title: Early monitoring of the human polyomavirus BK replication and sequencing analysis in a cohort of adult kidney transplant patients treated with basiliximab.
abstract: BACKGROUND
  Nowadays, better immunosuppressors have decreased the rates of acute rejection in kidney transplantation, but have also led to the emergence of BKV-associated nephropathy (BKVAN). Therefore, we prospectively investigated BKV load in plasma and urine samples in a cohort of kidney transplants, receiving basiliximab combined with a mycophenolate mofetil-based triple immunotherapy, to evaluate the difference between BKV replication during the first 3 months post-transplantation, characterized by the non-depleting action of basiliximab, versus the second 3 months, in which the maintenance therapy acts alone. We also performed sequencing analysis to assess whether a particular BKV subtype/subgroup or transcriptional control region (TCR) variants were present.
  
  
  METHODS
  We monitored BK viruria and viremia by quantitative polymerase chain reaction (Q-PCR) at 12 hours (Tx), 1 (T1), 3 (T2) and 6 (T3) months post-transplantation among 60 kidney transplant patients. Sequencing analysis was performed by nested-PCR with specific primers for TCR and VP1 regions. Data were statistically analyzed using χ² test and Student's t-test.
  
  
  RESULTS
  BKV was detected at Tx in 4/60 urine and in 16/60 plasma, with median viral loads of 3.70 log GEq/mL and 3.79 log GEq/mL, respectively, followed by a significant increase of both BKV-positive transplants (32/60) and median values of viruria (5.78 log GEq/mL) and viremia (4.52 log GEq/mL) at T2. Conversely, a significantly decrease of patients with viruria and viremia (17/60) was observed at T3, together with a reduction of the median urinary and plasma viral loads (4.09 log GEq/mL and 4.00 log GEq/mL, respectively). BKV TCR sequence analysis always showed the presence of archetypal sequences, with a few single-nucleotide substitutions and one nucleotide insertion that, interestingly, were all representative of the particular subtypes/subgroups we identified by VP1 sequencing analysis: I/b-2 and IV/c-2.
  
  
  CONCLUSIONS
  Our results confirm previous studies indicating that BKV replication may occur during the early hours after kidney transplantation, reaches the highest incidence in the third post-transplantation month and then decreases within the sixth month, maybe due to induction therapy. Moreover, it might become clinically useful whether specific BKV subtypes or rearrangements could be linked to a particular disease state in order to detect them before BKVAN onset.
authors.affiliation: Department of Public Health and Infectious Diseases, "Sapienza" University of Rome, Rome, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Anzivino
authors.forename: Anna
authors.initials: A
authors.lastname: Bellizzi
authors.forename: Anna Paola
authors.initials: AP
authors.lastname: Mitterhofer
authors.forename: Francesca
authors.initials: F
authors.lastname: Tinti
authors.forename: Mario
authors.initials: M
authors.lastname: Barile
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Colosimo
authors.forename: Daniela
authors.initials: D
authors.lastname: Fioriti
authors.forename: Monica
authors.initials: M
authors.lastname: Mischitelli
authors.forename: Fernanda
authors.initials: F
authors.lastname: Chiarini
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Ferretti
authors.forename: Gloria
authors.initials: G
authors.lastname: Taliani
authors.forename: Valeria
authors.initials: V
authors.lastname: Pietropaolo
mesh_terms: D000328:Adult; D000911:Antibodies, Monoclonal / Q000008:administration & dosage / Q000009:adverse effects; D001739:BK Virus / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D001483:Base Sequence; D000077552:Basiliximab; D015331:Cohort Studies; D004279:DNA, Viral / Q000097:blood / Q000235:genetics / Q000652:urine; D005500:Follow-Up Studies; D006801:Humans; D007165:Immunosuppression Therapy / Q000009:adverse effects*; D007166:Immunosuppressive Agents / Q000008:administration & dosage / Q000009:adverse effects*; D007558:Italy; D007668:Kidney / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology / Q000821:virology*; D016030:Kidney Transplantation / Q000276:immunology; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009173:Mycophenolic Acid / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives; D027601:Polyomavirus Infections / Q000097:blood* / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology / Q000652:urine* / Q000821:virology; D060888:Real-Time Polymerase Chain Reaction; D011993:Recombinant Fusion Proteins / Q000008:administration & dosage / Q000009:adverse effects; D017422:Sequence Analysis, DNA; D019562:Viral Load / Q000235:genetics; D014779:Virus Replication / Q000235:genetics
chemical_list: D000911:Antibodies, Monoclonal; D004279:DNA, Viral; D007166:Immunosuppressive Agents; D011993:Recombinant Fusion Proteins; D000077552:Basiliximab; D009173:Mycophenolic Acid