Which anti-HTLV III/LAV assays for screening and confirmatory testing?

Reducing False-Positive Results With Fourth-Generation HIV Testing at a Veterans Affairs Medical Center

Background

In 2006, the Centers for Disease Control and Prevention issued guidelines advocating routine HIV screening for all patients. However, false-positive results are a potential patient care threat for low-risk populations even with accurate screening assays. A reduction in HIV false-positive screening results can potentially be seen by switching from the third-generation to a more sensitive and specific fourth-generation screening assay.

Methods

We studied the impact on the false-positive screening rate of a change to a fourth-generation assay at a regional US Department of Veteran Affairs Medical Center. HIV screening tests performed by the laboratory from March 1, 2016 to February 28, 2017, prior to implementation of the new assay were compared with fourth-generation HIV screening tests performed from March 1, 2017 to February 28, 2018.

Results

Of 7,516 third-generation HIV screening tests reviewed, 52 were reactive on the screening assay; 24 were true positives, 28 were false positives. The following year 7,802 fourth-generation HIV screening tests were performed and 23 were reactive on the screening assay; 16 were true positives and 7 were false positives. The positive predictive value for the third-generation test was 46% and 70% for the fourth-generation test.

Conclusions

There were fewer false-positive results with testing with the more specific fourth- vs third-generation assay (0.09% vs 0.37%, respectively), which was statistically significant (P = .002). This reduction in false-positive screening would reduce the laboratory workload and would save an estimated $3,875 yearly and reduce the adverse effects of false-positive screening results for patients.

Two decades of successes and failures in controlling the transmission of HIV through injecting drug use in England and Wales, 1990 to 2011

Responses to injecting drug use have changed focus over the last 20 years. Prevalence and incidence of human immunodeficiency virus (HIV) among people who inject drugs (PWID) in England and Wales were examined in relation to these changes. A voluntary unlinked-anonymous surveillance study obtained a biological sample and questionnaire data from PWID through annual surveys since 1990. Prevalence and incidence trends were estimated via generalised linear models, and compared with a policy time-line. Overall HIV prevalence among 38,539 participations was 1.15%. Prevalence was highest among those who started injecting before 1985; throughout the 1990s, prevalence fell in this group and was stable among those who started injecting later. Prevalence was higher in 2005 than 2000 (odds ratio: 3.56 (95% confidence interval (CI) 1.40–9.03) in London, 3.40 (95% CI 2.31–5.02) elsewhere). Estimated HIV incidence peaked twice, around 1983 and 2005. HIV was an important focus of policy concerning PWID from 1984 until 1998. This focus shifted at a time when drug use and risk were changing. The increased incidence in 2005 cannot be ascribed to the policy changes, but these appeared to be temporally aligned. Policy related to PWID should be continually reviewed to ensure rapid responses to increased risk.

AIDS in Africa: distinguishing fact and fiction

The data widely purporting to show the existence and heterosexual transmission in Africa of a new syndrome caused by a retrovirus which induces immune deficiency are critically evaluated. It is concluded that both acquired immune deficiency (AID) and the symptoms and diseases which constitute the clinical syndrome (S) are of long standing in Africa, affect both sexes equally and are caused directly and indirectly by factors other than human immunodeficiency virus (HIV). Seropositivity to HIV in Africans usually represents no more than cross-reactivity caused by an abundance of antibodies induced by the numerous infectious and parasitic diseases which are endemic in Africa. The apparently high prevalence of 'AIDS' and 'HIV' seropositives is therefore not surprising and is not proof of heterosexual transmission of either HIV or AIDS.

HIV testing--the perspective from across the pond

The first assay to screen blood donations for HIV was licensed in the USA in 1985. Since then there has been a dramatic increase in the types and numbers of assays available for HIV testing coupled with improvements in the sensitivity and specificity of these assays. However, with this increase in choice the algorithms for the initial diagnosis and confirmation of HIV infection have also increased in diversity and complexity and no uniform algorithm exists. Different regulatory regimes have meant that different assays and assay formats are available worldwide. In the UK we have been fortunate in having access to the so called 4th generation HIV antigen/antibody assays for 10 years. The first 4th generation assay in the US was licensed last year. The availability of this class of assays has led to the development of new algorithms for use in the US market and this paper describes how after many years of diversity the HIV algorithms between the UK and US are now converging.

A longitudinal study of the neuropsychiatric consequences of HIV-1 infection in gay men. I. Neuropsychological performance and neurological status at baseline and at 12-month follow-up

The aim of this study was to determine whether HIV infection is associated with neurological or neuropsychological impairment in the asymptomatic and early symptomatic stages of disease. Subjects included 61 gay men (41 HIV-, 20 HIV+) who were assessed at the time of requesting their first HIV test and again 12 months later. The assessments at baseline were conducted double-blind to HIV serostatus. Measures included a neuropsychological battery, neurological examination and full psychiatric assessment. There were no differences between the asymptomatic HIV+ and HIV- groups at baseline or at follow-up in terms of mean scores on neuropsychological tests. Mean scores were within the normal range for all neuropsychological tests for both groups. Multiple regression analysis was used to predict each individual's performance at follow-up on the basis of their baseline performance, psychiatric state, neurological history and drug use for each of the neuropsychological tests. HIV+ subjects were more likely than control subjects to perform at a significantly lower level at follow-up on one or more tests than predicted on the basis of their baseline performance.

Neuropsychiatric aspects of HIV-1 infection in gay men: controlled investigation of psychiatric, neuropsychological and neurological status

The aim of this study was to determine whether HIV infection is associated with psychiatric morbidity or neuropsychological impairment in asymptomatic and early symptomatic stages of disease in gay men. The subjects were 100 gay men (68 HIV-ve, 32 HIV+ve, 6 being CDC IV). All subjects were recruited at the time of requesting their first HIV test and the assessment was double-blind to HIV serostatus. There were no differences in psychiatric status or neuropsychological performance between the HIV-ve and HIV+ve groups. Multiple regression analysis and logistic regression were used to identify factors associated with psychiatric morbidity, neuropsychological impairment and subjective reporting of memory problems and physical symptoms for all 100 subjects. Previous psychiatric history and current illegal (non-dependent) drug use were associated with psychiatric morbidity, poor education was associated with neuropsychological impairment and psychiatric status (score on HAD and PSE) was associated with subjective reporting of memory problems and physical symptoms.

Post-transfusion NANBH in the light of a test for anti-HCV

The incidence of post-transfusion hepatitis (PTH) varies over an order of magnitude in different parts of the world. For example, prospective studies from Spain and the UK reveal rates of PTH of approximately 10 and 0.5% respectively. Similarly the association of a history of transfusion in patients with chronic liver disease varies widely; in Japan, with high rates of PTH, the association appears obvious whereas in the UK less obvious. These factors must be taken into account when assessing the cost-effectiveness of pre-transfusion screening for anti-HCV. A useful approach to assessing the value of screening donors for anti-HCV is to study prospectively the correlation of anti-HCV and PTH. In carefully selected cases of PTH, the correlation of anti-HCV and PTH in donor-recipient sets of samples may be very high. However, the predictive value of 'first-generation' assays for anti-HCV in routine studies of unselected cases of PTH may be less than 20% in countries with low rates of transfusion-transmitted non-A, non-B hepatitis (NANBH). The anti-HCV screening tests and supplementary assays are continually evolving. More recent assays incorporate structural as well as non-structural antigens in both types of ELISA used for screening and in the supplementary tests such as the recombinant based immunoblots.(ABSTRACT TRUNCATED AT 250 WORDS)

Advantages of a human immunodeficiency virus type 1 (HIV-1) persistently infected HeLa T4+ cell line for HIV-1 indirect immunofluorescence serology

A HeLa T4+ cell line persistently infected with human immunodeficiency virus type 1 (HIV-1) was used in an indirect immunofluorescent antibody assay (IFA) system to explore its potential suitability as an alternative source of viral antigen for confirmatory IFA in HIV serology. In a study of 121 serum samples chosen because they were reactive on repeat examination by enzyme immunoassay but nonspecific by IFA by using HIV-1-infected H9 cells (H9 IFA) or gave discrepant results by enzyme immunoassay and H9 IFA, the specificity and sensitivity of the HeLa T4+ IFA were comparable to those of Western blot (immunoblot), and identification of the true positive samples among these discrepant or nonspecific samples by HeLa T4+ IFA was approximately twice that by H9 IFA. The primary advantages of using the HeLa cell line rather than lymphoid cell lines in IFA are that cells can be grown as a monolayer and that the individual cells are much larger. The cell membrane, cytoplasm, and nucleus are easily discernible; this allows specific and nonspecific staining to be distinguished. At least eight different nonspecific nuclear and cytoplasmic staining patterns were identified in this study by using T4+ cells.

Trends in sexual behaviour and HIV testing among women presenting at a genitourinary medicine clinic during the advent of AIDS

Changes in female sexual behaviour with the advent of AIDS and safer sex campaigns were studied. Subjects were drawn from a wide social spectrum of women attending an STD clinic in West London where there is a high prevalence of HIV infection among homosexual men. Between 1982 and 1989, 4224 women answered a self-administered questionnaire: women who reported more than one sexual partner in the previous year fell from 56.9% in 1982 to 51.8% in 1989 (p = 0.003). Anal intercourse showed no change and was reported by 8.8% in 1982 and 9.4% in 1989 (p = 0.8). Oral intercourse increased from 36.9% in 1982 to 44.7% in 1989 (p = 0.001). Condom use for contraception increased from 3.6% in 1982 to 16.2% in 1989 (p less than 0.001). Between 1987 and 1989, 35.6% of 3199 women reported having non-regular partners with no significant trend over this period; these women had earlier coitarche (17.0 years cf 17.9 years), many more partners (p less than 0.0001) and more practised anal (p = 0.007) and oral (p less than 0.0001) intercourse. However, frequent use of condoms doubled from 23.6% in 1987 to 47.6% in 1989. During this period, the prevalence of antibody to HIV (anti-HIV) remained unchanged (0.27-0.37%), but more women declined to be tested. Anonymised testing showed that none of those who refused consent for named testing was anti-HIV positive. It is concluded that significant changes in female sexual behaviour have taken place with the advent of AIDS but there has been no evidence of heterosexual spread beyond the confines of well defined risk behaviours. Risks of the magnitude reported in homosexual men were not found in heterosexual women.

Use of electron microscopy in examination of faeces and rectal and jejunal biopsy specimens

The stools and rectal biopsy specimens of 44 patients with AIDS and diarrhoea were examined by culture, light microscopy, and electron microscopy. In 13 patients examination of rectal biopsy material and faecal samples showed no pathogen, but in two of these, microsporidiosis was found by electron microscopical examination of jejunal biopsy specimens. This organism was also identified electron microscopically in one of the further five jejunal biopsy samples taken from patients with a known cause of diarrhoea. Blastocystis hominis infection was identified electron microscopically in six patients, all of whom had cryptosporidiosis additionally seen by light microscopy. Four of these six patients remained well for long periods, with only moderate diarrhoea, and follow up showed no evidence of blastocystis infection. In only four of 11 patients found to have cryptosporidium in their stools at light microscopy were organisms found at electron microscopy. Viral inclusions were only identified at electron microscopy in one of 10 patients with an opportunistic viral infection seen at light microscopy (cytomegalovirus n = 7, herpes simplex virus n = 3). No additional viral pathogens were detected in either stools or rectal biopsy material by electron microscopy. It is concluded that routine electron microscopic examination of stool samples or rectal biopsy material taken from patients with AIDS and diarrhoea is unnecessary and does not increase the yield of potential pathogens compared with standard microbiological techniques and histology.

Enzyme-linked immunosorbent assay (ELISA) for HIV antibody by a glass slide technique

An enzyme-linked immunosorbent assay (ELISA) technique is described which utilizes a commercially available glass microscope slide coated with hydrophobic teflon in such a pattern as to give 30 small circular wells, each of which has a glass bottom. Each well serves as a solid phase, analogous to a microtiter well for adsorption of purified human immunodeficiency virus (HIV) antigens. Since only 5-10 microliter volumes of reagents are used and rinsing processing is simple, the cost per test is much less than most other ELISA technologies. HIV antigen is stable for over 1 year at 37 degrees C when dried on the glass slides. The sensitivity and specificity of the micro slide immunoenzymatic assay (Micro-SIA) was studied by testing randomly selected, known HIV-seropositive and seronegative plasma. Results compare well with microtiter and Western blot assays. A simple vertical-beam colorimeter is described (useful in the Micro-SIA) which can be easily assembled by the user from commonly available components.

Chromatographic methods for the bioanalysis of antiviral agents

The present review has concentrated on chromatographic techniques for the quantitative determination of antiviral drugs in biological samples. Special attention has been paid to the elements of chromatographic assays that are essential to ensure selectivity, sensitivity, accuracy and precision of the various methods. Wherever possible, attempts have been made to determine the suitability of the methods for application to investigations in pharmacokinetics in man and experimental animals, biopharmaceutics, therapeutic drug monitoring, metabolism and pharmacology. Because of the serious consequences of infection from material contaminated with viruses, special consideration has been given to the handling of contaminated samples. It was convenient to divide the antiviral drugs for the purpose of this review into two groups, the nucleoside and the non-nucleoside antiviral drugs. The nucleosides discussed are vidarabine, cytarabine, ribavirin, riboxamide, acyclovir, ganciclovir, desciclovir, carbovir, 2',3'-dideoxyadenosine, 2',3'-dideoxycytidine, zidovudine, 2',3'-dideoxyinosine, 2',3'-didehydro-3'-deoxythymidine, idoxuridine, 5-(2-bromovinyl)-2'-deoxyuridine, 2'-fluoro-5-iodoaracytidine and 5-iodo-2'-deoxycytidine. The non-nucleoside antiviral drugs discussed are arildone, amantidine, rimantidine, moroxydine, enviroxime, foscarnet and ampligen.

HIV infection in intravenous drug abusers in Berlin: risk factors and time trends

To investigate the epidemiology of HIV infection among intravenous drug abusers (IVDA) in Berlin (West), from October 1984 to October 1988, 741 heterosexual IVDA were recruited from facilities for drug treatment and counseling. In this group 22.8% were seropositive for antibodies against HIV, representing 21.1% of the females and 23.5% of the males. Seroprevalences of hepatitis B, hepatitis A, and lues were 67.7%, 40.1%, and 4.0%, respectively. Seropositivity for HIV antibodies correlated with positive seromarkers for hepatitis B and A, and with certain behavioral and social features such as sharing of injection equipment, imprisonment, and intravenous drug use in prison. The crude time trend of HIV seroprevalence shows an increase from 17.1% in those subjects who discontinued i.v. drug abuse in 1983 or earlier to 31.5% in 1985, and a decrease over the past 3 years to 14.1% in 1988. After adjusting for temporary changes in the study group, the estimated HIV seroprevalence odds show an almost steady increase and were significantly higher for those who were injecting drugs in 1987 and 1988 compared with those who stopped i.v. drug use before 1984. Thus IVDA with a persistent risk profile are at a still-increasing risk of acquiring HIV infection.

Evaluation of enzyme-linked immunoassay systems for detection of human immunodeficiency virus type 1 antibody from filter paper disks impregnated with whole blood

Five commercial enzyme-linked immunoassay systems for the detection of human immunodeficiency virus type 1 antibody from filter paper disks impregnated with whole blood were evaluated for technical and operational performance. All five systems performed adequately in the technical challenges posed, with specificities in excess of 99% for 1,020 specimens. In a serial dilution sensitivity challenge, all of the kits were able to detect specific antibody within one dilution of a Western blot (immunoblot) standard, except for a Du Pont Co. kit, which detected antibody within two dilutions of the standard. The Du Pont assay showed the least variation in control values between test runs and between lots. All of the systems produced acceptable results, but their operational parameters differed significantly.

Detection of antibodies to the human immunodeficiency virus by a silver-enhanced gold-labelled immunosorbent assay

We describe a new immunoassay for the detection of antibodies to the human immunodeficiency virus. The method is based on a silver enhanced gold-labelled immunosorbent assay (SEGLISA). Test sera are incubated in microtitre wells on which antigens have been coated. If present in the test sera, antibodies to the human immunodeficiency virus bind to the solid-phase antigens. Bound antibodies are quantitated with anti-human immunoglobulin labelled with gold. Positive specimens produce a faint pink deposit which is better visualised by silver enhancement which gives an intense black colour. The intensity of the colour is proportional to the bound antibody concentration. All the reagents are stable and the silver enhancement takes place under ambient light conditions. The assay has many of the advantages of micro enzyme-linked immunosorbent assays but does not suffer from the drawbacks associated with the use of an enzyme label. It requires fewer manipulations and is quicker to carry out than an equivalent enzyme-linked test. As the silver layer is permanent dried wells may be stored for future reading or checking.

Evaluation of enzyme-linked immunosorbent and alternative assays for detection of HIV antibodies using panels of Brazilian sera

Sera from 472 Brazilian subjects, confirmed to be either positive or negative for HIV antibodies and comprising the total clinical spectrum of HIV infection, were utilized in the evaluation of six commercially available enzyme-linked immunosorbent assays (ELISA), as well as of four alternative assays, namely indirect immunofluorescence (IIF), passive hemagglutination (PHA), dot blot and Karpas AIDS cell test. The sensitivities ranged from 100% (Abbott and Roche ELISA) to 84.2% (PHA) and the specificities ranged from 99.3% (IIF) to 80.2% (PHA). The sensitivity and specificity of the PHA and the sensitivity of the Karpas cell test were significantly lower than those of the other tests. Although the IFF and dot blot had good sensitivities and specificities, the six ELISA were more attractive than those tests when other parameters such as ease of reading and duration of assay were considered.

Evaluation of three enzyme immunoassays for HIV-1 antigen detection

Three enzyme immunoassay (EIA) methods for the detection of human immunodeficiency virus (HIV-1) were evaluated. Serum or plasma samples from 22 individuals seropositive for HIV-1 antibodies were tested with the Abbott, Coulter, and DuPont kits for presence of HIV-1 p24 antigen. Another 12 samples were tested with two kits only. Discordant results were obtained with 9 of 34 (26%) HIV-1-antibody-positive patient samples tested. Most of these discrepancies were found in samples containing less than 30 pg/ml of HIV-1 p24 core antigen. A sampling of sera from normal blood donors and patients with infectious or autoimmune diseases revealed a low level of false positive reactions, especially with sera containing antinuclear antibodies or rheumatoid factor. Noteworthy is the frequency of false positive reactions seen with the DuPont EIA for HIV-1 p24 antigen. 18/111 sera (16.2%) containing auto-antibodies tested positively with the DuPont HIV-1 p24 antigen EIA. The nonspecific nature of the test reactivity for 9/10 of these samples was confirmed using an HIV-1 p24 antigen inhibition assay. These findings are discussed in light of the need for HIV-1 antigen detection in the clinical laboratory and of other methods for HIV-1 detection: the polymerase chain reaction and measurements of reverse transcriptase activity.

Natural history of acquired immunodeficiency syndrome in women in Rhode Island

PURPOSE

Current recommendations for treatment of human immunodeficiency virus (HIV) infection and for prophylaxis against associated opportunistic infections in North America are largely based on observations of HIV infection in males. In an effort to determine whether the natural history and clinical course may be different, with implications relevant to prophylaxis against opportunistic infections, we have documented the clinical courses of the first 24 known cases of acquired immunodeficiency syndrome (AIDS) in women in Rhode Island, most of whom developed Centers for Disease Control-defined AIDS before the availability of an effective antiviral agent (i.e., zidovudine) or a well-defined approach to prophylaxis against opportunistic infections (e.g., oral trimethoprimsulfa).

PATIENTS AND METHODS

The subjects in this study are 24 women with AIDS who were treated by members of the Brown University medical faculty from June 1982 through June 1988. All patients had thorough clinical evaluations and appropriate laboratory studies as they became available. All were followed at intervals no greater than two months. All opportunistic infections were treated by appropriate, specific antimicrobial therapy. When zidovudine became available, it was administered to all remaining patients in the study. All subjects were counseled about HIV infection, its modes of transmission, and the early symptoms of opportunistic infections.

RESULTS

These observations yielded the following three major findings: (1) Candida esophagitis was the most common (38%) AIDS-defining event; (2) Pneumocystis carinii pneumonia was less frequently the AIDS-defining event (13%) and occurred less commonly during the illness (29%) than in North American males with AIDS; (3) Of 14 women in whom the diagnosis of AIDS was established before January 1, 1987, the mean survival time after diagnosis was greater than 20 months.

CONCLUSION

More information on the natural history of HIV infection in North American women is urgently needed. If more extensive data from other geographic regions confirm the observations in this study, the optimal approach to prophylaxis against opportunistic infections in women with AIDS may be substantially different from that which is most appropriate for males.

Effect of gamma irradiation on the human immunodeficiency virus and human coagulation proteins

The effect of gamma irradiation on HIV and plasma coagulation factors F VIII:C, F VIII:vWF and FIX was studied. Donor plasma was harvested from single donations, frozen and irradiated in the frozen state at target doses from 0 to 40 kGy (0-4 mRad). HIV was inoculated into human plasma and irradiated in a similar manner. A range of other viruses, not suspended in plasma, were also irradiated to establish viral inactivation. An inactivation rate of 0.164 TCID50 dose/ml/kGy was demonstrated for HIV compared to rates of 0.00173, 0.00526 and 0.00286 log10 units/ml/kGy for F VIII:C,F VIII:vWF and FIX respectively. The use of gamma irradiation to inactivate infectious agents present in human plasma may eliminate the need for any post-production viral inactivation methods and provide a means of assuring the safety of as yet untreated products such as cryoprecipitate and fresh frozen plasma.

[Retrospective seroepidemiology of HIV-1]

Serum samples collected between 1974 and 1980 out of populations from the States of Pará and Goiás, Brazil, were tested for antibodies against HIV-1 through ELISA, immunofluorescence, and immunoblot. The aim was to describe the possibility of the virus presence in this country before the present epidemic. Four samples from an epidemiologically closed community, the Xicrin indians, gave positive reaction in the ELISA test, but were negative in the confirmatory tests. The negative results suggest the absence of HIV-1, in the groups tested, prior to the 1980's.

Non-cryptosporidial diarrhoea in human immunodeficiency virus (HIV) infected patients

Thirty of 81 consecutive HIV antibody positive patients referred with non-cryptosporidial diarrhoea had no potential infectious cause; most had AIDS related complex rather than the full blown syndrome. Opportunistic infections with cytomegalovirus (CMV), mycobacterium avium-intracellulare (MAI), and herpes simplex virus (HSV), which allowed a diagnosis of AIDS to be made, were found in 19 patients and were the presenting features of AIDS in five. Other potential pathogenic species included entamoeba, giardia, campylobacter, and salmonella (without septicaemia). Cytomegalovirus infection was often accompanied by abdominal pain. Severe weight loss (greater than 10 kg) at presentation was found in patients with CMV infection and MAI. Bloody diarrhoea was confined to the group with HSV procitis. Malignant causes of diarrhoea were rare. Two patients developed a squamous carcinoma of the anorectal margin and one a non-Hodgkin's lymphoma. In only two of 12 patients who had Kaposi's sarcoma was this considered as a cause of diarrhoea. Rigid sigmoidoscopy showed macroscopic abnormalities in over a third (32) of the 81 patients with non-cryptosporidial diarrhoea. Most commonly this was severe inflammation (17) or discrete ulceration (four) [three of whom had CMV colitis]. Kaposi's sarcoma was identified in 11 patients. Non-specific inflammation was seen histologically in 40 of the 60 patients with no sigmoidoscopic inflammatory changes. Barium enema only revealed an abnormality in a minority of the patients and a colonoscopy only revealed information additional to rigid sigmoidoscopy in two patients--one with CMV ulcers in the transverse colon and the other with evidence of Kaposi's sarcoma not seen in the rectum. Ten patients had a rectal biopsy examined by electron microscopy as no infective cause of diarrhoea was uncovered. In four of these microtubular structures which are commonly seen in viral infections were found and two had prelymphomatous changes and in one of these frank lymphoma has developed. We recommend multiple stool analysis, sigmoidoscopy and rectal biopsy as the initial investigations in these patients reserving tests of malabsorption, colonoscopy, and barium enema for the small number of more difficult cases.

Trends in sexual behaviour and risk factors for HIV infection among homosexual men, 1984-7

To assess whether the spread of infection with HIV can be reduced by changes in behaviour among groups most at risk because of their sexual practices sexual behaviour was monitored among 1050 homosexual men tested for HIV infection at a genitourinary medicine clinic in west London from November 1984 to September 1987. Four cohorts, defined by date of presentation, were studied by questionnaire at their presentation, and blood samples were analysed. Between the first and last cohorts there was a considerable fall in the proportion reporting casual relationships (291/329 (88%) v 107/213 (50%] and high risk activities, such as anoreceptive intercourse with casual partners (262/291 (90%) v 74/106 (70%], with the greatest changes occurring before the government information campaign began in 1986. Nevertheless, half of the men in the last cohort studied reported having casual partners. Multiple logistic regression showed that behavioural risk factors for HIV infection most closely resembled those for hepatitis B and that previous sexually transmitted diseases (syphilis, hepatitis B, and anogenital herpes) were themselves independent risk factors. A history of syphilis ranked above anoreceptive intercourse as the strongest predictor of HIV infection. Actively bisexual men showed a much lower prevalence of HIV infection (3/57, 5%) than exclusively homosexual men (113/375, 30%). Sexual behaviour among homosexual men changed during the period studied, and the incidence of HIV infection fell, although more education programmes directed at homosexual men are needed to re-emphasise the dangers of infection.

Passive hemagglutination test for detection of antibodies to human immunodeficiency virus type 1 and comparison of the test with enzyme-linked immunosorbent assay and Western blot (immunoblot) analysis

A passive hemagglutination test (PHA) was developed for detecting antibodies to human immunodeficiency virus type 1 (HIV-1) utilizing sheep erythrocytes cross-linked with purified envelope glycoprotein (gp160) of HIV-1. In an analysis of 216 human serum samples, 100% correlation was observed in 86 reactive and 124 nonreactive serum samples between PHA and commercial enzyme-linked immunosorbent assays and Western blot (immunoblot) analysis. Serum samples from gp160-immunized chimpanzees also reacted equally well in PHA. The test is simple, rapid, and inexpensive, thus providing an alternate, quick method of detecting HIV antibodies. These advantages and the thermal stability of the reagents that are used make this an attractive alternative for detecting prior exposure of individuals to HIV-1.

Zidovudine treatment of patients with acquired immune deficiency syndrome and acquired immune deficiency syndrome-related complex: St Stephen's Hospital experience

Zidovudine was used in an open uncontrolled study for treatment of 145 human immunodeficiency virus (HIV) patients, 102 with acquired immune deficiency syndrome (AIDS) and 43 with symptomatic HIV disease (acquired immune deficiency syndrome related-complex, ARC). The mean period of follow-up was 6 +/- 2.5 months. The median survival time of AIDS patients on zidovudine was 4.5 times longer when compared to a historical zidovudine untreated AIDS group (1657 vs. 370 days). This should be interpreted with reserve regarding improvements in treatment of all aspects of HIV infection and heightened awareness of AIDS which may have led to earlier diagnosis in the zidovudine treated groups. Pneumocystis carinii pneumonia (PCP) was very rarely a cause of death in zidovudine-treated patients (4.8%), while it was responsible for the death in 46.2% of historical controls (P less than 0.001). Extensive Kaposi's sarcoma was equally the cause of death in treated as well as in historical patients. Median T4 cell counts increased on zidovudine reaching a peak at the end of the fourth month of therapy in the ARC group and at the end of the first month in the AIDS group with a subsequent fall. Sixty per cent (53 of 87) patients were p24 viral antigen positive at the start of treatment and 19% of them had a fall of more than 50% in antigen level in three months while 32% became antigen negative within 2.5 months. Survival in patients where the antigen disappeared or in whom there was a major (greater than 50%) fall in antigen level was significantly higher than in those for whom there was no change in antigen level or in whom the antigen was negative at the start of the study (P less than 0.05). Forty-seven of the 145 zidovudine treated patients needed to be transfused because of anaemia. The mortality was significantly higher in this group of patients, particularly in those transfused prior to zidovudine therapy. Neutropenia occurred in four subjects. Platelets rose after the start of zidovudine but subsequently fell to thrombocytopenic levels in eight patients.

Detection of antibodies to the human immunodeficiency virus by a rapid fluorescence-labelled immunosorbent assay

The development and assessment of a fluorescence-labelled immunosorbent assay for the detection of antibodies to the human immunodeficiency virus is described. Test serum is incubated in microtitre wells on which antigens have been coated. If present in the test serum, antibodies to the human immunodeficiency virus bind to the solid-phase antigens. In turn the antibodies are quantified with anti-human immunoglobulin labelled with fluorescein. Positive samples produce an intense fluorescence which is measured in a spectrofluorimeter. When used to test a panel consisting of normal serum and antibody-positive serum from infected patients the assay proved to be 100% specific and to have a sensitivity of 100%. The assay has many of the advantages of micro enzyme-linked immunosorbent assays, but does not suffer from the drawbacks associated with the use of an enzyme label. It requires fewer manipulations and is quicker to carry out than an equivalent enzyme-linked test.

Performance and reliability of five commercial enzyme-linked immunosorbent assay kits in screening for anti-human immunodeficiency virus antibody in high-risk subjects

Anti-human immunodeficiency virus enzyme-linked immunosorbent assay kits marketed by Electro-Nucleonics Inc. (ENI), Genetic Systems Corp. (GSC), Organon Teknika Inc. (OTI), Ortho Diagnostic Systems Inc. (ODSI), and Wellcome Diagnostics (WD) were evaluated by using 289 randomly selected serum samples from a high-risk population and 53 serum samples likely to produce false-positive results. The radioimmunoprecipitation assay was used as the reference test. Sensitivities ranged from 96.51% (ODSI, WD) to 97.67% (ENI, GSC, OTI). Sera showing antibodies to viral glycoproteins only produced the false-negative results. Specificities ranged from 99.6% (ENI, GSC, ODSI, OTI) to 100% (WD). False-positive results were obtained with sera from patients with autoimmune disease or Epstein-Barr virus infection. Only results from GSC and OTI kits were distributed in two compact clusters well segregated on either side of the cutoff point. ODSI and GSC kits had the best intralot reproducibility. The GSC kit had the best interlot reproducibility. Cutoff values for ODSI and GSC kits were the least variable. Intraplate repeatability was good for all kits. Sample localization was not an important source of variability. Our results do not point out one outstanding kit among the five evaluated. However, the GSC kit showed the best overall results.

Comparison of a monoclonal anti-HIV 1 gag solid phase with a polyclonal anti-HIV solid phase for detecting anti-HIV 1 in a competition ELISA

An anti-HIV 1 competitive ELISA was developed using a monoclonal anti-HIV 1 gag to capture viral antigen to the solid phase. This format of assay was compared with a competitive ELISA where a polyclonal human anti-HIV 1 was used, to capture the viral antigen. Several benefits were observed using the monoclonal-antibody form of the assay. Firstly, less viral antigen was needed on solid phase to give an equivalent test in terms of positive and negative optical density 450 nm values. Secondly, a slight increase in sensitivity was also gained without any loss of specificity and finally, as a result of the murine nature of the antibody on the solid phase, no cross-reaction with the labelled human antibody in the test conjugate was observed. Such cross-linking has been observed with the polyclonal form of the assay and can lead to false-negative reactions.

The Karpas AIDS Cell Test compared with an enzyme-linked immunosorbent assay for detecting antibody to the human immunodeficiency viruses (HIV-I and HIV-2)

We have compared the Karpas AIDS Cell Test for antibodies to the human immunodeficiency viruses (HIV) with a commercial enzyme-linked immunosorbent assay (ELISA) (Organon Teknika) by testing serum samples from 324 intravenous drug abusers in Turin. The cell test was found to be more sensitive and as specific as the ELISA with the serum samples from the drug abusers. In Lisbon, 30 samples were tested on slides containing cells infected with HIV-1 and/or HIV-2. All 15 samples, which were positive for HIV-2 alone (in the HIV-2 Elavia test and by the Western blotting technique), were also positive in the Karpas AIDS test. In contrast, only one of the 15 samples (7%) gave a positive reading in the ELISA for HIV-1. Results of 30 samples tested in Turin and Lisbon by the Western blotting technique agreed closely with those obtained with the Karpas AIDS Cell Test. We were also able to show that the entire test can be performed at room temperature and completed within 1 hour. Moreover, the cell test requires minimal skill and simple equipment and is inexpensive. It also includes non-infected cells as a control and the specificity of positive samples may be verified with a bench microscope. Furthermore, this test which detects antibodies to both HIV-1 and HIV-2 allows rapid typing of the infecting strain.

Evaluation of rubella immune status by three commercial enzyme-linked immunosorbent assays

Three commercial indirect enzyme-linked immunosorbent assays (ELISAs) (Enzygnost-Rubella, RUBELISA, and ORTHO Rubella) were evaluated for the determination of immune status by testing 1,090 serum specimens, 410 of which were from nonimmune patients. In comparison with the standard reference technique, the hemagglutination inhibition (HAI) test, the sensitivities of ORTHO Rubella (100%) and Enzygnost-Rubella (99.26%) were excellent, whereas the sensitivity of RUBELISA (95.60%) was marginally lower because of the inability of this assay to detect antibody in 22% of the serum specimens with HAI titers of 10 and 11% of sera with HAI titers of 20. The specificity of all three systems was greater than 97%. There was a linear correlation between mean ELISA values and increasing HAI titers (r greater than or equal to 0.94). Both ORTHO Rubella and Enzygnost-Rubella were shown to be suitable replacements for the HAI test, provided that an equivocal zone is incorporated in the ORTHO system and only unheated sera are used in the Enzygnost system.

Serologic testing for human immunodeficiency virus antibodies

Familiarity with available serologic tests for antibodies to human immunodeficiency virus (HIV) has become increasingly important in a wide variety of clinical settings. Enzyme-linked immunosorbent assay (ELISA) commercial kits are most often used as Enzyme-linked immunosorbent assay (ELISA) commercial kits are most often used as screening tests, and Western blot techniques are used for confirmation of positive results. ELISA specificity and sensitivity exceed 98%; the predictive value of a positive test varies from 2% for a weakly positive test in a low-prevalence population to 99% for a strongly positive test in a high-risk group. Confirmatory Western blot testing identifies antibodies with affinity for specific HIV antigens. Indeterminate Western blot antibody patterns necessitate subsequent testing or alternative methods for interpretation. A "window" period of up to 3 or more months follows acute HIV infection before seropositivity occurs.

Human immunodeficiency virus infection, hepatitis B virus infection, and sexual behaviour of women attending a genitourinary medicine clinic

During the six months immediately after a public information campaign about the acquired immune deficiency syndrome 1115 women who attended a genitourinary medicine clinic in west London were tested for antibodies to the human immunodeficiency virus (HIV). Three women (0.27%) were positive, and all three were regular sexual partners of men with high risk lifestyles--two intravenous drug users and one bisexual. A consecutive series of 647 women from the cohort was tested for antibodies for hepatitis B core antigen: 27 were positive, of whom six had been born in the United Kingdom and were not known to have been at risk. The two women who were seropositive for HIV who completed a questionnaire on their sexual behaviour before they were tested reported both anal and oral receipt of semen and were in the upper fifth percentile for lifetime sexual partners. More than half (53%) of 424 women who reported that they had non-regular sexual partners never used a condom. It is concluded that heterosexual women in London are at a low risk of becoming infected with HIV.

Specificities and sensitivities of three systems for determination of antibodies to human immunodeficiency virus by electrophoretic immunoblotting

Electrophoretic immunoblotting (EIB [Western blotting]) has emerged as the major method for verification of seropositivity for human immunodeficiency virus (HIV) and therefore needs to be thoroughly characterized. The specificities of three EIB systems, our own and two commercial systems, were studied with anticellular sera and serial dilutions of human sera. We demonstrated that in one system, anti-HLA classes I and II gave bands comigrating with viral proteins, which can be controlled by EIB with uninfected H9 cells. In addition, animal antisera, including anti-immunoglobulin enzyme conjugates, occasionally reacted with HIV gag proteins, necessitating appropriate controls. Whereas none of 10 blood donors reacted at the standard dilution in serum (1/100 or 1/400) in any of the three systems, 6, 1, and 2 of 10 donors reacted with p24, p55, or both at a dilution of 1/10 for the three systems tested. Thus, nonspecific reactions can arise in several ways and justify critical EIB interpretation. The sensitivity of the three systems was studied by comparative titrations and direct quantification of bound immunoglobulin G (IgG). In the titrations with all three, the minor anti-HIV bands p53 and p64, coded from pol, were often detectable in higher dilutions than were antibodies to any other HIV protein. The minimum visible amounts of IgG bound per HIV protein band estimated by extra- and interpolation in densitometric curves and liquid scintillation counting of radiolabeled patient IgG were approximately 0.1, 0.05, and 0.02 ng per band in the three systems. One of the commercial systems had both the highest sensitivity and highest specificity.

HIV antibody screening of blood donations in the United Kingdom

Routine screening of blood donations for anti-HIV commenced in the UK during October 1985 and by the end of February 1987 approximately 3.7 million donations had been tested. Seventy-two were confirmed anti-HIV positive, i.e. 0.002%. Of the anti-HIV-positive donors interviewed to date, the majority are young homosexual or bisexual men or intravenous drug abusers. Included in the study are data collected on approximately 470,000 donors giving blood for the first time. Twenty of these have been confirmed anti-HIV positive (0.004%), and 19 interviewed have admitted to being in risk categories. In 5 instances a positive anti-HIV donor was found negative on a previous occasion, and in 1 instance the products from the donation led to seroconversion in the recipients. The majority of anti-HIV-positive donors attending for blood donation did so because they did not consider that the self-exclusion categories specified in the leaflet issued to donors applied to them since homosexual activity or drug abuse was not currently being practised.

Comparison of Western blot (immunoblot) based on recombinant-derived p41 with conventional tests for serodiagnosis of human immunodeficiency virus infections

To evaluate the performance of a serological test for human immunodeficiency virus type 1 (HIV-1) infections based on the use of a recombinant envelope gene-derived protein as the antigen, we caused expression of a 1.4-kilobase fragment of HIV.DNA that codes for the complete gp41 transmembrane protein in an Escherichia coli expression vector and used Western blots (WB; immunoblots) prepared with recombinant material (pEX-41) to detect antibodies to HIV-1. This test detected all 339 sera which were positive by a combination of conventional serodiagnostic assays and produced no false-positive results with 311 negative samples. Also no false-positive results were obtained with 20 sera from systemic lupus erythematosus patients which had high titers of cross-reactive autoantibodies. In six cases, the pEX-41 WB proved to be more sensitive than individual assays applied on their own, and in five cases it was even more sensitive than a combination of conventional assays. We tested 221 sera in both our pEX-41 WB and a commercially available recombinant enzyme immunoassay (EIA [Abbott]). The results were identical in 188 cases. A total of 27 sera containing antibodies to gp41 as demonstrated in the pEX-41 WB, as well as the Abbott recombinant EIA, had no antibodies to the recombinant core antigen as measured in the Abbott EIA. However, 25 of these sera did stain the 24-kilodalton band on a WB with purified virus. Six sera that were positive in all of the conventional confirmatory assays and reacted strongly with the pEX-41 WB did not recognize the surface antigen used in the Abbott recombinant EIA. We conclude that the use of WB prepared with recombinant-derived p41 offers a very sensitive and specific method to detect antibodies to HIV.

Quantification of immunoglobulin on electrophoretic immunoblot strips as a tool for human immunodeficiency virus serodiagnosis

Electrophoretic immunoblotting (EIB [Western blotting]), the main method for verification of human immunodeficiency virus (HIV) seropositivity, needs thorough characterization and standardization. We explored the possibilities of quantifying immunoglobulin G (IgG) bound to EIB strips both by densitometry of the peroxidase-stained bands and by measurement of radioactivity with labeled anti-HIV IgG. The radioactivity method is inherently more exact but was more cumbersome. However, despite saturation phenomena at high IgG densities, the densitometric method was more convenient and yielded reproducible estimates of the amount of bound IgG. We found it useful primarily for documentation of changes in the relative abundance of antibodies to different HIV proteins from individual patients over time. To explore the potential usefulness of the method, we studied a small set of HIV-seropositive persons. The average p24/gp41 color yield ratios and standard deviations in 3 persons with recent seroconversion, 15 healthy subjects, and 6 diseased HIV-seropositive persons were 6.6 +/- 0.9, 2.3 +/- 1.9, and 1.3 +/- 0.5, respectively. These data are in accord with previous qualitative or semiquantitative observations but are too limited for any conclusions regarding the use of quantitative EIB for prognostic use with individual patients. Quantitative EIB is a valuable tool for comparative methodological studies and for research on the protective role of anti-HIV antibodies in acquired immunodeficiency syndrome pathogenesis. Its possible use in prognostication for individual patients must be evaluated in long-term studies.

Comparison of two commercially available anti-HIV ELISAs: Abbott HTLV III EIA and Du Pont HTLV III-ELISA

Serum specimens were tested for HIV antibodies by two commercially available ELISAs (Abbott HTLV III EIA and Du Pont HTLV III-ELISA). The specificity and sensitivity of these assays were determined by comparison with indirect immunofluorescence and Western blot analysis. Specificity ranged from 94.3% in the Abbott assay to 97.9% in the Du Pont-ELISA. The sensitivity was 100% in the Abbott-ELISA and 99% in the Du Pont test. With both tests, false-positive results occurred predominantly in sera from patients with immunological disorders (kidney transplant recipients, lymphoma, Stevens-Johnson syndrome, etc.), whereas symptomatic AIDS-patients, patients with ARC, and persons with a defined risk for HIV infection could be diagnosed unequivocally. Specificity and sensitivity of anti-HIV ELISAs seemed to depend not only on definition of the cutoff value but also on other factors, such as antigen preparation and inactivation measures. Testing of ELISA-reactive sera by confirmatory tests remains necessary.

Liquid competition radioimmunoassay for the detection and quantitation of the HIV p24

Productive infection of permissive cell cultures by HIV has been detected by different assays of which the measurement of reverse transcriptase (RT) activity has been considered highly specific and sensitive. Here we describe the production and characterization of a mouse hybridoma cell line, MB12, secreting monoclonal antibodies to HIV p24, the major core protein, and the use of this monoclonal antibody to develop a type specific indirect liquid competitive radioimmunoassay (RIA) capable of providing earlier detection of the replicating virus than the RT assay. This assay also provides a quantitative analysis of HIV p24, which can be used to study the viral replication in permissive cell cultures. The ease of methodology and the adaptability of the competitive RIA to various assay conditions make this immunoassay suitable for the study of HIV expression in infected cell cultures.

Detection of early anti-p24 HIV responses in EIA- and immunoblot-negative individuals. Implications for confirmatory testing

A sensitive and specific radioimmunoprecipitation assay was developed for the detection and analysis of anti-HIV antibody response in human sera with the use of 125I-labelled purified HIV proteins with subsequent sodium-dodecylsulfate gel electrophoresis (125I-RIPA). The 125I-RIPA was shown to be as specific but at least 1 log more sensitive with respect to the detection of gp41env and p24gag than the immunoblot analysis as tested in serum samples from several risk groups. Sequential sera were obtained from 9 individuals who seroconverted for HIV antibodies. In 4 individuals, antibody to p24gag was detected in earlier serum samples by the 125I-RIPA than by EIA or immunoblot; in the other 5 individuals, the detection of p24gag concorded in enzyme-linked immunosorbent assay (EIA), immunoblot and 125I-RIPA. Moreover, in one of 78 randomly chosen EIA-negative sera from individuals at high risk, antibodies to p24gag could be detected by the 125I-RIPA. This early seroconversion was confirmed 3 months later by means of immunoblotting and EIA. The specificity of the 125I-RIPA was further demonstrated by analyzing sequential EIA-negative serum samples from 10 individuals at risk for AIDS, collected during 2 years at 3-monthly intervals. All 80 serum samples were found to be negative in the 125I-RIPA and the individuals revealed no signs of HIV infection. The 125I-RIPA technique may be a valuable confirmatory assay in the serology of HIV infections. The sensitivity of this test provides a reliable measure of effective sensitivity when new-generation screening tests are evaluated.(ABSTRACT TRUNCATED AT 250 WORDS)

Dot enzyme immunoassay. A simple, cheap and stable test for antibody to human immunodeficiency virus (HIV)

A dot enzyme immunoassay for antibody to HIV has been developed and tested with a panel of positive and negative sera. It has proved to be of equal or greater sensitivity compared with a commercial ELISA kit, is simple and quick to perform, requires neither sophisticated equipment nor highly trained technical staff. The reagents are stable enough for postal distribution in tropical countries and, other than for the antigen, the costs are low, making it an appropriate test for use in the developing world when funds for expensive commercial kits are not available.