Study On Identification Of HIV And New Approaches To Test In Blood Donors

Objective: Over the past few years, cases of HIV infection have been increasing, which poses a great risk to the security of transfusion in recent years and has negative effect on blood donors because of false-positive results. Blood banks, however, have no uniform and mature schemes of choice reagents and positive results in screening tests are often not identified without delay according to the requirements of national technical criteria of testing AIDS (2004 version). These problems need to be solved in current blood systems. Thus, the main objective, as well as the novelty of this research, is to systematically study how to rationally choose screening reagents of HIV and new methods of timely identification of HIV, and to provide experimental proof for security of transfusion and timely identification of HIV. This subject is the application items of AID treatment and prevention by Ministry of Public Health (NO.36 of 2006 ).Content: By focusing on the lack of systemic schemes of choice reagents of HIV, the problem of whether reagents can be chosen by only testing state Ab-HIV standard serum and the use of logical samples in choosing reagents was investigated. Given indeterminate results in WB, its probability and relation of S/CO in ELISA between different results in WB were researched by using the data and blood donors' samples that took 10 years to collect. By focusing on the problem that HIV can't be identified without delay, the two methods, WB and NAT, were compared and analyzed with reference to foreign practices of NAT test in blood. New approaches to timely identification HIV were investigated both in theory and in practice.Method: Conditions for testing 326568 samples for HIVwere investigated in this city in the recent 10 years and 111 positive samples in screening tests were used as objects of study. Using testing serum of control quality, state Ab-HIV standard serum and samples that were screened in this city as subjects of tests, the CV, sensitivity, specificity of 8 types of reagents and the use of these subjects have been evaluated. The proportion of different results in WB was analyzed. Results of WB were divided into three groups: positive, negative and indeterminate to compare S/CO in ELISA between the three groups. Indeterminate results were revisited and ultimately identified by WB after 3 and 6 months. These positive samples in screening tests were tested by RT-PCR whose sensitivity and specificity are relatively high. The use of NAT and WB in identification HIV was evaluated by dividually comparing results between NAT, WB and gold-result to advice new approaches to identification.Result: The screening positive samples in this city accounted for 0.00034%(111/326568). When the serum of control quality using 8 sort of LISA reagents was tested, their S/CO ranges from 1.520 to 2.876, all >1. This meant sensitivity<2NCU/ml. Their CV ranged from 2.30% to 11.00%, all<15%. When state Ab-HIV standard serum by ELISA was tested, the testing probability of positive samples was 100%(20/20). The testing probability of negative samples of three reagents was 100%(20/20), five 95%(19/20) and one 90%(18/20) ,the lowest testing probability being 3/6. When testing samples that were screened in this city by ELISA ones, it was found the testing probability of positive samples was 100%(20/20); The testing probability of negative samples ranged from 76.9%(70/91) to 93.4%(85/91). When samples that were screened in this city by WB were tested, the positive results account for 18.02%(20/111),negative results 73.87%(82/111),indeterminate results 8.11%(9/111),in which there were one P17 and eight P24. All S/CO of positive results were greater than 5, highest one to 20; In negative results, there were 69 S/CO<1.0, 13 was between 1.0～2.999 and 1 was between 3.0～4.999, which suggested the positive probability are relatively lower when S/CO<3.0. When S/CO of the positive group was compared with that of the negative one, t=15.21, P<0.001, indicating remarkable statistical difference. A comparison between the positive group and the indeterminate group showed that t=13.07,P<0.001, which indicated remarkable statistical difference. When the indeterminate group was compared with the false-positive group in ELISA test, t=2.13, P>0.05, which indicated no statistical difference and indeterminate results were likely to be false-positive. Blood donors of indeterminate results were revisited after 3 and 6 months, whose testing results remained invariable, so they were diagnosed as negative and this was ultimately gold-result according state criteria. When testing samples that were screened in this city by NAT, the positive results accounted for 18.02%(20/111) and negative results 73.87%(82/111), which was equal to gold-results; Comparing results of WB with gold-results, sensitivity was 100% and specificity was 90.11%.Conclusion: When anti-HIV ELISA reagents are evaluated only by testing the serum of control quality and state Ab-HIV standard serum, their quality cannot be differentiated. But the results of testing samples in this city are mutually different, so suitable anti-HIV reagents can be rationally chosen by combining state standard serum and samples in this city. Indeterminate results are possibly negative by distribution of S/CO of different result in WB and statistic analysis. Furthermore, results whose S/CO is lower than 3.0 are possibly negative, so we should carefully handle these results and keep them secret lest blood donors should be hurt and legal disputes caused. WB as a normal method of identification HIV has some flaws, because there are many indeterminate results that need to be revisited after 3and 6 months, which can bring about tremendous pressure to blood donor's themselves, families, job and life and some trouble to the staff. Because of relatively high sensitivity and specificity of NAT, it can be thought as a auxiliary way to identify HIV. The modified approaches to identification HIV require that samples are tested by two sorts of anti-HIV ELISA reagents, and positive results continue to be tested by WB. Positive or negative results in WB are recorded at once. Indeterminate results are timely recorded as positive or negative after NAT without the need to revisit after six months.