A Phase 2a Study of IV BCV in Subjects With Adenovirus Infection

Inclusion Criteria: * Male or female, aged 2 months and older at the time of informed consent. * AdV DNA viremia \>10,000 copies/mL from a single sample, or 2 samples greater than 48 hours apart with the second result higher than the first and both greater than 1000 copies/mL, from the data obtained from the designated central virology laboratory of the local laboratory using the blood sample(s) collected informed consent has been obtained and within 7 days prior to Day 1 (AdV DNA viremia results collected within the 7 day window, but prior to consent may be used if the Informed Consent Form (ICF) signed by the subject provides approval) . CMV viremia with or without evidence of tissue invasive CMV disease. For laboratory results that are generated in units other than copies/mL or IU/mL, please refer to the testing laboratory for guidance on the appropriate conversion calculation. * Either (a) have disseminated AdV disease or (b) have an underlying immunocompromised state, and have asymptomatic AdV infection or localized AdV disease. * In the judgment of the investigator, be in a serious condition to be treated with intravenous cidofovir for AdV. Exclusion Criteria: * Subjects who weigh ≥120 kg. * NIH/NCI CTCAE (United States \[US\] National Institutes of Health \[NIH\]/National Cancer Institute) Grade 2 or higher diarrhea (i.e., increase of ≥ 4 stools per day over usual pre-transplant stool output) within 7 days prior to Day 1. * NIH Stage 4 acute GVHD of the skin (i.e., generalized erythroderma with bullous formation) within 7 days prior to Day 1. * NIH Stage 2 or higher acute GVHD of the liver function (i.e., bilirubin \>3 mg/dL \[SI: \>51 μmol/L\]) within 7 days prior to Day 1. * NIH Stage 2 or higher acute GVHD of the gut (i.e., diarrhea \>556 mL/m2/day for pediatric subjects \[or \>1000 mL/day for young adults as applicable, at centers in the United States only\], or severe abdominal pain with or without ileus) within 7 days prior to Day 1.