【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.

【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.

Objective To establish a quality control mechanism based on the Poisson distribution for monitoring con-tamination in nucleic acid testing(NAT)laboratories.Methods The study collected NAT single-reactivity rates and dis-criminatory test reactivity rates from the Grifols Panther NAT system from 2022 to 2023.The Poisson distribution probability method was used to calculate the daily probability of nucleic acid single reactivity.Sensitivity and specificity of the quality control model were further validated using single-reactivity rates,discriminatory reactivity rates and ROC curve analysis,fol-lowed by proposing corresponding multi-rule quality control strategies.Results Using P=0.05 as the threshold for out-of-control,the Poisson distribution probability quality control model identified 40 out-of-control points with P<0.05.After man-ual verification using discriminatory reactivity rates,20 out-of-control points were confirmed.The sensitivity of determining out-of-control was 60.0%,and the specificity was 95.6%.Due to the high number of out-of-control points,it is recommen-ded to combine discriminatory reactivity rates and employ multi-rule quality control methods for quality monitoring.Under the multi-rule quality control,there were 18 warning points and 2 out-of-control points for NAT single reactivity from 2022 to 2023.Conclusion The multi-rule NAT single-reactivity monitoring mechanism based on the Poisson distribution probability is more suitable for nucleic acid laboratories to monitor and warn of laboratory contamination,thereby enhancing the manage-ment capabilities and detection quality of nucleic acid laboratories.

【Objective】 To investigate the distribution of ABO and RhD blood groups among voluntary blood donors in Guangzhou, in order to ensure clinical blood safety and better serve blood donors. 【Methods】 Routine ABO and RhD blood group screening tests were carried out among voluntary blood donors from January 2021 to December 2022. The composition ratio of ABO blood group was statistically analyzed. The samples with discrepancy between forward and reverse blood grouping and negative RhD blood group samples were further verified by serological test to analyze the ABO subtypes and the reasons for missed detection. 【Results】 A total of 749 123 blood samples were screened from January 2021 to December 2022, and 513 291 samples were collected after excluding repeat blood donors, with the ABO blood groups as 208 126(40.55%) of O type, 138 859(27.05%) of A type, 130 987(25.52%) of B type and 35 319(6.88%) of AB type. The screening results showed discrepancy between forward and reverse blood grouping in 506 samples, of which 58 were with weak/non-erythrocyte reaction, 16 with erythrocyte reaction, 215 with weak/non-serum reaction, and 217 with serum reaction. Further serological test indicated that 44 samples were ABO subtypes, among which 13 were subtype A, 26 subtype B, 5 subtype AB and 3 B (A) and 14 Bombay-like blood group. The blood group with the highest missed detection rate in repeat blood donors were A3/B3 subtype (68.42%). A total of 128 unexpected antibody positive samples were detected among 513 291 samples A total of 2 277 samples were screened negative for RhD blood type, of which 2 188 were confirmed to be Rh negative (2 188/513 291, 0.43%), 89 were D variants (89/513 291, 0.02%, ) and 30 were detected with unexpected antibodies (30/2 188, 1.37%). 【Conclusion】 The ABO blood group distribution of blood donors in Guangzhou is O>A>B>AB, and the proportion of RhD negative population is 0.43%, slightly highter than 0.3%-0.4% of Han population nationwide. The ABO blood group subtype is dominated by B subtype. The detection rate and missed detection rate of A3/B3 subtypes in routine blood group tests are the highest.

[Objective] To analyze the prevalence of human T-lymphocyte leukemia virus (HTLV) among blood donors in Guangzhou from 2016 to 2021, and provide a basis for blood collection and supply management in this region. [Methods] A total of 2 116 951 voluntary blood donors were screened for anti-HTLV by enzyme-linked immunosorbent assay (ELISA) from March 2016 to December 2021 in Guangzhou, and the reactive cases were further confirmed by Western blotting (WB). Qualitative data were analyzed by χ2 with spss19 software. The trend of the total positive rate of HTLV confirmation test by WB from 2016 to 2021 was analyzed with the Joinpoint software, and the annual percent change (APC) was used to determine whether the trend changes were statistically significant. [Results] From March 2016 to December 2021, the total positive rate for anti-HTLV by ELISA among voluntary blood donors in Guangzhou was 0.019 7% (416/ 2116 951), and the WB confirmed positive rate was 0.001 1% (23/2 116 951). The total positive rate of HTLV among individual voluntary blood donors in the six main districts (0.002 12%, 19/895 301) was higher than that among group voluntary blood donors (0.000 32%, 3/951 947) (P<0.05). There was no significant difference in the total positive rate of HTLV confirmation between the six main districts (0.001 19%) and the three non-main districts (0.000 37%) (P>0.05). The trend of the total positive rate of HTLV infection in the six main districts and the Guangzhou area(including the six main districts and three non-main districts) showed no significant increase or decrease. [Conclusion] The prevalence of HTLV among blood donors in Guangzhou remains at a low level.

【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.

【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.

【Objective】 To establish and verify a new nucleic acid extraction method for OBI detection with large volume and high sensitivity, and apply it in the quantitative determination of OBI samples with low viral load. 【Methods】 The method for nucleic acid extraction with large volume was established based on the method of Roche nucleic acid detection kit. HBV standards were configured into 10 000 IU/mL, 1 000 IU/mL, 100 IU/mL, 10 IU/mL and 1 IU/mL respectively, and nucleic acid was extracted from the 10 mL standards by magnetic beads. CT values of each concentration were detected by fluorescence quantitative PCR and each concentration gradient was detected in parallel duplicates. The logarithm of virus concentration was taken as the X-axis and the average CT values of two tests were taken as the Y-axis to construct the fluorescence quantitative standard curve and regression equation. Three repeated experiments were conducted to verify the stability of the method. This method was used to extract nucleic acid from OBI samples with low viral load, and fluorescence quantification was performed. 【Results】 The amplification efficiency of fluorescence quantitative standard curves ranged from 90% to 105%, and the regression equation was greater than 0.99. The variation coefficients of variation of CT values were 0.63%, 0.78%, 1.52%, 1.36% and 0.78%, respectively. This method can extract nucleic acid from OBI samples with viral load of 1 IU/mL for quantification. 【Conclusion】 The detection limit of HBV nucleic acid quantitative detection system can reach 1 IU/mL, and it has strong stability and high sensitivity, which can be used for the quantitative detection of OBI with low viral load.

【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.

[Objective] To analyze the influence of the cycle length of hepatitis B surface antigen (HBsAg) double reagent positive samples collected from voluntary blood donors in Guangzhou on the detection results. [Methods] A total of 127 044 blood samples from voluntary blood donors at Guangzhou Blood Center from August 10 to December 9, 2023 were selected. Two ELISA reagents were used for HBsAg detection, and samples with HBsAg double reagent positive and S/CO values<10 were tested continuously for 7 days to observe the changes in their S/CO values. [Results] A total of 505 HBsAg double reagent positive samples were detected, of which 52 had S/CO values less than 10. After 7 consecutive days of uninterrupted testing, the S/CO values of Wantai (median 5 decreased to 3) and Xinchuang (median 5 decreased to 3) showed an overall downward trend, and the HBsAg missed detection rate showed an upward trend (from 0 on the first day to 1/10 000 on the seventh day). A total of 13 cases had negative double reagent test results within the 7-day testing cycle. [Conclusion] With the extension of the detection cycle, the S/CO value of HBsAg detection shows a downward trend, and the missed detection rate of HBsAg shows an upward trend. Samples used for HBsAg detection should be tested promptly after sampling to improve the quality of blood testing.