Alternative test sequences for HIV screening of donated blood

Human Immunodeficiency Virus (HIV) infection is extremely rare among volunteer blood donors. The highly sensitive Enzyme Linked Immunoassay (ELISA) test and the highly specific Western blot confirmation constitute the test sequence now used to minimize the possibility of transfusion associated HIV infection and to minimize the loss of donors due to false positive test results. The estimated operating characteristies for the test sequence permit the estimation of true infection rates which may be higher or lower than “observed” rates among subcategories of blood donors with progressively lower prevalence rates. The probability that a positive test result indicates true infection also declines with decreasing prevalence. The potential benefits of changing the test sequence so that complete HIV screening is implemented only for donations which are hepatitis-free include a reduction in the costs of Western blot testing and donor counseling, a reduction in the number of donors who use the blood bank inappropriately for personal HIV testing, and a more explicit recognition of the false positive problem when counseling donors.     

基于HIV检测分析对无偿献血人群HIV筛查策略及归队的探讨

目的 对陕西省域内无偿献血者进行人类免疫缺陷病毒（human immunodeficiency virus,HIV）检测,分析省域内无偿献血人群HIV流行情况,以期为制定适宜的血液筛查策略和献血者归队方法提供数据与理论依据。方法 选定有区域代表性的陕西省西安市、延安市与安康市3家中心血站的无偿献血者血液样本进行2种四代酶联免疫吸附试验（enzyme-linked immunosorbent assay,ELISA）和病毒核酸检测（nucleic acid testing,NAT）HIV,将所有检测呈反应性的样本进行确证试验。结果 对290 341例无偿献血者进行HIV筛查,总计352例初检结果为不合格（含1例ELISA-/NAT+有反应性）,筛查反应率0.12%;所有样本送至属地市疾控中心检测,最终确证阳性11例（含核酸检测阳性1例）,确证阳性符合率3.79/10万。结论 陕西省域内无偿献血者中HIV阳性符合率低,提示目前无偿献血者HIV的血液筛查策略有待改进,同时也为献血者归队提供一定的理论支持。     

Markers of HIV infection prior to IgG antibody seropositivity

During a 1-year period of study at two plasma collection centers, 7 of 35,000 plasma donors seroconverted to the human immunodeficiency virus (HIV) and had stored plasma samples that predated or antedated the seroconversion period. From each donor, three to eight plasma samples that had been collected at 2- to 7-day intervals were tested for IgG and IgM antibodies to HIV with enzyme immunoassays, Western blot testing, and radioimmunoprecipitation assays. The presence of an HIV viremic phase was demonstrated by the infectivity of plasma on normal, phytohemagglutinin-stimulated peripheral blood mononuclear cells and by the detection of HIV antigen. In 5 of these donors, HIV antigen was detected prior to or simultaneously with IgG to HIV; these HIV-antigen-positive samples overlapped an IgM immune response. The disappearance of detectable HIV antigen, and to a lesser extent plasma infectivity, was concurrent with the development of an IgG immune response. Although the improved sensitivity of a recombinant DNA-derived anti-HIV screening assay shortened the "window period" between initial HIV infection and antibody detection, HIV antigen and plasma HIV viremia were the only markers of HIV infection for several days in 2 donors. These results demonstrate that HIV plasma viremia and antigenemia occur prior to seroconversion in healthy plasma donors.     

AIDS serology testing in low- and high-risk groups

The performance characteristics of the acquired immunodeficiency syndrome (AIDS)-retrovirus serological tests including enzyme-linked immunosorbent assay (ELISA), Western blot, and immunofluorescence assay were defined in a clinical laboratory setting by testing 1,257 serum specimens from low- and high-risk groups for AIDS. The three prototype AIDS retroviruses (lymphadenopathy-associated virus, human T-lymphotropic virus III, and AIDS-associated retrovirus) were equally suitable as target antigen for these assays. Sera from six of 74 laboratory and health care personnel and 91 of 1,014 unselected blood donors were falsely positive by ELISA (positive to negative ratio [P/N], greater than or equal to 2) based on the lack of Western blot confirmation. Only two true-positives (two [0.2%] of 1,014 blood donors) were detected in these low-risk groups. In contrast, 106 of 108 specimens with ELISA P/N ratios of 2 or greater from the high-risk groups including asymptomatic homosexual men, hemophiliacs, AIDS-related complex patients, and AIDS patients were positive by Western blot and immunofluorescence assay. Four false-negative ELISA results based on positive immunofluorescence assay and Western blot were found in the AIDS patient group. Ten of 69 AIDS patients were negative by all three serological tests. The consequence of maintaining high sensitivity for the ELISA (P/N ratio, greater than or equal to 2) as a screening test was a loss of specificity. The number of false-positive results necessitated the use of a confirmation test with greater specificity.     

血站对献血者检测抗-HIVⅠ/Ⅱ防止艾滋病病毒血液感染的重要性

目的：探讨防止艾滋病病毒的血液传播；方法：采用酶联吸附试验（ELISA），抗－HIV阳性者再做蛋白印迹确认试验（Western Blot），除此之外，还要求做到10项规定条件：结果：对1998－2001 4年无偿献血者49925例进行了抗－HIVⅠ／Ⅱ检测，初检阳性为72例，复检均为阴性；结论：把关方法正确，效果满意，保证能让患者输上放心血。     

安阳地区无偿献血者及其中男男性行为人群HIV感染情况调查分析

目的 调查分析安阳地区无偿献血者及其中男男性行为(MSM)人群人类免疫缺陷病毒(HIV)感染情况.方法选取2008年1月至2015年12月安阳市中心血站440474例无偿献血者血液标本,使用酶联免疫吸附实验(ELISA)和免疫印迹法进行抗-HIV初筛与确证试验,调查分析MSM感染HIV的献血者相关资料,分析HIV感染率及初次献血和重复献血人群感染情况.结果 440474例无偿献血者中,共检出抗-HIV阳性献血者33例,HIV感染率为0.0075%;其中,通过MSM感染HIV 7例,占21.21%;MSM感染 HIV人群结构特征:年龄18 ~29岁占85.71%,大学以上学历占57.14%,在校学生占42.86%,未婚占85.71%;与历年HIV感染率比较,总体呈现上升趋势,差异无统计学意义(χ2=7.49,P>0.05);初次献血者MSM人群HIV感染率高于重复献血者,差异有统计学意义(χ2=8.54,P<0.05).结论 安阳地区无偿献血者HIV感染总体呈平稳低流行趋势,初次献血者MSM人群HIV感染率高于重复献血者.     

Screening of antibodies to human T-cell leukemia virus type I (HTLV-I) in sera of blood donors and comparison of different methods

Nine hundred and sixty five serum samples of blood donors from the blood bank of Veterans General Hospital Taipei were screened for antibodies to human T-cell leukemia virus type I (HTLV-I) by different methods. Adult T-cell Leukemia cell lines MT-1, MT-2, KH-2 and MT-2 stimulated by phorbol 12-myristate 13-acetate (PMA) were used as target cells in immunofluorescence microscopy (IF) examination with positive rates as 0.20% (2/965), 0.62% (6/965), 0.20% (2/965) and 0.51 (5/965) respectively. In addition to these, enzyme-linked immunosorbent assay (ELISA) gave a 2.59% (25/965) positive rate and particle agglutination (PA) test revealed a positive rate of 0.93% (9/965). The samples positive in IF were also positive in PA and those positive in PA were found positive in ELISA without exceptions. The 25 ELISA positive samples as well as 75 samples randomly chosen from the ELISA negative ones received Western blot (WB) analysis as a confirmation test. Only 3 of these 100 were considered positive in WB, giving a final positive rate of 0.31%, (3/965), and all of them were originally positive in both PA and ELISA. Particle agglutination test as the screening test and Western blot analysis as the confirming one were suggested to be a routine procedure for detecting anti-HTLV-I antibodies in blood banks through detailed comparison and discussion.     

珠海市无偿献血人群HIV感染状况分析

目的：分析近年来珠海市无偿献血人群HIV感染状况,为更好地开展无偿献血招募工作,确保血液安全提供科学依据。方法2009年1月至2012年12月经ELISA筛查珠海市无偿献血者标本93216份,其中HIV Ag/Ab阳性标本149份,经珠海市疾病预防控制中心采用免疫印迹法做确证试验,收集和整理确证为HIV感染者的基本信息,对HIV感染率和HIV感染人群特征进行分析。结果2009-2012年珠海市无偿献血者的HIV感染率为0.020%（19/93216）。HIV感染者中男性占94.74%（18/19）,明显高于女性的5.26%（1/19）;以未婚为主,占84.21%（16/19）;18～39岁年龄段高达94.74%（18/19）;外地户籍占78.95%（15/19）;高中或中专以下文化程度占73.98%（14/19）;职业呈散在分布;所有HIV感染者均通过性途径传播,其中异性传播占52.63%（10/19）,略高于同性传播的47.37%（9/19）。结论近几年珠海市无偿献血人群中HIV感染率与1998-2005年相比呈明显增长态势,应加强献血者血液安全宣传教育,建立高危献血者主动退出机制,从而有效遏制献血者HIV感染率上升的趋势。     

Laboratory and epidemiologic evaluation of an enzyme immunoassay for antibodies to HTLV-III

The enzyme immunoassays (EIAs) for antibody to human T-cell lymphotropic virus type III (HTLV-III) were rapidly adopted for screening donated blood and plasma. To evaluate the significance of a positive EIA reaction, test performance was examined in a blood bank screening program. Specimens were tested by EIA, Western blot assay, and HTLV-III/lymphadenopathy-associated virus (LAV) culture. The EIA was positive in 0.25% of 67 190 blood donations. Specimens were categorized and 57.3% had low (weak) reactivity, 12.7% had moderate reactivity, and 30.0% had high reactivity. Highly reactive specimens were strongly associated with a positive Western blot or culture (86.7%) in contrast to moderately and weakly reactive specimens (1.9%). Twenty-five of 29 donors interviewed with a highly reactive EIA had risk factors for HTLV-III/LAV infection. Risk factors were not identified for 74 of 75 interviewed donors with specimens of lower reactivity. The minimum calculated specificity was 99.82%. The use of the HTLV-III EIA has virtually eliminated the use of blood and plasma from HTLV-III/LAV infected donors.     

Status of HIV infection among the pregnant women attending in outpatient department

Human immunodeficiency virus (HIV) infection has been spreading rapidly in the developing countries and vertical transmission also taking place. This study has been done to find out the prevalence of HIV infection among the pregnant women, so that necessity of routine screening test can be identified. It is a cross sectional study. Five hundred two pregnant women were included. Three ml venous blood was taken and then HIV screening test was done by ELISA method. All reactive tests were confirmed by Western blot antibody testing. The positive cases were followed up and necessary treatment was given. Delivery was conducted in this hospital. Baby's blood was tested to see vertical transmission after 18 months. Most of the subject were educated housewife, mean age was 25 years. Six (6%) husband was overseas service holder, 12% were smoker and 1.6% had drug addiction. Eight (8%) subject had previous history of blood transfusion and 49% subject or her husband had history of surgery or got parental therapy. 2% subject gave the history of familial disharmony and 2% had multiple sex partners. HIV infection was found in 2 patients (0.4%). Both of them got infection from their husband. One husband was over seas service holder and another one was injecting drug user. For the prevention of spread, reduction of vertical transmission and providing early management to the positive patient all pregnant women should be screened for HIV routinely.     

HIV(1+2)抗体/P24抗原联合法与胶体硒法在临床检测HIV中的应用研究

目的比较第4代酶联免疫吸附测定(ELISA)[HIV(1+2)抗体与P24抗原联合检测]和胶体硒法在临床检测HIV中的特点。方法分别用第4代ELISA检测试剂和胶体硒试剂检测HIV抗体,初筛阳性样本送重庆市疾病预防控制中心进行Western blot确证试验。结果第4代ELISA试剂检测、胶体硒检测及Western blot检测HIV的阳性率分别为0.34%、0.29%及0.27%。第4代ELISA的HIV漏检率(1.3%)低于胶体硒法(4.9%),而其检测HIV的假阳性率(0.03%)高于胶体硒试剂(0.01%)。结论第4代ELISA和胶体硒法联合应用可提高HIV检测的准确性。     

两种检测梅毒螺旋体抗体方法的比较

目的:比较ELISA TP-IgG和快速血浆反应素试验(rap id p lasm a reagin c irc le card test,RPR)梅毒检测试剂的敏感性和特异性。方法:采用ELISA TP-IgG和RPR 2种试剂同时对56份临床疑似标本进行检测,结果阳性者采用梅毒螺旋体特异性抗体乳胶凝集试验(Toreponem a pallidum latex immuno assay,TPLA)方法进行验证。结果:ELISA TP-IgG检测率高于RPR,且与TPLA确证实验完全吻合。结论:ELISA TP方法在敏感性和特异性方面均好于RPR方法,是临床检测梅毒感染和筛选献血员的首选方法。     

Risk of HIV infection from blood transfusion in Montreal

OBJECTIVES: To determine the incidence (including associated donor characteristics and time trends) of HIV infection among repeat blood donors and to estimate the risk of HIV transmission from blood transfusion in Montreal and in Canada as a whole. DESIGN: Retrospective cohort analysis. SETTING: Montreal Centre Blood Transfusion Service. PARTICIPANTS: People who donated blood at least twice after Nov. 1, 1985, and at least once from Apr. 1, 1989, to Mar. 31, 1993. INTERVENTION: Blood was screened for HIV by enzyme-linked immunosorbent assay and results were confirmed by Western blot analysis. OUTCOME MEASURES: Incidence density (the incidence rate per person-time) of HIV infection among repeat blood donors by sex, age group and region of residence, and incidence density and risk among first-time donors and for Canada as whole. RESULTS: There were 200,196 eligible donors and 432,631 person-years (PY) of observation. From 1989 to 1993, there were 18 HIV seroconversions among repeat donors. The crude incidence density was 3.3 per 100,000 PY (95% confidence interval [CI] 1.8 to 5.4 per 100,000 PY); it was 4.9 per 100,000 PY among men and 0.61 per 100,000 PY among women. Age-specific incidence per 100,000 PY was 2.5 among those 12-29 years of age, 5.1 among those 30-49, 2.9 among those 40-49, and 1.4 among those 50 and older. Based on an estimated mean "window period" (from when a donor's blood is capable of transmitting HIV until detectable antibody appears) of 25 days, the current risk of HIV infection from repeat donors in the window period is estimated at 1 in 440,000. Inclusion of blood units from first-time donors produces an overall risk of 1 in 390,000 (95% CI 1 in 250,000 to 655,000). The estimated risk per blood unit in Canada as a whole is 1 in 913000 (95% CI 1 in 507,000 to 2,050,000). CONCLUSIONS: This "sentinel" population of repeat blood donors is subject to important trends in HIV spread. Therefore, estimating the incidence density of HIV infection in repeat donors provides insight into the epidemiologic characteristics of HIV infection at minimal expense. As a result of measures to improve blood safety, including HIV testing, the incidence of HIV infection among blood donors in Canada is low and the risk of HIV transmission from transfusion is extremely small, although not zero.     

湖北省仙桃市无偿献血血液标本检测情况分析

目的分析仙桃市无偿献血血液标本检测情况,探讨血液标本不合格因素及输血相关病原体感染的危险性,为临床安全用血提供技术支持。方法对仙桃市血站2006年1月～2010年12月31602名献血人员资料进行分析,比较不同性别、不同年龄献血者血液检测不合格率。结果无偿献血者血液总标本数31602份,检测合格标本数30330份,检测合格率为95．98％;检测不合格标本数1272份,检测不合格率为4．02％。其中ALT阳性检测不合格率2．13％;HBsAg阳性检测不合格率1．02％;抗-HCV阳性检测不合格率0．35％;SYP阳性检测不合格率0．38％;抗-HIV阳性检测不合格率0．15％。结论了解和掌握无偿献血群体、制定符合临床用血规律的采供血计划十分必要,而实行血液集中检测、严格筛查经血液感染性疾病直接关系到供血者的身体健康和受血者的安全,是提高临床安全用血的关键。     

应用ROC曲线评价耐甲氧西林葡萄球菌的检测方法

目的：通过对耐甲氧西林葡萄球菌（MRS）的常用检测方法及实验条件进行评价，选择特异性和敏感性较好的方法和理想的实验条件。方法：以PCR法检测葡萄球菌的mecA基因为“金标准”，比较PBP2a胶乳凝集试验法、头孢西丁（FOX）琼脂筛选法、苯唑西林（OXA）琼脂稀释法（MIC）、FOX纸片扩散法、OXA琼脂筛选法、OXA纸片扩散法检测MRS的敏感性和特异性。同时应用ROC曲线对实验方法及不同的实验条件进行评价。结果：PCR法共检出79株mecA基因阳性菌株，阳性率为73．8％。以PCR法为“金标准”，上述6种方法的ROC曲线下面积分别为0．994，0．964，0．955，0．946，0．932，0．862。结论：选择最佳实验条件，用两种表型检测方法作平行检测，对可疑结果用PBP2a胶乳凝集试验或PCR法确诊。     

唐山市无偿献血人群HIV的感染及人群特征分析

目的了解唐山市无偿献血人群抗-HIV感染情况及人群特征,为HIV预防及完善无偿献血招募工作提供参考。方法回顾分析2010年1月—2015年12月唐山市无偿献血人群抗-HIV筛查及确证情况,对HIV感染者流行病学资料进行统计学分析。血样HIV抗体筛查检测采用酶联免疫吸附法(ELISA),呈阳性的血样采用Western蛋白免疫印迹(WB)法进行确证检测。结果 2010年1月—2015年12月唐山市无偿献血人群HIV感染率为1.177/万(62/526 622),年龄以31~40岁为主,男性感染率高于女性,献血首次者感染率高于≥2次者,初中及以下学历者感染率明显高于高中、大专及以上学历者。62例抗-HIV阳性血液标本的WB带型中,以gpl60、gpl20、gp41、p66、p51、p31、p24条带为主,出现率均在90%以上。以合并TP感染的最多,占13.75%(11/62)。结论近年来唐山市HIV阳性率有所增加,不同人群HIV阳性率明显不同,以文化程度低的中青年男性为主,应加强献血前的健康询问和献血者的自我排查,建立固定无偿献血队伍,以保证血液质量安全。     

Early Diagnosis of Human Immunodeficiency Virus Infection by p24 Antigen Detection

p24 antigen was estimated in human immunodeficiency virus (HIV) sero-negative individuals attending various sexually transmitted diseases (STD) clinics and also in sero-negative voluntary blood donors. A total of 300 STD cases and 500 voluntary blood donors, who also acted as controls, were included in this study. Antibody to HIV was detected by ELISA and was confirmed by western blot. In sero-negative individuals, p24 antigen detection was carried out by standard assay and immune-complex dissociation assay (ICD assay) using ELISA method and confirmation was done by neutralisation assay. In voluntary blood donors, 4 (0.8%) individuals were found to be HIV positive and no sero-negative individual was positive for p24 antigen. 41 out of 300 patients attending STD clinics were found to be positive for HIV and in 259 sero-negative patients, p24 antigen was detected in 6 (2.3%) cases by ICD assay whereas only 4 cases were detected by standard assay. By estimating p24 antigen an additional 2.3% HIV positive cases that were in window period were detected. Further, an ICD assay improves the detection of p24 positive individuals.Key Words: ICD assay, p24 antigen, STD, Window period     

三种初筛方法检测HIV抗体的结果比较及评估

目的比较酶联免疫吸附试验(ELISA)、明胶颗粒凝集试验(PA)、胶体硒免疫层析法(ICA)检测人类免疫缺陷病毒抗体的结果,了解这三种方法的优劣,探讨临床实验室初筛诊断HIV方法的灵敏性和准确性。方法用卫生部HIV质控血清和免疫印迹法(WB)确认的HIV抗体阳性标本和阴性标本,分别用ELISA法、PA法及ICA法检测;用免疫印迹法确认的HIV阳性的标本作倍比稀释后,再分别用PA法、ELISA法及ICA法检测。结果80例经免疫印迹法确认的HIV阳性患者,ELISA法、PA法、ICA法的检出符合率分别为100%、98.8%、97.5%;经稀释法检测,ELISA法较PA法和ICA法敏感,其检测的准确性分别为97.5%、97.5%、92.5%。结论筛查HIV抗体方法最好选用ELISA法或PA法,以防漏检。     

三种检测抗链球菌溶血素O方法的比较

目的对三种检测抗链球菌溶血素O(ASO)的方法进行比较。方法同时用自动化散射比浊法、乳胶凝集试验和溶血抑制法检测120例临床患者的血清ASO。结果不同方法检测ASO增高率,溶血抑制法为44.17%(53/120),比浊法为40.83%(49/120),乳胶凝集法为34.16%(41/120),三法检测结果呈平行关系(r=0.988～0.997)。ASO水平较高(>1000U/ml)或较低水平增高时,乳胶法和溶血抑制法易有误差。结论比浊法检测ASO敏感性好,结果重复性好,是检测ASO的优选方法。     

Laboratory strategic defense initiatives against transmission of human immune deficiency virus in blood and blood products

Serological methods based on enzyme linked immunosorbent assay (ELISA) and Western blot tests for detecting the presence of antibodies against the human immune deficiency virus are the standard techniques for identifying infected blood donors. However, these tests could not detect infected seronegative donors who were in the window period at the time of donation. Such donors can be identified by more elaborate methods including antigen detecting ELISA and polymerase chain reaction, which can detect viral antigens and nucleic acids in infected donor blood even in window period. In addition, the process of donor selection whereby individuals who were at high risk for HIV infections were excluded from the donor panel had substantially reduced the risk of window period donation. Furthermore, in order to ensure greater safety, transfusion centers nowadays undertake additional measures in the form of virucidal techniques such as the use of heat, detergents and photochemical agents to treat blood and blood products. Despite all of these measures, a risk-free transfusion was not practically achievable. However, risk-free transfusion is now possible with the introduction of recombinant blood products, the use of which is severely limited by their cost. Nonetheless, a risk-free transfusion is still achievable at a relatively little cost by transfusing suitably eligible patients with their own blood through the autologous blood transfusion program. Antibody testing is virtually the only method currently available in Nigerian blood banks. There is the need to reactivate and expand the scope of our National Blood Transfusion Service in order to make our blood and products safer.