2-Hour cytomegalovirus pp65 antigenemia assay for rapid quantitation of cytomegalovirus in blood samples

Evaluation of an abbreviated protocol for cytomegalovirus pp65 antigenemia testing

The cytomegalovirus antigenemia assay remains a useful tool for monitoring reactivation among transplant recipients. In this study, we compared protocols using direct lysis of small-volume, whole blood (WB) samples vs peripheral blood leukocyte (PBL)-enriched fractions. Of 363 evaluable samples, 51 (14.0%) were positive by one or both methods. Sensitivity, specificity, and negative and positive predictive values were similar (76%, 99%, 96%, and 95% vs 71%, 100%, 96%, and 100% for the WB and PBL methods, respectively). Stratification of qualitative results by WBC count revealed comparable detection rates by each method, although the total number of positive results from leukopenic samples was significantly lower than from nonleukopenic samples (P= .04). Correlation between quantitative results was high, yet the degree of clinical agreement was suboptimal. We conclude that the small-volume, WB lysis method yields results statistically comparable to that of a PBL fractionation method but with fewer technical steps and less complexity.

A simplified cytomegalovirus pp65 antigenemia assay procedure

A simplified cytomegalovirus (CMV) pp65 antigenemia assay using a one-step erythrocyte lysis, fixation and permeabilization process was compared with a standard protocol, the CMV CINAkit (Argene Biosoft) assay. The results were comparable, both quantitatively and qualitatively. The new method saves time. It also provides flexibility because the cell suspension can be stored so that test completion can be deferred if so desired.

Correlation between CMV genotypes, multiple infections with herpesviruses (HHV-6, 7) and development of CMV disease in kidney recipients in Kuwait

The possible correlation between cytomegalovirus, human herpesvirus types 6, 7 and cytomegalovirus-related clinical symptoms was studied in kidney transplant patients in Kuwait. Cytomegalovirus infection was diagnosed using the pp65 antigenemia assay. DNA of cytomegalovirus was detected by nested polymerase chain reaction (nested-PCR). PCR was also used to amplify the genes coding for structural proteins of human herpesvirus-6 (240 bp) and human herpesvirus-7 (186 bp). Glycoprotein B genotypes of cytomegalovirus were determined by restriction fragment length polymorphism. The average number of cells positive for cytomegalovirus pp65 antigen showed a steady increase with the severity of the cytomegalovirus-related symptoms. Furthermore, cytomegalovirus pp65 antigen positivity was significantly more frequent among recipients of cadaver kidney (45.5%) than among those who received live related kidneys (22.6%). Cytomegalovirus gB genotype 1 was detected more frequently (P<0.036) in recipients with live related donor kidney (38%) than in patients of cadaver kidney (13%). The genome of human herpesvirus-6 was detected at the same rate in patients with or without cytomegalovirus-related symptoms. However, the genome of human herpesvirus-7 was detected significantly more frequently (P<0.0001) in asymptomatic patients (41.7%) than in recipients with symptomatic cytomegalovirus infection (17%). We conclude that cytomegalovirus gB genotypes are not associated with the outcome of a cytomegalovirus infection in kidney transplant patients, that human herpesvirus-6 does not play a role in cytomegalovirus pathogenesis and that the role of human herpesvirus-7 in cytomegalovirus-related morbidity in kidney recipients remains unclear.

Comparison of the CMV brite turbo assay and the digene hybrid capture CMV DNA (Version 2.0) assay for quantitation of cytomegalovirus in renal transplant recipients

We compared the CMV Brite Turbo Kit (BT) and the Digene Hybrid Capture CMV DNA (version 2.0) assay (HC2) in the quantitation of pp65 antigenemia and cytomegalovirus (CMV) DNA levels in immunosuppressed renal transplant recipients. Of 123 blood specimens collected from 24 renal transplant recipients, BT and HC2 assays detected 35 and 39 positive samples, respectively. The overall concordance rate between the two assays was 90%. Discordant results were observed at low levels of viremia, so that 8 samples were HC2 positive but BT negative and another 4 were BT positive but HC2 negative. There was good correlation (R(2) = 0.766; P<0.01) between the levels of CMV DNA and pp65 antigenemia in the 31 concordant positive samples. Correlation between results obtained with the two assays was confirmed by longitudinal studies for a patient who developed clinical CMV disease. HC2 may be more sensitive at low viremia levels and allow earlier detection of impending CMV disease. The BT assay offered the advantage of a rapid (2-h) turnaround time. We conclude that BT and HC2 assays have similar sensitivity and efficacy in the diagnosis and monitoring of CMV infection and disease in renal transplant recipients. While the HC2 assay would be appropriate for centers that handle a large number of samples, the BT test may be more suitable for small sample numbers or when results are needed urgently.