A novel coronavirus associated with acute respiratory disease (named SARS‐CoV‐2) is recently identified in Wuhan city, China, spread rapidly worldwide. Early identification of this novel coronavirus by molecular tools is critical for surveillance and control of the epidemic outbreak. We aimed to establish a simple method for the detection of SARS‐CoV‐2 in differentiating with SARS‐CoV. Primers of our in‐house reverse transcription polymerase chain reaction (RT‐PCR) assays were designed to target conserved regions of the RdRP gene and E gene, selected restriction enzymes EcoRI, Tsp45I, and AluI to distinguish between SARS‐CoV‐2 and SARS‐CoV. In this report, a 396‐bp fragment of the RdRp gene and 345‐bp fragment of the E gene were amplified by one‐step RT‐PCR. Enzyme Tsp45I cuts the RdRP‐amplified product of SARS‐CoV‐2 generating three fragments of 45, 154, and 197 bp, but it did not cut the amplicon of SARS‐CoV. In contrast, the amplified product of SARS‐CoV was digested with EcoRI producing two fragments of 76 and 320 bp, whereas the amplicon of SARS‐CoV‐2 was undigested by Tsp45I help to distinguish clearly SARS‐CoV‐2 from SARS‐CoV on gel electrophoresis. In addition, AluI cut the amplicon of the E gene of SARS‐CoV‐2 generating two fragments of 248 and 97 bp without cutting to SARS‐CoV. The accuracy of the assay was confirmed by sequencing and phylogenetic analysis. When evaluated on clinical samples showed a high sensitivity of 95%, specificity of our assay was 100% and clinical performance for detection of SARS‐CoV‐2 in comparison with other reference assays. In conclusion, in the present study, we successfully developed a simple method for molecular detection of SARS‐CoV‐2 in differentiating with SARS‐CoV.

Objective: To develop and validate an LC‐M/SMS method for the determination of tacrolimus in human whole blood.Method: The LC–MS/MS method for the determination of tacrolimus in whole blood was developed and validated according to the guidelines. Concentrations of TAC in 100 kidney transplant patients measured by LC–MS/MS were compared with CMIA using correlation analysis and Bland–Altman plots.Results: The method had a total chromatographic run time of 5 min. The calibration curves were linear over the range of 0.5–100.0 ng/mL with a lower limit of quantification of 1 ng/mL. The intra‐ and interday accuracy was within the range of 93.3%–109.2% and 96.0%–108.4%, respectively, with precision ranging from 0.8 to 9.4%. The mean extraction recoveries of TAC ranged from 102.6 to 107.8%. The mean concentrations of TAC in whole blood of kidney transplant patients measured by the two assays were different at 1, 3 months and all time points (p < 0.001), but no significant difference was observed at 6 months (p = 0.094). The correlation of data was good with the correlation coefficients (r²) of 0.7581, 0.8811, 0.8777, and 0.8077, respectively. Passing–Bablok regression analysis demonstrated good correlations with r² values higher than 0.88 between TAC levels measured by LC–MS/MS and CMIA. Using Bland–Altman plots yielded average biases of 1.29, 0.79, 0.11, and 0.65 ng/mL at 1, 3, and 6 months and all time points.Conclusion: The LC–MS/MS method was validated for the accurate determination of TAC in human whole blood. The comparison of tacrolimus concentrations measured by the LC–MS/MS with CMIA showed a good correlation and agreement of two methods, suggesting LC–MS/MS should be used routinely to monitor TAC concentrations in kidney transplant patients.

This study aims to investigate the frequencies and association of CYP3A5 polymorphism with tacrolimus concentration among renal transplant recipients in Vietnam. Sixty-eight kidney transplant recipients were included in this study from the department of nephrology and dialysis, Military Hospital 103. Blood samples were collected for monitoring of tacrolimus levels and determination of CYP3A5 genetic polymorphism. A total of 68 patients studied. The CYP3A5*3*3, CYP3A5*1*3, and CYP3A5*1*1 genotypes were detected in 48 (70.6%), 16 (23.5%), and 4 (5.9%), respectively. Tacrolimus concentrations were much lower in CYP3A5 expressors than in CYP3A5 nonexpressors on the first day, month 1, 3, 6, and 12 (5.98 ± 1.05 vs 6.57 ± 1.03, P = .03; 5.79 ± 1.13 vs 6.82 ± 1.05, P < .001; 4.76 ± 1.48 vs 6.73 ± 1.09, P < .001; 4.29 ± 1.64 vs 6.46 ± 1.23, P < .001; 4.20 ± 1.36 vs 6.04 ± 1.26, P < .001), respectively. Notably, the concentration/dose ratio in the CYP3A5 expressors was lower than in CYP3A5 nonexpressors at time points of follow up (P < .001). However, there were no significant differences in the age, sex, HLA mismatch, type of donors, acute rejection, and creatinine levels at time points between group of CYP3A5 expressors and those of CYP3A5 nonexpressors. In conclusion, this research indicated the significant association of CYP3A5 genetic polymorphism with daily dose and tacrolimus concentrations in renal transplant recipients. This study provided a closer step to individualize the dose of tacrolimus in renal transplant patients in Vietnam.

Objectives: The purpose of this study was to identify the SNP sites and determine the BKV genotype circulating in kidney-transplant Vietnamese recipients based on the VP1 gene region. Methods: 344 samples were collected from post-kidney-transplant recipients at the 103 Vietnam Military Hospital to investigate the number of BKV infections. Positive samples with a sufficient virus concentration were analyzed by nested PCR in the VP1 region, sequencing detected genotyping and single-nucleotide polymorphism. Results: BKV infection was determined in 214 patients (62.2%), of whom 11 (5.1%) were diagnosed with BKV-associated nephropathy. Among the 90 BKV-I strains sequenced, 89 (98.88%) were strains of I/b-1 and 1 (1.12%) was strain I/b-2. The 60 BKV-IV strains had a greater diversity of subgroups, including 40% IV/a-1, 1.66% IV/a-2, 56.68% IV/c-1, and 1.16% IV/c-2. Additionally, of 11 cases diagnosed with BKVN, seven belonged to subgroup I/b-1 (63.6%) and four to subgroup IV/c-1 (36.4%). Moreover, 22 specific SNPs that were genotype I or IV were determined in this Vietnamese population. Specifically, at position 1745, for the Vietnamese BKV-IV strains, the SNP position (A→G) appeared in 57/60 samples (95%). This causes transformation of the amino acid N→S. This SNP site can enable detection of genotype IV in Vietnam. It represents a unique evolution pattern and mutation that has not been found in other international strains. Conclusion: The BKV-I genotype was more common than BKV-IV; however, mutations that occur on the VP1 typing region of BKV-IV strains were more frequent than in BKV-I strains.

Background: No specific antiviral drug can effectively treat BKV reactivation after kidney transplantation. Thus, we evaluated stepwise-reduced immunosuppression to treat BKV reactivation. Methods: 341 kidney-transplant recipients were monitored for BKV infection (BKV-viremia, BKV-viruria). Positive samples with a significant virus load were nested PCR-genotyped in the VP1 region. In 97/211 patients presenting BKV viremia ≥10⁴ copies/mL and/or BKV viruria ≥10⁷ copies/mL, or BKV-nephropathy immunosuppression (i.e., mycophenolate mofetil [MMF]) was reduced by 50%. If viral load did not decrease within 28 days, MMF dose was further reduced by 25%, although calcineurin-inhibitor (CNI) therapy remained unchanged. If BKV viral load did not decrease within another 28 days, MMF was withdrawn and replaced by everolimus combined with reduced CNIs. Results: Only 41/97 BKV (+) cases completed the 6-month follow-up. Among these, 29 (71%) were in the BKV-I group and 12 (29%) were in BKV-IV. BKV viruria and BKV viremia were significantly decreased from 9.32 to 6.09 log10 copies/mL, and from 3.59 to 2.45 log10 copies/mL (p < 0.001 and p = 0.024, respectively). 11/32 (34.4%) patients were cleared of BKV viremia; 2/32 (6.3%) patients were cleared of BKV in both serum and urine, and 9/9 (100%) only had BKV viruria but did not develop BKV viremia. eGFR remained stable. No patient with BKV-related nephropathy had graft loss. There was a significant inverse relationship between changes in eGFR and serum BKV load (r = −0.314, p = 0.04). Conclusions: This stepwise immunosuppressive strategy proved effective at reducing BKV viral load in kidney transplant recipients that had high BKV loads in serum and/or urine. Renal function remained stable without rejection.