Cytomegalovirus (CMV) Blood DNA Load, CMV Retinitis Progression, and Occurrence of Resistant CMV in Patients with CMV Retinitis

Abstract

The amount of cytomegalovirus (CMV) DNA in the blood (CMV load) may be a marker for detection of resistant CMV.METHODS. A total of 165 patients with AIDS and CMV retinitis had CMV load measurements (plasma and leukocyte) and cultures performed every 3 months; these measurements were correlated with CMV resistance to antiviral drugs and CMV retinitis progression (from masked readings of retinal photographs).RESULTS. Detectable plasma and leukocyte CMV loads were associated with CMV retinitis progression (odds ratios [OR], 6.3; P<.0001 and OR, 6.6; P<.0001, respectively), phenotypic resistance (OR, 6.1; P<.0001 and OR, 23.4; P=.0002, respectively), and genotypic resistance (OR, 17.5; P<.0001 and OR, 51.6; P=.0004, respectively). The sensitivity, specificity, and positive and negative predictive values of plasma CMV loads were 0.47, 0.86, 0.36, and 0.91, respectively, for progression and 0.59, 0.81, 0.07, and 0.99, respectively, for resistance; those of leukocyte CMV loads were 0.52, 0.83, 0.35, and 0.91, respectively, for progression and 0.82, 0.78, 0.08, and 0.99, respectively, for resistance. A detectable plasma CMV load at the time of diagnosis of CMV retinitis was associated with mortality (median survival time, 13.6 vs. 29.7 months; P=.007).CONCLUSIONS. CMV load has limited clinical utility, because of its low positive predictive value. Its high negative predictive value for occurrence of resistant CMV suggests that it may have utility as a screening tool to exclude resistance.

Detection of Ganciclovir Resistance in Patients with AIDS and Cytomegalovirus Retinitis: Correlation of Genotypic Methods with Viral Phenotype and Clinical Outcome

“…Because CMV is latent in leukocytes (including monocytes and granulocytes) [57,58], leukocyte sources may detect smaller CMV populations, as was evidenced by the somewhat greater frequency of amplifiable CMV from the blood leukocyte source. Detection of a mutation in plasma specimens requires viral replication sufficient to have resulted in virus shed into plasma; this suggests that, when detectable by PCR amplification of plasma, a resistant virus is likely to be present in greater amounts and may have a greater effect on clinical behavior [46].…”

“…Blood specimens for direct PCR amplification and UL97 gene sequencing were obtained at the same time as culture specimens. Leukocytes (including lymphocytes, monocytes, and granulocytes) and plasma were separated, as described elsewhere [45,46]. DNA was extracted from plasma and leukocytes, as described previously, and the CMV UL97 gene was amplified using PCR, as described elsewhere [38,45,46].…”

“…Leukocytes (including lymphocytes, monocytes, and granulocytes) and plasma were separated, as described elsewhere [45,46]. DNA was extracted from plasma and leukocytes, as described previously, and the CMV UL97 gene was amplified using PCR, as described elsewhere [38,45,46]. The amplified UL97 genes were sequenced using dRhodamine or the BigDye Terminator Ready Reaction Kit, as outlined above [38].…”

“…The first definition was that agreement occurred only when there was exact agreement between the UL97 gene sequences from both the culture isolate and the PCR-amplified blood specimen. Because of the presence of mixed populations of CMV and of non-resistance-conferring polymorphisms [26,45,46,48,49], it also was possible that the 2 methods could identify different gene sequences or mixtures of sequences that resulted in the same phenotype of resistance or susceptibility, and a second analysis was undertaken in which the 2 sources were considered to be in agreement if any mutation was identified.…”

Herpetic Viral Retinitis

“…In immunocompromised persons, CMV can undergo reactivation and hematogenous dissemination to target organs. The majority of patients with newly-diagnosed CMV retinitis have evidence of systemic CMV replication, which can be detected by culture of the blood or urine (~80%) or by PCR amplification of blood samples to detect CMV DNA (~60%) (Jabs et al, 1998;2005). The bloodretina barrier is created by the tight junctions of retinal vascular endothelial and RPE cells, but this barrier is circumvented by the virus via endocytosis, with subsequent intracellular replication and latency (Bodaghi et al, 1999).…”