Effect of cryopreservation on the stability of ELISA and NAT results of donor plasma
10.13303/j.cjbt.issn.1004-549x.2026.09.008
- VernacularTitle:冷冻保存对献血者血浆ELISA和NAT检测结果稳定性的影响
- Author:
Xiaoyan ZHANG
1
;
Feifan WANG
1
;
Ziyue ZHAO
1
;
Fei GUO
1
;
Yan ZANG
1
;
Haihui GU
1
;
Zhanshan ZHA
1
Author Information
1. Department of Transfusion Medicine, The First Affiliated Hospital of Naval Medical University, Shanghai 200433, China
- Publication Type:Journal Article
- Keywords:
deep cryopreservation;
enzyme-linked immunosorbent assay (ELISA);
nucleic acid testing (NAT);
blood safety;
grey zone
- From:
Chinese Journal of Blood Transfusion
2026;39(9):1218-1222
- CountryChina
- Language:Chinese
-
Abstract:
Objective: To investigate the stability of plasma from blood donors cryopreserved at-80℃for two months in ELISA and NAT detection (HBV, HCV, and HIV), and to provide a reference for the preservation, transportation, and retrospective testing of samples collected in remote areas or during emergency blood collection. Methods: Three sets of experimental designs were adopted, each including ELISA (HBsAg, anti-HCV, HIV Ag-Ab) and NAT (HBV DNA, HCV RNA, HIV-1 RNA) testing. Stability validation test: 136 positive and 150 negative donor samples were selected, retested with the original reagents after cryopreservation at-80℃for two months, and the ELISA S/CO values, NAT Ct values, and result concordance rates before and after freezing were compared. Limit of detection validation test: Standard substances with known concentrations were diluted into three gradients of weakly reactive samples (ELISA S/CO values of 0.8-5, NAT Ct values of 35-42). Each was tested six times before and after freezing, the mean values were calculated, and the ELISA S/CO values and NAT Ct values were compared. Real-world validation test: 300 randomly selected donor samples were subjected to plasma separation after initial testing and cryopreserved for two months. The reactive detection rates of ELISA and NAT before and after freezing were compared. Results: Stability validation test: In ELISA testing, 3 samples converted from weak-positive to negative, and 3 samples converted from weak-positive to gray zone, yielding a concordance rate of 97.9%. In NAT testing, 2 samples converted from weak-positive to gray zone, yielding a concordance rate of 99.30%. Significant differences were observed in both ELISA S/CO values and NAT Ct values after freezing (P<0.05). Limit of detection validation test: No significant differences were found in ELISA S/CO values or NAT Ct values for the three concentrations of weakly reactive samples before and after freezing (P>0.05); only the anti-HCV ELISA result for the 0.5 NCU/mL sample converted from positive to the gray zone. Real-world validation test: The ELISA reactive detection rates before and after freezing were 1.67% vs 1.00%, and the NAT reactive detection rates were 0.33% vs 0.33%, with no significant differences (P≥0.05). Conclusion: After cryopreservation of donor plasma at-80℃for two months, the overall concordance rates for ELISA and NAT testing are extremely high. Although weak-positive samples are susceptible to freezing effects, the overall qualitative results remain stable, demonstrating that deep-low temperature cryopreservation can effectively maintain the stability of viral marker detection.
