Seroprevalence of transfusion transmissible infections (TTI), in first time blood donors in Abeokuta,Nigeria

BackgroundTransfusion transmissible infections, such as HIV, HBV, HCV and syphilis are on the rise and pose a threat to blood safety.ObjectiveTo determine prevalence and demographic profiles of TTI''s among first time blood donors in Abeokuta, Nigeria.MethodsThe study was conducted between February to November 2013; 130 first time blood donors were tested for the presence of HIV, HBsAg, HCV antibodies and Treponema palidium antibodies using EIA based rapid immunochromatographic kits. Data analysis was done using SPSS with a level of significance of p<0.05.ResultsPrevalence rates to HIV, HBsAg, HCV antibody, were 6.2% (n=8), 10% (n=13) and 1.5% (n=2), there was 0% prevalence to Treponema palidium antibodies. Group specific prevalence rates revealed that educational status was associated with HBsAg positivity (p = 0.028), donors with a history of previous blood transfusion was also statistically associated with HIV sero-reactivity (p = 0.013).ConclusionsHigh levels of HBsAg and HIV were observed, there is need to revise the donor testing algorithm in Nigeria in line with the prevalence of TTI''s. We also advocate that a National surveillance system for TTI''s be established through our National blood transfusion service (NBTS) program, a second serological test is also suggested to reduce the risk of occult HBV infection in Nigeria.     

AIDS and transfusion practice.

AIDS has reached epidemic proportions in many regions of the world and is rapidly spreading. Among other modes of transmission, HIV may be transmitted through the transfusion of blood and blood products. The potential for such transmission warrants and has sparked the screening of donor blood and blood products for antibodies to HIV. Safe practices for transfusion services would include promoting voluntary donors, motivating and recruiting donors from low-risk groups, encouraging high-risk donors to exclude themselves from the donor pool, obtaining trained donor pool, obtaining trained donor recruiters, and linking programs with AIDS education campaigns. Further, the Blood Safety Initiative of the World Health Organization stresses the importance of transfusing blood and its products only when required to prevent mortality or major morbidity. 4082 of 589,824 individuals screened in India over the period 1985-90 were identified as HIV-seropositive. Of these individuals, 2068 were heterosexually promiscuous, 6 were homosexual, 600 sold blood professionally, 64 were recipients of blood and blood products, and 861 were IV drug users. To help control the spread of HIV, known seropositive donors should be told of their status and permanently barred from giving blood. Since HIV seroprevalence in samples of professional blood sellers has been shown to be comparatively higher than that among voluntary donors, the professional sale of blood should be discouraged in favor of increased the voluntary supplies. ELISA and Western blot tests are used to screen blood for antibodies to HIV, while serum neopterin estimation is also helpful. Viricidal techniques for blood parasites plasma include the application of dry heat of 600 degrees Celsius for 24 hours, heptane, or treatment with solvent-detergents. Viricidal techniques for cellular components of blood remain experimental.     

Risk of HIV-1 or 2 infection associated with transfusion in Benin

OBJECTIVE: To evaluate the residual risk of transmission of HIV 1/2 infection through transfusion of seronegative blood. METHODS: This study was carried out between January and July 2000. It was based on eight hundred and twenty-one (821) blood donors screened negative for HIV antibodies by ELISA using Vironostika Uni-form II plus 0 (Organon Teknika). 675 (82.2%) were men and 146 (17.8%) women all aged between 18 and 56 years with a mean age of 25.5 +/- 7.8 years. Serum aliquots of these seronegative blood donor were frozen and further tested with two tests: Enzymun-Test HIV Combi (Roche Immunodiagnostics) and Murex HIV Antigen Mab (Murex). RESULTS: Twenty six out of 821 (3.2%) seronegative specimens were repeatedly reactive for Enzymun-test. All were tested negative once again for anti-HIV antibodies by ELISA using Vironostika Uni-form II/plus 0. Out of these 26, only one was repeatedly reactive for Murex. For further analysis of the 25 donors tested negative for Murex, only 9 came back for another donation five months later. All of them were tested negative for anti-HIV antibodies by ELISA (Vironostika). CONCLUSION: Our study shows the existence of residual risk of transmission of HIV1/2 infection associated with transfusion of seronegative blood donors. This risk was higher in our countries compared with industrialised nations. Therefore implementing strategies should be a priority to avoid the residual risk and improve blood transfusion safety.     

河北省输血后艾滋病病毒感染暴发的追踪监测

目的 研究河北省输血后艾滋病暴发流行特征及家庭传播情况.方法 在全省范围内,通过艾滋病监测网络和输血感染重点区域的疫情普查,对在河北省某市发现的输血感染艾滋病及其导致的家庭传播进行分析,用ELISA法初筛HIV抗体,用Western-blot进行确认试验,用套式PCR进行HIV env基因扩增.对扩增产物进行亚型分析.结果 发现在河北省某市医疗机构输血后HIV感染173例,占全省输血感染的68.7%(173/252),其中医院发现89例,疾病预防控制中心发现84例.家庭传播率为32.0%(49/153),夫妻家庭传播率为17.0%(26/153),母婴家庭传播率为32.7%(32/98).输血感染者以青壮年为主,女性多于男性,输血原因以怀孕分娩及妇女病为主,其次是外伤手术.输血时间为1990年至1999年,高峰为1995年;发现时间为1999年至2009年,高峰为2003年,输血后感染者主要分布于该市境内的某康泰医院和某煤矿医院,分别占45.1%(78/173)和42.2%(73/173).病原型别为HIV-1 B'亚型.结论 该市基层医疗机构由于不对有偿供血者筛查HIV抗体,导致了输血者HIV感染的暴发.     

Evaluation of a simultaneous HIV antigen and antibody detection test in Korean population

Current diagnosis of human immunodeficiency virus (HIV) infection relies on the detection of anti-HIV antibodies by enzyme-linked immunosorbent assay (ELISA). Recently, kits detecting both p24 antigenemia and anti-HIV/anti-HIV2 antibodies have been developed. Thus, it is necessary to compare those kits developed as such. The aim of this study was to evaluate the diagnostic efficiency of a simultaneous detection test of p24 antigen and anti-HIV1/2 antibodies in a low prevalence area. Eight hundred and four randomly selected sera proven negative for HIV infection and 110 sera from 54 patients diagnosed as HIV infected, obtained between 1999 and 2000, were used for this study. One commercial lot of panels composed of consecutive sera obtained from known HIV-infected patient was included. Anti-HIV1/2 antibodies were detected by two different commercial ELISA kits, one from Korean and the other from German manufacturer. P24 antigen test was performed by ELISA. The simultaneous HIV antigen and antibody detection test was carried out. In the meantime, HIV RNA PCR and anti-HIV and anti-HIV2 western blot assays were also performed to confirm the test results in cases the test results didn't agree. The simultaneous detection kit showed 100% sensitivity and 99.6% specificity. Furthermore, the test displayed the possibility of earlier diagnosis than conventional anti-HIV1/2 ELISA with the results obtained from a group of consecutive panel sera infected with HIV. From these results, we concluded that the simultaneous HIV antigen and antibody detection test can be applied as a substitute clinical screening test in the place of conventional anti-HIV1/2 ELISA, and there is the probable benefit of early diagnosis.     

Evaluation of FDA licensed HIV assays using plasma from Cameroonian blood donors

Several diagnostic assays for the detection of HIV infection have been approved and licensed by the FDA for blood donor screening. However, the performance of these assays is unknown when testing genetically divergent blood specimens. To evaluate the performance of these assays with diverse HIV strains, we chose to study specimens collected from blood donors in Cameroon where genetic diversity and recombinant variants are prevalent. In this study, we tested 240 human plasma specimens collected from two blood centers in Cameroon. These samples were screened initially in Cameroon for antibody to HIV using a rapid assay. We also performed sequencing to determine subtype. Our evaluation has demonstrated that HIV infection in most HIV plasma samples could be detected by most of the US FDA licensed diagnostic assays. With the exception of a few specimens, HIV-1 p24 antigen was not detected in any of the samples. In addition, some nucleic acid tests (NAT) assays were not able to detect a few serologic reactive samples and all new variants including some CRF02_AG variants.     

Isolated anti-HBc-IgM antibody among blood donors in the semi-arid region of Nigeria

Laboratory screening for the diagnosis of hepatitis B virus (HBV) infection in blood donors currently consists of testing for hepatitis B surface (HBsAg) antigen alone. The prevalence of isolated anti-HBc-IgM is not yet known in the semi arid region of Nigeria. The major objective of this study was to determine the sero-prevalence of antibody to hepatitis B core antigen (anti-HBc-IgM) and other infectious agent markers; HBsAg, HCV, HIV and Syphilis among blood donors in the North Eastern region of Nigeria. In a cross sectional study from October 2010 to January 2011, 266 blood donors were tested for the infectious disease markers using standard ELISA procedures as contained in the manufacturer's standard operating procedures. The prevalence of various infectious markers obtained were as follows: HBsAg (8.6%); anti-HCV (1.5%); HIV (2.6%) and anti-HBc-IgM(18.4%). There was a zero percent prevalence of Syphilis in this donor population. The proportion of isolated anti- HBc-IgM antibody obtained was 18.1%. Performance indices for HBsAg were as follows: Sensitivity (10.2%), specificity (91.7%), positive predictive value (PPV) (21.7%), Negative predictive value (81.9%), and efficiency (76.7%). The prevalence of anti-HBc- IgM antibody was higher among first time blood donors (21.4%), and in some ethnic groups. There is a high prevalence of isolated anti-HBc-IgM antibody among blood donors in Maiduguri. The sensitivity of HBsAg was found to be very low and as such many recent HBV infections may be missed during pre-transfusion screening. The use of anti-HBc-IgM screening as a mandatory pre-transfusion screening test is hereby advocated.     

多种单抗联合检测HIV抗原

目的 建立多种单抗联合早期检测HIV抗原的夹心ELISA方法.方法 以SAS盐析沉淀法和亲和层析法纯化抗HIV-1 p24、gp41、gp120及抗HIV-2 gp36的腹水型单克隆抗体(McAb),用高碘酸钠法将纯化的McAb以HRP进行标记.建立针对单个抗原的双抗体夹心ELISA法,对其灵敏度及特异性进行检测.将筛选得到的4株捕获McAb按比例混合作为捕获抗体,4株酶标McAb按比例混合作为检测抗体,建立多种单抗联合检测HIV抗原的夹心ELISA方法,检测混合HIV抗原.结果 按确定的最优反应条件建立的多种McAb联合夹心ELISA方法,检测到的最高稀释度的HIV混合抗原中各抗原的终浓度分别为:重组HIV-1 p24:0.625 pg/ml,gp41:6.25 ng/ml,gp120:6.25 ng/ml;HIV-2 gp36:9.25 ng/ml.结论 建立了具有高度敏感性的鸡尾酒式多种单抗联合检测HIV抗原的夹心ELISA法,为早期榆测HIV抗原提供了新的思路,为后续的研究奠定了一定基础.     

多种单抗联合检测HIV抗原

目的 建立多种单抗联合早期检测HIV抗原的夹心ELISA方法.方法 以SAS盐析沉淀法和亲和层析法纯化抗HIV-1 p24、gp41、gp120及抗HIV-2 gp36的腹水型单克隆抗体(McAb),用高碘酸钠法将纯化的McAb以HRP进行标记.建立针对单个抗原的双抗体夹心ELISA法,对其灵敏度及特异性进行检测.将筛选得到的4株捕获McAb按比例混合作为捕获抗体,4株酶标McAb按比例混合作为检测抗体,建立多种单抗联合检测HIV抗原的夹心ELISA方法,检测混合HIV抗原.结果 按确定的最优反应条件建立的多种McAb联合夹心ELISA方法,检测到的最高稀释度的HIV混合抗原中各抗原的终浓度分别为:重组HIV-1 p24:0.625 pg/ml,gp41:6.25 ng/ml,gp120:6.25 ng/ml;HIV-2 gp36:9.25 ng/ml.结论 建立了具有高度敏感性的鸡尾酒式多种单抗联合检测HIV抗原的夹心ELISA法,为早期榆测HIV抗原提供了新的思路,为后续的研究奠定了一定基础.     

Shortening of the diagnostic window with a new combined HIV p24 antigen and anti-HIV-1/2/O screening test

Because antibodies to the human immunodeficiency virus (HIV) are absent in the very early phase of HIV infection, there remains a slight residual risk for HIV transmission by blood donations by viremic but antibody negative donations. To shorten the diagnostic window between infection and the detection of antibodies, Enzygnost® HIV Integral (Dade Behring, Germany) was developed. With this new test, HIV p24 antigen and HIV antibodies can be detected simultaneously in a single test. In a multicenter study the new screening assay has been compared with various tests that detect only HIV antibodies or HIV p24 antigen and with assays which permit a simultaneous detection of HIV antigen and HIV antibodies. The new assay showed 100% sensitivity for the detection of antibodies to HIV-1, groups M (n=1102) and O (n=55), and HIV-2 (n=289). In 23 out of 52 seroconversion panels, seroconversion was detected 2–18 days earlier with the new combined antigen/antibody test compared to single antibody tests. All samples from a viral load panel (n=451), all samples containing p24 antigen (n=302), and all but one of the cell culture supernatants (n=38) infected with various HIV-1 subtypes or HIV-2 were identified reliably by the new test. The specificity of the assay for 4002 unselected blood donors was 99.78% initially and 99.80% after retesting. Potentially interfering factors had no systematic influence on specificity. By testing for p24 antigen, which is present prior to the onset of antibody production in some cases of recent HIV infection, the new assay reduces the diagnostic window as compared to third generation screening assays, thus permitting an earlier diagnosis of HIV infection.     

HIV transmissions from a window-period platelet donation

Recently, blood centers began investigational testing for HIV RNA by pooled nucleic acid testing (NAT). A 35-year-old frequent platelet donor tested HIV p24 antigen positive, antibody negative before implementation of NAT. He made 2 platelet donations (day -4 and -11) immediately before testing positive for HIV. The donor's HIV seroconversion was monitored, and stored samples were tested retrospectively for HIV RNA. Platelet recipients were tested for HIV infection. The day -4 sample tested positive for HIV RNA by pooled and individual sample NAT. The day -11 sample tested negative for HIV RNA by both NAT tests. The 2 recipients of the day -4 platelets tested HIV RNA and p24 antigen positive. The recipient of the day -11 platelets could not be tested because he had died. HIV NAT would have prevented transmission of HIV had it been available at the time of this donor's HIV seroconversion.     

Failure and success of HIV tests for the prevention of HIV-1 transmission by blood and tissue donations

French blood banks recently implemented nucleic acid testing (NAT) of all blood donations to reduce the risk of HIV transmission during the pre-seroconversion period. For tissue donation, HIV infection screening relies on HIV p24 antigen and anti-HIV-1 and 2 antibody detection. In this report, two related cases of infectious donations are described from a cornea donor during the preseroconversion window who was infected by an HIV antibody and NAT negative blood donor. After investigation, the blood donor was found to be herself in the preseroconversion window. Two months after donation, she was found to be HIV positive. The residual risk of HIV infectious blood donations since NAT has been introduced is estimated to be lower than one out of 2.5 millions. Individual NAT instead of minipool testing would not increase significantly the blood transfusion safety. In contrast, introduction of NAT should be considered to increase tissue donation safety as soon as such screening will be possible technically.     

An analysis of blood sera by the immunoblot method using natural and recombinant antigens of the human immunodeficiency virus

A recombinant antigen produced in CV-I cells infected with vaccinia virus vC5 carrying the HIV-I gag gene was used to test sera. This antigen (rp50) reacted with 95 serum specimens shown to have anticore antibodies by immunoblot based on natural HIV antigens. Six sera from blood donors positive in ELISA contained antibodies to p17, p24, or p55 by natural antigen-based blot. All these sera did not react with rp50. These patients did not belong to any known risk groups and showed no dynamics in the immunoblot pattern. We consider the reaction of their serum samples as false positive. We believe that the recombinant antigen rp50 may be used for verification of positive ELISA results.     

Prevalence and prevalence trends of transfusion transmissible infections among blood donors at four chinese regional blood centers between 2000 and 2010

ABSTRACT: BACKGROUND: In China, high prevalence of HBV and HCV parallels with the growing epidemic of syphilis and HIV in the general population poses a great threat to blood safety. This study investigated the prevalence of serologic markers for transfusion transmissible infections (TTIs) among four Chinese blood centers. METHODS: We examined whole blood donations collected from January 2000 through December 2010 at four Chinese blood centers. Post-donation testing of TTIs (HIV, HBV, HCV and syphilis) were conducted using two different enzyme-linked immunosorbent assay kits for each seromarker. The prevalence of serologic markers for TTIs (%) was calculated and additional analysis was conducted to examine donor characteristics associated with positive TTIs serology. RESULTS: Of the 4,366,283 donations, 60% were from first-time donors and 40% were from repeated donors. The overall prevalence of HIV, HBsAg, HCV and syphilis was 0.08%, 0.86%, 0.51% and 0.47%, respectively. The prevalence profile of TTIs varied among different blood centers and appeared at relatively high levels. Overall, the prevalence of HBsAg and HCV demonstrated a decline trend among four blood centers, while the prevalence of HIV and syphilis displayed three different trends: constantly steady, continually increasing and declining among different centers. CONCLUSIONS: This study reflects the risk of TTIs has been greatly reduced in China, but blood transfusion remains an ongoing risk factor for the spread of blood-borne infections, and further work and improvements are needed to strengthen both safety and availability of blood in China.     

Problems and solutions associated with transmission of HIV via donated blood in Tanzania

Donor-blood from populations with high prevalence of HIV infection carry the risk of transmitting HIV to a significant proportion of recipients. This paper presents a review of experience gained in efforts towards ensuring availability of HIV-free blood for transfusion in tropical Africa, with emphasis on Tanzania. The effect of introducing a countrywide screening programme in averting possible HIV transmission, and the main problems of controlling transfusion associated with HIV infection have been identified. Lack of organized blood transfusion services in tropical Africa, widespread occurrence of transfusion associated diseases, shortage of skilled staff, unreliable electricity supply and communication networks, and absence of a 100% sensitive antibody test for HIV are among the problems encountered in attempts to provide safe blood. To reduce transfusion associated HIV infection, efforts should be directed to; reduction of unnecessary blood transfusions; exclusion of HIV high-risk donors, provision of affordable, rapid and reliable HIV antibody test kits, using heat-treated and HIV-free blood products for treatment of bleeding disorders; and establishment of separate facilities fur voluntary HIV testing and counselling form blood donation centers. With continuing successes globally in the development of simple, rapid, affordable and highly sensitive HIV antibody tests, the control of HIV transmission through blood transfusion should be feasible in all areas of Africa.     

Site-directed ELISA with synthetic peptides representing the HIV transmembrane glycoprotein

Two partially overlapping 19 and 22 amino acids long peptides representing a highly immunogenic site of the transmembranous glycoprotein (gp41) of human immunodeficiency virus (HIV) were used as antigen in ELISA tests. The results of antibody determination with this assay were compared with those of three or more conventional ELISAs and Western blot (WB) tests and radioimmunoprecipitation assay. Twenty-six sera from patients with AIDS or LAS and from asymptomatic carriers of HIV infection all showed a pronounced reaction in the peptide ELISA as well as positive results with other tests. In contrast, 27 sera from laboratory workers and blood donors were negative by all tests. A group of 39 blood donor sera, which had shown false positive or ambiguous results in the ELISAs and sometimes in WB tests employed for confirmation, also were negative in all cases with the peptide ELISA. Consecutive samples collected from individuals with primary HIV infection were also analyzed. In 6 out of 9 cases, the peptide ELISA revealed an antibody response within one month after onset of clinical symptoms and sensitivity for antibody detection equaled that of other ELISA tests. Eight sera from five West African persons infected with HIV-related viruses did not react in the peptide ELISA, reflecting differences in properties of the envelope components. The peptide ELISA used in this study appears to represent a simple technique employing chemically synthesized antigen for accurate and sensitive estimation of antibodies to the HIV group of nontransforming human retroviruses.     

New Lineal Immunoenzymatic Assay for Simultaneous Detection of p24 Antigen and HIV Antibodies

 The aim of this study was to evaluate a new lineal immunoenzymatic assay for the simultaneous detection of HIV-1/HIV-2 antibodies and p24 antigen. A total of 320 serum samples were obtained from individuals infected by HIV (HIV 1, n=183; HIV 2, n=2), individuals with risk factors for HIV infection (n=49), recipients of multiple transfusions (n=40), and blood donors (n=46). The Western blot for detection of HIV antibodies and an enzyme immunoassay for detection of p24 antigen, both established techniques, were used for direct comparison. In cases of recent infection, p24 antigen was generally detected at the same time by the lineal test and the established assay. The p24 antigen sensitivity was about 200 pg of HIV antigen per milliliter. The results seem to indicate that the new test could be used with sufficient reliability for screening biological samples (sensitivity, 99.5%; specificity, 94.8%). Use of the lineal immunoenzymatic assay may shorten the amount of time needed to diagnose acute infection with HIV to approximately 2 weeks.     

High seropositivity of IgG and IgM antibodies against cytomegalovirus (CMV) among HIV-1 seropositive patients in Ilorin,Nigeria

BackgroundHuman immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) is a major public health problem in sub-saharan Africa. Cytomegalovirus (CMV) has been reported to enhance HIV replication and accelerate the progression of HIV infection to AIDS.ObjectiveThis study reports on the high seropositivity of immunoglobulin (Ig) G and M antibodies against CMV and the risk factors for CMV infection among HIV/AIDS patients in Ilorin, Nigeria.MethodA total of 180 consented HIV-1 seropositive patients (age-range 16–56 years; 108 females and 72 males) were consecutively recruited. Socio-demographic/behavioral data and 5 ml blood samples were collected from each patient. Plasma of each sample was assayed for anti-CMV IgG/IgM using a CMV IgG and IgM Enzyme Linked ImmunoSorbent Assay (ELISA) kit.ResultsTwenty (11.1%) of the 180 HIV-1 seropositive subjects were positive for anti-CMV IgM antibody while 169(93.9%) were positive for anti-CMV IgG antibody. Age, marital status, number of sexual partners, CD4 cells counts and previous history of blood transfusion were the main correlates of CMV seropositivity among these patients. However, occupation, sex, highly active antiretroviral therapy (HAART) were not statistically associated with CMV seropositivity in this study.ConclusionThis study has shown that greater percentages of HIV-1 seropositive patients had active CMV infection. It has further shown that CMV is hyperendemic in HIV-1 seropositive patients in Ilorin, Nigeria.     

Seroprevalence of HIV,HBV, HCV,and HTLV among Pregnant Women in Southwestern Nigeria

Sexually transmitted infections (STIs) are major public health challenge especially in developing countries. This study was designed to determine the prevalence of Hepatitis B virus (HBV), Hepatitis C Virus (HCV), Human immunodeficiency virus (HIV), and Human T-cell lymphotropic Virus type I (HTLV-I) among pregnant women attending antenatal clinic, in Ladoke Akintola University Teaching Hospital, Osogbo, and South-Western Nigeria. One hundred and eighty two randomly selected pregnant women were screened for HBsAg, anti-HCV, anti-HIV and HTLV-1 IgM antibodies using commercially available ELISA kit. Of the182 blood samples of pregnant women screened whose age ranged from 15–49 years, 13 (7.1%), 5 (2.7%), 9 (4.9%), and 44 (24.2%) were positive for HBsAg, anti-HCV, anti-HIV, and HTLV-1 IgM antibodies, respectively. The co-infection rate of 0.5% was obtained for HBV/HCV, HBV/HIV, HIV/HTLV-1, and HCV/HTLV-1 while 1.1% and 0% was recorded for HBV/HTLV-1 and HCV/HIV co-infections, respectively. Expected risk factors such as history of surgery, circumcision, tattooing and incision showed no significant association with any of the viral STIs (P > 0.05). This study shows that there is the need for a comprehensive screening of all pregnant women for HBsAg, anti-HCV, anti-HIV and HTLV-1 to prevent mother to child transmission of these viral infections and its attending consequences.     

Detection of early antibodies in human immunodeficiency virus infection by enzyme-linked immunosorbent assay, Western blot, and radioimmunoprecipitation.

A current concept of the serological response to human immunodeficiency virus (HIV) infection in humans is that antibodies to core antigens (p55, p24, and p15) are detectable earlier during initial stages of antibody production than antibodies against envelope antigens (gp160, gp120, and gp41). Comparative studies of Western blot (immunoblot), radioimmunoprecipitation assay (RIPA), and enzyme-linked immunosorbent assay (ELISA) during initial antibody production are limited to case reports and have not resolved the issue. Thirty of the 37 participants who are part of a prospective study had at least one specimen that was negative for anti-gp41 but had one or more other bands on Western blot. Twenty-seven of these 30 specimens were reactive for anti-gp120/160 in the RIPA. Of the same 30 specimens, kits from Bionetics identified 2 (7%), ElectroNucleonics 4 (13%), Abbott 13 (43%), Du Pont 25 (83%), and Genetic Systems 25 (83%). All participants had evidence of serological progression by Western blot, including a gp41 band, on subsequent visits; the ELISA kits of all manufacturers identified these later specimens with greater accuracy. These data show that the RIPA detects anti-envelope antibodies that may be not detectable by Western blot and that the production of anti-envelope antibodies approximately parallels the production of anti-core antibodies. The false-negative results by ELISA would permit transmission of HIV by blood transfusion from donors in early stages of infection. The sensitivity of licensed ELISA kits should be improved to identify antibody as soon as possible after infection.