WASHINGTON - The families of children who participated in a gene therapy trial at St. Jude Children's Research Hospital learned last week that the gene therapy product used in an experiment was not contaminated with HIV or hepatitis C.

Laura Bowman, the principal investigator in the trial, told BioCentury that FDA testing determined that the vaccine used in the study was not contaminated. Previous assays had suggested that the viruses were present in a "master viral bank" from which the vaccine was derived, but Bowman said the FDA's analysis had proven that to be false. The two children who received vaccine derived from the seed source died from their underlying neuroblastoma.