Abstract
Purpose: :
To compare direct PCR amplification and sequencing of the CMV UL97 gene from blood specimens to sequencing of the UL97 gene from culture isolates for the detection of CMV resistance to ganciclovir.
Methods: :
Prospective, epidemiologic study in which blood specimens were simultaneously obtained every 3 months for: 1) direct PCR amplification and CMV UL97 gene sequencing and 2) for CMV cultures. The two methods of detecting mutations in the UL97 gene were compared with each other, with susceptibility testing (phenotypic resistance), and with retinitis progression, which was determined from masked gradings of fundus photographs. Both plasma and blood leukocytes were evaluated as sources of specimens for direct PCR amplification and sequencing.
Results: :
845 blood specimens were obtained from 165 patients. There was >90% agreement between the UL97 gene sequences from directly PCR–amplified blood specimens and from culture isolates. There was >94% agreement between the detection of UL97 gene mutations from PCR–amplified blood specimens and phenotypic measures of resistance from culture isolates. Plasma and leukocytes performed similarly. The detection of a UL97 mutation from a PCR–amplified blood specimen correlated with retinitis progression, with adjusted odds ratios (OR) of 7.02 (P = 0.002) for blood leukocytes, and 9.11 (P = 0.02) for plasma. Although UL97 gene sequencing of directly PCR–amplified blood specimens correlated both with phenotypic measures of resistance and with clinical behavior, UL97 gene sequencing of culture isolates correlated better both with phenotypic resistance and with retinitis progression (OR = 17.6; P <0.0001).
Conclusions: :
Because directly PCR–amplified blood specimens can be analyzed in < 48 hours, versus > 4 weeks to perform cultures and sequence the CMV UL97 gene from an isolate, sequencing the CMV UL97 gene from PCR–amplified blood specimens appears to have potential clinical usefulness.
Keywords: AIDS/HIV • clinical laboratory testing • cytomegalovirus