HIV EIA Research Articles

P07.13 Detection oftreponema pallidumdna from whole blood and earlobe specimens in patients from two sti clinics in lima, peru

Background Prior studies have reported PCR detection of Treponema pallidum DNA from whole blood and earlobe scrapings. Factors affecting efficiency such as PCR target gene and clinical stage of syphilis have been studied. We aimed to determine other factors associated with detection of T.pallidum DNA from whole blood and earlobe samples. Methods Data were obtained from baseline samples collected for a prospective cohort study of 401 men who have sex with men (MSM) and transgender women (TW) in Lima, Peru. Participants were assessed for HIV using rapid HIV testing (Alere Determine, USA), a combined Antigen/Antibody HIV EIA, and Western blot confirmation (Genscreen ULTRA HIV Ag-Ab and Genetic Systems HIV-1 Western Blot, Bio Rad, USA). Syphilis infection was assessed with RPR (BD Macro-Vue, USA) and TPPA (Fujirebio, Japan). Whole blood samples and earlobe capillary blood was collected from patients with a positive RPR and TPPA. DNA extraction was performed using the QIAamp mini kit (Qiagen, Valencia, CA), and samples were then concentrated. Ujchowsing specific primers for the TpN47 gene, an aliquot of the DNA sample was amplified using conventional PCR for participants with high RPR titers (≥1:16). Positivity was determined by visual detection of PCR product on 1% agarose gel. Results 56 participants had RPR titer ≥1:16 (1:16(n = 18), 1:32(n = 16), 1:64(n = 17), 1:128(n = 3), and 1:256(n = 2)). A total of 7 (12.5%) participants had T.pallidum DNA detected from whole blood, and 6 (10.7%) from earlobe capillary blood (10 participants total). Of these 10 participants, 5 were HIV positive, and 5 were HIV negative. Conclusion Our relatively low efficiency of detection from both whole blood and earlobe samples suggest that neither HIV status nor high RPR titer (≥1:16) seem to predict high likelihood of DNA detection. Further study is ongoing to determine if these or other characteristics are associated with positive detection of T.pallidum DNA. Disclosure of interest statement The Picasso study is funded by a grant from the United States NIAID and was implemented by the Universidad Peruana Cayetano Heredia in collaboration with the University of California, Los Angeles. The molecular part of the study was implemented under the supervision of the University of Washington. No pharmaceutical grants were received during the development of this study.

English

First AIDS case was reported in 1986. In India, 71.4% of all HIV estimated to be women with an accompanying increase in vertical transmission & pediatric HIV(1).The HIV epidemic has penetrated into the general population(2). The transmission may occur late in pregnancy & during delivery(3) & through breast milk(4). AIMS: To find out the prevalence of HIV in pregnancy and its effect on perinatal outcome. METHODS: A prospective study was conducted in Loni Maharashtra during July 2001– June2003. All the women registered in the antenatal clinic were subjected to Rapid test :comb Aids – RSkit, HIV EIA Comb Test and CAPILLUS Test after counseling and written informed consent according to the PPTCT programme. Positive result of all three tests were taken as confirmed positive result. All Sero–positive women received tab Nevirapine 200 mg single dose in active phase of labour. Babies of all sero-positive women received syrup Nevirapine 2ml/kg body weight within 72 hrs of birth. Statistical analysis was done using chi-square test. RESULTS: The prevalence rate of HIV in present study was found to be 1.85%. The relationship of HIV seropositivity with preterm labour (16% VS 7% ,Z=1.97,P<0.05) was statistically significant. The difference in mean birth weight of HIV positive versus HIV negative women was 176 , which is significant statistically. CONCLUSION: The HIV prevalence in the present study was found to be 1.85% . Considering the low risk behavior & rural based study population, it appears to be quite high.We can conclude from this study that pregnant women are not at risk of adverse maternal & perinatal outcome. INTRODUCTION: First AIDS case was reported in 1986. In India, 71.4% of all HIV estimated to be women with an accompanying increase in vertical transmission & pediatric HIV (1).The HIV epidemic has penetrated into the general population (2). The transmission may occur late in pregnancy & during delivery (3) & through breast milk (4). AIMS: o To find out the prevalence of HIV in pregnancy. o To study the effect of HIV on perinatal outcome. o To provide comprehensive counselling support & to control the vertical transmission of HIV infection. METHODS: A prospective study was conducted at -Pravara Medical College, loni Maharashtra during July 2001– June2003.Counselling & written informed consent through prevention of parent to child transmission (PPTCT) programme was done. A sample of 2cc blood was collected in a plain bulb & subjected for HIV testing as per PPTCT protocol-

Correlation of Prospective and Cross-Sectional Measures of HIV Type 1 Incidence in a Higher-Risk Cohort in Ho Chi Minh City, Vietnam

The primary aim of this study was to estimate HIV incidence within a high-risk population in Ho Chi Minh City (HCMC), Vietnam using both cross-sectional and prospective methodologies. A secondary aim was to develop a local correction factor for the BED and avidity index incidence assays. The research study design consisted of three phases: (1) cross-sectional, (2) prospective, and (3) BED false recent (BED FR). A total of 1619 high-risk, sexually active individuals were enrolled in the cross-sectional phase and 355 of the opiate-negative, HIV-negative women were subsequently enrolled in the prospective phase. Four-hundred and three men and women with known HIV infection duration of greater than 12 months were enrolled in the BED FR phase. The HIV prevalence for all participants in the cross-sectional phase was 15.8%. HIV incidence in the cross-sectional group was estimated using the BED IgG capture assay and AxSYM avidity index assay for recent HIV infection and incidence within the prospective cohort was determined by observations of HIV seroconversion. HIV incidence in opiate-negative women was estimated using the BED assay to be 0.8% unadjusted and 0.5% after applying the locally derived BED false recent rate of 1.7%; no seroconversions were observed in the prospective cohort. We also screened the cross-sectional samples for evidence of acute infection using nucleic acid testing, 4th generation HIV EIA, and SMARTube coupled with Genscreen and Determine diagnostic tests; no confirmed acute infections were identified by any method. HIV incidence within this opiate-negative study population was low and incidence estimates from the two methods compared favorably with each other. Incidence estimates and false recent rates using the AxSYM assay were higher: AI FRR of 2.7% and adjusted incidence of 1.7% per year (95% CI, 0.6, 2.8). By comparison, both HIV prevalence and incidence estimates for the opiate-positive group were higher.

Towards targeted screening for acute HIV infections in British Columbia.

BackgroundOur objective was to describe the characteristics of acute and established HIV infections diagnosed in the Canadian province of British Columbia. Province-wide HIV testing and surveillance data were analyzed to inform recommendations for targeted use of screening algorithms to detect acute HIV infections.MethodsAcute HIV infection was defined as a confirmed reactive HIV p24 antigen test (or HIV nucleic acid test), a non-reactive or reactive HIV EIA screening test and a non-reactive or indeterminate Western Blot. Characteristics of unique individuals were identified from the British Columbia HIV/AIDS Surveillance System. Primary drug resistance and HIV subtypes were identified by analyzing HIV pol sequences from residual sera from newly infected individuals.ResultsFrom February 2006 to October 2008, 61 individuals met the acute HIV infection case definition, representing 6.2% of the 987 newly diagnosed HIV infections during the analysis period. Acute HIV infection cases were more likely to be men who have sex with men (crude OR 1.71; 95% CI 1.01-2.89], to have had a documented previous negative HIV test result (crude OR 2.89; 95% CI 1.52-5.51), and to have reported a reason for testing due to suspected seroconversion symptoms (crude OR 5.16; 95% CI 2.88-9.23). HIV subtypes and rates of transmitted drug resistance across all classes of drugs were similar in persons with both acute and established HIV infections.ConclusionsTargeted screening to detect acute HIV infection is a logical public health response to the HIV epidemic. Our findings suggest that acute HIV infection screening strategies, in our setting, are helpful for early diagnosis in men who have sex with men, in persons with seroconversion symptoms and in previously negative repeat testers.

Detection of Early Sero-Conversion HIV Infection Using the INSTI HIV-1 Antibody Point-of-Care Test

We compared the INSTITM HIV-1 Antibody Point-of-Care (POC) Test to laboratory-based tests for detection of early sero-conversion (i.e. acute) HIV infections. Fifty-three (53) individuals with early HIV infection, (i.e. 3rd generation anti-HIV EIA non-reactive or reactive, HIV-1 Western Blot non-reactive or indeterminate and HIV-1 p24 antigen reactive) were tested by INSTITM. The INSTITM test was reactive for 34/49 (sensitivity 69.4%; 95% confidence interval 54.6-81.8%) early-infected individuals whose laboratory-based 3rd generation HIV EIA test was reactive. Four (4) were non-reactive by both the laboratory-based EIA and INSTITM tests, but were p24 antigen reactive. The INSTITM POC test performs well compared with other POC tests for the detection of early sero-conversion HIV infection, but it may miss 20% to 30% of those detected by laboratory-based 3rd generation anti-HIV tests. Both POC and laboratory-based anti-HIV tests will fail to detect a proportion of infected individuals in the first weeks after infection.

PV-9 Validation of two commercial 4th generation HIV EIA assays for the detection of HIV in oral fluid samples using the oracol collection device

PV-9 Validation of two commercial 4th generation HIV EIA assays for the detection of HIV in oral fluid samples using the oracol collection device

Prevalence of indeterminate human immunodeficiency virus western blot results in pregnant women attended at a public hospital in Presidente Prudente, Brazil

The AIDS epidemic is spreading rapidly among women worldwide, offering increasing opportunities for vertical transmission of HIV. In Brazil, the prevalence of HIV infection among pregnant women is less than 1%. Therefore, the positive predictive value of an HIV EIA test tends to be lower than the more frequent indeterminate Western blot result. Pregnant women receiving antenatal care, from 2000 to 2004, at a public secondary hospital in the city of Presidente Prudente, São Paulo, Brazil, were systematically screened for HIV by means of two distinct EIA tests, in order to determine the prevalence of indeterminate Western blot results among pregnant women showing discordance in both HIV EIA tests and indirect immunofluorescence assay. Confirmatory indirect immunofluorescence was performed on material for all women with positive results in both EIA tests. Whenever there were positive results in EIA and IIA, the applicant was retested by the initial screening assay. Only those not showing concordance in results in EIA and IAA had a Western blot performed. The viral load was measured in pregnant women with positive or indeterminate Western blot results. Out of 9,786 sera, 105 (1.0%) were positive in the two HIV EIA screening tests, confirmed by indirect immunofluorescence. Among these women, Western blot was interpreted as indeterminate in 11 (0.1%) cases and their viral load was <50 copies/mL. We found a prevalence of 0.1% HIV indeterminate Western blots in pregnant women from Presidente Prudente and the surrounding region; none of these pregnant women had positive HIV viral loads.

Incidence of HCV and HIV NAT Positive in Cord Blood Donors.

Introduction:Donors of cord blood (CBD) are screened similarly to whole blood donors (WBD). It has been reported that CBD have a higher incidence of both true positive and false positive disease markers tested by EIA[1]. This abstract compares the rate of positive results for viral RNA (NAT) in CBD vs. WBD in a large cohort of donors.Methods:NAT was performed using the Chiron Procleix MPX or discriminatory assays. EIA testing was performed using Abbott bead methodology following manufacturer's instructions. Confirmatory results for EIA were performed with Chiron RIBA. Results from 12/17/04 to 6/30/05 were collated.ResultsEIA HIVEIA HCVNAT HIV/HCVHIV EIA POS(%)HCV EIA POS (%)HIV NAT POSHCV NAT POSWBD74299742997429975(0.10)107(0.14)1 (0)31(0.04)CBD11996120011200750(0.42)46(0.38)013 (0.11)A higher percentage of CBD were positive for HIV and HCV EIA as previously reported1. HIV NAT positive donors were 0.00% for both populations. The ratio of HCV EIA positive to HCV NAT positive donors was 28.97% for WBD and 28.26% in CBD. The ratio of CBD HCV EIA positives to WBD HCV EIA positives is 2.71 and the ratio of WBD HCV NAT positives to WBD HCV NAT positives is 2.75. The ratio of HIV CBD EIA positives to HIV WBD EIA positives is 4.10, which is significantly higher (p=<0.01).ConclusionsBoth CBD and WBD have a low rate (0%) of HIV NAT positive donors, but CBD have a 4x higher rate of HIV EIA. This suggests a 4x higher donor loss to false positive antibody results. The CBD donors have a 2.7x higher rate for both EIA and NAT positive results, showing a higher rate of viremic donors in CBD. The similar ratios for EIA positive to NAT positive donors in the two populations suggest that the false positive rate is not elevated in CBD versus WBD.The higher incidence of HCV infection in CBD could be geographic or ethnic in origin. More study is needed to determine the reasons and further predict donor loss. The HIV EIA results are not predictive of actual infection in this population. A more aggressive logarithm for reentry than used for WBD may be merited.

Evaluation of HIV ELISA diagnostic kit developed at the Institute of Primate Research, Nairobi Kenya

The first diagnostic kits utilizing the enzyme-linked immunosorbent assay (ELISA) technique were developed in mid-eighties, and since then, this technique has become an increasingly important tool for screening multiple samples of blood or serum for presence of antibodies to various infectious pathogens, especially human immunodeficiency virus (HIV) in blood banks. However, most of the commercial diagnostic kits currently available in the market are too expensive, hence not easily affordable in most Diagnostic Laboratories. We designed an ELISA kit for diagnosis of HIV and compared it with some of the commercial kits. We used blood samples from the blood bank at the National Public Health Laboratory Services (NPHLS) in Nairobi and from patients referred to the Kenya Medical Research Institute (KEMRI) for HIV screening. Two commercial kits were used, Wellcozyme HIV Recombinant kit and Recombigen (env & gag) HIV-1 EIA kit. Out of 1350 samples tested by Recombigen (env & gag) HIV-1 EIA kit, 419 (31.0% ) were positive while 421 (31.2% ) samples were positive by Wellcozyme HIV Recombinant kit. Our ELISA kit detected a total of 431 positive samples out of 1350 (31.9% ), which was almost identical to the results from the other kits. Our kit was nearly identical in terms of sensitivity and specificity to the other two commercial kits used in this study. Thus our ELISA system, which is much cheaper than the commercial kits currently available in the market, offers a more affordable system for routine HIV tests.

Transmission of HIV-1 and HCV by head-butting

Two men who had never met before had a fight as a consequence of a motor car accident. One, who was HIV-1 positive, head-butted the other who was wearing metal-framed spectacles on his forehead. The spectacles left imprints on the foreheads of both men, and there was copious bleeding. The man who was head-butted tested negative for HIV-1 3 days after the fight. 14 days later, however, he developed symptoms consistent with primary HIV-1 infection. About 3 months after the assault, he also had acute type B hepatitis; at which time he was found positive for antibodies against all the major HIV-1 structural proteins, although HIV-1 EIA was negative, and with CD4 T-cell counts of 606 10/L. The assailant had a history of intravenous-drug use. In May, 1990, he reported syringe exchange and sexual intercourse with an HIV-seropositive woman. At the time, he tested negative for antibodies against HIV-1 p24 antigen. Positive tests for HIV-1, hepatitis C virus (HCV), and hepatitis B virus (HBV) were found in May, 1991, when his CD4 T-cell count was 720 10/L. His CD4 cell counts were 124 10/L at the time of the fight. Sequencing of a 183 base pair of the gp120 V3 env region of DNA from both men’s peripheral blood mononuclear cells was done 126 days after the fight. Nucleotide sequence distances of the men and four Italian HIV-1 infected mother/infant pairs living in the same region were calculated with the DNADIST program of the 3.572c Phylogeny Inference Package. The average distance of the men (2·80 [SD 0·26]) was similar to those calculated for the mother/infant pairs, which ranged from 1·91 (0·36) to 7·05 (0·66). By contrast, distances between either of the men and mothers and infants were those typical of epidemiologically unlinked infections (variability range from 9·37% to 18·44%). The men’s pairwise distances were significantly different (p<0·0025) from the distances between either of them and the less divergent control, suggesting that the similarity between the men’s HIV-1 DNA was not random. The skin injuries in the man likely provided HIV-1 and HBV with a direct access to the bloodstream. Although the assailant was also infected with HCV, the other man tested negative for HCV 4 months after the accident. Parenteral exposure via blood or blood products leads to HCV infection in most cases, particularly at high levels of viraemia. The head-butter’s HCV viral burden was less than 1000 copies/mL plasma, which may explain the lack of HCV transmission.

The relationship between maternal-infant antibody levels and vertical transmission of HIV-1 infection.

This study assesses the predictive value of the ratio of HIV-1 antibodies in the newborn at birth to that in the mother for perinatally transmitted infection confirmed subsequently by age 18 months. The ratio of HIV-1 (EIA) antibody levels in the baby at birth to that in the seropositive mother after the first trimester (sequenstration index SI) was available in 114 of a perinatal cohort of 137 infants. We related this ratio to the HIV infection status of the children by 18 months, HIV-1 DNA PCR and HIV-specific IgA antibody detection at birth, between 3 and 6 months, and morbidity and mortality. Thirty-five of the 137 (26 per cent) children were diagnosed as infected by 18 months. The mean (SD) HIV SI was 1.57 (0.88) in 29 infected and 0.83 (0.42) in 85 uninfected infants (P < 0.0001). Sensitivity and specificity of a threshold SI of 1.27 (mean +/- 2 SD of uninfected group) for the prediction of perinatal HIV-1 infection were 41 and 98 per cent, respectively. The reason for the higher SI in the infected babies is the combination of lower antibody titres in the transmitting mothers with raised levels in the infected babies. A similar analysis of antibody ratios showed no statistical differences for measles and tetanus (P > 0.1) between HIV infected and uninfected groups. There was a tendency to increased morbidity (Pearson's correlation coefficient r = 0.31) and more severe disease in those with higher HIV-1 SI. Three of 17 (18 per cent) peripheral blood samples from infected children at birth were PCR positive; all had SI's above the threshold. Overall sensitivity and specificity of PCR were 85 per cent each. Eleven of the 29 infected children were HIV-1 specific IgA positive at birth; six (64 per cent) of these had an SI > 1.27. This simple SI of HIV-1 EIA antibodies at birth is comparable to elaborate techniques in its power to predict perinatally acquired infection. It may be a cheap, reliable and rapid screening test for vertically transmitted HIV-1 infection.

Multi-center european evaluation of HIV testing on serum and saliva samples

to evaluate the reliability of HIV antibody testing on saliva. matched serum and saliva samples were collected from both seronegative (n = 344) and seropositive (n = 125) individuals in five European countries. Duplicate saliva samples collected with Omni-Sal devices provided by Saliva Diagnostic System (SDS) were pooled before analysis. all samples were analyzed by Recombinant HIV1 EIA Cambridge Bioscience and 2nd generation Abbott HIV 1&2 1A80. EIA procedures were adapted for saliva testing by modification of sample dilution and/or cut-off calculation. All saliva recording positive and/or doubtful EIA results were further analyzed by Western blot as a confirmatory method. EIA results obtained from sera analysis from both seropositives and seronegatives allowed for calculation of the tests' sensitivity (HIV1 Biotech: 99.2%-100%; Abbott: 100%) and specificity (both tests 100%). In the series of 125 saliva samples collected from seropositives, the EIA results were as follows: with Biotech (3 negative, 3 in the grey-zone and 119 reactive) and with Abbott (1 negative, 1 in the grey-zone and 123 reactive). One saliva sample found negative by both EIA tests, although fulfilling HIV1 WB criteria of positivity, was collected from an HIV2 infected person. Out of 125 saliva samples collected from seropositives, 121 produced positive Western Blot profiles, 4 were indeterminate and 1 was found negative whereas 125/125 sera were found positive. the reliability of HIV testing of saliva is dependent on the sensitivity of EIA tests and on the criteria used for the interpretation of Western blot tests as well. Although saliva testing offers numerous advantages for epidemiological purposes, it should not be recommended for diagnosis.

Rapid HIV-1 Antibody Screening

This study compared the Single-Use Diagnostic HIV-1 antibody screening test (SUDS; Murex, Norcross, Ga) with the HIVAB HIV-1 EIA screen (Abbott Diagnostics, Abbott Park, III). The SUDS test was challenged with 251 random patient samples, 86 samples from patients with various non-HIV immunologic–related conditions, and 38 samples from patients with confirmed HIV infections. All 38 of the Western blot–confirmed HIV samples were detected as positive by the SUDS test. Of the randomly selected patient samples, 244 of 251 were negative by the Murex procedure. The seven positive results were individually investigated and found to have been from patients with previous diagnosis of HIV infection. Seventy-eight of the 86 specimens from patients with non-HIV conditions tested negative by both methods. Western blot results on the 8 discrepant HIV-1 antibody–positive samples were negative or indeterminate. Five SUDS false-positive results were found in two patients with monoclonal gammopathies, one patient with a high-titer mitochondrial antibody, one patient with active mycoplasma infection, and one patient with a markedly elevated prostate-specific antigen. When confirmed by Western blot, the SUDS test was 100% sensitive and 98.4% specific.

Risk Factors for Repeatedly Reactive HIV-1 EIA and Indeterminate Western Blots

Causes of indeterminate results of Western blot testing (IWB) for human immunodeficiency virus (HIV) type 1 include seroconversion, HIV-2 cross-reactivity, and autoimmune disease, but most IWB results remain unexplained. This case-control study assessed risk factors for IWB results, including early HIV infection, other retroviral infection, autoantibodies, and other medical conditions. Prospective study to determine HIV seroconversion rate, with a case-control design to assess other risk factors for IWB. Cases (persons with one or more repeatedly reactive HIV-1 enzyme immunoassay with IWB), their current sexual partners, and controls (persons with negative enzyme immunoassay and Western blot results) were recruited from blood banks, health department and prenatal clinics, and private providers in Washington and Oregon. Of 244 cases enrolled, 206 were followed up for 6 months or longer, and six (3.0%; 95% confidence interval [CI], 0.7% to 5.3%) with recent HIV risk behaviors seroconverted. The Western blot banding patterns differed among groups; cases usually had p17 or p24 bands, while controls and cases' sexual partners usually had polymerase bands. Conditional logistic regression indicated that independent risk factors for IWB among male cases and controls were a tetanus booster in the past 2 years (odds ratio, 3.2; 95% CI, 1.2 to 8.6) and sexual contact with a prostitute (odds ratio, 3.0; 95% CI, 1.0 to 9.5). Independent risk factors for women were parity (odds ratio, 1.2; 95% CI, 1.02 to 1.4) and autoantibodies, either rheumatoid factor or antinuclear antibodies (odds ratio, 2.3; 95% CI, 1.03 to 5.6). No cross-reactivity was detected with HIV-2, human T-lymphotrophic virus type 1, feline immunodeficiency or feline leukemia, or bovine immunodeficiency viruses. Evaluation of persons with reactive HIV-1 enzyme immunoassays and IWB should include an assessment of HIV risk and other possible risk factors, such as alloimmunization (ie, parity or recent immunization) or autoantibodies (ie, antinuclear antibodies and rheumatoid factor). The relationship of IWB among men who reported sex with prostitutes is intriguing and warrants further study.

Risk factors for repeatedly reactive HIV-1 EIA and indeterminate western blots. A population-based case-control study

Risk factors for repeatedly reactive HIV-1 EIA and indeterminate western blots. A population-based case-control study

Multicenter evaluation of a new recombinant enzyme immunoassay for the combined detection of antibody to HIV-1 and HIV-2

A newly developed recombinant antigen-based anti-HIV-1/HIV-2 enzyme immunoassay (Abbott Recombinant HIV-1/HIV-2 EIA) was evaluated against a second generation anti-HIV-1 EIA (Abbott Recombinant HIV-1 EIA). Five thousand and twenty-nine sera from European blood donors and 403 sera from central African blood donors were used in the evaluation, along with four panels and one cohort. The panels included 99 'problem' sera, 733 sera with antibodies to HIV-1 from asymptomatic people and from patients at different disease stages, 25 serial bleeds from five plasmapheresis donors seroconverting for antibodies to HIV-1, and 202 sera with antibodies to HIV-2 collected from healthy and diseased people of European or west African origin. In addition, 734 sera collected from a west African cohort were tested. Using Western blot as the reference standard, the specificity obtained by the recombinant anti-HIV-1 EIA (HIV-i EIA) was 99.90% [99.81-99.99%; 95% confidence limits (95% CL)] with European blood donor sera; 99.50% (98.78-100%) with Central Africa blood donor sera; 92.93% (87.78-98.08%) with 'problem' sera and 99.43% (98.87-100%) with sera from a west African cohort. Using the same samples, the recombinant anti-HIV-1/HIV-2 EIA (HIV-1/HIV-2 EIA) yielded a specificity of 99.84% (99.73-99.95%), 99.50% (98.78-100%), 95.96% (92.00-99.92%) and 98.58% (97.69-99.47%), respectively. All 776 Western blot-confirmed anti-HIV-1 sera were reactive in both EIAs, and the EIA-reactive samples from seroconverting plasma donors were always observed for both assays in the same serial bleed. For HIV-2, the HIV-1 EIA yielded an overall sensitivity of 75.83% (69.93-81.72%) compared with 99.53% (98.58-100%) for HIV-1/HIV-2 EIA. The addition of a recombinant env-protein of HIV-2 to the recombinant env and core proteins of HIV-1 on the solid phase of HIV-1 EIA improved the detection of anti-HIV-2 while preserving the assay's overall specificity and sensitivity for the detection of anti-HIV-1.

A new second-generation anti-HIV-1 enzyme immunoassay using recombinant envelope and core proteins

In a multicenter collaborative study a new second-generation HIV-1 antibody enzyme immunoassay (Abbott recombinant HIV-1 EIA) using Escherichia coli-expressed recombinant p24 and p41 proteins as solid-phase antigens was compared with the first-generation H9 cell-line-based Abbott HIV-1 EIA. The results of the confirmatory assays (Western blot, immunofluorescence), combined with clinical information, were used as the reference standard for the detection of HIV-1 antibodies in 10,676 random blood donor serum specimens, in a panel of 840 specimens from symptomatic and asymptomatic patients and a total of 63 serial blood specimens from 23 people at risk. With fresh blood donor sera, the specificity of the first-generation assay ranged between 99.54 and 99.76% (95% confidence limits, CL) compared with 99.81-99.95% (95% CL) for the second-generation EIA. With panel specimens the recombinant HIV-1 EIA achieved an overall sensitivity of 100% and a specificity range of 98.3-99.7% (95% CL); the corresponding sensitivity and specificity ranges observed for the first-generation EIA were 98.0-99.5% (95% CL) and 94.3-96.8% (95% CL), respectively. The improved sensitivity for the second-generation assay was confirmed by testing serial samples from seroconverting patients. The use of recombinant proteins eliminated non-specific reactions due to class II human leukocyte antigen (HLA)-directed antibodies.