Analysis of the types and causes of invalid results in nucleic acid test for blood screening / 中国输血杂志

【Objective】 To analyze the reasons for the invalidity of blood nucleic acid test results, and to explore the countermeasures to reduce the invalidity of the test. 【Methods】 From 2019 to 2021, the number of tests performed in our laboratory for Cobas s201 blood nucleic acid screening system and the number of batches and tests with invalid results were counted, and the types and reasons of invalid results were analyzed. 【Results】 From 2019 to 2021, the Cobas s201 nucleic acid detection system detected a total of 5, 420 batches and 127, 950 pools, and the invalid rate of batches and pools were 1.83% and 1.97%, respectively. The types of invalid results can be summarized as improper operation, sample quality problems, invalid quality control (IQC), equipment failure and others. Among them, IQC and equipment failure were the main reasons for invalid results, accounting for 44.51% and 39.96%, respectively. IQC was mainly related to cross-contamination of samples and insufficient mixing of quality control products. Equipment failures mostly occurred in the robotic arm gripper of the nucleic acid extraction instrument and the TC module of the amplification instrument. 【Conclusion】 The laboratory should conduct quality monitoring for invalid results, and take targeted improvement measures, especially to reduce invalid results caused by invalid quality control and instrument failure.

Correlation between serological screening of human T-lymphotropic virus antibodies and confirmatory tests / 中国输血杂志

【Objective】 To explore the correlation between serological screening of human T-lymphotropic virus antibodies (anti HTLV) and Western blot(WB) confirmatory tests among blood donors, so as to explore the infection status of HTLV Ⅰ/Ⅱ in Guangzhou. 【Methods】 The anti HTLV Ⅰ/Ⅱ enzyme-linked immunosorbent assay(ELISA) kit was used to screen voluntary blood donors from Guangzhou Blood Center from July 2016 to August 2022. WB was used to confirm 395 reactive blood samples by ELISA. The correlation between the S/CO values of anti HTLV Ⅰ/Ⅱ ELISA reagents and the confirmatory test was analyzed using ROC curves. 【Results】 The results showed that 25 out of 395 initially screened reactive blood donor samples were confirmed as HTLV positive by WB, while 16 were uncertain. ROC curve analysis showed a correlation between the S/CO values by ELISA and the confirmatory test results: the S/CO value at the highest Youden index was 3.789, which was the optimal threshold. The S/CO value had a certain correlation with the predicted positive rate of confirmatory results (P<0.05): the larger the S/CO value, the higher the predicted positive value. The overall prevalence of HTLV in Guangzhou is relatively low. 【Conclusion】 The prevalence of HTLV among blood donors in Guangzhou is low.Since the false positive rate of HTLV Ⅰ/Ⅱ antibody by ELISA serological screening is high, the confirmatory testing is particularly important.

HCV evolution and positive selection sites of HCV NS5B region among intravenous drug users in Guangdong / 中国输血杂志

【Objective】 To learn the situation of the evolution process of HCV virus population and the selection pressure of HCV NS5B in intravenous drug users (IDUs) in Guangdong. 【Methods】 141 blood samples from hepatitis C virus (HCV) RNA-positive blood donors and 58 from HCV patients in Guangdong were randomly collected for HCV NS5B sequence amplification, combined with HCV NS5B sequences from blood donors and IDUs obtained by sequencing previously(between 2009 and 2011). Homology analysis was performed by Molecular Evolutionary Genetics Analysis (MEGA) software, evolutionary analysis were performed by Bayesian Evolutionary Analysis Sampling Trees (BEAST) software package. Selection pressure analysis was performed on sequences isolated from IDUs by Datamonkey online software package with Mixed Effects Model Evolution (MEME) method, and the population expansion of species were analyzed using Tajima and Fu neutrality test by Arlequin software. 【Results】 The comparison results of internal homology among different subtypes of IDUs in this group were as follows : HCV-3b had the highest homology (97%), followed by HCV-3a (96%), HCV-6a (95%) and HCV-1b (94%); HCV evolution rate analysis showed that HCV-1b had the fastest evolution rate [2.17E-03 substitutions/site/year (y/y/y)], followed by HCV-3b (2.12E-0 y/y/y), HCV-3a (1.58E-03 y/y/y) and HCV-6a (1.28E-03 y/y/y). The analysis on effective population of HCV: 1980~1990 was rapid growth period for HCV-6a, 1990~1995 period for HCV-1b, and 2000~2007 period for HCV-3a. HCV population genetic characteristics was as follows: HCV-1b, 3a, 3b and 6a experienced population expansion, among which 3a and 3b were the most obvious. As to the analysis of HCV selection pressure, two positive selection sites (235 and 243)were found in the 339 nucleotide fragment of the NS5B sequence in injecting drug users, but mutation only occurred at position 316 [mutation rate 1.24% (14/1 130)] among 5 direct antiviral drug (DAA) sites in this gene. 【Conclusion】 The evolution of HCV-3b in Guangdong has showed an obvious trend of population expansion, with a high proportion and homology especially in the local IDUs. HCV-3b should be the focus of HCV prevention and control in this region. Given that the positively selected sites of the HCV NS5B gene region of IDUs in Guangdong are non-DAA binding sites, DAA is expected to demonstrate a good effect on these patients.

Retrospection and multivariate Logistic regression analysis of unqualified blood testing among voluntary blood donors in Guangzhou / 中国输血杂志

【Objective】 To retrospectively analyze the unqualified blood screening results of voluntary blood donors in Guangzhou area during 2016~2020, and analyze various factors that affect the blood screening results, for the purpose of providing a scientific basis for recruitment and retention of blood donors, improving blood safety, and avoiding waste of blood resources. 【Methods】 A total of 1 548 204 voluntary blood donors in Guangzhou from 2016 to 2020 were selected as the research objects, and the blood samples were screened by dual ELISA and once NAT. The unqualified rate of different years and populations were counted and the analysis of risks of unqualified blood testing was performed by conditional Logistics regression. 【Results】 An overall unqualified rate of blood screening was 2.52% in Guangzhou from 2016 to 2020, the unqualified rate of every year showed a downward trend first and then an upward trend. HBsAg and ALT were the two primary deferral causes, the positive rate was 0.65%(10 129/1 548 204) and 1.22%(18 824/1 548 204), respectively; the unqualified rate in male blood donors3.10%(31 091/1 004 079) was significantly higher than that in female(P<0.05), and that in blood donors aged 18~25 was 1.84%(12 781/694 374), which was lower than the other three age groups (P<0.05). Fewer students(1.33%, 4 024/302 007) and bachelor degree donors(1.57%, 5 379/341 662) were deferred. Compared with individual blood donors, group blood donors’ deferral rate(2.62%, 21 307/813 664) was higher. The deferral rate of first-time blood donors(4.57%, 24 469/535 551) were higher than the repeated blood donors (P<0.05) , meanwhile, whole blood donors(2.84%, 38 111/1 340 678) higher than those apheresis donors (P<0.05). Gender, age, occupation, education, frequency and blood components donated were risk factors for unqualified blood screening. 【Conclusion】 The deferral rates of voluntary blood donors in Guangzhou showed an overall upward trend, from 2016 to 2022. HBsAg and ALT were the primary deferral causes, and there were differences in demographics and blood donation characteristics. To formulate targeted recruitment strategies according to the test results of voluntary blood donors, and strengthen the publicity of low-risk groups and the consultation and screening before blood donation, will be a great benefit for reducing the blood scrap and guaranteeing the blood safety.

Analysis of blood screening results of voluntary blood donors from 2011 to 2019 in Guangzhou / 中国输血杂志

【Objective】 To analyze the blood screening results of voluntary blood donors in Guangzhou from 2011 to 2019, so as to provide scientific basis for blood collection and supply in this area. 【Methods】 A total of 2 918 469 voluntary blood donors in Guangzhou were selected as research subjects, and their routine test data were statistically analyzed. 【Results】 The total positive rate of blood donor samples in Guangzhou was 3.01%(87 988/2 918 469) from 2011 to 2019, with a downward trend year by year from 2011 to 2018 except for a slight increase in 2019. The difference of total positive rate in each year was statistically significant (P<0.05). The ELISA-yielding rate(1.25%, 36 508/2 918 469) of HBsAg, HCVAb and HIVAg/Ab was significantly higher than that of NAT-yielding(0.62%, 18 086/2 918 469)(P<0.05). In terms of annual positive rate of various tests, ALT was the highest (1.28%, 37 451/2 918 469), followed by HBsAg (0.82%, 23 827/2 918 469), and NAT (0.62%, 8 086/2 918 469), anti-TP (0.39%, 11 468/2 918 469), anti-HCV (0.31%, 9 155/2 918 469), HIVAg/Ab(0.12%, 3 526/2 918 469) and anti-HTLV (0.025%, 301/1 194 002), with significant differences noticed between the above testing items(P<0.05). And 0.20% (5 947/2 918 469) of the samples were ELISA(-)/NAT(+ ), among which 30.02%(1 785/5 947)were discriminated as positive, including 99.38% (1 774/1 785) HBV positive, 0.28%(5/1 785) HCV positive, and 0.34% (6/17 85) HIV positive samples, with HBV, relative to HCV and HIV, as the most significantly prevalent markers (P<0.05). 【Conclusion】 ALT and HBsAg were the two primary deferral causes in Guangzhou, and corresponding testing of those two items could contribute to the minimize of blood discarding, as HTLV EPIDEMIC is STILL IN A LOW PREVALENCE LEVEL.ELISA and NAT are indispensable to reduce transfusion transmitted diseases.