SETTING: Specialist HIV medicine department of a London hospital. MAIN OUTCOME MEASURES: Incidence of CMV retinitis, time to death following diagnosis, episodes of progression, incidence of inflammatory complications. The date of first use of HAART was January 1995. Data were censored on 30 June 1998. RESULTS: The incidence of CMV retinitis has declined dramatically following the introduction of HAART. Survival following CMV retinitis increased from a median of 0.65 years prior to 1995 to a median of 1.07 years after this date (P = 0.004). In multivariate analyses HAART was independently associated with improved survival (P = 0.02) and the association with year of diagnosis was no longer significant, suggesting that this effect is predominantly due to HAART. None of the patients receiving HAART experienced progression after 6 months of treatment. Complications of retinitis such as retinal detachment, uveitis and optic atrophy occurred in 39% of patients. The rare inflammatory complications of vitritis and cystoid macular oedema occurred only in recipients of HAART. CONCLUSIONS: The introduction of HAART has had a major impact on the natural history of CMV retinitis with improved survival time and decreased risk of progression following diagnosis. However, immune reconstitution may be associated with inflammatory complications which can result in significant visual loss in the absence of active CMV disease.

AIDS-Related Opportunistic Infections↗
PubMed2000

Prospective study of human betaherpesviruses after renal transplantation: association of human herpesvirus 7 and cytomegalovirus co-infection with cytomegalovirus disease and increased rejection.

BACKGROUND: Human herpesvirus 6 (HHV-6) and HHV-7 are two lymphotropic herpesviruses, which, like cytomegalovirus (CMV), have the potential to be pathogenic in immunocompromised individuals. We have conducted a prospective investigation to compare the natural history of HHV-6 and HHV-7 infection with that of CMV after renal transplantation. METHODS: Polymerase chain reaction was used to identify infections and quantify the viral load of CMV, HHV-6, and HHV-7 in peripheral blood samples from 52 renal transplant recipients. Betaherpesvirus infections were related to defined clinical criteria obtained by detailed examination of the clinical records of each patient for the immediate 120-day posttransplant period. RESULTS: CMV was the most commonly detected virus after transplant (58% of patients), followed by HHV-7 (46%) and HHV-6 (23%). Examining the time to first polymerase chain reaction positivity, HHV-7 infection was detected earlier than CMV (P=0.05). The median maximum CMV viral load was significantly higher than those for HHV-6 (P=0.01) and HHV-7 (P<0.0001) and a trend for HHV-7 viral load to be greater than HHV-6 (P=0.08). Clinicopathological analyses revealed that, in those patients with rejection, HHV-7 was associated with more episodes of rejection (P=0.02). In addition, there was a significant increase in CMV disease occurring in patients with CMV and HHV-7 co-infection compared to those with CMV infection only (P=0.04). CONCLUSIONS: HHV-7 should be further investigated as a possible co-factor in the development of CMV disease in renal transplant patients and may potentially exacerbate graft rejection. No clear pathological role was observed for HHV-6.

Betaherpesvirinae↗
PubMed2000

Application of viral-load kinetics to identify patients who develop cytomegalovirus disease after transplantation.

BACKGROUND: Cytomegalovirus (CMV) continues to be a major problem post-transplantation; early markers for predicting patients at risk of CMV disease are needed. Peak CMV load in the blood correlates with CMV disease but frequently occurs too late to provide prognostic information. METHODS: 359 transplant recipients (162 liver, 87 renal, and 110 bone marrow) were prospectively monitored for CMV DNA in the blood with qualitative and quantitative PCR. 3873 samples were analysed. The CMV load in the first PCR-positive sample and the rate of increase in CMV load in blood during the initial phase of replication were assessed as risk factors for CMV disease using logistic regression. FINDINGS: 127 of the 359 patients had CMV DNA in the blood and 49 developed CMV disease. Initial viral load correlated significantly with peak CMV load (R2=0.47, p=<0.001) and with CMV disease (odds ratio 1.82 [95% CI 1.11-2.98; p=0.02; 1.34 [1.07-1.68], p=0.01, and 1.52 [1.13-2.05], p=0.006, per 0.25 log10 increase in viral load for liver, renal, and bone-marrow patients, respectively). The rate of increase in CMV load between the last PCR-negative and first PCR-positive sample was significantly faster in patients with CMV disease (0.33 log10 versus 0.19 log10 genomes/mL daily, p<0.001). In multivariate-regression analyses, both initial CMV load and rate of viral load increase were independent risk factors for CMV disease (1.28 [1.06-1.52], p=0.01, per 0.25 log10 increase in CMV load and 1.52 [1.06-2.17], p=0.02, per 0.1 log10 increase in CMV load/mL daily, respectively). INTERPRETATION: CMV load in the initial phase of active infection and the rate of increase in viral load both correlate with CMV disease in transplant recipients; in combination, they have the potential to identify patients at imminent risk of CMV disease.

Cytomegalovirus↗
PubMed2000

Cytomegalovirus seropositivity and human immunodeficiency virus type 1 RNA levels in individuals with hemophilia.

The effect of cytomegalovirus (CMV) seropositivity on the course of human immunodeficiency virus (HIV) type 1 RNA levels and HIV disease progression was assessed in a cohort of 109 hemophilic men infected with HIV-1 for a median of 12.7 years. There was no evidence of higher HIV RNA levels in the first year after HIV seroconversion (P=. 88) or faster rates of increase over infection (P=.20) in the 59 CMV-seropositive individuals than in the CMV-seronegative individuals. In univariate analyses, CMV seropositivity was associated with significantly faster progression to AIDS and death (relative hazards of 1.58 and 2.22, respectively). These effects were unchanged after adjusting for the RNA level, but they were reduced after adjusting for the CD4 cell count, age at seroconversion, and calendar year of follow-up. Thus, the effect of CMV seropositivity on clinical progression remains significant in this cohort but does not appear to be mediated through an increase in HIV RNA levels.

Acquired Immunodeficiency Syndrome↗
PubMed2000

A non-radioisotopic quantitative competitive polymerase chain reaction method: application in measurement of human herpesvirus 7 load.

Quantitative-competitive polymerase chain reaction (QCPCR) is a well-optimised and objective methodology for the determination of viral load in clinical specimens. A major advantage of QCPCR is the ability to control for the differential modulation of the PCR process in the presence of potentially inhibitory material. QCPCR protocols were developed previously for CMV, HHV-6, HHV-7 and HHV-8 and relied upon radioactively labelled primers, followed by autoradiography of the separated and digested PCR products to quantify viral load. Whilst this approach offers high accuracy and dynamic range, non-radioactive approaches would be attractive. Here, an alternative detection system is reported, based on simple ethidium bromide staining and computer analysis of the separated reaction products, which enables its adoption in the analysis of a large number of samples. In calibration experiments using cloned HHV-7 DNA, the ethidium bromide detection method showed an improved correlation with known copy number over that obtained with the isotopic method. In addition, 67 HHV-7 PCR positive blood samples, derived from immunocompromised patients, were quantified using both detection techniques. The results showed a highly significant correlation with no significant difference between the two methods. The applicability of the computerised densitometry method in the routine laboratory is discussed.

DNA, Viral↗
PubMed2000

Betaherpesviruses in transplant recipients.

The three betaherpesviruses known to infect humans are cytomegalovirus (CMV) and human herpesviruses 6 and 7 (HHV-6 and -7). All three viruses can infect opportunistically after organ transplantation. CMV causes a variety of end-organ diseases, including pneumonitis, hepatitis and gastrointestinal ulceration. Patients who develop overt CMV disease have significantly higher CMV viral loads than infected patients without evidence of clinical disease. A high CMV viral load largely explains the previously described risk factors for the development of CMV disease, which include donor/recipient serostatus before transplant and viraemia after transplant. CMV also causes some cases of allograft rejection, which can be prevented by antiviral prophylaxis. Application of similar quantitative methods for the study of HHV-6 and -7 have shown that HHV-6 and CMV are significantly and independently associated with biopsy-proven graft rejection after liver transplantation. The full clinicopathological significance of the betaherpesviruses may, thus, be greater than is currently appreciated.

Antiviral Agents↗
PubMed2000

Histopathological detection of owl's eye inclusions is still specific for cytomegalovirus in the era of human herpesviruses 6 and 7.

BACKGROUND: Cytomegalovirus (CMV) is the prototype member of the beta-herpesvirinae, which can cause multiple organ dysfunction in the immunocompromised host. Human herpesvirus 6 (HHV-6) and HHV-7 are newer members of the beta-herpesvirinae that can cause febrile illness in young children and are also possible pathogens in the immunocompromised patient. AIM: CMV is detected in histopathological sections by visualisation of owl's eye inclusion bodies. The aim of this study was to quantify the relation between CMV, HHV-6, and HHV-7 viral loads and the presence of owl's eye inclusions in histological sections. METHODS: Histopathological examination of postmortem material and recording of owl's eye inclusion bodies were performed. CMV, HHV-6, and HHV-7 were detected by qualitative and quantitative polymerase chain reaction (PCR) from the same postmortem samples. Statistical analysis of the histopathological and PCR results was performed. RESULTS: There was a significant association between the detection of owl's eye inclusion bodies and positive CMV PCR (p < 0.001); the median CMV viral load was significantly higher in samples that were positive for owl's eye inclusions (p < 0.001). No association was found between the presence of owl's eye inclusions and HHV-6 or HHV-7 positivity. CONCLUSION: Histological detection of owl's eye inclusion bodies is an insensitive but highly specific method for detecting CMV organ involvement. Owl's eye inclusion bodies are not associated with HHV-6 or HHV-7 infection.

Cytomegalovirus↗
PubMed2000

High levels of human herpesvirus 6 DNA in peripheral blood leucocytes are correlated to platelet engraftment and disease in allogeneic stem cell transplant patients.

The aim of this study was to correlate human herpesvirus (HHV)-6 viral load with clinical symptoms in allogeneic stem cell transplant (SCT) patients. Seventy-four patients were monitored during the first 3 months after SCT using a qualitative polymerase chain reaction (PCR) for HHV-6 DNA. HHV-6 was detected in 181 out of 494 samples (36%) from 58 (78%) patients. These 181 samples were analysed using a quantitative competitive PCR. DNA could be quantified from 146 out of 181 samples (80.6%). The HHV-6 viral load was highest at 4 weeks compared with 8 weeks (P < 0.001) and 12 weeks (P = 0.01) after SCT. Three patients had HHV-6 encephalitis and one patient had hepatitis. The HHV-6 DNA levels were higher in patients with HHV-6 than in those without HHV-6 (P = 0.01). Patients who received grafts from unrelated or HLA-mismatched family donors had significantly higher HHV-6 DNA levels than patients who received grafts from matched sibling donors (P < 0.001). In a multiple regression model, unrelated donor grafts (P < 0.001) and use of intravenous immunoglobulin prophylaxis (P = 0.04) influenced HHV-6 DNA levels. HHV-6 viral load was significantly correlated with delayed platelet engraftment in both univariate (P < 0.01) and multivariate analysis, and to the number of platelet transfusions.

Acyclovir↗
PubMed1999

The dynamics of human cytomegalovirus replication in vivo.

Cytomegalovirus (CMV) is generally described as a slowly replicating virus. During studies of immunocompromised patients, we observed rapid changes in the quantity of CMV DNA present in serial blood samples by quantitative-competitive polymerase chain reaction commensurate with a doubling time of <2 d. To further investigate the dynamics of replication in vivo, patients in three distinct situations were studied in detail: (a) those receiving intravenous ganciclovir; (b) those in whom ganciclovir-resistant strains appeared during long-term therapy; and (c) those in whom ganciclovir-resistant strains disappeared with alternative drug therapy. In all cases, it was possible to provide accurate estimates of the doubling time of CMV and its half-life of disappearance after antiviral chemotherapy. The results from all three approaches demonstrated that the doubling time/half-life of CMV in blood is approximately 1 d when frequent samples are collected. These results show that CMV DNA replication in vivo is a highly dynamic process. We conclude that the reputation of CMV as a slowly replicating virus based on the time taken to produce cytopathic effects in vitro is unwarranted. These findings have implications for the potency, dose, and duration of antiviral chemotherapy needed for the effective treatment of this important human pathogen.

Antiviral Agents↗
PubMed1999

Loss of cytomegalovirus (CMV) viraemia following highly active antiretroviral therapy in the absence of specific anti-CMV therapy.

OBJECTIVE: To determine the effect of highly active antiretroviral therapy (HAART) on cytomegalovirus (CMV) viraemia and retinitis in patients at high risk of disease. DESIGN: Sixteen patients with CMV viraemia, but no evidence of end organ disease at the time of first receipt of HAART including a protease inhibitor, were studied. No patient had ever received specific anti-CMV therapy. METHODS: CMV load in blood was measured using quantitative competitive PCR at baseline and for a median follow-up of 21 months. Regular ophthalmological screening for retinitis was conducted throughout the study period. RESULTS: All 16 patients became CMV negative by PCR following the commencement of HAART. CMV loads prior to treatment ranged from 2.0 x 10(3) to 4.1 x 10(6) copies/ml (median, 7.6 x 10(4) copies/ml). The median time to becoming PCR negative was 13.5 weeks (range, 5-40 weeks). Fourteen patients remained CMV negative throughout follow-up. CMV viraemia recurred in two patients; these individuals were indistinguishable with respect to either baseline parameters or response to antiretroviral therapy. None of the 16 patients developed CMV retinitis. CONCLUSIONS: HAART including a protease inhibitor can result in the complete suppression of CMV viraemia, an effect not previously observed in HIV-infected patients in the absence of specific anti-CMV therapy. This response correlated with protection against CMV retinitis in a group of patients at high risk of development of disease. These results help to explain why the natural history of CMV disease has altered since the introduction of such therapeutic regimens.

AIDS-Related Opportunistic Infections↗
PubMed1999

Interactions between beta-herpesviruses and human immunodeficiency virus in vivo: evidence for increased human immunodeficiency viral load in the presence of human herpesvirus 6.

In vitro, beta-herpesviruses can stimulate or inhibit HIV replication under particular circumstances. In order to investigate the effects of beta-herpesvirus infection on HIV replication and vice versa at an organ level, we determined the quantitative relationships between cytomegalovirus (CMV), human herpesviruses (HHV) 6 and 7, and HIV-1 proviral DNA using quantitative competitive PCR methods in 141 organs collected at autopsy from 11 AIDS patients. The presence of HHV-6 DNA in an organ was significantly associated with elevated HIV-1 proviral DNA (difference in HIV median loads, 1.3 log10 genomes; P = 0.004). Consistent with this, there was a trend for the presence of HIV-1 proviral DNA to be associated with an elevated HHV-6 load (0.44 log10 difference; P = 0.07). In contrast, there were no significant differences between viral loads in the combinations of either CMV or HHV-7 with HIV-1 proviral DNA load. Pairwise combinations of the beta-herpesviruses revealed that the quantity of HHV-7 was increased in the presence of HHV-6 (difference in median loads, 1.3 log10; P = 0.001) and the quantity of HHV-6 was increased in the presence of HHV-7 (difference in median loads, 0.7 log10; P=0.002). These results demonstrate that the presence of HHV-6 in an organ is significantly associated with an elevated HIV-1 proviral load and have implications for understanding HIV pathogenesis in the human host and the role that beta-herpesviruses, especially HHV-6, might play as cofactors in the HIV disease process.

AIDS-Related Opportunistic Infections↗
PubMed1999

Human herpesviruses 6 and 7 as potential pathogens after liver transplant: prospective comparison with the effect of cytomegalovirus.

Because cytomegalovirus (CMV) is an important opportunistic infection after liver transplant, we conducted a prospective study to see if the same applied to human herpesviruses (HHV)-6 and -7. We used polymerase chain reaction (PCR) methods optimised to detect active, not latent, infection and studied patients not receiving antiviral prophylaxis for CMV. Post-transplant, 536 blood samples were tested by PCR (median 7; range 4-50). Active infection with CMV was detected in 28/60 (47%), HHV-6 in 19/60 (32%), and HHV-7 in 29/60 (48%) of patients. The PCR-positive samples were tested by quantitative-competitive PCR to measure the virus load of each betaherpesvirus. The median peak virus load for CMV was significantly greater than that for HHV-6 or HHV-7. Detailed clinicopathological analyses for the whole population showed that CMV and HHV-6 were each significantly associated with biopsy-proven graft rejection. Individual case histories suggested that HHV-6 and HHV-7 may be the cause of some episodes of hepatitis and pyrexia. It is concluded that HHV-6 is a previously unrecognized contributor to the morbidity of liver transplantation, that HHV-7 may also be important and that both viruses should be included in the differential diagnosis of graft dysfunction.

Adult↗
PubMed1999

Diagnostic approaches to cytomegalovirus infection in bone marrow and organ transplantation.

Cytomegalovirus (CMV) continues to be a clinical problem, impairing the overall success rate of transplantation, either through direct involvement of a variety of end-organs or by inducing indirect effects such as graft rejection. We review here how the virus manages to evade host immune responses and replicate extensively in allograft recipients. Recent studies show that the quantity of CMV (viral load) is related directly to the development of CMV disease. We review how clinically significant levels of CMV viral load can be defined and summarize the results of studies showing that a high CMV viral load is the major determinant of CMV disease, explaining the previously reported risk factors of pre-transplant serostatus and the post-transplant detection of CMV viremia.Note

Bone Marrow Transplantation↗
PubMed1999

Quantitative effects of valacyclovir on the replication of cytomegalovirus (CMV) in persons with advanced human immunodeficiency virus disease: baseline CMV load dictates time to disease and survival. The AIDS Clinical Trials Group 204/Glaxo Wellcome 123-014 International CMV Prophylaxis Study Group.

Virus load is a major risk factor for disease in many human viral infections, especially human immunodeficiency virus (HIV) disease. The effect of cytomegalovirus (CMV) load on disease progression and the influence of antiviral chemotherapy on surrogate markers of replication was investigated in 310 patients with advanced HIV disease in a randomized controlled trial that compared the effects of valacyclovir with those of acyclovir. Sequential blood and urine samples were analyzed by polymerase chain reaction (PCR), for human CMV (HCMV) DNA. In multivariate analyses, elevated virus load in both blood and urine at baseline was associated with increased risk of HCMV disease (relative hazard, 1.49 and 1.44 per log increase, respectively). Elevated virus load in blood at baseline was also associated with a significantly shorter survival time (log rank, P=. 0001). In time-updated analyses, valacyclovir significantly suppressed the virus load in subjects who were PCR positive at baseline (in blood or urine), when compared with the combined acyclovir arms.

AIDS-Related Opportunistic Infections↗
PubMed1999

Asymptomatic primary cytomegalovirus infection: virologic and immunologic features.

We followed 45 seronegative adolescents for acquisition of cytomegalovirus (CMV); 6 (5 female, 1 male) seroconverted after a median of 7.5 months. All were free of signs and symptoms. CMV was isolated from 32 (59.2%) of 54 urines, 2-80 weeks after infection; viruria was less frequent after 6 months. CMV was isolated from saliva of 3 subjects, vaginal swabs of 2 of 5, and 1 white blood cell (WBC) sample. CMV DNA was detected by polymerase chain reaction in WBCs and plasma from all subjects tested. The proportion of WBC samples with CMV DNAemia was 75%-80% within 16 weeks of infection, declining to 0%-25% after 48 weeks. The rate of plasma DNAemia was 25%-40% at 8-16 weeks, declining with time. IgG antibody to CMV, glycoprotein B (gB), and neutralizing antibody were present after 6-8 weeks. Lymphocyte proliferative responses to CMV and to gB were low, compared with those of controls. CMV shedding was of shorter duration than expected. Although antibody response was prompt and vigorous, CMV DNA could be detected in blood for months.

Adolescent↗
PubMed1999

The U69 gene of human herpesvirus 6 encodes a protein kinase which can confer ganciclovir sensitivity to baculoviruses.

The protein encoded by the U69 open reading frame (ORF) of human herpesvirus 6 (HHV-6) has been predicted to be a protein kinase. To investigate its functional properties, we have expressed the U69 ORFs from both HHV-6 variants, A and B, by using recombinant baculoviruses (BV6AU69 and BV6BU69). Nickel agarose and antibody affinity chromatography was used to purify the proteins to homogeneity and when incubated with [gamma-32P]ATP, both U69 proteins became phosphorylated on predominantly serine residues. These data strongly suggest that U69 is a protein kinase which autophosphorylates. The phosphorylation reaction was optimal at physiological pH and low NaCl concentrations. It required the presence of Mg2+ or Mn2+, and Mg2+ was able to support phosphorylation over a wider range of concentrations than Mn2+. Both ATP and GTP could donate phosphate in the protein kinase assay and the former was more efficient. U69 was capable of phosphorylating histone and casein (serine/threonine kinase substrates) but not enolase (a tyrosine kinase substrate). For the autophosphorylation reaction, the Michaelis constants for ATP of baculovirus-expressed HHV-6A and HHV-6B U69 were calculated to be 44 and 11 microM, respectively. U69 is a homologue of the UL97 gene encoded by human cytomegalovirus which has been shown to phosphorylate the antiviral drug ganciclovir (GCV). We analyzed whether the U69 ORF alone was capable of conferring GCV sensitivity on baculoviruses BV6AU69 and BV6BU69. In plaque reduction experiments, these baculoviruses displayed a GCV-sensitive phenotype compared to a control baculovirus (BVLacZ). The 50% inhibitory concentrations (IC50) of BV6AU69 and BV6BU69 were calculated to be 0.35 and 0.26 mM, respectively, whereas the control baculovirus had an IC50 of >1.4 mM. This shows that the U69 gene product is the only one required to confer GCV sensitivity on baculovirus.

Antiviral Agents↗
PubMed1999

Viral dynamics during active cytomegalovirus infection and pathology.

The central role that cytomegalovirus (CMV) load plays in its pathogenesis is being unravelled. In AIDS patients with active CMV replication, many months prior to the development of CMV disease, elevated CMV load in the blood and urine are significantly associated with an increased risk of disease progression. In addition, elevated load in blood is associated with an increased risk of death. Intervention with ganciclovir acts to rapidly inhibit CMV replication in vivo and has allowed estimates of the clearance/replication rate of CMV to be performed. These data indicate that CMV replicates dynamically in the human host with a doubling time of approximately 1 day. This knowledge has been used to determine the relative contribution of initial viral load and rate of change of viral load as predictors of CMV disease in organ transplant recipients. The data show that both these parameters have prognostic value in multivariate models and should allow the development of novel patient management strategies.

AIDS-Related Opportunistic Infections↗