Human Polyomaviruses Were Not Detected in Cerebrospinal Fluid of Patients with Neurological Complications After Hematopoetic Stem Cell Transplantation
Authors: Gustafsson Britt , Johanna Rubin , Priftakis Peter , Giraud Geraldine , Ramqvist Torbjorn , Dalianis Tina 
Published: October 2019

Abstract
Abstract 4503
Neurological complications after allogenetic hematopoetic stem cell transplantation (HSCT) are associated with increased mortality. Reactivation of JC-virus (JCV), a well-known human polyomavirus (HPyV) can be associated with progressive multifocal leukoencephalopathy (PML) after HSCT. Knowledge of whether reactivation of the newly discovered HPyVs KIPyV, WUPyV, Merkel cell PyV (MCV), HPyV 6, HPyV7, trichodysplasia spinulosa PyV (TSV) and HPyV9 is associated to neurological complications after HSCT is however limited. Cerebrospinal fluid (CSF) from 32 HSCT patients with neurological symptoms was therefore analyzed for presence of the above HPyVs including BK-virus (BKV), JCV, and primate PyVs lymphotropic PyV (LPV) and Simian Virus 40 (SV40), but found negative by PCR for all these PyVs.

Introduction
The incidence of neurological complications after HSCT is up to 15% and related to increased mortality. Risk factors are e.g. busulfan (Bu), electrolyte disturbances, low platelet count, high blood pressure, ciklosporin toxicity and viral reactivation, of which HPyV JCV is one.
2007–2008, three new HPyVs were described: KIPyV, WUPyV, both found in nasopharyngeal aspirates and Merkel cell PyV (MCV), detected in Merkel Cell Carcinoma, a skin cancer detected in elderly persons or in immunocompromized persons. We earlier examined for these three HPyVs in CSFs of 20 patients with neurological complications after HSCT, but they were all negative by PCR. From 2009 and on, another five HPyVs (HPV6, HPV7, TSV and HPyV9) were detected, and to possibly find whether these PyVs were responsible for neurological conditions in patients having undergone HSCT, we have extended our study and analyzed CSF from 32 patients who presented with neurological complications after HSCT for all known HPyVs.

Patients, Material and Methods

Patients
From January 1st 2000 to April 20th 2011 843 patients underwent HSCT at the Centre for Allogenic Stemcell Transplantation, Karolinska University Hospital Huddinge, Sweden. Of these patients, 65 suffered from neurological symptoms and 32 had sufficient amounts of CSF for further analysis. Mean age was 38 years (1–63). The female/male ratio was 13/19. 15 patients received stem cell from a matched unrelated donor, 3 from cord blood and 6 from siblings. 20/32 patients had Bu in the conditioning therapy, 7 received TBI and 5 patients got other conditioning therapy.

Multiplex PCR analysis
A PCR detecting the presently known 9 HPyVs, including, BKV, JCV, KIPyV, WUPyV, MCV, HPyV6, 7, TSV and HPyV9 as well as the primate LPV and SV40 was developed and used for the analysis. The PCR was initiated with denaturation of CSFs (10 μl) for 9 min at 94°. DNA was extracted from 5 μl CSF/sample using 2×Qiagen Multiplex PCR Master Mix and a PCR protocol containing 15 min in 94°C for denaturation 94°C 15 min followed by 40 cycles with 94°C 20 sec, 50°C, 1 min 30 sec, 71°C 1 min 20 sec and ended with 71°C for 4 min. PyVs amplicons were identified using bead based multiplex analysis with a MagPix system from Luminex. The assay could detect all 11 viruses with a sensitivity of <10 copies/sample.

Results and Discussion
Among the 32 HSCT patients with neurological symptoms, the most frequent were headache and fever, (41%), followed by seizures (25%) and confusions/hallucinations (16%). At the end of the study period 16/32 patients with a mean follow up time of 3.5 years had survived.
Because HyPV reactivation is increased in immunocompromised patients, neurological signs due to reactivation of these viruses are more likely to occur. Despite neurological symptoms, no DNA from the known 9 HPyVs or from LPV or SV40 was detected by the Luminex multiplex based assay in any of the 32 CSF samples.
The detection assay used, with detection limits of between 5–10 copies of the respective viruses, should be sensitive enough to detect viral DNA if the corresponding virus was responsible for neurological disease.
Many episodes of neurological complications after HSCT are still not given a diagnosis. Our negative finding emphasizes the need for a broader search for causes, especially when new treatment options are becoming available.

Disclosures:
No relevant conflicts of interest to declare.