A survey on frequency of BK virus genotypes in renal transplant recipients in three hospitals in Tehran,2019-2020
A survey on frequency of BK virus genotypes in renal transplant recipients in three hospitals in Tehran,2019-2020
Maryam Ghotbi,1Farhad Rezaei,2,*Talaat Mokhtari azad,3Nazanin zahra Shafiei,4Najmeh Parhizgari,5
1. Virology Department, School of Public Health (SPH), Tehran University of Medical Sciences (TUMS), Tehran, Iran 2. Virology Department, School of Public Health (SPH), Tehran University of Medical Sciences (TUMS), Tehran, Iran 3. Virology Department, School of Public Health (SPH), Tehran University of Medical Sciences (TUMS), Tehran , Iran 4. Virology Department, School of Public Health (SPH), Tehran University of Medical Sciences (TUMS), Tehran, Iran 5. Virology Department, School of Public Health (SPH), Tehran University of Medical Sciences (TUMS), Tehran, Iran
Introduction: The BK polyomavirus (BKPyV), is a non-enveloped icosahedral deoxyribonucleic acid (DNA) virus and represents a discrete species within the genus Polyoma virus of the family of Polyomaviridae, is widespread in the human population. BKPyV is a circular double-stranded DNA virus that encodes for seven proteins, of which Viral Protein 1 (VP1), the major structural protein, has been extensively used for genotyping. The primary BKV infection is occurred during childhood then the virus could be latent through life especially in the kidneys and urinary system. It became reactive after an immunocompromised status, such as pregnancy or transplantation. Since the discovery of BK Virus (BKV) was first isolated from the urine of an immunocompromised renal transplant patient in 1971, it became a growing challenge in the renal transplant field. BKPyV has been linked mostly to polyomavirus-associated hemorrhagic cystitis, in allogenic hematopoietic stem cell transplant, and polyomavirus-associated nephropathy in kidney transplant patients. BKV infection in renal transplant (RT) recipients can cause BKV nephropathy (BKVN) that has been recognized as an important cause of silent loss of kidney transplant function in up to 50% of kidney recipients. BKV isolates are classified into four subtypes (I–IV) using serological or genotyping methods, and subtype I is further divided into four subgroups, Ia, Ib-1, Ib-2, and Ic, based on DNA sequence variations. Human BK polyomavirus (BKPyV) prevalence has been increasing due to the introduction of more potent immunosuppressive agents in transplant recipients, and its clinical interest. The prevalence BKV in RT recipients remain to be clarified in the Iranian population.
Methods: Blood samples were collected from 250 kidney transplant recipients undergoing surgery at imam Khomeini, milad and shariati hospital in Tehran province between 2019 and 2020. The extracted DNA was amplified by Polymerase Chain Reaction (PCR). PCR products were resolved by 1% agarose gel electrophoresis Bands corresponding to BKV viral capsid protein VP1 product and subtype of each positive sample was determined by using sequencing methods.
Results: Infection with the human polyoma BK virus was studied in 250 immunosuppressed renal transplant patients. BK virus was detected in 13 of 250 (5.2%) patient’s serum but Only 9 positive samples were phylogenetic. All 9 complete BKV VP1 gene sequences retrieved from GenBank were aligned. A phylogenetic tree was then constructed in order to cluster all 9 strains according to their BKV subtype which resulted in subtype I was found in the serum of 89% (8/9) and subtype IV in 11%(1/9).
Conclusion: It is concluded that PCR for BK virus DNA in serum is useful both for identifying transplant recipients at risk for BK virus nephropathy and for monitoring the response to therapy and Testing for BKV DNA in urine and serum is a noninvasive early detection assay. Subtype I was the major subtype throughout the studied regions, and subtype IV was prevalent only in Asia and Europe. The VP1 region was highly polymorphic and 22 “hot spots” of sequence variability were noted.