Relationship between cytomegalovirus DNA load in epithelial lining fluid and plasma of lung transplant recipients and analysis of coinfection with Epstein-Barr virus and human herpesvirus 6 in the lung compartment

Abstract

Cytomegalovirus (CMV) is a significant cause of morbidity and mortality in lung transplant recipients (LTRs). The aim of the present study was to elucidate the relationship between the CMV DNA load in the lung compartment and that in plasma. For CMV load determination, the level of CMV DNA in plasma and bronchoalveolar lavage (BAL) samples was measured in a total of 97 paired BAL and plasma samples obtained from 25 LTRs. The original virus concentration in the epithelial lining fluid (ELF) was calculated from the BAL samples by correcting for dilution using the urea dilution method. In addition, the load of Epstein-Barr virus (EBV) and that of human herpesvirus 6 (HHV-6) DNA also were determined in BAL samples, recalculated for their concentrations in the ELF, and compared with the CMV DNA load. CMV DNA was found more frequently and at significantly higher levels in the lung compartment than in plasma (P<0.001, Wilcoxon test), and the CMV load in the ELF was associated with symptomatic CMV disease. EBV and HHV-6 were detected in 43.6% and 21.7% of the ELF samples, respectively. A statistically significant association was found between the CMV and EBV DNA loads in the ELF (P<0.001; Spearman's rho=0.651). Thus, in LTRs, determination of the CMV DNA load in the lung compartment may be advantageous compared to monitoring only viremia. The significant relationship between EBV and CMV DNA loads in the ELF of LTRs and its clinical impact require further investigation.

FIG. 1.

Comparison of the CMV DNA levels in ELF and in simultaneously obtained plasma (PLA) samples (n = 97). Negative PCR results were set equal to 1 (log₁₀ = 0). The bar indicates the median viral load (ELF, 1.2 × 10e3 copies/ml; plasma, negative).

FIG. 2.

Comparison of the CMV DNA load with the clinical status. Negative PCR results were set equal to 1 (log₁₀ = 0). The bars indicate the median viral loads. Symptomatic patients prior to therapy (n = 13): ELF median, 1.3 × 10e6 copies/ml; PLA median, 1.7 × 10e2 copies/ml. Asymptomatic patients (n = 29): ELF median, 2.4 × 10e3 copies/ml; PLA median, negative.

FIG. 3.

Association of CMV and EBV DNA loads in the ELF. Only samples with viral loads within the respective dynamic range of the quantitation assays are included (n = 62).