Human lymphoid cells frequently carry adenoviruses and DNA sequences have been identified in peripheral blood lymphocytes by Southern blot and PCR, although these cells are not permissive for virus replication, suggesting persistence of the viral genome. In order to investigate this phenomenon we screened non-symptomatic volunteers for adenovirus DNA presence and E1A gene expression. DNA samples extracted from peripheral blood mononuclear cells of 51 volunteers were submitted to PCR using primers for a conserved hexon sequence, followed by nested PCR. Adenovirus sequences were detected in 27 samples (52.9%). After more than one year, new samples of these positive volunteers were analyzed and in 70.8% of the cases the result was maintained. Since this could be due to a possible persistence we checked if the early gene E1A was involved analyzing its expression by RT-PCR. For that purpose we developed a pair of primers to target a conserved region in the E1A gene. The RT-PCR results for E1A were negative for all samples. Using these primers it was possible to detect adenovirus sequences directly by PCR in DNA samples and we found 84% agreement in comparison to the hexon analysis. Our data suggest a high occurrence and persistence of adenovirus genome sequences in human lymphoid cells, and an indication that a region other than E1A is involved in persistence. We also can say that E1A gene is a good choice for amplification as a tool in adenovirus detection, avoiding the high risk of contamination in the nested PCR procedure necessary for hexon detection.
adenoviral infection; viral persistence; lymphocytes; nested PCR assay
