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

The role of the cytomegalovirus antigenemia assay in the detection and prevention of cytomegalovirus syndrome and disease in solid organ transplant recipients: A review of the British Columbia experience

BACKGROUND

The pp65 cytomegalovirus (CMV) antigenemia assay has been used as a means of guiding the pre-emptive therapy of CMV disease in solid organ transplant (SOT) recipients. Recently, concerns have been raised regarding the utility of the test to accurately and precisely detect viral activity early enough to reduce the morbidity and mortality associated with CMV OBJECTIVE: To determine the performance characteristics of the method of antigenemia testing of SOT recipients used at Vancouver General Hospital, Vancouver, British Columbia.

METHODS

All SOT recipients between January 1, 1999, and June 30, 2000, were retrospectively reviewed for six months following transplantation. Physical examination results, laboratory parameters, antigenemia results and treatment information were reviewed.

RESULTS

A total of 134 kidney, liver, lung and kidney-pancreas transplant recipients were included in the analysis. The overall performance characteristics of the antigenemia assay in predicting CMV disease included a sensitivity of 64%, a specificity of 81%, a positive predictive value of 76% and a negative predictive value of 71%. A mean of 18 days passed between the onset of signs and symptoms of CMV disease/syndrome and the first recorded positive antigenemia result, and only 26% of patients had a positive test result before the onset of symptoms. It was found that an antigenemia test breakpoint of at least one positive cell for defining a positive test provided the most sensitive and specific prediction, with increased odds of developing CMV disease.

CONCLUSIONS

Based on performance characteristics, the Vancouver General Hospital's current method of antigenemia testing to guide pre-emptive ganciclovir therapy in SOT patients is not optimal for the early detection of disease. Further study is needed on new molecular testing methods to determine if our ability to predict CMV disease can be improved.

Monitoring cytomegalovirus T-cell immunity in small bowel/multivisceral transplant recipients

BACKGROUND

Cytomegalovirus (CMV) is a major cause of graft failure and posttransplantation mortality in intestinal/multivisceral transplantation. CMV infection exhibits a wide range of clinical manifestations from asymptomatic infection to severe CMV disease. STUDY'S PURPOSE: The purposes of this study were to assess the utility of measuring CMV-specific cellular immunity in bowel/multivisceral transplant recipients and to provide additional information on the risk of infection and development of CMV disease.

METHODS

We studied 10 bowel/multivisceral transplant recipients to investigate the kinetics of CMV infection using real-time polymerase chain reaction (on blood and biopsy tissue samples) and CMV-specific T-cell reconstitution by Enzyme-linked ImmunoSPOT Assay (ELISPOT) that enumerates Interferon-gamma-secreting CMV-specific T cells upon in vitro stimulation with viral antigens (pp65 and IE-1).

RESULTS

All patients were seropositive for CMV. According to the pattern of T-cell reconstitution occurring either within the first month after transplantation or later, patients were classified as early (n = 7) or late responders (n = 3). Clinically, early responder patients (3/7; 43%) experienced asymptomatic or mild CMV infections, whereas all late responders (3/3; 100%) developed moderate or severe CMV disease. A reduction in mean and peak CMV viral load was observed in early responders, whereas the onset time of infection did not differ significantly between early and late CMV responders.

CONCLUSIONS

A good and early reconstitution of CMV-specific T-cell immune responses after transplantation is a critical determinant in controlling CMV infections. Simultaneous monitoring of CMV infection and CMV-specific T-cell immunity predicts T-cell-mediated control of CMV infection.

Analysis of risk factors for early hepatic artery thrombosis after liver transplantation. Possible contribution of reperfusion in the early morning

BACKGROUND

Since the incidence of myocardial infarction and other cardiovascular ischaemic events is highest in early morning, on account of a relative hypercoagulable state occurring in this time period, an attempt was made to test whether reperfusion of the hepatic artery at this time of the day, at liver transplantation, produces an increased risk of early thrombosis.

METHODS

The records of 255 consecutive patients receiving a first transplant for chronic liver disease were retrospectively analysed. As possible risk factors, for early post-operative thrombosis (<30 days from transplantation), several medical and surgical parameters were taken into consideration. Arterial reperfusion was considered to have taken place at a time of high coagulability when occurred between 6.00 a.m. and 10.00 a.m. on the basis of previous reports.

RESULTS

Logistic regression identified donor age (OR for age >60: P=0.017), bench reconstruction of the artery (OR: 5.06, P=0.013) and time of high coagulability at reperfusion (OR 2.93, P=0.087), as independently associated with early hepatic artery thrombosis.

CONCLUSIONS

The present findings identified three independent predictors of early hepatic thrombosis, warranting stricter post-surgical follow-up of patients presenting such conditions. Interestingly, these factors are consistent with arterial reperfusion in the early morning being associated with an increased risk of early hepatic artery thrombosis, suggesting relative coagulative imbalances to provide a contribution in the pathogenesis of this severe complication of liver transplantation.

Monitoring for human cytomegalovirus infection in solid organ transplant recipients through antigenemia and glycoprotein N (gN) variants: evidence of correlation and potential prognostic value of gN genotypes

Human cytomegalovirus (HCMV) ORF UL73 encodes the envelope glycoprotein gpUL73-gN, which shows seven genotypes (gN-1, gN-2, gN-3a, gN-3b, gN-4a, gN-4b, gN-4c). The goal of this study was to determine retrospectively the distribution of gN variants in solid organ transplant recipients with HCMV infection and to establish an association with parameters important for monitoring post-transplantation clinical course during a follow-up of up to 2 years. Peripheral blood leukocytes from 40 solid organ transplant recipients were analysed for pp65-antigen by immunofluorescence and gN genotyped by sequencing or RFLP analysis. A correlation between gN genotypes and antigenemia peak was found, showing a highly significant difference between gN-1 and gN-4b variants (P<0.005). In particular, gN-1 seems to be associated with patients developing low level antigenemia (<50 pp65-positive cells/2 x 10(5) PBLs; PPV = 90%), whereas gN-4b predicts significantly higher values (>50 pp65-positive cells/2 x 10(5) PBLs; PPV = 80%). Furthermore, the onset of positive antigenemia is significantly earlier in patients infected with a gN-4b strain, compared with those infected by a gN-1 variant. Reported data further support a role for gN genotypes in HCMV pathogenesis. gN-1 and gN-4b show a significantly different virulence and could serve as early predictors for the progression of HCMV infection in transplant patients.

Valganciclovir: oral prevention and treatment of cytomegalovirus in the immunocompromised host

Herpes virus infections, particularly those caused by cytomegalovirus (CMV), lead to significant and, sometimes severe, clinical problems for the immunocompromised host. As effective agents have become available, several treatment and prevention strategies have evolved over the past decade, first in intra-venous form and more recently, as oral preparations. Valganciclovir, the valine ester of ganciclovir, is an orally administered, potent, antiviral agent active against all herpes viruses. When taken orally, valganciclovir has much-improved bioavailability compared with oral ganciclovir and achieves ganciclovir exposures similar to intravenous ganciclovir. Clinical trials evaluating the safety and efficacy of valganciclovir for the treatment of new AIDS-associated CMV retinitis showed equivalency to intravenous ganciclovir and prevented progression of quiescent disease. In solid organ recipients, once-daily valganciclovir has been proven equivalent to oral ganciclovir for the prevention of CMV infection. The high bioavailability and convenient dosing formulation make valganciclovir an attractive option for these indications.

Congenital cytomegalovirus infection in twin pregnancies: viral load in the amniotic fluid and pregnancy outcome

Human cytomegalovirus (CMV) is the most common cause of viral intrauterine infection and fetal damage largely attributable to maternal primary infection. Most cases of congenital CMV infection in twins reported in the literature involved only 1 twin. We assessed the validity of polymerase chain reaction (PCR) and quantitative PCR on amniotic fluid (AF), at 21 to 22 weeks' gestation and at least 6 to 8 weeks after seroconversion, to predict the outcome of newborns in twin pregnancies. Two pregnant women with twin pregnancies and 1 woman with a triple pregnancy with primary CMV infection defined by the presence of immunoglobulin (Ig) M and low IgG avidity and/or by the presence of clinical symptoms and abnormal liver enzyme values were evaluated. CMV infection was found in 6 fetuses/newborns, 3 of whom were symptomatic. In the first twin pregnancy with diamniotic-dichorionic separate placentas, CMV symptomatic infection of the female twin was demonstrated by positive virus isolation and high viral load in AF. The male fetus was not infected as demonstrated by negative CMV culture and DNA detection in AF. In the triple pregnancy, the woman had a placenta with 2 monozygotic twins (females) and a separate placenta with a heterozygotic twin (male). The quantitative PCR results were 10(3) genome equivalents (GE)/mL of females AF and 1.9 x 10(5) GE/mL of male AF. Both female twins were asymptomatic at birth, whereas the male presented petechiae, thrombocytopenia, and cerebral ventriculomegaly. In the last twin pregnancy with fused dichorionic placentas, congenital CMV infection of both twins was diagnosed at birth in contrast with prenatal diagnosis. At time of amniocentesis, the left side twin was not infected as shown by negative results of CMV culture and DNA detection in the AF. CMV infection of the right side twin was demonstrated by positive CMV DNA detection with a CMV DNA load of 4.9 x 10(4) GE/mL and positive virus isolation in the AF. The morphologic and histologic examinations of the placentas strongly supported a prenatal horizontal acquisition of CMV infection. These twin pregnancies showed a marked difference in the quantity of virus load documented by the prenatal diagnosis suggesting that twin fetuses may react differently to primary maternal infection despite being exposed to the same maternal influences. A high viral load is correlated with congenital CMV infections symptomatic at birth. In such cases, with fetal infection of only 1 twin (at amniocentesis) and fusion of placentas, fetal outcome of both twins needs to be evaluated for the possibility of viral transfer from one fetus to the other.

Relevance of cytomegalovirus infection and coronary-artery remodeling in the first year after heart transplantation: a prospective three-dimensional intravascular ultrasound study

BACKGROUND

Transplant coronary artery disease (TxCAD) is a major cause of long-term mortality after heart transplantation. Although vascular remodeling has been implicated in the pathophysiology of TxCAD, its determinants remain unknown.

METHODS

Twenty-nine consecutive heart-transplant recipients prospectively received intravascular ultrasound (IVUS) of the left-anterior descending artery 1 and 12 months after transplant, with volumetric reconstruction of the proximal 30 mm.

RESULTS

Overall, patients exhibited intimal volume increase (+83%, P<0.001), wheras vessel volume remained largely unchanged (+4%, P=0.270); consequently, overall lumen volume decreased (-6%, P=0.058). Among the clinical and laboratory variables, cytomegalovirus (CMV) infection requiring treatment (occurring in 12 patients), as assessed by pp65 antigenemia, was independently associated with the impaired ability of the vessel wall to enlarge in response to intimal volume increase, ultimately resulting in lumen loss (OR [95% CI]=0.098 [0.010-0.920]; P=0.042). However, adequate vessel response to intimal hyperplasia with consequent lumen preservation was observed in the remaining 17 patients who did not present CMV infection requiring treatment.

CONCLUSIONS

The present study demonstrates that either adequate or inadequate coronary remodeling may occur during the first year after transplantation. Moreover, for the first time, it strongly suggests that remodeling modalities may be negatively influenced by the occurrence of clinically relevant CMV infection. Randomized prospective trials are warranted to investigate whether aggressive treatment of CMV infection may help prevent TxCAD.

Preemptive strategy for ganciclovir administration against cytomegalovirus in liver transplantation recipients

In utilizing a preemptive strategy to minimize the occurrence of symptomatic cytomegalovirus (CMV) infection following liver transplant, only patients with proven CMV activity by direct detection are treated. We applied the following preemptive strategy for CMV infection to 49 sequential liver transplant recipients between 1998 and 2001. Patients were monitored for CMV activity using CMV p65 antigen assay for the first 10 months of the study. Thereafter, we changed the detection method to a quantitative PCR for plasma CMV-DNA. All patients were monitored post transplant, weekly for the first 3 months and then monthly. Only patients with detected CMV activity were treated with ganciclovir. Patients were divided into four groups, based on donor (D) and recipient (R) CMV status. In seven out of 49 patients (14.3%) CMV activity was detected: four in group D+/R-, and three in group D-/R-. Five out of these seven patients had asymptomatic CMV infection. Symptomatic CMV infection developed only in two of these seven patients, to give total rate of 4.1% (2/49). All seven patients developed CMV IgG antibody. 'Transient' CMV replication detected by PCR in five patients in group D+/R+ was not defined as infection. No patients developed organ-invasive CMV disease. The cost of anti-CMV treatment using the preemptive strategy was $1000/patient/1st year. Using preemptive strategy, early detection of CMV infection was achieved, allowing timely treatment. The use of ganciclovir for CMV infection in only 4.3% of the patients should have a positive impact on minimizing the risk of ganciclovir-resistant virus, and should reduce the cost of CMV prevention strategies.

Infections and solid organ transplant rejection: a cause-and-effect relationship?

Although evidence is far from being conclusive, several studies have suggested that infections could trigger rejection in different transplant settings. In this review we examine the evidence linking cytomegalovirus (CMV), adenovirus, enterovirus, parvovirus, and herpes simplex virus infections to the vasculopathy leading to cardiac allograft rejection, the association between CMV and chronic kidney, lung, and liver graft rejection, and the association of human herpesvirus 6 reactivation with CMV-related disease in kidney and liver transplant recipients. We also review the numerous antiviral prophylactic or pre-emptive treatments in use to control CMV infection, and suggest that they do not limit immune reactions leading to graft rejection or lower the risk of developing post-transplantation atherosclerosis in allograft recipients. Finally, we emphasise the need for prospective, international studies to clarify the role of infections in transplant rejection, to look at virus-to-virus interactions, and to establish specific therapeutic strategies. Such strategies must not rely exclusively on expensive antiviral agents but also on vaccination or other, innovative approaches, such as the use of agents able to inhibit the activity of natural killer cells, which might have an important role in acute allograft rejection.

Different profiles of cytomegalovirus RNA transcripts and anti-cytomegalovirus IgM antibodies in renal transplant recipients

BACKGROUND

A difference in anti-cytomegalovirus IgM antibody profile has been found between sera from acutely cytomegalovirus (CMV)-infected patients and sera from CMV-infected patients with subclinical infection.

OBJECTIVES

The aim of this study is to investigate whether such different IgM antibody responses are correlated with differences in the expression of CMV immediate early and late mRNAs.

STUDY DESIGN

We have investigated the anti-CMV IgM response in 46 renal transplant recipients by employing two commercially available IgM kits (AxSYM and IMX) as well as two novel enzyme-linked immunosorbent assays (ELISAs), which were developed using recombinant ppUL32 (pp150) and pUL80a (p38), respectively. The results were compared with four direct CMV diagnostic tests: pp65 antigenemia, viral culture and nucleic acid sequence-based amplification (NASBA), detecting either CMV immediate early 1 (IE1) mRNA (IE1-NASBA), or CMV pp67 (late) mRNA (pp67-NASBA).

RESULTS

Analysis of all CMV-infected recipients (n=28) showed that in 16 recipients (group I) more than one direct test became positive after transplantation, while in the other 12 recipients (group II), IE1-NASBA was the only direct test to become positive. In group I, 100, 81, 100 and 50% of the recipients were IgM-positive with AxSYM, IMX, p38 and pp150, respectively. In group II, 100, 83, 17 and 83% of the recipients were IgM-positive with AxSYM, IMX, p38 and pp150, respectively.

CONCLUSIONS

Our data indicate that the IgM-response against p38 and pp150 differs significantly (P<0.01) between group I recipients with productive CMV infection, and group II recipients with a non-productive CMV infection which may be of diagnostic and prognostic relevance.

Neonatal aortic arch thrombosis as a result of congenital cytomegalovirus infection

Thrombotic disease is rare in neonates. The main risk factors at this age are perinatal asphyxia, maternal diabetes, sepsis, polycythemia, dehydration, a low cardiac output, and in primis the catheterization of central lines. Another important risk factor is inherited thrombophilia. Arterial thrombosis is even more rare than venous thrombosis and less related to most of the risk factors listed above; it occurs more frequently in the iliac, femoral, and cerebral arteries but very rarely in the aorta. Most of the described cases of aortic thrombosis are associated with the catheterization of an umbilical artery and involve the descending tract and the renal arteries; very few relate to the ascending tract and the aortic arch. The possible role of virus-induced primary vascular endothelium damage in the etiopathogenesis of neonatal arterial thrombosis has been previously hypothesized. Herpesviruses, particularly human cytomegalovirus (HCMV), can infect endothelial cells and directly damage intact vascular endothelium, altering its thromboresistant surface as a result of procoagulant activity mediated by specific viral surface phospholipids, necessary for the coagulation enzyme complex assembly that leads to thrombin generation. We describe a case of congenital aortic arch thrombosis. The clinical, laboratory, and virologic pictures; the anatomopathologic findings (fully compatible with viral infection); the detection of HCMV in various tissues (including the aorta); and the absence of other causes of aortic thrombosis make it possible to attribute the case to a severe congenital HCMV infection with multiple organ involvement, after the primary infection of the mother. The hemostatic system disorders and hemodynamic disturbances related to viral cardiac damage explain the clinical features of the case and indicate that congenital HCMV infection should be included among the causes of neonatal aortic thrombosis.

Recent advances in the diagnosis of cytomegalovirus infection

Herpesviruses are highly disseminated in nature, and nearly 100 Herpesviruses have been at least partially characterized. Seven Herpesviruses have been isolated so far from humans and one has recently been detected by sequence analysis. Consequently, the diagnosis of human Herpesvirus infection is based on eight different viruses. The diagnosis of a Herpesvirus infection can be achieved through the direct demonstration of the presence of the virus or its components (mainly nucleic acids and antigens) in pathological materials or indirectly through serology. In recent years much progress has been made in both directions and thanks to the detailed study of the viral genomes and their antigenic gene products and by the determination of the immune reactivity against individual antigenic polypeptides in different clinical settings. Progress in the direct detection of the viruses in pathological materials mainly regards the production of specific probes and their use with or without DNA amplification for the detection of viral genomes. Serological advances are mainly linked to the production, characterization and use of specific viral antigens by DNA recombinant procedures and by the production and use of synthetic peptides acting as good antigenic epitopes.