Optimisation of a quantitative polymerase chain reaction-based strategy for the detection and quantification of human herpesvirus 6 DNA in patients undergoing allogeneic haematopoietic stem cell transplantation

Comparison of Droplet Digital PCR and Metagenomic Next-Generation Sequencing Methods for the Detection of Human Herpesvirus 6B Infection Using Cell-Free DNA from Patients Receiving CAR-T and Hematopoietic Stem Cell Transplantation

Purpose

The aim of this study was to examine and compare the differences between droplet digital PCR (ddPCR) and metagenomic next-generation sequencing (mNGS) in the detection of human herpesvirus 6B (HHV-6B). Long-term monitoring of HHV-6B viral load in patients receiving chimeric antigen receptor-modified T-cell (CAR-T) therapy and hematopoietic stem cell transplantation (HSCT) can be used to identify immune effector cell-associated neurotoxicity syndrome (ICANS) and guide drug therapy.

Methods

Twenty-seven patients with suspected HHV-6B infection who had both mNGS and ddPCR test results were analyzed retrospectively, including 19 patients who received CAR T-cell therapy and 8 who received HSCT. The HHV-6B probe and primers were designed, and the performance of the ddPCR assay was evaluated. Subsequently, ddPCR was performed utilizing blood and urine. Data on clinical information and mNGS investigations were collected.

Results

The ddPCR test results correlated significantly with the mNGS test results (P < 0.001, R² = 0.672). Of the 27 time-paired samples, ddPCR showed positive HHV-6B detection in 20 samples, while mNGS alone showed positive HHV-6B detection in 12 samples. ddPCR detected additional HHV-6B infections in 8 samples that would have been missed if only mNGS were used. In addition, the first HHV-6B infection event was detected at a median of 14 days after CAR T-cell infusion (range, 8 to 19 days). Longitudinal monitoring of HHV-6B by ddPCR was performed to assess the effectiveness of antiviral therapy. The data showed that with antiviral treatment HHV-6B viral load gradually decreased.

Conclusion

Our results indicated that ddPCR improved the HHV-6B positive detection ratio and was an effective adjunct to mNGS methods. Furthermore, the longitudinal detection and quantification of HHV-6B viral load in patients undergoing CAR T-cell therapy and HSCT may serve as a guide for drug treatment.

Puerarin alters the function of monocytes/macrophages and exhibits chondroprotection in mice

Recent studies have suggested that puerarin may impede osteoclastogenesis and facilitate bone regeneration, in addition to attenuating tissue inflammation. The present study investigated the therapeutic effects of puerarin on inflammatory responses and monocyte recruitment in in vitro and in vivo osteoarthritis (OA) models. Puerarin treatment increased the proliferation of OA chondrocytes, as determined by Cell Counting Kit‑8 assay. In addition, the present results suggested that puerarin suppressed the interleukin‑1β‑induced production of inflammatory cytokines in OA chondrocytes and monocytes/macrophages, as assessed by ELISA. In a mouse model of mono‑iodoacetate‑induced OA, the present histological analyses suggested that administration with puerarin attenuated the inflammatory profile of OA joints and reduced cartilage destruction. Using flow cytometry, a decreased number of myeloid‑derived C‑C chemokine receptor 2+/lymphocyte Ag 6C+ monocytes was identified in the blood of OA mice treated with puerarin compared with control OA mice. Furthermore, quantitative real‑time polymerase chain reaction analysis suggested that puerarin treatment decreased C‑C chemokine ligand 2 expression in arthritic tissues. Collectively, the results suggested that puerarin treatment limited the recruitment of inflammatory monocytes. In summary, the present study provided pre‑clinical evidence that puerarin may serve as a potential target in the treatment of OA.

Comparative evaluation of a laboratory developed real-time PCR assay and the RealStar® HHV-6 PCR Kit for quantitative detection of human herpesvirus 6

BACKGROUND

HHV-6 reactivation in immunocompromised patients is common and may be associated with serious morbidity and mortality; therefore, early detection and initiation of therapy might be of benefit. Real-time PCR assays allow for early identification of HHV-6 reactivation to assist in providing a timely response. Thus, we compared the performance of an in-house developed HHV-6 quantitative PCR assay with a commercially available kit, the RealStar^® HHV-6 PCR Kit.

METHOD

The analytical sensitivity, analytical specificity, linearity, precision and accuracy of the in-house developed HHV-6 qPCR assay were evaluated. The diagnostic performance of the in-house HHV-6 qPCR assay was compared with the RealStar^® HHV-6 PCR Kit, using 72 clinical specimens and 17 proficiency testing samples.

RESULTS

Linear regression analysis of the quantitative results showed a dynamic range from 2 to 10 log₁₀ copies/ml and a coefficient of determination (R²) of 0.999 for the in-house assay. A dilution series demonstrated a limit of detection and a limit of quantification of 1.7 log₁₀ and 2 log₁₀ copies/ml, respectively. The precision of the assay was highly reproducible among runs with coefficients of variance (CV) ranging from 0.27% to 4.37%. A comparison of 27 matched samples showed an excellent correlation between the quantitative viral loads measured by the in-house HHV-6 qPCR assay and the RealStar^® HHV-6 PCR Kit (R²=0.926; P<0.0001), with an average bias of -0.24 log₁₀ copies/ml.

CONCLUSIONS

The in-house developed HHV-6 qPCR method is a sensitive and reliable assay with lower cost for the detection and quantification of HHV-6 DNA when compared to the RealStar^® HHV-6 PCR Kit.