Detection of cytomegalovirus (CMV) in granulocytes by polymerase chain reaction compared with the CMV antigen test

Methodology for monitoring cytomegalovirus infection after renal transplantation

BACKGROUND

The aim of this study was to evaluate the diagnostic value of different detection methods for cytomegalovirus (CMV) infection after renal transplantation and also to establish a system to monitor therapy for CMV infection.

METHODS

We retrospectively studied 1516 renal transplant recipients from June 1994 to December 2006. All patients were screened for CMV-DNA. A total of 1402 patients had received CMV-IgG/IgM detection since June 1996 and 660 had received CMV antigen detection since June 2000.

RESULTS

A total of 664 (43.8%) recipients developed CMV infection. The sensitivity, specificity and Youden index of the three methods, respectively, were 18.84%, 100% and 0.1884 for ELISA, 91.86%, 82.98% and 0.7484 for PCR, and 88.06%, 96.95% and 0.8501 for the CMV-pp65 antigenemia test. The sensitivity and specificity of the two combined detection methods (CMV-DNA and CMV-pp65) for post-operation CMV infection were 93.49% and 99.06%; the two detection methods had significant dependability (p<0.05) in diagnosis of CMV infection and in evaluation of therapeutic effect of antiviral drugs.

CONCLUSIONS

Only ELISA can be used as a screening index in order to distinguish whether the donors or recipients are infected with CMV or not. CMV-pp65 antigenemia can help guide clinical therapy for CMV infection. CMV-pp65 and CMV-PCR combined together provide a more effective method to monitor CMV infection and predict its outcome.

Monitoring of cytomegalovirus infection in solid-organ transplant recipients by an ultrasensitive plasma PCR assay

Early and accurate monitoring of cytomegalovirus (CMV) infection in solid-organ transplant recipients is of major importance. We have assessed the potential benefit of an ultrasensitive plasma-based PCR assay for renal transplant recipients. The pp65 CMV antigen (pp65 Ag) assay using leukocytes was employed as a routine test for the monitoring of CMV in 23 transplant recipients. We compared the pp65 antigenemia with the CMV load quantified by an ultrasensitive PCR (US-PCR) with a limit of detection of 20 CMV DNA copies/ml of plasma. CMV infection was detected in 215 (67%) of 321 plasma samples by the US-PCR compared with 124 (39%) of 321 samples by the pp65 Ag assay. The US-PCR assay permitted the detection of CMV infection episodes following transplantation a median of 12 days earlier than the pp65 Ag assay. Moreover, during CMV infection episodes, DNA detection by the US-PCR was consistently positive, whereas false negative results were frequently observed with the pp65 Ag assay. We found a good correlation between the two assays, and the peak viral loads were significantly higher in patients with CMV-related complications (median, 5000 DNA copies/ml) than in those without symptoms (1160 DNA copies/ml) (P = 0.048). In addition, patients that did not require preemptive therapy based on the results of the pp65 assay had CMV loads significantly lower (median, 36 DNA copies/ml) than those that needed treatment (median, 4703 DNA copies/ml) (P < 0.001). These observations provided cutoff levels that could be applied in clinical practice. The ultrasensitive plasma-based PCR detected CMV infection episodes earlier and provided more consistent results than the pp65 Ag assay. This test could improve the monitoring of CMV infection or reactivation in renal transplant recipients.

Molecular diagnostics of infectious diseases: state of the technology

In this review, the basic technologies and procedures currently used in clinical laboratories performing molecular diagnostics are described. Special emphasis on specimen processing has been made since it is one of the most challenging steps involved in molecular testing. Representative examples are given for each type of technology, especially tests that are currently available in the market. The types of hybridization-based and amplification-based procedures are detailed. Finally, current problems and future developments are discussed.

High frequency of positive surveillance for cytomegalovirus (CMV) by PCR in allograft recipients at low risk of CMV

Cytomegalovirus (CMV) causes significant morbidity and mortality following allogeneic haemopoietic stem cell transplantation. A pre-emptive strategy for ganciclovir therapy is widely used, where treatment is commenced on finding positive evidence of CMV replication. Surveillance by PCR has increased the sensitivity for CMV detection, but it is not known whether this may detect cases with evidence of CMV DNAemia who have a low probability of CMV disease. We reviewed our experience of CMV infection and disease since introducing CMV surveillance by PCR. All 30 allografts received bedside leucodepleted CMV-negative blood products. Seven of 10 CMV-positive recipients of a CMV-positive graft developed CMV DNAemia, with three developing clinical disease requiring ganciclovir treatment. In contrast, of 11 low risk patients (CMV-negative recipients of CMV-negative grafts), six developed evidence of CMV DNAemia although only one had clinical evidence of CMV disease requiring ganciclovir. Transfusion records confirmed that four of these had received exclusively CMV-negative blood products. The aetiology of the CMV DNAemia in these cases is unclear. It is suggested that before commencing ganciclovir therapy, confirmatory CMV antigenaemia testing is carried out on samples which test positive for CMV DNA, unless there is high clinical suspicion of CMV disease.

Abstension from treatment of low-level pp65 cytomegalovirus antigenemia after liver transplantation: a prospective study

BACKGROUND

Ganciclovir is a highly effective and relatively safe drug to treat cytomegalovirus (CMV) infection in liver transplant patients; CMV resistance to ganciclovir is progressively emerging due to the extensive use of the drug in transplant and AIDS patients; CMV pp65 antigenemia allows early diagnosis of CMV infection and quantitation of the viral load; preemptive antigenemia-guided therapy of CMV infection can prevent CMV disease but the threshold of antigenemia value above which treatment has to be instituted is unclear.

METHODS

To demonstrate the safety of abstention from preemptive treatment in the presence of low levels of antigenemia 77 consecutive liver transplant recipients were prospectively evaluated. Antigenemia was tested twice a week from transplantation until discharge, then once a week until the third postoperative month. In absence of risk factors for CMV disease, namely donor positive/recipient negative CMV serology, treatment with antibodies to lymphocytes and retransplantation, only patients with antigenemia of more than 50 or symptoms possibly related to CMV infection had preemptive treatment.

RESULTS

A total of 32 patients had at least one positive antigenemia test with a value less than 50; 22 (68.7%) spontaneously cleared the virus, 3 were treated with i.v. ganciclovir for the presence of fever, and the other 7 (21,8%) progressed to values of antigenemia of more than 50 and were treated even if asymptomatic. No CMV disease was observed in these patients.

CONCLUSION

CMV antigenemia less than 50 in liver transplant recipients with low and intermediate risk for CMV disease does not mandate preemptive ganciclovir treatment. Close surveillance with repeated determination of antigenemia until its negativization and careful clinical and laboratory monitoring is advisable.

Detection of cytomegalovirus proteins by flow cytometry in the blood of patients undergoing hematopoietic stem cell transplantation

Cytomegalovirus (CMV) infection and associated diseases continue to be a major complication encountered by patients undergoing high-dose chemoradiotherapy and hematopoietic stem cell transplantation (HSCT). A number of studies revealed that identification of CMV in the blood of HSCT patients was a predictor of future CMV disease. The purpose of this study was to determine if CMV proteins detected by flow cytometry could be a rapid and more quantitative way to monitor CMV infections and CMV antigenemia in HSCT patients. Preliminary studies showed that CMV immediate early (IE), early (E), and late (L) tegument proteins were specifically identified in CMV-infected cell lines and not in uninfected cells. We evaluated CMV antigen detection by flow cytometry in blood samples collected before and after transplantation in 56 serially collected blood samples from 17 HSCT patients and CMV protein expression was compared to CMV isolation. CMV IE and E proteins were not detected in any of the samples analyzed. However, CMV L protein detection by flow cytometry correlated with virus isolation in serially collected blood samples. Samples from 14 patients were evaluated by both techniques, at the same time intervals. There was a 100% correlation (8/8) between the lack of CMV antigen detection by flow cytometry and the failure to isolate infectious virus. Moreover, 5 of 6 patients who were positive for CMV L antigen by flow cytometry also were positive by virus isolation techniques. When flow cytometry and virus isolation did not detect CMV antigen on the same day, CMV positivity was first detected by flow cytometry. Then, 1-2 weeks later, positive virus isolation was documented. This study indicates that flow cytometric identification of CMV antigenemia correlates with isolation of CMV in HSCT patients and may be a predictive test for the rapid detection of CMV in the blood.

Quantitation of human cytomegalovirus DNA in peripheral blood leukocytes of heart transplant recipients: relationship with pp65 antigenemia and with antiviral therapy

OBJECTIVE: To retrospectively determine DNA levels in blood polymorphonuclear leukocytes (PMNLs) of 21 heart transplant patients who suffered from HCMV infection and who were monitored by the antigenemia assay (pp65 test) during follow-up, by use of a quantitative competitive polymerase chain reaction (PCR) assay for human cytomegalovirus (HCMV) DNA. METHODS: Quantitation of HCMV DNA by PCR was expressed as genome equivalents (GE) per 200 000 PMNLs. RESULTS: Ten patients experienced symptomatic HCMV infection (five primary infections and five reactivations) with mild symptoms and received ganciclovir treatment, whereas 11 asymptomatic HCMV infections were not treated. Therapy was discontinued when a 90% reduction of the pretreatment antigenic load was achieved in a symptomless patient. The mean HCMV DNA and antigenic loads were significantly higher in symptomatic than in asymptomatic patients: 4.6 x 105 plus minus 4.7 x 105 GE and 1.1 x 104 GE (p<0.0001) and 390 plus minus 350 versus 25 plus minus 12 pp65-positive PMNLs (p<0.0001), and in primary than in secondary infections (583 plus minus 403 pp65-positive PMNLs versus 85 plus minus 111, p=0.002 and 5.2 x 105 plus minus 5.2 x 105 GE instead of 1.5 x 105 plus minus 3.2 x 105 GE, p=0.02). A single course of 14--21 days of ganciclovir caused a marked decrease of HCMV DNA and antigenemia in eight of 10 patients in whom a 90% reduction of the antigenic load correlated with a 98% DNA reduction of the pretreatment levels. In two primary infections, a 90% antigenic reduction was achieved by 21 days of ganciclovir treatment, but those data only correlated with a DNA load reduction of 28% and 60% of the pretreatment levels. Fifteen and 12 days later, respectively, the two patients relapsed and underwent a second ganciclovir course, at the end of which a 90% reduction of the antigenic load correlated with a >98% DNA drop. GCV was discontinued and the patients recovered completely. In those two patients we retrospectively found persistent high DNA levels before the second ganciclovir course, whereas the antigenic load slowly increased after an apparent reduction. CONCLUSIONS: Our data suggest that: (1) DNA levels have the same trend as the pp65 antigen test---they are significantly higher in symptomatic and in primary HCMV-infected patients than in asymptomatic patients and those with secondary infection; (2) a 90% antigenic load reduction from the pre-treatment level may be a less reliable predictor of the efficacy of anti-HCMV therapy than DNA load, at least in primary infection, in which a much higher viral load and much more severe disease are present; and (3) a DNA load reduction of >98% of the pretreatment value is required for therapeutic success.

Discordant detection of human cytomegalovirus DNA from peripheral blood mononuclear cells, granulocytes and plasma: correlation to viremia and HCMV infection

BACKGROUND

There exist only few data about the HCMV infection of single positive leukocyte subtypes in immunosuppressed patients. Most reports describe HCMV coinfection of cells of the myelomonocytic line or even T- and B-cell populations. Correlation of positive PCR findings from two major leukocyte fractions and plasma to viremia and HCMV infection in general should contribute to select suitable sources of HCMV DNA for diagnostic purposes.

OBJECTIVE

The diagnostic value of qualitative leukoDNAemia of simultaneously isolated peripheral blood mononuclear cells (PBMC), granulocytes as well as plasmaDNAemia was evaluated by comparing the positive results of nested PCR from blood with virus isolation either from leukocytes or from any other sources, with serology and the clinical status of immunosuppressed patients.

STUDY DESIGN

PBMC, granulocytes and plasma were prepared of a total of 220 blood samples of 75 immunosuppressed patients with clinically suspected primary or recurrent HCMV infection. In a collective of 35 patients consisting mainly of recipients of marrow or solid organ transplants positive results of leuko- or plasmaDNAemia were correlated with data from HCMV screening and the clinical status. For standardization, HCMV IE Exon 4 DNA was amplified from 100 ng cellular DNA of each leukocyte population. Cross contamination can be excluded. DNA from plasma was extracted by phenol/chloroform. Using this experimental design, HCMV DNA was not detectable in PBMC, granulocytes and plasma of 23 healthy HCMV seropositive blood donors.

RESULTS

Leukocyte separation in a collective of 30 patients with positive leukoDNAemia revealed in only 12 cases (40%) double infection of PBMC and granulocytes. In the majority of cases (18 patients, 60%) however, HCMV DNA was detectable in only one leukocyte fraction, either in PBMC or granulocytes. LeukoDNAemia did not correlate to viremia. HCMV DNA amplified from plasma was shown to be cell free. Infectious virus from plasma was not isolated. The predictive value of qualitative nested PCR from blood to detect HCMV infection was high for plasma and decreased in the following sequence: plasma (0.92) > PBMC (0.83) > granulocytes (0.65).

CONCLUSIONS

Qualitative nPCR from plasma and PBMC seems to be sufficient to detect (an ongoing) HCMV infection of immunosuppressed patients. However, the rate of single positive leukocyte fractions is approximately 60%. Therefore, viral leukoDNAemia in 40% of cases seems to be restricted to either PBMC or granulocytes. For diagnostic purposes the whole leukocyte population should be used for PCR analysis.

The clinical utility of viral quantitation using molecular methods

BACKGROUND

The quantitation of viral nucleic acids in biological fluids has become increasingly desirable over the past several years. To this end, a number of quantitative molecular procedures have been developed.

OBJECTIVES

The objective was to review the current literature on the molecular techniques used in the quantitation of viral nucleic acids and to assess the appropriateness of these methods for clinical use.

RESULTS

Assays involving both target and signal amplification are now available for the accurate and precise quantitation of viral burden in infected patients. These methods include quantitative polymerase chain reaction (PCR), branched chain signal amplification (bDNA), nucleic acid sequence-based amplification (NASBA) and the SHARP signal and hybrid capture systems. Our understanding of the natural history and pathogenesis of viruses such as the human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV), cytomegalovirus (CMV) and Epstein-Barr virus (EBV) may be greatly facilitated by accurate determinations of viral and infected cell burden. Quantitation of viral load in infected individuals may also be useful to assess disease progression, monitor the efficacy of therapy and to predict treatment failure and the emergence of drug-resistant viruses.

CONCLUSION

Precise, accurate and reproducible quantitation of viral load is now feasible. Molecular assays for viral quantitation should have a considerable impact on medical research and clinical care.

Management of cytomegalovirus infection after solid-organ or stem-cell transplantation. Current guidelines and future prospects

Recent developments in diagnosis and therapy of cytomegalovirus (CMV) infection have helped to reduce CMV-associated mortality following organ transplantation. However, CMV is still associated with significant morbidity in recipients of an allogeneic stem cell or solid-organ transplant. The clinical symptoms of active CMV infection per se and, most importantly, the prevalence of life-threatening CMV disease show broad variation between different patient populations depending on the type of transplant and the intensity of immuno-suppression. Therefore, management of CMV infection must be stratified according to risk profiles of a given patient population. In the past decade, novel diagnostic assays (such as rapid shell-vial culture, polymerase chain reaction, pp65 antigen assay and sensitive hybridisation techniques) have been developed. Broad variations in the ability of a given test to predict a positive or negative risk of developing CMV disease have been observed between different transplant modalities. Highly effective therapeutic agents against CMV, such as ganciclovir and foscarnet, have become available, improving the outcome of patients with CMV disease. Moreover, antiviral prophylaxis with ganciclovir or aciclovir has been shown to reduce CMV infection and CMV disease following organ transplantation. However, these drugs are often associated with considerable toxicity. Moreover, antiviral resistance to ganciclovir and foscarnet has been observed in recipients of organ transplants and, even more frequently, in patients with AIDS. Short courses of pre-emptive antiviral therapy, administered after CMV infection has been documented by sensitive diagnostic techniques prior to the development of clinical symptoms, help to reduce duration and incidence of adverse effects associated with antiviral drugs and are thus an attractive strategy compared with antiviral prophylaxis. Newer options, such as oral ganciclovir, cidofovir, benzimidavir (1263W94) and lobucavir, are currently under investigation and might further improve the management of CMV infection in recipients of solid-organ or stem-cell transplants.

Comparative study of cytomegalovirus (CMV) antigenemia assay, polymerase chain reaction, serology, and shell vial assay in the early diagnosis and monitoring of CMV infection after renal transplantation

BACKGROUND

Early diagnosis of cytomegalovirus (CMV) infection, which is an important cause of morbidity and mortality in renal transplant recipients, remains of great importance. This prospective study was performed in kidney transplant recipients to determine the diagnostic value of the CMV antigenemia assay in comparison with polymerase chain reaction (PCR), serology, and shell vial assay.

METHODS

Seventy-five consecutive renal transplant recipients were enrolled in this study and monitored by both antigenemia assay and serology. The initial 34 of the 75 patients were subjected to PCR and shell vial assay.

RESULTS

Antigenemia, PCR, and shell vial assay became positive before the onset of CMV-related symptoms in 31/34 (89%), 13/16 (81%), and 2/16 (13%), respectively. None of the 34 patients who had symptomatic CMV disease showed a significant increase in IgG or IgM before the onset of symptoms. Antigenemia and PCR assays turned positive, 7 and 11 days (median), respectively, before the onset of clinical symptoms. Serology and shell vial assay became positive 21 and 25 days (median), respectively, after the onset of CMV-related clinical symptoms. To examine the clinical value of these assays, "good correlation" was defined based on the correlation between the clinical course and the results of the assays. Good correlation with the antigenemia assay was observed in 33 (96%) out of 34 renal transplant recipients who recovered from their CMV disease after ganciclovir therapy. Only one of 16 (7%) patients showed good correlation by shell vial assay, whereas PCR and serology did not show a good correlation. Consequently, antigenemia was considered the best way to monitor CMV infections after kidney transplantation.

CONCLUSIONS

Only the CMV antigenemia assay can be successfully employed after renal transplantation for the early diagnosis and extensive monitoring of active CMV infection.

Predictive value of cytomegalovirus DNA detection by polymerase chain reaction in blood and bronchoalveolar lavage in lung transplant patients

BACKGROUND

Despite promising results, the efficacy of polymerase chain reaction (PCR) for clinical management of cytomegalovirus (CMV) infection in transplanted patients is still controversial.

METHODS

A prospective study of CMV detection, with concurrent shell vial cultures and PCR in blood and bronchoalveolar lavage (BAL), was conducted in 13 lung transplant recipients, monitored for 15 months (range: 1-42 months). CMV DNA was detected by PCR amplification of a 406-bp fragment in the Us region and a 290-bp fragment in the immediate early region of the viral genome.

RESULTS

When comparing PCR to viral culture, the sensitivity and specificity of CMV DNA detection were 100% and 65.7% in blood (n=122) and 100% and 75% in BAL (n=104). The positive and negative predictive values of PCR for a forthcoming diagnosis of CMV infection were 50% and 97% in blood, and 67% and 85% in BAL. Seventeen CMV infections were evaluated at the end of treatment: when PCR was still positive either in blood or BAL, CMV infection relapsed within 35+/-5 days; when PCR was negative, CMV infection relapsed after 142+/-57 days (P=0.01).

CONCLUSIONS

Negative CMV detection by PCR strongly advocates against a forthcoming CMV infection. PCR assay seems to be a good predictor for early recurrence of CMV infection, and would be useful for monitoring the response to antiviral therapy.

Quantitation of cytomegalovirus (CMV) DNA in leukocytes of human immunodeficiency virus-infected subjects with and without CMV disease by using PCR and the SHARP Signal Detection System

We report the development of a simple and rapid PCR assay for quantitation of the cytomegalovirus (CMV) DNA load in polymorphonuclear leukocytes. Using this system, a very good correlation was found between a high number of CMV copies in the blood and the presence of CMV disease in subjects with AIDS.

Patterns of viremia in liver transplant recipients with symptomatic cytomegalovirus infection

Cytomegalovirus (CMV) titer in blood seems to be the principal determinant of clinical symptoms in immunosuppressed patients. We have developed an assay for quantitation of CMV DNA in serum. The assay requires the coamplification by polymerase chain reaction (PCR) of extracted serum DNA with 1000 molecules of mutated internal standard DNA, and then an ELISA detection system. We examined 133 paired buffy coats and sera from 15 patients with symptomatic infection. Sera were examined by quantitative PCR, and buffy coats were examined by qualitative PCR (with a detection threshold of approximately 40 copies per 150,000 cells). Serum viral titers peaked during the seventh week after transplant (median day 40, range 26-58) at about the time of symptom onset. Mean viral titer measured during the seventh week was 1.2 x 10(5) copies per milliliter of serum (standard error 6.5 x 10(4). Buffy-coat PCR results were generally concordant with results of serum PCR (overall concordance 103/133=77.4%). Serum CMV titer fell, as symptoms resolved with reduction of immunosuppression and specific antiviral therapy. High titers and poor response to antiviral therapy were observed in the context of excessive immunosuppression and bacterial sepsis. Measurement of serum CMV titer may be useful for the management of immunosuppressed transplant recipients, and provides a tool for the better understanding of factors that enhance or inhibit viral replication.

Diagnosis of cytomegalovirus (CMV) infection in pediatric transplant patients by the antigenemia, shell vial, and conventional culture assays performed on blood: correlation with CMV disease

BACKGROUND

Human cytomegalovirus (CMV) is a significant cause of morbidity and mortality in transplant recipients. Isolation of CMV from blood leukocytes (CMV viremia) is considered predictive of CMV disease in transplant recipients. Therefore, investigation of methods for the rapid detection of CMV in the blood is important for diagnosis and management of these patients.

OBJECTIVE

To compare three techniques for the diagnosis and monitoring of CMV infection in a pediatric transplant population through the quantitative detection of CMV in peripheral blood leukocytes (PBL).

METHODS

Serial blood specimens were obtained for most patients. After separation of the PBL from each specimen, aliquots of the PBL were used for direct detection of CMV antigenemia by immunoperoxidase staining of acetone-fixed cells (CMV-vue kit, INCSTAR), and by immunofluorescence staining of formaldehyde-fixed cells (Complete 1C3 kit, Biosoft Argene). PBL were also inoculated into conventional cell culture tubes and shell vials. Patients' medical records were reviewed to ascertain the clinical significance of the results.

RESULTS

A total of 154 specimens obtained from 38 pediatric transplant recipients were evaluated. CMV was detected in 16 specimens obtained from eight patients: 11 specimens were found positive with the CMV-vue kit, 10 with the Complete 1C3 kit, four by conventional culture, and one by the shell vial assay. Seven of the eight patients with CMV-positive PBL had clinical signs and other laboratory evidence of active CMV infection. In general, a high-level antigenemia was demonstrated in the presence of clinical disease, but there were exceptions.

CONCLUSIONS

The two antigenemia kits were more sensitive than conventional culture and the shell vial assay for the detection of CMV in the blood of pediatric transplant patients. Our results suggest that CMV antigenemia is a sensitive and specific rapid method for the diagnosis and monitoring of CMV infection in our patient population.

Studies of in vivo distribution of bovine herpesvirus type 4 in the natural host

The in vivo distribution of bovine herpesvirus type 4 (BHV-4) was examined by testing nasal and conjunctival exudates, peripheral blood leukocytes, and various organs of experimentally infected calves. For virus detection, a nested PCR assay, virus isolation, and immunohistochemistry were applied. The nervous system and the muscles were free of viral DNA. Liver and intestinal lymph nodes contained low amounts of virus (less than two copies per 1 microgram of cellular DNA). Intestinal, tonsil, thymus, and kidney tissues contained more viral DNA copies (5 to 50 copies per 1 microgram of cellular DNA). The highest amounts of BHV-4 DNA (50 to 500 copies per 1 microgram of cellular DNA) were found in the spleen, lungs, trachea, and nasal epithelium. Amplification of DNA from blood lymphocytes through postinoculation (p.i.) day 48 proved that the virus started to replicate in these cells immediately after inoculation of the calves and that intensive virus growth took place during the 7 to 8 weeks of the infection. The number of virus-infected lymphocytes reached the maximum on p.i. days 22 to 26 and slowly declined thereafter. Virus-infected cells were found only in the spleen on p.i. day 48 by immunohistochemistry. Western blotting (immunoblotting) detected signs of an immune response against 9 of the 29 BHV-4 proteins.

Significance of human cytomegalovirus DNA detection in immunocompromised heart transplant patients

Peripheral blood samples (n= 1240), obtained at variable intervals from 483 heart transplantation (HTx patients under immunosuppressive therapy, and blood samples (n=1013) obtained upon blood donation from 1013 healthy anti-human cytomegalovirus (HCMV) positive blood donors, were tested for HCMV DNA by nested polymerase chain reaction (PCR). The detection limit of the nested PCR was determined to be less than 10 copies of the plasmid pRR 47, containing the HCMV immediate early gene. HCMV DNA was detected in 79 of 483 HTx patient (17%). To the contrary' HCMV DNA was only detected in 1 of 1013 anti-HCMV positive, healthy blood donors (0.1%). This PCR positive donor had recently contracted a primary HCMV infection. The rate of HCMV PCR positive immunosuppressed HTx patients in our study was lower than the rate of HCMV PCR positive healthy blood donors in previous reports in the literature. Blood samples (269 from 117 HTx patients) were assayed for HCMV DNA in peripheral blood leukocytes, HCMV DNA in plasma, and HCMV tegument protein 65 kDa (pp 65 antigen). Three laboratory diagnostic patterns were observed and related to clinical findings: (1) HCMV DNA only in leukocytes was observed in 26 patients, 7 of whom had HCMV disease, 5 of whom had graft rejection, and 14 of whom had no specific symptoms; (2) HCMV DNA both in leukocytes and in plasma (viremia) was observed in 3 patients, who were all symptomatic with HCMV disease; (3) HCMV DNA in leukocytes and in plasma (viremia) and pp 65 antigen were observed in 13 patients, all of whom were symptomatic (10 patients had HCMV disease, and 3 patients had graft rejection). A similar sequence of diagnostic patterns was observed in all symptomatic HCMV infections and reactivations in this study: HCMV DNA appeared first in peripheral blood leukocytes, then also in plasma, followed by pp 65 antigen detectable in peripheral blood leukocytes. Upon clinical recovery, these findings disappeared in reverse order. However, HCMV DNA remained detectable in peripheral blood leukocytes for several weeks. The detection of HCMV DNA in the peripheral blood is an exception, not the rule, even in severely immunosuppressed HTx patients. It indicates a pathological condition, albeit without clinical symptoms in some patients, and it is the earliest signal of HCMV replication. Of 42 patients in whom HCMV DNA was initially detected only in peripheral blood leukocytes, 16 patients progressed into viremia. Thus, HCMV-specific PCR performed on nucleic acid extracts from lysed peripheral blood is an appropriate method for the monitoring of HCMV infections in immunosuppressed HTx patients.

Comparison of polymerase chain reaction and pp65 antigen test for early detection of human cytomegalovirus in blood leukocytes of cardiac transplant recipients

OBJECTIVE: To establish whether polymerase chain reaction (PCR) for cytomegalovirus deoxyribonucleic acid (DNA) can provide clinical information for the management of the infection. METHODS: Leukocytes in 30 heart transplant recipients were monitored by pp65 antigen testing and PCR for 82 to 365 days after transplantation. RESULTS: Of the 30 patients, 26 developed cytomegalovirus infection, nine of whom were symptomatic. Altogether, 300 leukocyte samples were examined. The concordance between PCR and pp65 antigen test was 82.6%. In symptomatic patients after surgery, PCR detected cytomegalovirus infection after 38 plus minus 16 days and the pp65 antigen test, after 48 plus minus 15 days. Symptomatic infection correlated with a higher number of pp65-positive leukocytes than did asymptomatic infection: 310 plus minus 356 vs 24 plus minus 35 (p < 0.005)/200,000 examined, respectively. Clearance of virus was observed by PCR after 125 plus minus 73 days (range 29 to 225) in symptomatic, and after 82 plus minus 70 days (range 16 to 301) in asymptomatic, cases of infection. CONCLUSIONS: The positive predictive value of PCR for symptomatic infection was 34.6%. Our findings correlate with previous reports and show that the qualitative detection of cytomegalovirus DNA is not associated with overt disease whereas quantitation of pp65-positive leukocytes closely correlate with symptom onset. Insofar as the results are not quantitative, PCR is not a marker of clinically apparent infection. Careful monitoring of cytomegalovirus infection based on quantitative pp65 antigen assay can fulfill all clinical needs for early diagnosis and proper management of the infection

Quantitation of cytomegalovirus in the blood of liver transplant recipients

An assay for quantitation of cytomegalovirus (CMV) has been developed. The assay combines DNA amplification and enzyme-linked immunosorbent assay (ELISA) detection. In this study, the assay has been used to examine sequential buffy-coats from 32 consecutive liver transplant recipients. In a febrile patient, CMV titres in excess of 10(4) copies per 150,000 cells strongly suggest a diagnosis of symptomatic CMV infection. Antiviral therapy causes a rapid decline in viral titre. Viral titres are seen to rise presymptomatically in some patients. Median peak viral titres differ significantly between symptomatic patients (1.1 x 10(5)), asymptomatic CMV IgM-positive patients (1.7 x 10(3)), and asymptomatic CMV immunoglobulin (Ig)M-negative patients (2.9 x 10(2)). CMV quantitation can be used for diagnosis and surveillance and can also be used to monitor antiviral treatment.

Monitoring of leukocyte cytomegalovirus DNA in bone marrow transplant recipients by nested PCR

A nested PCR assay for the detection of human cytomegalovirus (CMV) DNA was evaluated by weekly monitoring of blood samples taken from 101 bone marrow transplant (BMT) recipients. When peripheral blood leukocytes were used as the source of CMV DNA, even a modified assay with stringent temperature-cycling conditions was as sensitive as the standard assay. The sensitivity, specificity, and positive predictive value of two consecutively positive leukocytic PCR results with this modified assay in predicting CMV disease of 101 patients submitting 1,441 peripheral blood leukocyte samples were found to be 92.1, 63.5, and 60.3%, respectively. The positive predictive value of patients' seropositivity for CMV was 40%, while that of viremia was 72%. However, viremia followed CMV disease by a median of 1.5 days, while the first leukocytic positive PCR assay preceded disease by a median of 14 days. By use of the criteria of two consecutively positive PCR results instead of recipient CMV seropositivity for starting preemptive ganciclovir treatment, 38 of the 43 recipients with isolated single positive or negative assays (groups I and II) would be spared unnecessary ganciclovir treatment. Moreover, two other findings support the use of antiviral prophylaxis before engraftment in high-risk cases and subsequent preemptive treatment of patients with two consecutively positive PCR assays. First, for 7.9% of 76 patients with positive assays (groups II and III), the first positive PCR assay occurred before engraftment, which implied the presence of viral DNA in the blood (DNAemia) soon after transplantation. Second, isolated single positive assays which were clustered around the second to sixth weeks after transplantation were found for 18 patients (group II) and could represent abortive episodes of CMV infection.

Detection improvement of cytomegalovirus antigen in human peripheral blood using monoclonal antibodies and automated reading of cell preparations

One of the major drawbacks in cytomegalovirus (CMV)-antigenaemia detection for diagnosis of active CMV infection is the low number of CMV-antigen positive cells present in peripheral blood. It is therefore necessary to screen large numbers of peripheral blood granulocytes to find only a few antigen-positive cells. We have optimized this detection by testing several monoclonal antibodies (mAb) to CMV-antigens (mAbs C10/C11, C12, BM222, E13 and SL20). In total 550 blood samples from 40 patients were investigated. More blood samples were found positive with mAb C12 than with the other mAbs. Also the average number of positive cells per slide was highest for mAb C12. Furthermore, duplicate slides were examined automatically using an image analysis system (LEYTAS) and compared to visual detection (cytospin slides). The detection sensitivity of both screening methods was compared for mAb C12. In total 360 slides were analysed, from positive as well as negative blood samples. The sensitivity of the automated screening was 93% and for the visual evaluation of the cytospin slides 73%. In conclusion, mAb C12 was the most suitable of the mAbs tested for detection of antigenaemia, and automatic detection of CMV antigenaemia with image analysis of slides is a sensitive method due to the large numbers of cells that can be screened.

CMV-DNA detection in parenchymatous organs in cases of SIDS

A nested PCR approach has been developed especially for the detection of small amounts of cytomegalovirus (CMV) DNA in autopsy samples. Lung tissue and submandibular glands in 118 cases of infant death (92 SIDS cases, 13 natural deaths due to other defined causes and 13 unnatural deaths) were investigated by this technique and compared to the results obtained by other CMV detection methods (histology, immunohistochemistry, in situ hybridization and PCR). CMV-DNA could be detected in the lung tissue in 7 cases of SIDS using nested PCR. Compared to conventional PCR (3 positive cases in lung tissue) the nested approach always gave glear results and showed less additional bands. In all cases where CMV could be detected in the lungs, positive results were also obtained in the submandibular glands. The nested PCR method proved to be a more sensitive technique than the other detection methods including PCR and hot start, and even minimal amounts of target DNA could be detected in the presence of human and bacterial background DNA.

[Current status of human cytomegalovirus disease]

Human cytomegalovirus (HCMV) can establish lifelong persistence after primary infection with reactivation occurring as a result of immunosuppression. There is much evidence that molecular interactions between the immune system and the HCMV are responsible for immune escape. HCMV in many cells especially in mononuclear blood cells during latency are frequently the source of transmission and spreading and results in a variety of disorders. In this review some data about acute infection in immunocompetent host (mononucleosis, hepatitis), about intrauterine HCMV infection, about infection and endogenous reinfection in bone marrow and solid organ transplant recipients (pneumonitis) and about HCMV disease in AIDS patients (encephalitis, neuropathy, retinitis, colitis) are investigated. Moreover, HCMV associated vasculitis is described in patients with myocarditis, rheumatoid arthritis or polyradiculopathy. HCMV could play an important role in atherosclerosis. Several types of human malignancy have been linked to HCMV and it has been shown that HCMV ie genes upregulate expression of cellular oncogenes. The diagnosis of HCMV infection is carried out by viremia in cell culture using immediate early antigen staining, by antigenaemia which appears to be an early quantitative and predictive tool, by HCMV DNA detection using hybridization and PCR, and by IgM and IgG antibody evaluation. Two antiviral drugs are used for treatment: ganciclovir and phosphonoformic acid; few resistant clinical isolates have been reported. Specific gammaglobulin activity is discussed. HCMV vaccine is not available.

Quantitation of human cytomegalovirus glycoprotein H gene in cells using competitive PCR and a rapid fluorescence-based detection system

A technique is described for quantitation of the human cytomegalovirus (HCMV) glycoprotein H (gH) gene in cells using a quantitative-competitive polymerase chain reaction (QC-PCR). Two recombinant DNA molecules, differing in size due to a 92-bp deletion within the HCMV gH sequence, were used in co-amplification studies to construct a standard curve from which the copy number of the gH gene present in clinical samples could be interpolated. The use of primers labeled with a fluorescent dye allowed direct detection of the amplified products by measuring the amount of fluorescence emitted by each specific PCR fragment with an automated DNA sequencer coupled to a software program. This system was validated subsequently using bronchoalveolar lavage cells obtained from immunocompromised patients and found to be highly sensitive and reproducible over a range of 5-50,000 HCMV gH copies. This rapid procedure could easily be applied to study the pathogenesis of HCMV infection, identify the patients at high risk of developing HCMV disease, and monitor the effects of antiviral therapy at the molecular level.

Detection of human cytomegalovirus in peripheral blood leukocytes by the polymerase chain reaction and a nonradioactive probe

This study evaluated the effectiveness of polymerase chain reaction (PCR) combined with a nonradioactive probe for the early detection of cytomegalovirus (CMV) in buffy-coat specimens of immunocompromised patients. Dot-blot hybridization with a digoxigenin-labeled probe was used to detect a 262-bp PCR amplified fragment of the major immediate-early gene of CMV DNA. The results were compared with tissue cultures isolation of CMV. The study included 172 buffy-coat specimens from 72 immunocompromised patients. All 28 buffy-coat specimens positive by culture were also positive by PCR. The remaining 144 specimens were negative by culture; however, 47 of these were positive by PCR. Consequently, PCR was in agreement with culture results in 72% of the samples. Of the 47 PCR-positive-culture-negative specimens, 23 were from patients who had positive buffy-coat cultures at other times during their treatment. Chart review showed that an additional 16 of the PCR-positive-culture-negative samples were from patients with clinical evidence of active CMV disease. The eight remaining specimens were from five patients without signs of active disease. Specimens from 11 healthy volunteers were negative by PCR. In this study PCR was shown to be more sensitive than culture because it allowed earlier detection of viremia and demonstrated CMV in buffy-coat specimens that were negative by culture.

Postmortem findings in the Nijmegen breakage syndrome

Autopsy findings for two patients with the Nijmegen breakage syndrome (NBS) are presented. This syndrome has the same type of immunologic and cytogenetic abnormalities as ataxia telangiectasia (AT). In NBS, however, microcephaly is found and progressive cerebellar ataxia and oculocutaneous telangiectasia are lacking. We demonstrate a clear neuropathologic difference between these two syndromes, as the diffuse cortical cerebellar degeneration characteristic of AT was absent in NBS. In the thymus the histologic picture was suggestive of simple dysplasia. Lymphoid tissues were slightly atrophic but otherwise structurally normal. In one of the two presented cases an extranodal diffuse large cell malignant non-Hodgkin lymphoma of B cell immunoblastic type was found in Waldeyer's ring, in the small and large intestines, and in the brain, whose sequelae had caused death. Six of the 19 patients known with certainty to have this syndrome have developed lymphoid malignancy, which indicates that these patients are prone to develop malignancies.

Serological diagnosis of cytomegalovirus infection: comparison of 8 enzyme immunoassays for the detection of HCMV-specific IgM antibody

BACKGROUND

Recently, numerous commercial ELISA kits for the detection of HCMV-specific IgM antibodies have been developed and are available on the international market.

OBJECTIVE

The aim of the present study was to compare eight different ELISAs for the early serological diagnosis of HCMV infection.

STUDY DESIGN

A panel of paired sera obtained from patients suffering from primary or secondary infection and potential cross-reactive serum samples positive for IgM antibodies against other herpesviruses, antinuclear antibody and rheumatoid factor were investigated with 5 indirect ELISAs (1-5) and 3 mu-capture assays (ELISAs 6-8).

RESULTS

The highest sensitivity for IgM detection was achieved by a mu-capture assay (ELISA 8) and a traditional indirect ELISA (4). Their respective sensitivities were 78.0 and 76.0%. Overall, mu-capture immunoassays (ELISAs 6-8) detected HCMV infection earlier than indirect ELISAs (1-5) and showed a higher sensitivity for antibody detection in dilution series of IgM positive serum samples. Whereas ELISAs 1, 2, 5 and 6 showed a specificity of 100%, the alternative assays were affected by a variable number of false positive results obtained by testing potential cross-reactive serum samples. Their specificities ranged from 72.0% (ELISA 8) to 96.0% (ELISA 3).

CONCLUSION

The results of the present study show that recent mu-capture and indirect ELISAs permit a relatively sensitive and reliable diagnosis of HCMV infection. Cross-reactive antigens and interference from antinuclear antibody may limit the specificity of commercial kits.

Rapid detection of active cytomegalovirus infection by in situ polymerase chain reaction on MRC5 cells inoculated with blood specimens

An in situ polymerase chain reaction was developed to amplify immediate early genes of human cytomegalovirus in cells cultured in a 96 well plate and infected with leukocytes. The technical parameters enabling optimal detection of the DNA sequences were defined. The key to this method is the fixation of cells, which facilitates the access of the PCR mixture into the cell nuclei and preserves cell morphology. Such a technique could have wide application for the detection and identification of other infectious viruses in cultured cells very early after inoculation of clinical samples.

Comparison of nested PCR for detection of DNA in plasma with pp65 leukocytic antigenemia procedure for diagnosis of human cytomegalovirus infection

A nested PCR was used for the detection of human cytomegalovirus (HCMV) DNA in plasma. The presence of HCMV DNA and its correlation to pp65 leukocytic antigenemia were investigated with 299 blood samples from 45 organ transplant recipients and 63 AIDS patients. Of the 53 samples positive by nested PCR, 52 (98%) were also positive for leukocytic antigenemia and 23 had high levels of antigenemia (> 50 positive cells per 2 x 10(5) leukocytes). Of the 246 samples negative in PCR, only 3 (1.2%) had highly positive antigenemia. For 15 patients having a high antigenemia level in the course of their disease, consecutive blood samples were studied and also assessed for viremia in culture. The extent to which HCMV DNA, detected by PCR, was present in plasma correlated with increased levels of HCMV leukocytic antigenemia for six of the eight AIDS patients and for all the organ transplant recipients. Positivity for HCMV DNA in PCR and for viremia in cell culture was usually restricted to the highest antigenemia levels. From a total of 69 blood samples, PCR and culture gave positive results, respectively, for 17 of 32 samples (53%) and 14 of 32 samples (43%) from transplant recipients and for 15 of 37 samples (40%) and 9 of 37 samples (24%) from AIDS patients. Our findings have shown a strong correlation between high levels of leukocytic antigenemia and HCMV DNA in plasma. The detection of HCMV DNA in plasma by this nested PCR can prove HCMV dissemination in blood, but it lacks the rapidity and simplicity of the leukocytic pp65 antigenemia procedure.

Low correlation of human cytomegalovirus DNA amplification by polymerase chain reaction with cytomegalovirus disease in organ transplant recipients

Seventy-five organ transplant recipients underwent prolonged virological and serological follow-up for early detection of human cytomegalovirus (HCMV) infection after transplantation. HCMV DNA detection by nested polymerase chain reaction (PCR) and HCMV early structural antigen (pp65) detection were carried out in 576 peripheral blood leucocyte (PBL) samples. Furthermore, 563 blood specimens were investigated by a commercially available enzyme-linked immunosorbent assay (ELISA) for the detection of specific immunoglobulins G, M, and A against HCMV structural antigens. In eight of nine symptomatic organ transplant recipients, HCMV DNA was detected in one or more consecutive blood samples. HCMV DNA PCR was also positive in one or more samples from eight patients who never developed HCMV-related symptoms. HCMV pp65 antigen was detected almost exclusively in PBL samples from organ transplant recipients suffering from HCMV disease. However, antigenaemia was not detected in four PCR positive patients presenting clinical signs attributable to HCMV infection. Two of the initially HCMV DNA positive samples were not confirmed by retesting and hybridisation. The results of the present study demonstrate that despite the high specificity of nested PCR, HCMV DNA may be detected in the absence of clinical symptoms attributable to HCMV infection. In asymptomatic reactivation, limited replication of viral DNA may be responsible for positive results of PCR without any clinical relevance. In this context, pp65-antigen detection from PBL seems to have a better prognostic value, but is not always detected when clinical symptoms are present.

Comparison of PCR and pp65 antigenemia assay with quantitative shell vial culture for detection of cytomegalovirus in blood leukocytes from solid-organ transplant recipients

This study compared PCR and an assay for cytomegalovirus (CMV) pp65 antigenemia (CMV-vue; INCSTAR Corp.) with a quantitative shell vial culture (QSVC) technique for the detection of CMV in serial blood specimens from 46 solid-organ transplant recipients. In a comparison based on 535 specimens tested by PCR and QSVC, CMV was detected by PCR in 41 and by QSVC in 37 of 43 recipients at risk of CMV infection. The mean number of days after transplantation of initial detection of CMV was 29.9 for PCR and 34.0 for QSVC (P = 0.01). The antigenemia assay was performed on 395 specimens, including 304 of those also tested by PCR. In these specimens, CMV was detected by the antigenemia assay, QSVC, and PCR in 30, 32, and 35 (respectively) of 38 patients at risk, with no statistically significant difference in the time to detection. Each of the assays detected CMV in similar proportions of patients with and without clinically significant CMV infection. PCR stayed positive longer after transplantation than the other assays but frequently returned to negative when more than 6 months had elapsed after transplantation. The antigenemia assay and PCR stayed positive longer after institution of antiviral therapy than QSVC. PCR can provide highly sensitive detection of CMV viremia, but a PCR assay for CMV is not yet available in kit form. The pp65 antigenemia assay and shell vial culture are quantifiable and comparable in sensitivity. Either is recommended for rapid detection of CMV in blood specimens from solid-organ transplant recipients.

Detection of cytomegalovirus mRNA and DNA encoding the immediate early gene in peripheral blood leukocytes from immunocompromised patients

Detection of cytomegalovirus (CMV) DNA in peripheral blood leukocytes has been shown to be a sensitive marker of CMV infection. However, the specificity with regard to its clinical significance is less clear, since infections considered to be latent may be detected. In this report, the presence of CMV immediate early antigen (IEA) DNA and mRNA in peripheral blood leukocytes detected by PCR was investigated and related to the appearance of CMV pp65 antigen, CMV serology, and clinical status. Thirty-seven consecutive samples were submitted to the laboratory from 36 immunocompromised patients, on a routine basis for analysis because of a potential risk of CMV infection. To facilitate differentiation between DNA and mRNA, primers were chosen in exons 2 and 3 of the immediate early gene of CMV. Keratin type I mRNA and the ssu rRNA gene served as internal controls. Thirty specimens were CMV antibody positive, of which 11 were also CMV IEA DNA positive. Two of seven seronegative samples were CMV IEA DNA positive. No relation was found between serology and the presence of CMV IEA DNA as determined in 37 samples. Five of 32 samples that could be analyzed were positive for CMV IEA mRNA, of which four were also positive in the pp65 antigen detection technique. A clear relation was found between the presence of CMV IEA mRNA and CMV pp65 antigen in leukocytes and with the clinical findings as well (P < 0.01). It is concluded that detection of CMV mRNA may have a role in diagnosis of an active clinically relevant CMV infection.

Polymerase chain reaction detection of human cytomegalovirus in over 2000 blood specimens correlated with virus isolation and related to urinary virus excretion

The polymerase chain reaction (PCR) as applied to human cytomegalovirus (HCMV) detection should provide a valuable tool for rapid, reliable diagnosis of infection, thereby allowing prompt treatment. However, to date the high sensitivity of this technique and the lack of semi-quantitative interpretation have hindered establishing its validity for diagnosing systemic infection. We describe a rapid, simple, semi-quantitative PCR technique for HCMV detection. The validity of the technique was tested objectively by analyzing over 2000 leukocytes specimens by PCR and comparing the results with virus isolation from urine and blood in concomitant samples in the absence of any clinical data. It could thus be established that this technique had a sensitivity and specificity of 97%. When the PCR signal corresponded to > or = 8000 genome equivalents for 10(4) leukocytes, the predictive value for viremia was 86%. This semi-quantitative PCR technique should allow rapid diagnosis of systemic infection and provide a reliable means of monitoring clearance of CMV from blood during drug therapy.

Cytomegalovirus and latency: an overview

Cytomegalovirus (CMV) is a member of the herpes virus group. Infection results in a variety of disorders which depend largely on the immune status of the host. A well known property of CMV is that after primary infection the virus persists in the body of the host resulting in latency. Severe immunodepression or immunodeficiency can cause reactivation of the virus from its latent state, leading to endogenous reinfection. In contrast to other herpes viruses, such as herpes simplex virus which persists in neurons, and Epstein Barr virus which persists in B lymphocytes, little is known about the localization of latent CMV. In order to obtain more insight in the organ or cell type serving as a reservoir for latent CMV, it is important to know more about the course of natural infection and the cells and organs involved. When more information is available about the localization of latent virus, studies concerning the physical state of viral DNA or the extent of viral transcription and/or translation will follow in the near future. In this review some properties of the epidemiology and transmission of human CMV, as well as data about acute infection will be given. In addition, some characteristics of the localization of latent CMV and the physical state of the virus will be discussed. Where necessary, particularly regarding insight into CMV-host interactions, knowledge of animal, particularly murine, rat and guinea pig CMV infections, will be discussed.