Patient description: A 42-year-old healthy woman came to the clinic to have her flu shot in early October. She works in a rehab center and has no underlying disease. It's her first time getting the vaccine this year. She is married for 5 years and uses barrier methods of contraception. Her menstrual cycle is irregular. She does not smoke. She is not on any medications. She exercises regularly for 30 minutes a day at least 5 days a week. She has no history of allergies to any food or drugs. Her past surgical history is significant for tonsillectomy and she is otherwise healthy.

Clinical trial eligibility criteria: eligible ages (years): 0.0-999.0,  Infection For Initial VSTs and subsequent infusions: patients will be eligible following any type of allogeneic transplant if they have CMV, adenovirus, EBV, BK virus and/or HHV6 infection/disease persistent or recurrent despite 14 days of standard therapy OR after failure of treatment after 7 days of standard therapy OR if unable to tolerate standard therapy. Patients with persistent JC virus infection will be eligible as well. 1. Prior myeloablative or non-myeloablative allogeneic hematopoietic stem cell transplant using either bone marrow or peripheral blood stem cells or single or double cord blood. 2. Treatment of the following persistent or relapsed infections despite standard therapy; 1. CMV: Treatment of persistent or relapsed CMV disease or infection after standard therapy. For CMV infection, standard therapy is defined as antiviral therapy with ganciclovir, foscarnet or cidofovir CMV disease: defined as the demonstration of CMV by biopsy specimen from visceral sites (by culture or histology) or the detection of CMV by culture or direct fluorescent antibody stain in broncheoalveolar lavage fluid in the presence of new or changing pulmonary infiltrates or changes consistent with CMV retinitis on ophthalmologic examination CMV infection: defined as the presence of CMV positivity as detected by PCR or pp65 antigenemia or culture from ONE site such as stool or blood or urine or nasopharynx Failure of antiviral therapy: defined as a rise or a fall of less than 50% in viral load in peripheral blood or any site of disease as measured by PCR or pp65 antigenemia after 7 days of antiviral therapy. 2. Adenovirus: Treatment of persistent adenovirus infection or disease despite standard therapy. Standard therapy is defined as antiviral therapy with cidofovir or an alternative antiviral agent if patient will not tolerate cidofovir therapy because of poor renal function Adenovirus infection: defined as the presence of adenoviral positivity as detected by PCR or culture from ONE site such as stool or blood or urine or nasopharynx Adenovirus disease: defined as the presence of adenoviral positivity as detected by PCR, DFA or culture from two or more sites such as stool or blood or urine or nasopharynx Failure of therapy: defined as a rise or a fall of less than 50% in viral load in peripheral blood or any site of disease as measured by PCR or any other quantitative assay) after 7 days of antiviral therapy. 3. EBV: For treatment of persistent EBV infection despite standard therapy. For EBV infection, standard therapy is defined as rituximab given at 375mg/m2 in patients for 1-4 doses with a CD20+ve tumor EBV infection: defined as Biopsy proven lymphoma with EBV genomes detected in tumor cells by immunocytochemistry or in situ PCR,Or clinical or imaging findings consistent with EBV lymphoma and/or elevated EBV viral load in peripheral blood Failure of therapy is defined as: Increase or less than 50% response at sites of disease for EBV lymphoma OR, Increase or a fall of less than 50% in EBV viral load in peripheral blood or any site of disease after 1st dose of rituximab. 4. BK virus: Treatment of persistent BK virus infection or BK virus disease despite antiviral treatment with cidofovir or leflunomide. No clear standard treatment is defined. Cidofovir has been administered in low doses as well as high doses to HSCT patients with BK infections but no randomized trials are available proving its clinical efficacy. In small trials leflunomide had activity against BK virus, therefore we will consider this agent an acceptable alternative to cidofovir, given the absence of a clear first line option BK virus infection is defined as the presence of BK virus positivity as detected by PCR or culture in one site such as blood or urine  Patients receiving ATG, Campath or other immunosuppressive T cell monoclonal antibodies within 28 days of screening for enrollment. 2. Patients with other uncontrolled infections. For bacterial infections, patients must be receiving definitive therapy and have no signs of progressing infection for 72 hours prior to enrollment. For fungal infections patients must be receiving definitive systemic anti-fungal therapy and have no signs of progressing infection for 1 week prior to enrollment. Progressing infection is defined as hemodynamic instability attributable to sepsis or new symptoms, worsening physical signs or radiographic findings attributable to infection. Persisting fever without other signs or symptoms will not be interpreted as progressing infection. 3. Patients who are less than 28 days removed from their allogeneic hematopoieteic stem cell transplant or who have received donor lymphocyte infusions (DLI) within 28 days. 4. Patients with active acute GVHD grades II-IV. 5. Active and uncontrolled relapse of malignancy