CMV infection of liver transplant recipients: comparison of antigenemia and molecular biology assays

Asian Pacific Association for the Study of the Liver clinical practice guidelines on liver transplantation

Liver transplantation is a highly complex and challenging field of clinical practice. Although it was originally developed in western countries, it has been further advanced in Asian countries through the use of living donor liver transplantation. This method of transplantation is the only available option in many countries in the Asia-Pacific region due to the lack of deceased organ donation. As a result of this clinical situation, there is a growing need for guidelines that are specific to the Asia-Pacific region. These guidelines provide comprehensive recommendations for evidence-based management throughout the entire process of liver transplantation, covering both deceased and living donor liver transplantation. In addition, the development of these guidelines has been a collaborative effort between medical professionals from various countries in the region. This has allowed for the inclusion of diverse perspectives and experiences, leading to a more comprehensive and effective set of guidelines.

Early abnormal liver enzyme levels may increase the prevalence of human cytomegalovirus antigenaemia after hematopoietic stem cell transplantation

Objective Human cytomegalovirus (HCMV) infection is common after bone marrow transplantation (BMT), and it increases morbidity and mortality for transplant recipients. HCMV infection may cause hepatitis and elevate the liver enzymes aspartate transferase (AST) and alanine transferase (ALT). This study aimed to analyse the associations between liver enzyme levels and infection with HCMV antigenaemia after BMT. Methods Data from 30 patients after BMT were collected at different time points (0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 4.0, 5.0, and 6.0 months post-transplantation). The patients were divided into the HCMV antigenaemia-positive and HCMV antigenaemia-negative groups according to a peripheral blood pp65 antigen assay. Immunohistochemistry was used to identify HCMV pp65 antigen and conventional methods were used to detect liver enzyme levels. Results Twelve patients were pp65 antigenaemia-positive and 10 patients were positive in the first 3 months post-transplant. Liver enzyme levels were increased after positivity for HCMV antigenaemia (p = 0.034 and p = 0.018 for ALT and AST, respectively). One month before antigenaemia, AST levels were higher in the HCMV antigenaemia-positive group compared with the negative group (p = 0.006). Conclusion HCMV antigenaemia mostly occurs in the early stage of post-BMT and early abnormal liver enzyme levels may increase the chance of HCMV antigenaemia after BMT.

Clinical usefulness of plasma quantitative polymerase chain reaction assay: diagnosis of cytomegalovirus infection in kidney transplant recipients

BACKGROUND

Preemptive therapy is used to prevent cytomegalovirus (CMV) disease in transplant recipients. The CMV antigenemia assay, which has been commonly used as a predictive marker for preemptive therapy, requires intensive labor and immediate processing. We compared the cutoff value of plasma CMV polymerase chain reaction (PCR) with CMV antigenemia in kidney transplant recipients.

METHODS

We compared two diagnostic methods for CMV infection in kidney transplant recipients: quantitative PCR (qPCR) versus antigenemia. We evaluated the optimal cutoff value of plasma CMV qPCR by using receiver-operating characteristic curves for specific antigenemia values. All kidney transplant recipients from January 2004 to January 2005 were enrolled and followed with CMV antigenemia and plasma CMV qPCR.

RESULTS

The analyses were performed on 899 samples collected from 111 patients in the early posttransplant period, matching 84.1% of patients for the results of CMV antigenemia and plasma CMV qPCR. For patients with symptomatic CMV infection and disease, who showed ≥25 positive cells in the antigenemia assay, the cutoff value for qPCR was 17.8 copies/μL with a sensitivity of 97.1%, a specificity of 89.1%, and a positive predictive value of 26.6%.

CONCLUSIONS

Diagnostic assays for CMV such as CMV antigenemia and quantitative plasma PCR, showed similar diagnostic values. They are the methods of choice for the diagnosis and monitoring of active CMV infection after kidney transplantation. However, because of the relatively low positive predictive value of qPCR, this test may lead to unnecessary preemptive treatment in kidney transplant recipients.

Preemptive therapy for cytomegalovirus based on real-time measurement of viral load in liver transplant recipients

BACKGROUND

Real-time PCR has emerged as the preferred diagnostic assay for CMV. However, its utility as a preemptive therapy tool for CMV disease and related outcomes in liver transplant recipients has not been fully defined.

METHODS

Patients comprised 117 consecutive liver transplant recipients who underwent CMV surveillance monitoring using real-time PCR. Preemptive therapy with valganciclovir was employed upon detection of viremia. Baseline viral load was considered high based on log values (median).

RESULTS

CMV viremia developed in 54% (63/117) of the patients, including 77% of R-/D+, 63% of R+/D+, 43% of R+/D-, and 10% of R-/D- patients. Overall, 23% (15/63) of the patients had recurrent viremia; R- serostatus (p=0.065) but not initial viral load correlated with recurrent viremia (p=0.80). At 12 months post-transplant, CMV disease occurred in 0.85% (1/117) of the patients (R+/D+recipient). None (0/30) of the R-/D+patients had CMV disease. Patients with CMV viremia treated preemptively did not differ significantly from those who never developed CMV viremia with regards to bacterial or fungal infections, rejection, graft loss, mortality rate, and probability of survival at 12 months (p>0.05 for all variables). The above outcomes also did not differ for patients with high (>1.9 logs) vs. low viral load (<1.9 logs) (p>0.05 for all outcomes).

CONCLUSIONS

Preemptive therapy guided by real-time PCR based monitoring led to outcomes in all patients or in those with high viral loads that were comparable to outcomes in patients who never developed viremia or had low viral loads, respectively. Late-onset CMV disease at 12 months was observed in <1% of all patients.

Relationship between pp65 antigenemia levels and real-time quantitative DNA PCR for Human Cytomegalovirus (HCMV) management in immunocompromised patients

Background

Quantitative real-time PCR assays, which are more rapid and practical than pp65 antigenemia determination, are progressively becoming the preferred method for monitoring Human Cytomegalovirus (HCMV) reactivation. However, the relationship between HCMV DNA and antigenemia levels is still under investigation. The aim of this study was to analyse the relationship between HCMV DNA and pp65 antigenemia levels in order to identify clinically useful threshold values for the management of patients.

Methods

475 consecutive samples from 156 immunosuppressed patients were tested for HCMV by pp65 antigenemia and Real-time PCR assay.

Results

136 out of 475 consecutive samples derived from 48 patients showed evidence of HCMV infection. HCMV DNA was detected in 106 samples, pp65 antigen in 3, and both markers in 27. pp65 antigen detection was associated with higher HCMV DNA levels. The cut-off HCMV DNA level that best predicted pp65 antigenemia in this series of samples was 11,500 copies/ml, but different threshold levels could be observed for specific groups of patients. HCMV disease was observed in 5 out of 48 patients with active HCMV infection. The presence of clinical symptoms was associated with positive pp65 and with higher antigenemia levels. Higher HCMV DNA load at the onset of viral replication was correlated to the development of clinical symptoms.

Conclusion

Both pp65 antigenemia and HCMV DNA load can be useful for the prospective monitoring of immunocompromised subjects. Specific cut-off levels capable of triggering preemptive antiviral treatment should be determined in accordance to the type of test used and the characteristics of patients and prospectively validated.

Diagnostic value of reverse transcription-PCR for detection of cytomegalovirus pp67 in samples from solid-organ transplant recipients

We evaluated a highly sensitive quantitative real-time one-step reverse transcription-PCR (RT-PCR) for detection of human cytomegalovirus pp67 transcripts in monitoring of solid-organ transplant recipients. Results were compared with those of pp65 antigen testing and quantitative DNA-PCR. Due to a low clinical sensitivity, the pp67 RT-PCR was not able to replace these assays.

Evaluation of three polymerase chain reaction tests targeting morphological transforming region II, UL-83 gene and glycoprotein O gene for the detection of human cytomegalovirus genome in clinical specimens of immunocompromised patients in Chennai, India

Background

Human Cytomegalovirus (HCMV) continues to be an important cause of morbidity and occasional mortality in immunocompromised patients. Polymerase chain reaction (PCR) is the most sensitive and commonly used method for the assessment of HCMV infection in the immunocompromised patients at risk from severe associated clinical manifestations. However, there is little consistency in the qualitative PCR used for different regions of HCMV genome. Therefore, the performance of three Qualitative PCR tests to detect HCMV genome in clinical specimens from immunocompromised patients was evaluated. With pp65 antigenemia assay as the "gold standard", nested PCR for morphological transforming region II (mtr II) and glycoprotein O (gO) gene and uniplex PCR for UL 83 gene were applied on 92 consecutive clinical specimens obtained from 74 immunocompromised patients with clinically suspected HCMV disease. Virus isolation was attempted on 12 clinical specimens from six pp65 antigenemia positive patients. Based on the pp 65 antigenemia results as "gold standard", the sensitivity, specificity, positive predictive value and negative predictive value for each PCR was calculated.

Results

The PCR targeting mtr II region showed a higher sensitivity (100%) and negative predictive value (100%) than the other two PCRs in detecting HCMV DNA from clinical specimens obtained from different immunocompromised patient population of Chennai region, India.

Conclusion

The results suggests that the optimal method of detection of HCMV DNA could be achieved by PCR using primer sequences targeting mtr II region of genome of HCMV in Chennai region, India.

Assessment of CMV load in solid organ transplant recipients by pp65 antigenemia and real-time quantitative DNA PCR assay: Correlation with pp67 RNA detection

After bone marrow (BM) or solid-organ (SO) transplantation viremic Cytomegalovirus (CMV) infection is observed frequently. Quantitative assay of CMV in blood helps the management of this clinical condition. In the present report, 83 samples from 39 solid organ recipients, three CMV assays were compared simultaneously for the first time: the Nuclisens CMV pp67 assay (nucleic acid sequence-based amplification, NASBA), an "in-house" quantitative real-time PCR assay (TaqMan) for CMV DNA, and pp65 antigenemia. The relation between CMV DNA and pp65 antigenemia, the quantitative assays, was evaluated on a larger group including 251 blood samples from 118 solid organ recipients. Real-time PCR provided the best results; > or =130 CMV DNA copies/2 x 10(5) peripheral blood leukocytes (PBLs) predicted > or =1 pp65 antigen positive (Ag+) cell/2 x 10(5) PBLs. By taking pp65 antigenemia as the "gold standard," the sensitivity of CMV DNA quantitation and of the pp67 RNA assay were 0.95 and 0.20, respectively, while the corresponding specificity values were 0.50 and 0.93. When real-time PCR was considered as the "gold standard," the sensitivity and specificity of the pp65 antigenemia were 0.65 and 0.91, respectively. Among the three tests examined, the sensitivity of the pp67 RNA assay was the lowest. On the other hand, the pp67 RNA assay was highly specific and effective in pinpointing high viremia patients. The present report, by providing predictive values for all three diagnostic profiles, DNA load, antigenemia, and pp67RNA, is a contribution for validation of real-time PCR as a new standard for quantitative assessment of CMV viremia in clinical settings.