presented evidence that it caused AIDS. Gallo called the virus "human T-lymphotropic virus type III" (HTLV-III) because of perceived similarities with HTLV-I and -II, which had previously been discovered in his lab. Because of the timing of the discoveries, whether Montagnier's or Gallo's group was first to isolate HIV was for many years the subject of an acrimonious dispute. HIV isolates usually have a high degree of variability because the virus mutates rapidly. In comparison, the first two-human immunodeficiency virus type 1 (HIV-1) isolates, Lai/LAV (formerly LAV, isolated at the Pasteur Institute) and Lai/IIIB (formerly HTLV-IIIB, isolated from a pooled culture at the Laboratory of Tumor Cell Biology (LTCB) of the National Cancer Institute) were strikingly similar in sequence, suggesting that the two isolates were in fact the same, or at least shared a common source. In November 1990, the Office of Scientific Integrity at the National Institutes of Health attempted to clear up the matter by commissioning a group at Roche to analyze archival samples established at the Pasteur Institute and the Laboratory of Tumor Cell Biology (LTCB) of the National Cancer Institute between 1983 and 1985. The group, led by American epidemiologist Sheng-Yung Chang, examined archival specimens and concluded in Nature in 1993 that the American sample in fact originated from the French lab. Chang determined that the French group's LAV was a virus from one patient that had contaminated a culture from another. On request, Montagnier's group had sent a sample of this culture to Gallo, not knowing it contained two viruses. It then contaminated the pooled culture on which Gallo was working. Before the 1993 publication of Chang's results, Gallo's lab was accused and initially found guilty of "minor misconduct" by the Office of Scientific Integrity in 1991, and then by the newly created Office of Research Integrity in 1992 for the misappropriation of a sample of HIV produced at the Pasteur Institute. The subsequent publication in 1993 of Chang's investigation cleared Gallo's lab of the charges, although his reputation had already been tainted by the accusations. Today it is agreed that Montagnier's group first isolated HIV, but Gallo's group is credited with discovering that the virus causes AIDS and with generating much of the science that made the discovery possible, including a technique previously developed by Gallo's lab for growing T cells in the laboratory. When Montagnier's group first published their discovery, they said HIV's