Detection of MCMV viral DNA in cochlea of mice infected as newborns with MCMV.

<p><b>(A)</b> Newborn mice were inoculated intraperitoneally with 200PFU of Smith strain of MCMV and at the indicated times, mice were sacrificed, exhaustively perfused and cochlea removed. Viral DNA was detected using a quantitative PCR as described in Materials and Methods and expressed as log genome copies per mg of cochlear tissue. The limit of detection of this PCR assay was defined through comparison of the signal derived from DNA extracted from the cochlea of age-matched mock infected mice and was found to be less than 10 copies per mg of extracted tissue. Age post infection is shown on x-axis. On PNd14, cochlea from individual mice were pooled (n = 5) whereas at PNd120 (n = 9 mice) and 12 months (n = 5 mice), each symbol represents single cochlea. Note that results from cochlea of infected mice on PNd120 and 12 months that were below limits of detection of this assay were plotted as log = 0. The signal detected in tissue from mock infected animals was below the level of detection. <b>(B)</b> Newborn mice were inoculated with different amounts of recombinant BAC cloned Smith strain MCMV as indicated. On PNd8, cochlea (n = 12) were harvested from mice as above and the quantity of MCMV DNA (log genome copy) per mg of tissue determined as described above. Horizontal bar depicts median of total group and (*) indicates statistically significant difference in signals (50PFU vs 100PFU, p = 0.016; 50PFU vs 200PFU, p = 0.0003; 100PFU vs 200PFU, NS p = 0.215; Kruskal-Wallis test of medians with Dunn post-test correction). No signal was detected from cochlear DNA extracted from mock infected animals (n = 12 cochlea).