Chromosomal breaks in lymphocytes from respiratory syncytial virus-infected infants

Respiratory syncytial virus (RSV) has been reported to infect blood mononuclear cells in vitro. Thus, we investigated the effect of the virus on peripheral lymphocytes obtained from infected infants. A cytogenetic analysis was performed in 14 RSV-infected infants, aged 34 days-5 months, during the acute phase of bronchiolitis and, simultaneously, in 14 age- and sex-matched healthy controls. Infants with RSV infection were re-evaluated 3 and 6 months after recovery. To detect RSV, we used a direct immunofluorescent study on nasopharyngeal mucus as well as commercial ELISA tests and viral cell cultures. The cytogenetic analysis was performed to examine the incidence of chromosome and chromatid breaks, fragments, structural rearrangements and aneuploidies in 100 metaphases per each blood sample. Standard laboratory assays pointed to the presence of RSV in all affected infants only during the acute symptomatic phase of the illness, while it was not detected 3 and 6 months after recovery. Chromosomal ″pulverization″ was observed in RSV-infected infants during the acute phase of the illness (0.29±0.04%, mean±SEM), while it was not detected in controls (p