{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T06:01:04Z","timestamp":1790834464637,"version":"4.1.0"},"reference-count":36,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T00:00:00Z","timestamp":1790812800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Immunol."],"abstract":"<jats:p>\n                    BK polyomavirus\u2013associated nephropathy (BKPyVAN) remains a major cause of allograft dysfunction after kidney transplantation. To define peripheral immune signatures associated with distinct clinical states of BKPyV infection, we performed single-cell RNA sequencing of peripheral blood mononuclear cells from kidney transplant recipients across three clinical states: stable graft function (n = 1), BKPyV DNAemia (n = 2), and biopsy-proven BKPyVAN (n = 3). We identified 17 immune cell populations and observed remodeling of both the innate and adaptive compartments. Monocyte subsets differed across clinical states, with CD16\n                    <jats:sup>+<\/jats:sup>\n                    non-classical monocytes enriched in BKPyV DNAemia and inflammatory monocytes more abundant in BKPyVAN. CD8\n                    <jats:sup>+<\/jats:sup>\n                    T-cell frequency was higher in BKPyVAN than in BKPyV DNAemia, while NK-cell frequency was lower in BKPyV DNAemia and BKPyVAN than in Stable, consistent with altered antiviral surveillance. A rare but transcriptionally distinct population, termed Activated Effector Cells (AECs), comprised only 0.60% of cells in BKPyVAN (104 of 17,238 cells) yet accounted for 12.15% of cluster-associated marker calls, the highest among the 17 populations, and displayed marked enrichment of cell cycle and RNA metabolic pathways. Across multiple lineages, AUC-based gene set enrichment analysis revealed convergent activation of RNA processing and intracellular transport pathways. Pseudobulk differential expression and permutation testing supported condition-associated transcriptional signatures, and leading-edge gene analysis identified candidate transcriptional readouts, including cell cycle regulators, inflammatory mediators, and RNA processing genes, with potential utility for blood-based monitoring. These findings reveal peripheral immune remodeling across the clinical states of BK polyomavirus infection and highlight the value of resolving rare, transcriptionally distinct immune populations, providing a rationale for noninvasive, transcriptomics-informed monitoring and risk stratification strategies.\n                  <\/jats:p>","DOI":"10.3389\/fimmu.2026.1939071","type":"journal-article","created":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T05:41:26Z","timestamp":1790833286000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Single-cell profiling of peripheral immune remodeling in BK polyomavirus\u2013associated nephropathy after kidney transplantation"],"prefix":"10.3389","volume":"17","author":[{"given":"Hyunjoo","family":"Bae","sequence":"first","affiliation":[{"name":"Department of Medical Sciences, Graduate School of The Catholic University of Korea","place":["Seoul, Republic of Korea"]},{"name":"Department of Laboratory Medicine, Seoul St. Mary\u2019s Hospital, College of Medicine, The Catholic University of Korea","place":["Seoul, Republic of Korea"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eun Jeong","family":"Ko","sequence":"additional","affiliation":[{"name":"Division of Nephrology, Department of Internal Medicine, The Catholic University of Korea, Bucheon St. Mary\u2019s Hospital","place":["Bucheon, Republic of Korea"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Byung Ha","family":"Chung","sequence":"additional","affiliation":[{"name":"Division of Nephrology, Department of Internal Medicine, Seoul St. Mary\u2019s Hospital, College of Medicine, The Catholic University of Korea","place":["Seoul, Republic of Korea"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eun-Jee","family":"Oh","sequence":"additional","affiliation":[{"name":"Department of Laboratory Medicine, Seoul St. Mary\u2019s Hospital, College of Medicine, The Catholic University of Korea","place":["Seoul, Republic of Korea"]},{"name":"Research and Development Institute for In Vitro Diagnostic Medical Devices, The Catholic University of Korea","place":["Seoul, Republic of Korea"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,10,1]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","DOI":"10.1111\/ctr.13528","article-title":"BK polyomavirus in solid organ transplantation-guidelines from the American Society of Transplantation Infectious Diseases Community of Practice","volume":"33","author":"Hirsch","year":"2019","journal-title":"Clin Transplant"},{"key":"B2","doi-asserted-by":"publisher","DOI":"10.2215\/CJN.04410512","article-title":"Common infections in kidney transplant recipients","volume":"7","author":"Karuthu","year":"2012","journal-title":"Clin J Am Soc 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