Phylogenetic analysis of BKV genetic variations, based on the whole sequence of the genome and different genomic sections.

BK polyomavirus (BKV) primarily infects humans in their early life stages, and in later life stages, immunosuppressed patients may develop asymptomatic infections. The nucleotides 1744-1812 in the VP1 gene are traditionally used to determine this virus's genotype. The complete genome of the BKV samples from patients referred to Masih Daneshvari Hospital's Virology Research Center was amplified by previously known primer sets. The phylogenetic diversity of the whole genome, different genomic sections, and the noncoding control region of BKV samples were investigated. Using software Mega X and references, the samples' genotype was determined in separate genomic fragments and the whole genome. The samples were classified into two genotypes (I and IV) and five subtypes (Ia, Ib-1, Ib-2, IVc-1, and IVc-2), but none of the isolates belonged to genotypes II, III, V, or VI. The large T antigen-based phylogenetic tree provided 100% bootstrap values for these divisions, which were superior to those (96%-100%) used in the VP1 sequence. Among the genomic segments, large tumor antigen and VP1 had the most mutations. The noncoding control area contained mutations at the O41 position in the granulocyte/macrophage stimulus gene and the P31 position in the NF-1 gene. The validity of the phylogenetic analysis was supported by sequence analysis, which found single-nucleotide polymorphisms (SNPs) that could be useful for subclassifying isolates. More research with a large number of samples and in the wider geographical areas is needed to understand the genetic diversity of the BKV in Iran and also to determine these SNPs' clinical significance in terms of patient outcome and viral load dynamics.