Effect of foscarnet induction treatment on quantitation of human cytomegalovirus (HCMV) DNA in peripheral blood polymorphonuclear leukocytes and aqueous humor of AIDS patients with HCMV retinitis. The Italian Foscarnet Study Group

Intravitreal and Systemic Foscarnet in the Treatment of Aids-Related Cmv Retinitis

Cytomegalovirus retinitis is the most frequent ocular opportunistic infection in AIDS patients. Untreated, it is always a progressive and destructive disease of the retina that results in blindness. Specific treatment is therefore mandatory to halt the progression of the retinal lesions. The authors report their experience in the treatment of CMV retinitis with foscarnet in 25 AIDS patients; the drug is an analog of pyrophosphate, virostatic against all herpes-class viruses including CMV. Foscarnet was successful in halting the progression of CMV retinitis during induction treatment (180 mg/kg/day) by either a TID (three times a day) or a BID (twice a day) regimen, and in healing retinal lesions during maintenance (90 mg/kg/day) in 14 out of 19 patients. Five patients had a relapse of retinitis during maintenance. In these patients a brief course of intravitreal foscarnet, in association with the lowest dosage of the drug administered systematically (90 mg/kg/day), was effective in healing the retinal lesions. The main systemic side effects, such as renal impairment and electrolytic disturbances, were observed only during the induction treatment, and only in one case was it necessary to stop the therapy.

Clinical utility of viral load in management of cytomegalovirus infection after solid organ transplantation

The negative impact of cytomegalovirus (CMV) infection on transplant outcomes warrants efforts toward improving its prevention, diagnosis, and treatment. During the last 2 decades, significant breakthroughs in diagnostic virology have facilitated remarkable improvements in CMV disease management. During this period, CMV nucleic acid amplification testing (NAT) evolved to become one of the most commonly performed tests in clinical virology laboratories. NAT provides a means for rapid and sensitive diagnosis of CMV infection in transplant recipients. Viral quantification also introduced several principles of CMV disease management. Specifically, viral load has been utilized (i) for prognostication of CMV disease, (ii) to guide preemptive therapy, (iii) to assess the efficacy of antiviral treatment, (iv) to guide the duration of treatment, and (v) to indicate the risk of clinical relapse or antiviral drug resistance. However, there remain important limitations that require further optimization, including the interassay variability in viral load reporting, which has limited the generation of standardized viral load thresholds for various clinical indications. The recent introduction of an international reference standard should advance the major goal of uniform viral load reporting and interpretation. However, it has also become apparent that other aspects of NAT should be standardized, including sample selection, nucleic acid extraction, amplification, detection, and calibration, among others. This review article synthesizes the vast amount of information on CMV NAT and provides a timely review of the clinical utility of viral load testing in the management of CMV in solid organ transplant recipients. Current limitations are highlighted, and avenues for further research are suggested to optimize the clinical application of NAT in the management of CMV after transplantation.

Human cytomegalovirus tropism for endothelial/epithelial cells: scientific background and clinical implications

Human cytomegalovirus (HCMV) has been routinely isolated from and propagated in vitro in human embryonic lung fibroblast (HELF) cell cultures, while in vivo it is known to infect predominantly endothelial and epithelial cells. In recent years, genetic determinants of the HCMV tropism for endothelial/epithelial cells were identified in the UL131A/UL130/UL128 locus of HCMV genome of wild-type strains. UL131A-UL128 gene products form a complex with glycoprotein H (gH) and L (gL) resulting in a gH/gL/UL131A-UL128 complex that is required for HCMV entry into endothelial/epithelial cells. In contrast, virus entry into fibroblasts has its genetic determinants in the complex gH/gL/gO (or gH/gL). During primary HCMV infection, the neutralising antibody response measured in endothelial cells (EC) is potent, occurs very early and is directed mostly against combinations of two or three gene products of the UL131A-128 locus. On the contrary, neutralising antibodies measured in fibroblasts appear late, are relatively weak in potency and are directed against gH and gB. The T-cell immune response to UL131A-UL128 gene products remains to be investigated. Recently, a role has been proposed for neutralising antibody in conferring prevention/protection against HCMV infection/disease in pregnant women with primary HCMV infection. However, the level of cooperation between humoral immunity and the well-established T-cell protection remains to be defined.

Monitoring human cytomegalovirus infection in transplant recipients

Human cytomegalovirus (HCMV) infection remains one of the most challenging infectious complications in both solid organ transplant (SOT) and hemopoietic stem cell transplant (HSCT) recipients. In the last two decades advances have been made in the diagnosis and monitoring of HCMV infection in SOT and HSCT recipients following introduction of quantitative assays such as rapid virus isolation in blood (viremia), quantitation of pp65 in peripheral blood leukocytes (antigenemia), and quantitation of viral genome in blood (DNAemia). The availability of these rapid diagnostic assays has allowed treatment administration during the presymptomatic phase of HCMV infection (preemptive treatment) and greatly reduced HCMV-related morbidity and mortality, particularly among HSCT recipients. Definition of clinically validated thresholds for initiating preemptive treatment in SOT and HSCT recipients is a major goal in the transplantation setting. With respect to universal prophylaxis of HCMV infection in transplant recipients, the preemptive treatment approach shows advantages in (i) treating a lower number of patients for shorter periods of time and (ii) avoiding the reported emergence of HCMV disease after interruption of anti-HCMV prophylaxis. To understand the mechanism behind long-term control of HCMV infection in transplant recipients, the HCMV-specific T-cell response must be evaluated.

Quantification and identification of polyomavirus DNA in blood and urine of renal transplant recipients

A cohort of 201 kidney transplant recipients (KTR) including 7 patients with evidence of renal function deterioration (as defined by creatinine levels >20% over baseline values) was analyzed for polyomavirus DNA in blood and urine samples by a new quantitative polymerase chain reaction method. Of 201 patients, 14 (6.9%) were positive for polyomavirus DNA in blood (median level, 500 copies per milliliter of blood) including all 7 patients with renal function deterioration. Polyomavirus DNA detection in blood for diagnosis of renal function deterioration in KTR showed a sensitivity of 100% and a specificity of 96%, whereas positive and negative predictive values were 50% and 100%, respectively. Diagnostic value of decoy cells detection and polyomavirus DNA quantification in urine samples was negligible.

Impact of human metapneumovirus and human cytomegalovirus versus other respiratory viruses on the lower respiratory tract infections of lung transplant recipients

Viral respiratory tract infections in lung transplant recipients may be severe. During three consecutive winter‐spring seasons, 49 symptomatic lung transplant recipients with suspected respiratory viral infection, and 26 asymptomatic patients were investigated for presence of respiratory viruses either in 56 nasopharyngeal aspirate or 72 bronchoalveolar lavage samples taken at different times after transplantation. On the whole, 1 asymptomatic (3.4%) and 28 symptomatic (57.1%) patients were positive for human metapneumovirus (hMPV, 4 patients), influenza virus A (3 patients), and B (2 patients), respiratory syncytial virus (2 patients), human coronavirus (2 patients), human parainfluenza virus (2 patients), rhinovirus (5 patients), while 4 patients were coinfected by 2 respiratory viruses, and 5 were infected sequentially by 2 or more respiratory viruses. In bronchoalveolar lavage samples, hMPV predominated by far over the other viruses, being responsible for 60% of positive specimens, whereas other viruses were present in nasopharyngeal aspirates at a comparable rate. RT‐PCR (detecting 43 positive samples/128 examined) was largely superior to monoclonal antibodies (detecting 17 positive samples only). In addition, HCMV was detected in association with a respiratory virus in 4/18 HCMV‐positive patients, and was found at a high concentration (>10⁵ DNA copies/ml) in 3/16 (18.7%) patients with HCMV‐positive bronchoalveolar lavage samples and pneumonia. Coinfections and sequential infections by HCMV and respiratory viruses were significantly more frequent in patients with acute rejection and steroid treatment. In conclusion: (i) about 50% of respiratory tract infections of lung transplant recipients were associated with one or more respiratory viruses; (ii) hMPV largely predominates in bronchoalveolar lavage of symptomatic lung transplant recipients, thus suggesting a causative role in lower respiratory tract infections; (iii) RT‐PCR appears to be the method of choice for detection of respiratory viruses in lung transplant recipients, (iv) a high HCMV load in bronchoalveolar lavage is a risk factor for viral pneumonia, suggesting some measure of intervention for the control of viral infection. J. Med. Virol. 78:408–416, 2006. © 2006 Wiley‐Liss, Inc.

Diagnosis of human cytomegalovirus infections in the immunocompromised host

BACKGROUND

In the last decade several major advances have been made in the rapid diagnosis of human cytomegalovirus (HCMV) infections and disease in immunocompromised patients both at the immunological and molecular level.

OBJECTIVES

The objective was to review in some detail the new diagnostic tools allowing determination and quantitation of HCMV infection in blood of transplanted and AIDS patients.

STUDY DESIGN

The determination and quantitation as well as the clinical significance of antigenemia, viremia, HCMV-infected circulating endothelial cells (CEC) and DNAemia will be discussed in view of the therapeutic management of HCMV disease. Levels of viremia represent the number of p72-positive cultured fibroblasts inoculated with 2 x 10(5)PBL, while levels of antigenemia represent number of pp65-positive PBL/2 x 10(5) PBL examined. The number of CEC is determined simultaneously and in parallel with antigenemia. DNAemia, both qualitative and quantitative, can be determined by polymerase chain reaction (PCR) per 1 x 10(5)PBL. The clinical utility of determining either immediate-early or late mRNA is still debated.

RESULTS

In solid organ transplant recipients mean levels of viremia of 100 and of antigenemia of 400 correlate with onset of clinical symptoms. The time between first HCMV positivity and the onset of symptoms (>/= 10 days), together with the observation that most patients with reactivated infection clear virus without treatment, allowed the establishment of an antigenemia cut-off of 100 for the initiation of treatment. On the other hand, seronegative recipients of solid organs from seropositive donors must be treated preemptively, i.e. at first appearance of HCMV positivity in blood. Due to the risk of early appearance of HCMV pneumonia, the same preemptive approach must be used in bone-marrow transplant recipients. In acquired immunodeficiency syndrome (AIDS) patients with HCMV infection/disease, general criteria for initiation of treatment are more difficult to establish and treatment must be maintained. CEC are detected only in untreated disseminated HCMV infections with organ involvement. Qualitative DNA determination is useful only in special cases, such as in aqueous or vitreous humor of AIDS patients with HCMV retinitis. Quantitative DNA levels obtained by PCR are much more helpful for diagnosing HCMV disease and establishing initiation of treatment.

CONCLUSIONS

New diagnostic procedures currently ensure fine monitoring of HCMV infections/diseases and evaluation of the effect of specific antiviral treatment in the immunocompromised host.

Clinically-based determination of safe DNAemia cutoff levels for preemptive therapy or human cytomegalovirus infections in solid organ and hematopoietic stem cell transplant recipients

Transplantation Centers using human cytomegalovirus (HCMV) antigenemia-based preemptive therapy will need to replace in the near future the antigenemia assay with a more standardized and automatable assay, such as a molecular assay quantifying HCMV DNA in blood (DNAemia). Thus, in view of replacing antigenemia with clinically safe cutoff values, DNAemia levels corresponding to antigenemia cutoffs guiding HCMV preemptive therapy were determined retrospectively in solid organ and hematopoietic stem cell transplant recipients (HSCTR) using an "in-house" quantitative PCR (QPCR) method. Since preemptive therapy had prevented appearance of HCMV disease in all patients tested, DNA cutoffs determined retrospectively had to be considered as safe clinically as antigenemia cutoffs used prospectively. However, in solid organ transplant recipients (SOTR), initiating preemptive therapy upon an antigenemia cutoff of 100 pp65-positive leukocytes, a DNAemia cutoff of 300,000 copies/ml blood had positive and negative predictive values of >90%, indicating that a DNAemia cutoff could achieve, in terms of prevention of HCMV disease, the same clinical results as the antigenemia cutoff. In HSCTR, initiating preemptive therapy upon first antigenemia positivity, a DNAemia cutoff of 10,000 copies/ml blood had a positive predictive value of >90%, indicating that the great majority of patients treated under the antigenemia guidance would have been treated also using this DNA cutoff. On the other hand, the negative predictive value of 28.6% indicated that two out of three HSCTR had been treated under the antigenemia guidance having the same levels of viral DNA as the untreated patients. The data suggest that a quantitative cutoff could be adopted as a guiding criterion for preemptive therapy also in HSCTR. Regression analysis allowed to determine the DNAemia (corresponding to QPCR) cutoff values for two commercial assays tested both in solid organ and HSCTR. Retrospective DNAemia cutoff values will be verified for safety in prospective trials.

Human cytomegalovirus immediate-early mRNAemia versus pp65 antigenemia for guiding pre-emptive therapy in children and young adults undergoing hematopoietic stem cell transplantation: a prospective, randomized, open-label trial

In the search for better protocols of preemptive therapy of human cytomegalovirus (HCMV) infection in hematopoietic stem cell transplant (HSCT) recipients, we conducted a randomized trial comparing antigenemia with the nucleic acid sequence-based assay (NASBA) for determination of HCMV immediate-early messenger RNA (IEmRNA) as the guiding assay for initiation of pre-emptive antiviral treatment. In the IEmRNA arm, antiviral therapy was started upon IEmRNA positivity confirmed the following day, whereas in the antigenemia arm, therapy was started in the presence of either at least 2 pp65-positive leukocytes/2 x 105 examined or a single positive leukocyte confirmed the following day. In both arms, treatment was stopped upon 2 consecutive negative results. All patients were monitored for 3 months after HSCT. The primary end point of the study was duration of anti-HCMV therapy. On the whole, 80 children (41 in the IEmRNA and 39 in the antigenemia arm), recipients of transplants from either a relative or an unrelated donor, completed the study. No patient developed HCMV disease. In the IEmRNA arm, the incidence of HCMV infection was higher compared to the antigenemia arm (80% vs 51%, respectively, P =.0069), as well as the percentage of treated patients (66% vs 44%, respectively, P =.045). However, the percentage of relapses and treated relapses was comparable in the 2 arms. There was no significant difference in median duration of therapy per patient. Although these data indicate that IEmRNA determination does not offer advantages in terms of treatment duration, it can safely replace antigenemia, while semiautomation is the major advantage of the NASBA procedure.

The human cytomegalovirus

Human cytomegalovirus (HCMV), a betaherpesvirus, represents the major infectious cause of birth defects, as well as an important pathogen for immunocompromised individuals. The viral nucleocapsid containing a linear double-stranded DNA of 230 kb is surrounded by a proteinaceous tegument, which is itself enclosed by a loosely applied lipid bilayer. Expression of the HCMV genome is controlled by a cascade of transcriptional events that leads to the synthesis of three categories of viral proteins designated as immediate-early, early, and late. Clinical manifestations can be seen following primary infection, reinfection, or reactivation. About 10% of infants are infected by the age of 6 months following transmission from their mothers via the placenta, during delivery, or by breastfeeding. HCMV is a significant post-allograft pathogen and contributes to graft loss independently from graft rejection. Histopathologic examination of necropsy tissues demonstrates that the virus enters via the epithelium of the upper alimentary, respiratory, or genitourinary tracts. Hematogenous spreading is typically followed by infection of ductal epithelial cells. Infections are kept under control by the immune system. However, total HCMV clearance is rarely achieved, and the viral genome remains at selected sites in a latent state. Virological and molecular detection of HCMV, as well as serological demonstration of a specific immune response, are used for diagnosis. Treatment of HCMV infections is difficult because there are few options. The presently available drugs produced a significant clinical improvement, but suffer from poor oral bioavailability, low potency, development of resistance in clinical practice, and dose-limiting toxicities.

Human cytomegalovirus pp67 mRNAemia versus pp65 antigenemia for guiding preemptive therapy in heart and lung transplant recipients: a prospective, randomized, controlled, open-label trial

BACKGROUND

Preemptive therapy of human cytomegalovirus (HCMV) infections has gained popularity in transplantation centers. However, standardized protocols are not available. In particular, whether a qualitative molecular assay for detection of a late (pp67) HCMV mRNA represents a valuable alternative to quantitative antigenemia remains to be defined.

METHODS

Overall, 82 heart (HTR) and lung (LTR) transplant recipients were randomized into two arms, where therapy was guided by qualitative pp67 mRNA NASBA (40 patients) or quantitative antigenemia (42 patients). In the NASBA arm, both primary and recurrent infections were treated upon first confirmed positive NASBA result. In the antigenemia arm, primary infections were treated upon first confirmed positive result, while recurrent infections were treated upon cutoff of 100 pp65-positive leukocytes. In both arms, therapy was stopped upon virus disappearance. Primary endpoint was duration of therapy.

RESULTS

The number of treated/infected patients was significantly higher in the NASBA arm (25/30 vs. 15/39; P=0.015), as was the number of treated/relapsing patients (5/8 vs. 1/11; P=0.040), whereas the number of HCMV-infected/total number of patients was significantly higher in the antigenemia arm (39/42 vs. 30/40; P=0.026). Thus, in the NASBA arm, although the median duration of therapy was shorter compared to antigenemia (17 vs. 21 days, P>0.05), the overall number of days of therapy was significantly higher. No patient developed HCMV disease.

CONCLUSION

pp67 mRNA NASBA can safely replace antigenemia, with some apparent advantages (semiautomation and objectivity of test results) and disadvantages (overtreatment of patients and greater duration of overall treatment).

Detection of CMV in plasma and aqueous humor specimens from AIDS patients with CMV retinitis using the amplicor CMV test

A DNA hybridization test (the Amplicor CMV test) for CMV DNA was used to detect CMV DNA in paired plasma and aqueous humor specimens from 37 AIDS patients with ophthalmoscopically diagnosed CMV retinitis. CMV was detected in 25/37 (67.6%) plasma specimens and in 32/37 (86.5%) aqueous humor specimens. Thus, the Amplicor CMV test using aqueous humor specimens seems to be a useful diagnostic test for CMV retinitis and one that is more sensitive than determination of CMV DNA in plasma specimens.

Diagnosis and management of human cytomegalovirus infection in the mother, fetus, and newborn infant

Human cytomegalovirus (HCMV) is the leading cause of congenital viral infection and mental retardation. HCMV infection, while causing asymptomatic infections in most immunocompetent subjects, can be transmitted during pregnancy from the mother with primary (and also recurrent) infection to the fetus. Hence, careful diagnosis of primary infection is required in the pregnant woman based on the most sensitive serologic assays (immunoglobulin M [IgM] and IgG avidity assays) and conventional virologic and molecular procedures for virus detection in blood. Maternal prognostic markers of fetal infection are still under investigation. If primary infection is diagnosed in a timely manner, prenatal diagnosis can be offered, including the search for virus and virus components in fetal blood and amniotic fluid, with fetal prognostic markers of HCMV disease still to be defined. However, the final step for definite diagnosis of congenital HCMV infection is detection of virus in the blood or urine in the first 1 to 2 weeks of life. To date, treatment of congenital infection with antiviral drugs is only palliative both prior to and after birth, whereas the only efficacious preventive measure seems to be the development of a safe and immunogenic vaccine, including recombinant, subunit, DNA, and peptide-based vaccines now under investigation. The following controversial issues are discussed in the light of the most recent advances in the field: the actual perception of the problem; universal serologic screening before pregnancy; the impact of correct counseling on decision making by the couple involved; the role of prenatal diagnosis in ascertaining transmission of virus to the fetus; the impact of preconceptional and periconceptional infections on the prevalence of congenital infection; and the prevalence of congenitally infected babies born to mothers who were immune prior to pregnancy compared to the number born to mothers undergoing primary infection during pregnancy.

Diagnosis and management of human cytomegalovirus infection in the mother, fetus, and newborn infant

Human cytomegalovirus (HCMV) is the leading cause of congenital viral infection and mental retardation. HCMV infection, while causing asymptomatic infections in most immunocompetent subjects, can be transmitted during pregnancy from the mother with primary (and also recurrent) infection to the fetus. Hence, careful diagnosis of primary infection is required in the pregnant woman based on the most sensitive serologic assays (immunoglobulin M [IgM] and IgG avidity assays) and conventional virologic and molecular procedures for virus detection in blood. Maternal prognostic markers of fetal infection are still under investigation. If primary infection is diagnosed in a timely manner, prenatal diagnosis can be offered, including the search for virus and virus components in fetal blood and amniotic fluid, with fetal prognostic markers of HCMV disease still to be defined. However, the final step for definite diagnosis of congenital HCMV infection is detection of virus in the blood or urine in the first 1 to 2 weeks of life. To date, treatment of congenital infection with antiviral drugs is only palliative both prior to and after birth, whereas the only efficacious preventive measure seems to be the development of a safe and immunogenic vaccine, including recombinant, subunit, DNA, and peptide-based vaccines now under investigation. The following controversial issues are discussed in the light of the most recent advances in the field: the actual perception of the problem; universal serologic screening before pregnancy; the impact of correct counseling on decision making by the couple involved; the role of prenatal diagnosis in ascertaining transmission of virus to the fetus; the impact of preconceptional and periconceptional infections on the prevalence of congenital infection; and the prevalence of congenitally infected babies born to mothers who were immune prior to pregnancy compared to the number born to mothers undergoing primary infection during pregnancy.

Multiple changes in gene expression in chronic human Achilles tendinopathy

Atlas cDNA cell interaction arrays (CLONTECH) were used to examine degenerate tissue from four patients with Achilles tendon disorders, in order to identify changes in expression of genes important in cell-cell and cell-matrix interactions. The greatest difference between normal (post-mortem) and degenerate tissue samples was in the level of MMP-3 (stromelysin) mRNA, which was down-regulated in all the degenerate samples. Quantitative RT-PCR assay of RNA extracted from paired 'normal' and degenerate Achilles tendon tissue samples taken from tendons during surgery mirrored the results of the arrays. Levels of MMP-3 mRNA were lower, whereas levels of type-I and type-III collagen mRNAs were significantly higher, in the degenerate compared to the 'normal' samples. Immunoblotting of proteins extracted from the same tendon samples showed that three of four normal tissue samples taken from individuals without apparent tendon disorder had much higher levels of MMP-3 protein than 'normal' or degenerate samples from patients with tendinosis. We suggest that MMP-3 may play an important role in the regulation of tendon extracellular matrix degradation and tissue remodelling.

Use of CMV transcripts for monitoring of CMV infections in transplant recipients

The development of the nucleic acid sequence-based amplification (NASBA) technology has allowed qualitative determination of human cytomegalovirus (HCMV) immediate-early (IE) and late (pp67) transcripts for monitoring of HCMV infections in the post transplantation period. pp67-mRNA NASBA was shown to be less sensitive than pp65 antigenemia and leukoDNAemia, yet more sensitive than viremia in (i) detecting HCMV infection in both patients and blood samples and (ii) anticipating diagnosis of HCMV infection in solid organ (heart, lung) transplant recipients (SOTR). Use of pp67-mRNA NASBA, as a parameter for initiation of pre-emptive therapy, could be employed as an alternative to detecting antigenemia or DNAemia in SOTR, whereas in bone marrow transplant recipients (BMTR) its use would be too risky because of the delayed detection of HCMV infection. On the other hand, IE-mRNA NASBA was shown to be largely superior to the other assays both in detecting HCMV infection in patients and blood samples and in anticipating diagnosis of HCMV infection. This appears particularly useful in BMTR, where early initiation of antiviral treatment is mandatory in order to prevent the appearance of HCMV interstitial pneumonia. Pre-emptive therapy in BMTR, however, if based upon IE-mRNA NASBA would imply treatment of a greater number of patients as compared with antigenemia- or DNAemia-guided treatment. The clinical usefulness of this approach should be evaluated in prospective trials in the near future, pp67-mRNA NASBA in SOTR with reactivated HCMV infections and IE-mRNA NASBA in BMTR could represent two new virologic parameters to be used as a cutoff for pre-emptive therapy control of HCMV infections in the post-transplant period. Viral transcripts are more direct markers of viral replication in vivo and their disappearance indicates block of the replication process.

Quantitation of peripheral blood cytomegalovirus DNA for monitoring recurrent cytomegalovirus retinitis in pediatric solid organ transplant recipients

Cytomegalovirus (CMV) infection is a major concern following solid organ transplantation, especially in the pediatric population who remain at high risk of primary infection. CMV disease leads not only to increased patient and graft morbidity, but also to increased health care costs. This study describes the usefulness of a quantitative CMV polymerase chain reaction (PCR) technique for monitoring peripheral blood CMV DNA in pediatric recipients of kidney and liver allografts who had recurrent CMV retinitis. The incidence of CMV disease in 28 pediatric transplant recipients was 28.6%, one-half of whom developed retinitis. Two of these patients had recurrent retinitis on cessation of anti-viral treatment. A peripheral blood CMV DNA copy number of > or =500/microg of DNA was associated with recrudescence of the retinitis in these patients. We conclude that the measurement of peripheral blood CMV DNA by PCR is a useful tool for the surveillance of disease resolution and recurrence. This is particularly important in patients with CMV retinitis, who may remain asymptomatic for a period of time, despite recurrences.

Human cytomegalovirus immediate-early mRNA detection by nucleic acid sequence-based amplification as a new parameter for preemptive therapy in bone marrow transplant recipients

Human cytomegalovirus (HCMV) infection was monitored retrospectively by qualitative determination of immediate-early (IE) mRNA by nucleic acid sequence-based amplification (NASBA) in a series of 51 bone marrow transplant (BMT) recipients. The qualitative results for IE mRNA obtained by NASBA were compared with those obtained by prospective quantitation of HCMV viremia and antigenemia and retrospective quantitation of DNA in blood (DNAemia) by PCR as well as by qualitative determination of late pp67 mRNA by NASBA. On the whole, of the 39 HCMV-positive patients (all asymptomatic), HCMV was detected in 14 (35.9%) by quantitation of viremia, 15 (38.5%) by detection of pp67 mRNA by NASBA, 32 (82.1%) by quantitation of DNAemia, and 33 (84.6%) by quantitation of antigenemia, while HCMV was detected in 38 (97.4%) patients by detection of IE mRNA by NASBA. In the immunocompetent host, IE mRNA was not detected by NASBA in 100 blood donors or during reactivated infections in 30 breast-feeding mothers. Likewise, NASBA did not detect IE mRNA in 56 solid-organ transplant recipients in the first 21 days after transplantation. By using NASBA for detection of IE mRNA as the reference standard for detection of HCMV infection in blood samples, the diagnostic sensitivities were 67.7% for quantitation of DNAemia, 59.0% for quantitation of antigenemia, 18.3% for detection of pp67 mRNA by NASBA, and 16.0% for quantitation of viremia. Specificities and negative and positive predictive values were >90.0, >70.0, and >80.0%, respectively, for all four assays. The mean times to first HCMV detection after bone marrow transplantation were 37.7 +/- 15.4 days for detection of IE mRNA by NASBA, 39.6 +/- 15.6 days for quantitation of antigenemia, 40.9 +/- 15.2 days for quantitation of DNAemia, and 43.7 +/- 16.3 or 43.7 +/- 17.5 days for quantitation of viremia and detection of pp67 mRNA by NASBA, respectively. On the whole, 31 BMT recipients received preemptive therapy by using confirmed antigenemia positivity as a cutoff, while 35 patients could have been treated by using NASBA positivity as a cutoff and 31 could have been treated by using quantitation of DNAemia as a cutoff. In single patients, IE mRNA was detected in every episode of active HCMV infection, mostly preceding and sometimes accompanying antigenemia and DNAemia, whereas pp67 mRNA was detected only concomitantly with the highest peaks of infection. HCMV IE mRNA detection may represent a useful parameter for initiation of preemptive therapy in BMT recipients.

New strategies for prevention and therapy of cytomegalovirus infection and disease in solid-organ transplant recipients

In the past three decades since the inception of human organ transplantation, cytomegalovirus (CMV) has gained increasing clinical import because it is a common pathogen in the immunocompromised transplant recipient. Patients may suffer from severe manifestations of this infection along with the threat of potential fatality. Additionally, the dynamic evolution of immunosuppressive and antiviral agents has brought forth changes in the natural history of CMV infection and disease. Transplant physicians now face the daunting task of recognizing and managing the changing spectrum of CMV infection and its consequences in the organ recipient. For the microbiology laboratory, the emphasis has been geared toward the development of more sophisticated detection assays, including methods to detect emerging antiviral resistance. The discovery of novel antiviral chemotherapy is an important theme of clinical research. Investigations have also focused on preventative measures for CMV disease in the solid-organ transplant population. In all, while much has been achieved in the overall management of CMV infection, the current understanding of CMV pathogenesis and therapy still leaves much to be learned before success can be claimed.

Quantification of human cytomegalovirus DNA in amniotic fluid of mothers of congenitally infected fetuses

A quantitative PCR assay was used to quantitate human cytomegalovirus DNA in amniotic fluid of mothers of 21 fetuses with congenital infection. Seven fetuses presented ultrasound abnormalities or were born with symptoms, whereas 14 fetuses were subclinically infected. Although the median DNA level was higher in symptomatic fetuses, the difference was not statistically significant (P = 0.09).

Diagnostic and prognostic value of human cytomegalovirus load and IgM antibody in blood of congenitally infected newborns

BACKGROUND

Diagnosis of congenital human cytomegalovirus (HCMV) infection relies on virus isolation from urine collected in the first 3 weeks of life. However, very little is known about the presence, levels and duration of HCMV pp65 antigenemia, viremia and DNAemia in congenitally infected newborns.

OBJECTIVES

To investigate the diagnostic and prognostic value of HCMV load determination in blood of newborns/infants with congenital HCMV infection.

STUDY DESIGN

HCMV pp65 antigenemia, viremia and DNAemia were investigated in 116 sequential peripheral blood leukocytes (PBL) samples from 41 newborns/infants with congenital HCMV infection and in 34 PBL samples from 34 uninfected newborn. Virus-specific IgM were determined in parallel on 145 sequential serum samples.

RESULTS

Compared to virus isolation from urine, sensitivities of DNAemia, antigenemia, viremia, and IgM determination were 100, 42.5, 28.2, and 70.7%, respectively. Specificity was 100% for all assays. Antigenemia, viremia and DNAemia levels were significantly higher and persisted longer in newborns with symptomatic infection compared to subclinically infected babies, whereas no difference was observed for virus-specific IgM antibody between the two groups.

CONCLUSIONS

(i) determination of viral DNA in blood at birth appears to be a sensitive and specific marker for diagnosis of congenital HCMV infection; (ii) significantly higher levels of HCMV load were detected in infants with symptomatic HCMV infection; and (iii) virus clearance from blood occurs spontaneously both in symptomatic and subclinically infected infants. However, the process takes longer in infants presenting with symptoms at birth.

Cytomegalovirus antigenemia surveillance in the treatment of cytomegalovirus disease in AIDS patients

OBJECTIVE

Surveillance of quantitative cytomegalovirus (CMV) antigenemia among AIDS patients with CMV treated complications in order to determine its value in assessing the response to treatment and survival.

METHODS

A longitudinal follow-up of antigenemia measurement at diagnosis, after induction therapy with ganciclovir or foscarnet, and every 3 months during maintenance therapy was carried out in 25 patients with CMV retinitis and in 8 with extraocular CMV disease. Positive antigenemia was defined as the presence of any amount of immunofluorescent pp65-positive leukocytes/10(5) cells.

RESULTS

Mean antigenemia values were: 77+/-148/10(5) leukocytes at retinitis diagnosis; 45+/-114 after induction therapy; and 7+/-18 and 1.5+/-4 after 6 months and one year of therapy, respectively. Patients achieving undetectable antigenemia increased from 44% at baseline to 68% at postinduction and 80% during follow-up. Seven patients (28%) who remained free of relapses presented significant minor baseline antigenemias and became negative after induction therapy. Patients with extraocular disease showed erratic antigenemia values and absent therapeutic response. CMV blood cultures before and after induction therapy were positive in 39% and 21% of patients, respectively. Kaplan-Meier analysis revealed a significantly longer survival for patients with retinitis when compared to those with extraocular complications, and for patients with negative antigenemia after induction in comparison with those who failed to achieve it.

CONCLUSIONS

Low basal antigenemia and antigenemia clearance after induction therapy are variables directly related to good response to treatment and survival. Continuous surveillance of antigenemia during treatment could permit designing of individual strategies to obtain a better response.

A highly sensitive assay for detection and quantitation of human cytomegalovirus DNA in serum and plasma by PCR and electrochemiluminescence

We describe a diagnostic PCR assay (D-PCR) and a quantitative PCR assay (Q-PCR) for the detection of human cytomegalovirus (CMV) in plasma and serum. In the D-PCR, DNA was purified from plasma or serum together with internal control (IC) DNA, which monitored both DNA extraction efficiency and PCR efficiency. DNA was subjected to PCR with a single primer pair, and the amount of PCR products was determined by electrochemiluminescence (ECL) in the QPCR System 5000 (Perkin-Elmer) after hybridization with Tris (2,2'-bipyridine) ruthenium (II) chelate-labeled probes. The lower limit of sensitivity of the D-PCR was reached at about 25 CMV particles/ml. Even with extremely low DNA inputs (four molecules of IC DNA/200 microl of plasma), very high yields (near 100%) were reached. DNA extracted from specimens that were CMV positive by the D-PCR was subsequently used in the Q-PCR, which was similar to the D-PCR. The viral load was calculated directly from the ratio of CMV and IC signals obtained by ECL. The Q-PCR assay is quantitative in the range of 100 to 150,000 copies of CMV/ml, independent of the anticoagulant. Interassay variation, intra-assay variation, and interspecimen variation were about 25%, suggesting that the Q-PCR will reliably detect fourfold differences in viral load. Comparison of paired serum and plasma specimens from CMV-infected individuals showed that serum CMV loads were frequently more than 10-fold lower than plasma CMV loads.

Clinical significance of expression of human cytomegalovirus pp67 late transcript in heart, lung, and bone marrow transplant recipients as determined by nucleic acid sequence-based amplification

Human cytomegalovirus (HCMV) infection was monitored retrospectively by qualitative determination of pp67 mRNA (a late viral transcript) by nucleic acid sequence-based amplification (NASBA) in a series of 50 transplant recipients, including 26 solid-organ (11 heart and 15 lung) transplant recipients (SOTRs) and 24 bone marrow transplant recipients (BMTRs). NASBA results were compared with those obtained by prospective quantitation of HCMV viremia and antigenemia and retrospective quantitation of DNA in leukocytes (leukoDNAemia). On the whole, 29 patients were NASBA positive, whereas 10 were NASBA negative, and the blood of 11 patients remained HCMV negative. NASBA detected HCMV infection before quantitation of viremia did but after quantitation of leukoDNAemia and antigenemia did. In NASBA-positive blood samples, median levels of viremia, antigenemia, and leukoDNAemia were significantly higher than the relevant levels detected in NASBA-negative HCMV-positive blood samples. By using the quantitation of leukoDNAemia as the "gold standard," the analytical sensitivity (47.3%), as well as the negative predictive value (68. 3%), of NASBA for the diagnosis of HCMV infection intermediate between that of antigenemia quantitation (analytical sensitivity, 72. 3%) and that of viremia quantitation (analytical sensitivity, 28.7%), while the specificity and the positive predictive value were high (90 to 100%). However, with respect to the clinically relevant antigenemia cutoff of >/=100 used in this study for the initiation of preemptive therapy in SOTRs with reactivated HCMV infection, the clinical sensitivity of NASBA reached 100%, with a specificity of 68. 9%. Upon the initiation of antigenemia quantitation-guided treatment, the actual median antigenemia level was 158 (range, 124 to 580) in SOTRs who had reactivated infection and who presented with NASBA positivity 3.5 +/- 2.6 days in advance and 13.5 (range, 1 to 270) in the group that included BMTRs and SOTRs who had primary infection (in whom treatment was initiated upon the first confirmation of detection of HCMV in blood) and who presented with NASBA positivity 2.0 +/- 5.1 days later. Following antiviral treatment, the durations of the presence of antigenemia and pp67 mRNA in blood were found to be similar. In conclusion, monitoring of the expression of HCMV pp67 mRNA appears to be a promising, well-standardized tool for determination of the need for the initiation and termination of preemptive therapy. Its overall clinical impact should be analyzed in future prospective studies.

Quantitative cytomegalovirus DNA level in the blood and its relationship to cytomegalovirus retinitis in patients with acquired immune deficiency syndrome

OBJECTIVE

A pilot study was performed to determine whether relationships exist between changes in a quantitative solution hybridization assay for cytomegalovirus (CMV) DNA in the blood and development of CMV retinitis, development of nonocular CMV disease, or reactivation of pre-existing CMV retinitis lesions.

DESIGN

Observational case series.

PARTICIPANTS

Two groups of human immunodeficiency virus-infected patients: 10 CMV antibody-positive patients with CD4+ T-lymphocyte counts of less than 50 ml and no CMV disease at baseline and 11 patients with CMV retinitis but no extraocular CMV disease at baseline.

INTERVENTION

Quantitative changes in leukocyte-associated CMV DNA levels were observed over time. Anti-CMV therapies were based on clinical findings only.

MAIN OUTCOME MEASURES

Development of CMV end-organ disease or change in activity of pre-existing CMV retinitis lesions was measured.

RESULTS

Among patients with no CMV disease at baseline, four had CMV disease develop during follow-up (three cases of CMV retinitis, one case of presumed CMV esophagitis); all had CMV DNA levels greater than 5000 genomes/ml before the onset of CMV disease. The remaining six patients had levels less than 5000 genomes/ml throughout follow-up (P = 0.05). Among patients with CMV retinitis at baseline, all whose CMV DNA blood levels rose more than tenfold had extraocular CMV disease or reactivation of CMV retinitis develop. Raised CMV DNA blood levels were not seen in every patient with clinical reactivation of CMV retinitis.

CONCLUSION

Elevated or rising CMV DNA blood levels appear to be associated with the development of CMV disease in individuals with low CD4+ T-lymphocyte counts. In patients with CMV retinitis, rising levels appear to be associated with the development of extraocular CMV disease or reactivation of CMV retinitis. Conversely, reactivation of CMV retinitis also may occur in the absence of changes in CMV DNA blood levels. Further studies are warranted to determine whether changes in CMV blood levels can be used as a guide for preemptive therapy to prevent reactivation of CMV retinitis lesions or to help choose between local and systemic therapy for management of reactivations.

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.

Improved prenatal diagnosis of congenital human cytomegalovirus infection by a modified nested polymerase chain reaction

Two major variables may cause false-negative results in prenatal diagnosis of congenital human cytomegalovirus (HCMV) infection: sensitivity of the techniques(s) used; and time elapsed between maternal infection and antenatal testing. Previous results indicated that rapid HCMV isolation from amniotic fluid samples and viral DNA detection in amniotic fluid by nested polymerase chain reaction (nPCR) had comparable levels of sensitivity (69.2% and 76.9%, respectively). The nPCR protocol was reviewed following two additional false-negative antenatal diagnosis in a twin pregnancy during which two procedures were performed at 18 and 23 weeks of gestation, respectively. In the new assay, multiple (instead of single) and 100 (instead of 20) microliters amniotic fluid aliquots were individually amplified and tested by nPCR. By using this approach, low DNA levels (1-10 genome equivalents) were detected in 1-5/8 replicates of amniotic fluid samples taken from both twins during both procedures. In addition, viral DNA was detected in 5/6 replicates from two amniotic fluid samples still available from two previous false-negative cases. However, nPCR on multiple amniotic fluid replicates did not anticipate positive prenatal results in a retrospective case, which required two procedures for correct diagnosis and, when prospectively employed, did not avoid one additional false-negative prenatal diagnosis 8 weeks after maternal infection. Thus, delayed intrauterine transmission of the infection may be a potential cause of false-negative results. However, the combination of a very sensitive technique with appropriate timing of prenatal testing can substantially increase the reliability of prenatal diagnosis results.

Evaluation of the AMPLICOR cytomegalovirus test with specimens from human immunodeficiency virus-infected subjects

The AMPLICOR cytomegalovirus (CMV) test, a new qualitative assay for the detection of CMV DNA in plasma, was compared to conventional methods and quantitative PCR (Q-PCR) assays by using leukocytes and plasma from 179 blood samples from subjects with AIDS. For the diagnosis of CMV disease, cell-based assays such as a Q-PCR with polymorphonuclear leukocytes (Q-PCR-PMNL) and a pp65 antigenemia assay had the highest sensitivities but suffered from a lack of specificity. The best agreement between the results of the Q-PCR-PMNL assay and those of the AMPLICOR test was found when a threshold diagnostic value of 690 copies per 10(5) cells was selected for the Q-PCR-PMNL assay. In that context, the AMPLICOR CMV test had a sensitivity of 96.4% and a specificity of 95.3% when results were compared to results of the cell-based PCR assay. This threshold was close to the one described as associated with the best sensitivity and specificity for the diagnosis of CMV disease in a recently published study (4). Blood samples that tested positive by the Q-PCR-PMNL assay but negative by the AMPLICOR CMV test were associated with viral loads (mean, 785 copies, median, 96 copies per 10(5) leukocytes) lower than the viral loads of blood samples that tested positive by both assays (mean, 21,452 copies; median, 9,784 copies per 10(5) leukocytes) (P = 0.003). The AMPLICOR CMV test gave positive results at least 48 days before the development of symptomatic CMV disease in a longitudinal analysis of a limited subset of patients (n = 6) from whom sequential specimens were available for testing. In conclusion, the AMPLICOR CMV test is a very convenient assay combining rapidity, simplicity, and the possibility of batch testing. A positive result by this test seems particularly important since this implies, in most instances, the presence or the imminence of CMV disease, although a negative test result does not rule out disease.

Antibody response to human cytomegalovirus (HCMV) glycoprotein B (gB) in AIDS patients with HCMV end-organ disease

Human cytomegalovirus (HCMV)-specific antibody responses in HIV-1 infected individuals either with or without HCMV end-organ disease were examined to determine the whether development of HCMV disease was associated with a particular deficit in the antibody response. Antiwhole HCMV, anti-glycoprotein B (gB), and neutralizing antibody levels were higher in HIV-1 infected individuals than in healthy immunocompetent subjects, particularly in patients with AIDS either with or without HCMV-associated disease. Irrespective of location and spread of HCMV disease, patients who had received anti-HCMV therapy prior to sampling exhibited significantly higher anti-gB and neutralizing antibody titers than those who remained untreated. Likewise, patients with HCMV disease who were antigenemic or viremic had significantly lower anti-gB and neutralizing antibody titers than those who tested negative in either assay. Patients with untreated HCMV disease had significantly lower antibody titers than AIDS patients without disease. Analysis of the IgG subclass antibody responses to gB revealed no significant differences among HIV-1 infected individuals. These results suggest that levels of detectable anti-gB and HCMV neutralizing antibodies are inversely related to systemic viral load. Thus, antibodies with such specificities may be relevant in preventing the establishment of HCMV-associated disease or in modulating its progression.

Application of competitive PCR to cerebrospinal fluid samples from patients with herpes simplex encephalitis

The purpose of the present study was to determine if the quantity of herpes simplex virus (HSV) DNA in the cerebrospinal fluid (CSF) of patients with herpes encephalitis would be useful in establishing the prognosis of the disease and to determine the effect of antiviral therapy on the clearance of viral DNA from the CSF. Quantitation of HSV DNA was done by constructing an internal standard (IS) from the glycoprotein B amplicon which had a 25-bp deletion between primer annealing sites. Each CSF specimen was coamplified with the IS and the ratio of the amount of HSV/amount of IS was compared to the ratios on a standard curve constructed with the same IS plus known amounts of HSV DNA. CSF specimens were available from 16 patients who were treated with intravenous acyclovir, and the amount of HSV DNA ranged from < 25 to 18,000 copies per microliter in CSF obtained before or within 4 days of the initiation of acyclovir therapy. Patients with > 100 copies of HSV DNA per microliter were older, were found by computed tomography to have lesions, and had poorer outcomes than patients with < 100 copies. Follow-up CSF specimens were available from seven patients. In six of these seven patients, the HSV DNA levels decreased during therapy. One patient had a twofold increase in HSV DNA levels after 1 week of therapy and died on day 8. The application of this assay may be helpful in establishing the prognosis and in the monitoring of patients with herpes simplex encephalitis.

Use of the human cytomegalovirus (HCMV) antigenemia assay for diagnosis and monitoring of HCMV infections and detection of antiviral drug resistance in the immunocompromised

BACKGROUND

Quantification of viral load in blood has proven to be helpful in the follow-up of disseminated HCMV infections in immunocompromised patients.

OBJECTIVES

(i) To describe the antigenemia assay and its optimization and (ii) to analyze the use of the antigenemia assay for the diagnosis and monitoring of HCMV infections and for the detection of treatment failures.

STUDY DESIGN

This article is intended to give an overview of our experience in the use of the antigenemia assay.

RESULTS AND CONCLUSIONS

In solid organ transplant recipients and patients with AIDS, HCMV symptomatic infections mostly appear when antigenemia values are > 300 pp65-positive PBL/2 x 10(5) examined. To avoid the appearance of overt HCMV disease antiviral treatment could be administered when antigenemia levels are > 100 pp65-positive PBL/2 x 10(5) examined. Bone marrow transplant recipients show symptomatic HCMV infections when antigenemia values are > 100 pp65-positive PBL/2 x 10(5) examined. This group of patients should be treated when antigenemia levels are < 10 pp65-positive PBL/2 x 10(5) examined due to the higher mortality rate associated with HCMV complications. A decrease in antigenemia levels during therapy indicates a good response to antiviral drug, while stable or increasing values document a treatment failure and the emergence of drug-resistant HCMV strains.

Quantitation of cytomegalovirus: methodologic aspects and clinical applications

Cytomegalovirus (CMV) is an important pathogen in transplant recipients and human immunodeficiency virus (HIV)-infected individuals. Major progress has been made in developing quantitative detection methods for CMV in recent years. Due to their high sensitivity, these assays can detect CMV early, and quantitation may be useful in predicting the patient's risk for disease and in monitoring the effect of antiviral therapy. This review discusses methodological aspects of currently used quantitative assays for CMV (i.e., viral culture techniques, antigen detection assays, DNA detection assays including PCR, branched-DNA assay, and the DNA hybrid capture assay) and addresses the correlation of systemic and site-specific CMV load and CMV disease in different populations of immunosuppressed patients as well as the response to antiviral treatment. To date, direct antigen detection and molecular techniques have largely replaced traditional culture-based techniques for CMV quantitation. In general, a high systemic CMV load is correlated with CMV disease. This correlation is strong in the HIV-infected population and in solid-organ transplant recipients but less clear in allogeneic marrow transplant recipients. Measuring the viral load at specific anatomic sites may be an alternative way to assess disease activity in situations where the systemic viral load correlates poorly with disease activity. A reduction of the systemic CMV load also correlates with a response to antiviral treatment, but more research is needed to evaluate the role of viral load as a surrogate marker for drug resistance. Due to the widespread use of quantitative CMV detection techniques to direct and monitor antiviral treatment, there is a great need for an assessment of the reproducibility of test results and better standardization of the assays.

In vitro generation of human cytomegalovirus pp65 antigenemia, viremia, and leukoDNAemia

Immunocompromised patients with disseminated human cytomegalovirus (HCMV) infection have circulating PMN carrying HCMV pp65 (antigenemia), infectious virus (viremia), and viral DNA (leukoDNAemia). Because HCMV does not fully replicate in PMN, it is generally hypothesized that virions and viral materials are taken up by phagocytosis from fully permissive HCMV-infected endothelial cells. However, no experimental evidence has ever been provided for these PMN-endothelium interactions. PMN from 11 donors were cocultured with endothelial cells infected with an endothelium-adapted HCMV strain and with human fibroblasts infected with low-passaged clinical and laboratory-adapted HCMV strains. pp65-positive PMN were detected after coculture with both HCMV-infected endothelial and fibroblast cells, provided that wild and not laboratory-adapted strains were used. In addition, cocultured PMN carried infectious virus as demonstrated by virus isolation and presence of complete virus particles by electron microscopy. Moreover, high levels of viral DNA were consistently detected by quantitative PCR in cocultured PMN. Thus, we have generated in vitro the three most important viral parameters detected in patients with disseminated HCMV infection (antigenemia, viremia, and leukoDNAemia). The failure of laboratory-adapted HCMV strain to induce this phenomenon demonstrates that important modifications have occurred in attenuated viral strains affecting basic biological functions.

Human cytomegalovirus (HCMV) leukodnaemia correlates more closely with clinical symptoms than antigenemia and viremia in heart and heart-lung transplant recipients with primary HCMV infection

BACKGROUND

In the last few years, human cytomegalovirus (HCMV) viremia, pp65 antigenemia, and leuko- and plasma-DNAemia have been developed to quantitate virus in blood of immunocompromised patients with HCMV infection. However, thus far, no conclusive studies have been performed to define the correlation of each of the different assays with clinical symptoms in primary HCMV infections.

METHODS

This correlation was investigated in a population of 20 heart and heart-lung transplant recipients with primary HCMV infection using standardized virological methods.

RESULTS

Median peak HCMV viremia, antigenemia, and leukoDNAemia levels were 110 (0-2,000) p72-positive fibroblasts, 450 (27-2,000) pp65-positive leukocytes, and >10,000 (1,358-10,000) genome equivalents (GE) in the 14 symptomatic patients and 18 (1-130) p72-positive fibroblasts, 86.5 (5-350) pp65-positive leukocytes, and 248 (10-863) GE in the six asymptomatic patients, respectively. The difference was statistically significant for antigenemia (P=0.009) and leukoDNAemia (P<0.0001). However, on an individual basis, unlike viremia and antigenemia, all DNA peaks of the 6 asymptomatic patients were below the DNA range of the 14 symptomatic patients (<1,000 GE), while all the 14 symptomatic patients had DNA peaks higher than those of asymptomatic patients (>1,000 GE). Follow-up confirmed these results, showing that 1,000-2,000 GE was the threshold zone for emergence of clinical symptoms. Symptoms were never observed in patients with secondary DNA peaks, except for one patient suffering from an HCMV organ localization (HCMV gastritis).

CONCLUSIONS

LeukoDNAemia is the viral parameter of choice for monitoring of primary HCMV infections and antiviral treatment in heart and heart-lung transplant recipients. In this patient population, antigenemia-guided preemptive therapy could be replaced by leukoDNAemia-based antiviral therapy.

Cytomegalovirus (CMV) strain differences between the eye and blood in AIDS patients with CMV retinitis

OBJECTIVE

To investigate possible differences in cytomegalovirus (CMV) strain distribution between the eye and blood in AIDS patients with CMV retinitis.

METHODS

CMV DNA sequences from aqueous humour and peripheral blood leukocytes (PBL), obtained from 13 AIDS patients with CMV retinitis, were compared. DNA was isolated and the CMV IE-1 sequence (part of the immediate early-1 gene) and the a-sequence (located in the a-region) were amplified by polymerase chain reaction (PCR). The PCR products of the a-sequence were analysed by Southern blotting for amplified fragment-length polymorphisms. The level of divergence between the a-sequences of aqueous humour- and PBL-derived CMV was studied in two patients by cloning these sequences followed by sequence analysis.

RESULTS

CMV DNA could be detected in all aqueous humour samples and in 10 out of 13 paired blood samples. In the 10 patients, with CMV DNA detectable in both aqueous humour and PBL, seven cases showed differences between the amplified products of both compartments. Sequence analysis in two patients revealed that the aqueous humour and PBL of the same patient can harbour both identical, similar and highly divergent CMV a-sequences.

CONCLUSION

These results indicate that despite the haematogenous spread of CMV, the eye, being a relatively shielded organ, may contain CMV strains different from those found in the blood.

Utility of major leukocyte subpopulations for monitoring secondary cytomegalovirus infections in renal-allograft recipients by PCR

The feasibility of the major peripheral blood leukocyte (PBL) subsets for use in qualitative and quantitative PCR to monitor secondary cytomegalovirus (CMV) infection and ganciclovir therapy was assessed with 188 blood samples derived from 40 CMV immunoglobulin G-positive renal-allograft recipients. In pp65 antigen-positive patients all leukocyte fractions, but only 79.5% of plasma preparations, were PCR positive. In pp65 antigen-negative samples from patients after antiviral treatment only 7.3% of polymorphonuclear cell (PMNL) samples, but 81.8% of peripheral blood mononuclear cells (PBMC), and 10.9% of plasma samples remained PCR positive. Similarly, in patients with latent infections only 5.0% of PMNL, but 51.7% of PBMC preparations, and 8.0% of plasma samples were PCR positive. Regarding patients with active CMV infection, CMV DNA copy numbers in PMNL correlated significantly with pp65 antigen-positive cell counts before and after onset of ganciclovir therapy. Significant differences in CMV DNA copy numbers in PMNL and plasma were observed (i) between patients with symptomatic infection and those with asymptomatic infection and (ii) between patients with active infection and those with latent infection. In contrast, PBMC harbored equally low CMV DNA levels both in patients with active infection and those with latent infections, and no decline of CMV DNA load in PBMC was observed during antiviral treatment. We conclude that detection of CMV DNA in PMNL, not in PBMC, is associated with active infections and is more sensitive than detection of CMV DNA in plasma. Negative PCR results for PMNL after antiviral therapy indicate recovery, and fewer unwanted positive results occur compared to PBMC and plasma. Therefore, purified PMNL should be preferred for analysis by qualitative CMV PCR to avoid unwanted positive results. The CMV DNA load in PBMC compared with that in PMNL is negligible during active infection, so mixed PBL are sufficient for use in quantitative PCR.

Comparative study of different standardization concepts in quantitative competitive reverse transcription-PCR assays

Four different standardization approaches based on a competitive reverse transcription (RT)-PCR assay were compared with a noncompetitive assay based on an external standard curve. Criteria for assessment were accuracy in quantitation, correctness of recovery, sensitivity, dynamic range, reproducibility, throughput, and convenience of sample handling. As a model system, we used the 5'-noncoding region of hepatitis C virus (HCV) for amplification in all quantitative RT-PCRs. A computer program that allowed parallel data processing was developed. Surprisingly, all methods were found suitable for accurate quantitation and comparable with respect to the criterion correctness of recovery. All results differed only by a factor of about 2. The reason for this finding might be that all of our mimics, as well as the wild-type genome of HCV, exhibited exactly the same amplification and hybridization efficacy. Moreover, minimal competition occurred in our experiments over a 5-log dynamic range. A further topic of our investigation was the comparison of two different competitive RNA fragments, mimics, with regard to their suitability as internal standards. One was a heterologous mimic, in which only the primer binding sites were identical to the wild type. The second one was a homologous mimic identical to the wild type except for a small region used for differential hybridization, which was replaced by a permutated sequence of the same length. Both the homologous and heterologous internal mimics were found appropriate for an accurate competitive RT-PCR assay, provided that amplification efficacy, as well as capture efficacy, is proven identical for both analyte and mimic.

Early effects of ganciclovir therapy on the quantity of cytomegalovirus DNA in leukocytes of immunocompromised patients

The cytomegalovirus (CMV) DNA load in leukocytes was measured in 26 immunocompromised patients with CMV disease before and after 10 days of intravenous ganciclovir therapy. Before therapy, the circulating DNA burden of bone marrow transplant recipients was significantly lower than that of other transplant or AIDS patients. Ganciclovir induction therapy significantly decreased the viral DNA load in the leukocyte populations of most patients.

Quantitative systemic and local evaluation of the antiviral effect of ganciclovir and foscarnet induction treatment on human cytomegalovirus gastrointestinal disease of patients with AIDS. Italian Foscarnet GID Study Group

In a group of 29 AIDS patients with biopsy-proven human cytomegalovirus (HCMV) gastrointestinal disease (GID), HCMV GID was shown to correlate mostly with systemic HCMV infection. The antiviral induction treatment (IT) with either ganciclovir (GCV) or foscarnet (PFA) caused a significant reduction in the level of HCMV antigenemia, viremia and leukoDNAemia, and a complete virus clearance or a sharp drop of viral load in the blood of 13/13 patients and in the gastrointestinal (GI) mucosa of 12/13 (92%) patients in the GCV arm, and in the blood of 13/14 (93%) patients and in the GI mucosa of 10/12 (83%) patients in the PFA arm of the study, respectively. Similarly, the clinical response was good in 13/15 (87%) patients in the GCV arm and in 13/14 (93%) patients in the PFA arm. In addition, the finding that 2/6 patients positive for HCMV isolated from both GI mucosa and blood prior to IT were still positive in the GI tract after IT, suggested that IT could be prolonged to clear the virus from GI tract. In conclusion, both GCV and PFA showed a remarkable systemic and local antiviral effect in the treatment of HCMV GID in AIDS patients.

Quantitation of herpes simplex virus DNA in cerebrospinal fluid of patients with herpes simplex encephalitis by the polymerase chain reaction

BACKGROUND

Previous studies have shown the diagnostic utility of qualitative detection of herpes simplex virus (HSV) DNA by the polymerase chain reaction (PCR) in cerebrospinal fluid samples (CSF) from patients with herpes simplex encephalitis (HSE).

OBJECTIVES

To determine whether quantitation of HSV DNA in CSF could be useful for monitoring efficacy of antiviral therapy and provide prognostic indications.

STUDY DESIGN

A quantitative PCR assay using an internal control for evaluation of PCR efficiency and detection of PCR inhibitors was developed and used for retrospective testing of 98 CSF samples from 26 patients with serologically diagnosed HSE during the period 1980-1995.

RESULTS

HSV DNA was detected in 36 CSF samples from 23 patients. PCR positivity was 100% for CSF samples collected within 10 days after onset, and 30.4 and 18.7% for samples collected 11-20 and 21-40 days later, respectively. The 3 PCR-negative patients had their first CSF collected 14, 16, and 28 days after onset, respectively. Three of 98 (3.1%) CSF samples were completely or partially inhibitory to PCR. Initial DNA levels were not significantly different in patients with HSE due to either primary or recurrent HSV infection. In addition, they were not related to severity of clinical symptoms nor were predictive of the outcome. A progressive decrease in viral DNA levels was observed both in patients who received acyclovir therapy and in a small number of untreated patients.

CONCLUSIONS

This study: (i) confirms the high sensitivity of PCR for the diagnosis of HSE; (ii) emphasizes the need for an internal control of amplification of achieve maximal sensitivity and perform reliable quantitation of viral DNA; and (iii) suggests that CSF might not be the best specimen to investigate in studies of the natural history of HSE.

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.

Diagnostic assays in cytomegalovirus retinitis: detection of herpesvirus by simultaneous application of the polymerase chain reaction and local antibody analysis on ocular fluid

AIM

To determine the value of the polymerase chain reaction (PCR) technique and the analysis of intraocularly produced antibodies by calculating a Goldmann-Witmer quotient (GWq) as diagnostic assays in the confirmation of a clinically diagnosed cytomegalovirus (CMV) retinitis in a group of unselected AIDS patients.

METHODS

Eleven samples of undiluted ocular fluid, obtained from nine AIDS patients with a clinically diagnosed CMV retinitis were analysed for the presence of genomic DNA from CMV, HSV-1, VZV, and EBV by PCR. Nine of these samples were analysed for the presence of locally produced IgG antibodies against these herpesviruses by calculating a GWq. Ten samples obtained from patients with various entities of clinical non-herpetic uveitis and 17 samples of aqueous humour obtained at cataract surgery were used as controls.

RESULTS

In 10 out of 11 samples from AIDS patients (91%) the presence of CMV DNA was demonstrated. In four out of nine (44%) patients this was accompanied by CMV DNA in the blood indicating a CMV viraemia. In one sample, VZV DNA was detected and in another sample both CMV and VZV DNA were detected. No HSV-1 or EBV DNA could be demonstrated in these 11 samples. In contrast, simultaneous analysis of locally produced IgG antibodies against herpesviruses could not confirm the initial diagnosis of CMV retinitis. Ocular fluid samples obtained from 10 control uveitis patients were negative for DNA from CMV, VZV, and EBV by PCR. In one of 10 uveitis control samples HSV-1 DNA was detected; antibody analysis did not confirm this. In the uveitis control group, a significant GWq was calculated in one sample for HSV-1 and in another sample for VZV. The cataract control samples were all herpesvirus DNA negative by PCR.

CONCLUSIONS

To establish the diagnosis of CMV retinitis in AIDS patients, ophthalmoscopic examination is a sensitive method. In confirming a diagnosis in indistinctive cases, application of a PCR assay detecting CMV DNA is a more sensitive method than analysis of locally produced antibodies by calculating a GWq. In clinical non-herpetic uveitis, secondary release of HSV-1 and VZV should be considered requiring additional therapeutic anticipation.

Polymerase chain reaction for prenatal diagnosis of congenital human cytomegalovirus infection

The reliability of the polymerase chain reaction (PCR) for prenatal diagnosis of human cytomegalovirus (HCMV) infection was determined by retrospective testing of 35 amniotic fluids identified previously as positive or negative for HCMV by virus isolation. Amniocentesis was performed in 26 pregnant women with primary HCMV infection at 14-36 weeks gestation, 3-21 weeks after maternal infection. Blood samples were obtained from 20 fetuses for IgM determination and/or virus isolation. Amniotic fluid culture led to antenatal diagnosis of HCMV in 9 of the 13 infected fetuses (sensitivity 69.2%) with one case diagnosed at a second sampling. PCR was able to detect one additional infected fetus (10/13, sensitivity 76.9%). Nested PCR did not increase sensitivity of prenatal diagnosis. Three cases were not diagnosed by all the techniques employed. The specificity of virus isolation from and DNA detection by PCR in amniotic fluid was 100%. The negative predictive value for virus isolation from amniotic fluid was 76.5% and for DNA detection by PCR 81.2%, whereas the positive predictive value was 100% for both techniques. The results showed that neither approach can detect all cases of congenital HCMV infection prenatally, and that the time interval between maternal infection and sampling seems to be a major factor affecting the reliability of prenatal diagnosis.

Quantitation of human cytomegalovirus DNA in bone marrow transplant recipients

HCMV DNA was retrospectively quantitated in the early post-transplant period in 36 paediatric bone marrow transplant (BMT) recipients prospectively monitored for human cytomegalovirus (HCMV) infection on the basis of antigenaemia and viraemia assays. Viral DNA was quantitated in peripheral blood leucocytes (PBL) by PCR using an internal control of amplification and a series of external standards. Densitometric analysis of hybridization results obtained on PCR products enabled construction of a standard curve from which DNA amounts of clinical samples, expressed in terms of genome equivalents (GE), were interpolated. Of the 36 BMT recipients, three had clinically symptomatic HCMV infection with mean peak levels of viral DNA > 5000 GE (antigenaemia and viraemia mean peak levels were 873 and 35, respectively), whereas 19 with HCMV reactivation were asymptomatic (five of them had abortive HCMV infection) showing mean peak DNA levels of 131 GE (and of 6.8 and 1.3 for antigenaemia and viraemia, respectively) (P < or = 0.01). Single or multiple courses of pre-emptive therapy with ganciclovir or foscarnet were given to 14/19 asymptomatic children in whom antigenaemia levels were > 2 or lower yet persisting. Overall, in the 14 asymptomatic treated patients the mean antigenaemia level was 9.3 (range 1-22), and the mean DNA level was 184.6 (range 20-710) GE. Antiviral drugs were also administered to the three symptomatic patients who, due to late diagnosis of HCMV infection, escaped preemptive therapy. Antiviral treatment caused marked decrease or disappearance of viral DNA, antigenaemia and viraemia in both symptomatic and asymptomatic patients. In conclusion, our study suggests that: (i) starting therapy in the presence of a mean antigenaemia level of 9.3 (range 1-22) corresponding to a mean DNA level of 184.6 (range 20-710) GE avoided occurrence of any major HCMV-related clinical complication; (ii) clinical symptoms were associated with antigenaemia levels > 100 and DNA levels > 1000 GE; (iii) the effect of antiviral treatment could be more carefully monitored by quantitation of viral DNA.

Human cytomegalovirus (CMV) DNA in plasma reflects quantity of CMV DNA present in leukocytes

A quantitative DNA amplification assay for human cytomegalovirus (CMV) DNA has been used to evaluate the relationship between quantities of CMV DNA in plasma and those in infected leukocytes (WBC) from human immunodeficiency virus-infected patients. The target sequence for DNA amplification was a region of the immediate-early 1 gene of CMV. The quantitation assay uses an internal control that is coamplified with each patient sample DNA and contains a sequence for detection by colorimetric hybridization with the same bases, but in different order than in the CMV immediate-early 1 region used for hybridization of amplified patient sample DNA. Results showed that patients with CMV disease had more CMV DNA in both WBC and plasma than those without disease. However, in this study, copy numbers of CMV DNA in WBC were higher than those in plasma. The gB and gH variants were the same in plasma and WBC.