ARTICLE BK virus infection in human immunodeficiency virus-infected patients J. Ledesma & P. Muñoz & D. Garcia de Viedma & I. Cabrero & B. Loeches & P. Montilla & P. Gijon & B. Rodriguez-Sanchez & E. Bouza & BKV Study Group Received: 13 May 2011 /Accepted: 20 October 2011 # Springer-Verlag 2011 Abstract The aim of this study is to evaluate the prevalence of BK virus (BKV) infection in HIV-positive patients receiving highly active antiretroviral therapy (HAART) in our hospital. The presence of BKV was analysed in urine and plasma samples from 78 non-selected HIV-infected patients. Clinical data were recorded using a pre-established protocol. We used a nested PCR to amplify a specific region of the BKV T-large antigen. Positive samples were quantified using real-time PCR. Mean CD4 count in HIV-infected patients was 472 cells/mm 3 and median HIV viral load was <50 copies/mL. BKV viraemia was detected in only 1 HIV-positive patient, but 57.7% (45 out of 78) had BKV viruria, which was more common in patients with CD4 counts >500 cells/mm 3 (74.3% vs 25.7%; p =0.007). Viruria was present in 21.7% of healthy controls (5 out of 23 samples, p =0.02). All viral loads were low (<100 copies/mL), and we could not find any association between BKV infection and renal or neurological manifestations. We provide an update on the prevalence of BKV in HIV-infected patients treated with HAART. BKV viruria was more common in HIV- infected patients; however, no role for BKV has been demonstrated in this population. Introduction Human polyomavirus BK (BKV) is a ubiquitous, non- enveloped, double-stranded DNA virus that infects nearly 80% of the general population. Primary infection usually occurs during childhood and is sometimes associated with mild respiratory illness [1]. After primary infection, the virus remains latent, mainly in the kidney, but also in the brain and in leucocytes [2, 3]. Under immunosuppressive conditions, BKV may reactivate and cause disease. In kidney transplant recipients, BKV causes ureteral stenosis and nephritis and is responsible for graft loss in 1–10% of patients [4]. BKV reactivation has also been associated with haemorrhagic cystitis in bone marrow transplant recipients [5]. The role of BKV in patients with HIV infection has not been well established; however, the virus has occasionally been detected in urine, blood, cerebrospinal fluid and tissue from HIV-infected patients [6–8]. Cases of BKV-associated renal failure or haemorrhagic cystitis have been reported among patients with AIDS [6–14]. Besides, BKV has been reported in meningitis, encephalitis, retinitis, and pulmo- nary infection in HIV-infected patients [8, 12, 13]. The few studies that have analysed the presence of BKV in the HIV- infected population report very high incidences of BKV viruria (20–50%) [6, 7, 14], mainly in patients with low CD4 counts. However, none of these studies provided a complete perspective of the situation. Some of them selected patients with renal or neurological damage [8, 10, 11], others consist of case reports [9, 11–13], and the rest J. Ledesma : P. Muñoz (*) : D. Garcia de Viedma : I. Cabrero : B. Loeches : P. Montilla : P. Gijon : B. Rodriguez-Sanchez : E. Bouza Department of Clinical Microbiology-Infectious Diseases, Hospital General Universitario Gregorio Marañón, Doctor Esquerdo 46, 28007 Madrid, Spain e-mail: pmunoz@micro.hggm.es J. Ledesma : P. Muñoz : D. Garcia de Viedma : B. Rodriguez-Sanchez : E. Bouza CIBER de Enfermedades Respiratorias (CIBERES), Madrid, Spain Eur J Clin Microbiol Infect Dis DOI 10.1007/s10096-011-1474-9