Temporal fluctuations of leukemogenic versus attenuated virus replication in vivo after experimental infection. Early Bovine Leukemia Virus replication was compared over time between sheep infected with attenuated (open circles) versus leukemogenic (black circles) infectious molecular clones. S-3: 3 days before serconversion, S: seroconversion, S+3: 3 days after seroconversion, S+50: 50 days after seroconversion, i+240: 240 days post-incoculation. Comparisons were made for circulating proviral loads (A), overall measured RT events (B), abundant clones (C), less extensively expanded clones (clones < 62.5 copies per 1 mcg of DNA) (D), somatic (black histograms) and RT-dependent (grey histograms) proviral mutations; white histograms represent unmutated clones (E). Error bars are ± standard error of mean.