Presence Of anti-HIV Antibodies Research Articles

Prevalence and risk behaviour for human immunodeficiency virus 1 infection in Marajó Island, Northern Brazil

Background: Human immunodeficiency virus 1 (HIV-1) infection is a global public health problem, but, so far, there is no published information regarding the epidemiology of HIV-1 in Marajó Archipelago (Pará, Brazil).Aim: The present study reports the occurrence of infection by HIV-1 in four municipalities of the Marajó Island, Pará, Brazil.Subjects and methods: A total of 1877 samples were collected from volunteer blood donors (1296 women and 551 men) living in the municipalities of Anajás, Chaves, Portel and São Sebastião da Boa Vista. Information about risk behaviour assessment was obtained from a questionnaire. Plasma samples were tested for the presence of anti-HIV antibodies using serological tests. The infection was confirmed by nucleic acid amplification assays.Results: Twelve samples were seropositive for HIV by ELISA. Western blot analysis showed four positive samples, eight indeterminate patterns and one found to be negative. Molecular analysis revealed three positive samples. Risk factors for HIV-1 infection included absence of condoms during sexual intercourse (41.3%, São Sebastião da Boa Vista), use of illicit drugs (5.8%, Anajás) and early initiation of sexual activities, from 10–15 years (30.7%).Conclusion: Although the study indicates a low HIV-1 prevalence in Marajó Island, some factors may increase the risk for HIV-1 and these include early sexual initiation, unprotected sexual intercourse and the use of illicit drugs.

Allosteric molecular sensing of anti-HIV antibodies by an immobilized engineered β-galactosidase

The main objective is to demonstrate the feasibility of qualitative and semi-quantitative determination of anti-HIV antibodies, based on the allosteric response of an immobilized engineered Escherichia coli β-galactosidase. The suitability of this enzyme and the conditions for homogeneous assay had been previously demonstrated. In the present work, the operational conditions for engineered E. coli β-galactosidase immobilization on activated agarose supports have been determined. A solid biocatalyst has been prepared and characterized in order to determine the activation degree of the immobilized enzyme in the presence of anti-HIV antibodies. The solid-phase biocatalyst has been shown to be able to modulate its activity and produce an unequivocal signal in presence of anti-HIV containing sera from different patients. Finally, the conceptual design of a possible assay based on the above methodology is proposed.

False-negative HIV antibody test results

Ideally HIV antibody tests have to be both extremely sensitive and able to recognize all known HIV subtypes. Three patients whose sera failed to react with a synthetic oligopeptide-based HIV antibody test are described in this report. The patients were a Pakistani male infected recently, an Australian male infected for several years, and a Ugandan woman with AIDS. The presence of anti-HIV antibodies was confirmed by means of a standard algorithm with different assay formats. All three sera failed to react in one antiglobulin enzyme-linked immunosorbent assay (ELISA) (Bioelisa HIV-1+2, Biokit SA). No single underlying reason could be identified for the assay failure in the three cases. The first patient, probably infected recently when first tested, was strongly positive by the same assay a year later, confirming the relative insensitivity of oligopeptide assays reported previously for detecting the early antibody response. The other two patients appear to have been infected for several years. Although unlikely to have been infected with a non-clade B virus, the sample from patient 2 lacked detectable antibody to the transmembrane glycoprotein (gp41), the site of the synthetic oligopeptides. Patient 3, of Ugandan origin, was found to be infected with a non-clade B virus. Although her serum reacted strongly to subtype B gp41 in Western blot, it failed to react in the antiglobulin ELISA. Since there appears to be no single common explanation for these three failures there is little opportunity to identify prospectively those situations where testing using assays employing synthetic oligopeptides on the solid phase is likely to fail.

Two successive HIV contaminations from subjects in the window period

We report a case of HIV seroconversion in a health-care worker, due to successive contaminations (i) from a blood donor to a recipient and (ii) from the recipient to the health-care worker. Unexpectedly, both infections occurred during the HIV serological window period. A nurse sustained a needle-stick injury with a large gauge hollow-bore needle on 24 January 1996. On the same day, she and the source patient were tested for anti-HIV antibodies by Genelavia Mixte (Sanofi Diagnostics Pasteur, Marnes-la-Coquette, France) and Axsym HIV (Abbott laboratories, North Chicago, Illinois, USA) assays. The results were negative for both subjects. According to legal procedure, an HIV serology check was performed on the nurse 3 months after exposure. The presence of anti-HIV antibodies was observed by enzyme-linked immunosorbent assay and was confirmed by HIV-1 Western blot. Because the nurse reported no risk factors for HIV infection, HIV serology was again performed on a frozen sample from the source patient collected on the day of the needle-stick injury. This serum was found to be weakly positive (three times above cut-off) by Genscreen (Sanofi Diagnostics Pasteur), one of the most sensitive anti-HIV screening tests available [1]. p24 antigen was also positive with a high concentration (> 640 pg/ml). These results indicated that the patient was undergoing HIV seroconversion at the time of the nurse's exposure. The source patient, a 89 year-old woman who was hospitalized for a digestive bleeding, received six red cell units and two platelet concentrates between 6 December 1995 and the 28 January 1996. She died on the 2 February 1996. Sixteen out of the 17 implicated donors were traced, retested and found to be anti-HIV negative. The 17th donor did not answer to the inquiry, but HIV serology performed on 15 February 1996 in a hospital laboratory revealed the presence of anti-HIV-1 antibodies. His implicated donation was given on 24 November 1995 and was transfused to the patient on 6 December 1995. A frozen aliquot of this donation was investigated and was found to be anti-HIV-negative by Genscreen, p24 antigen-negative by Vironostika (Organon Teknika, Oss, The Netherlands), but was HIV RNA-positive by PCR (Amplicor, Roche, Branchburg, New Jersey, USA) and an in-house nested PCR performed in pol region. The results from the three subjects are summarized in Table 1.Table 1: . Data from three subjects implicated in two successive HIV contaminations.We describe an exceptional case of transfusion-transmitted HIV infection by a seronegative donor who was undergoing seroconversion and was in fact HIV RNA-positive. According to some predictions [2], this case highlights the capacity of nucleic acid amplification assays to eliminate the infectious but seronegative donors by reducing the length of the pre-seroconversion window period. Nevertheless, the cost and the complexity of such a measure in mass screening donations [3] must be balanced with the risk of transmitting HIV infection by transfusion of screened blood, which today is very small (1 per 1 million donations in France [4]). Because the precise date of the contamination is often unknown for HIV-infected patients, the length of window period is generally estimated by mathematical models [2]. In this transfusion-transmitted HIV infection, the interval from exposure to seroconversion was 49 days. The nurse was also infected by a subject in preserocon-version stage. The mean risk of transmission of HIV after percutaneous exposure has been estimated to be 0.3% with a higher rate when the HIV load in the source patient's blood is high [5]. Because the p24 antigen level was high and the injury was deep, it can be assumed that this was the case for this patient. On the other hand, if the source patient had been tested for p24 antigen in addition to anti-HIV antibodies, we can presume that the nurse would have been treated sooner by chemoprophylaxis. Thus, one of the recommendations for the improvement of the management of HIV post-exposure could be the implementation of a p24 antigen test in the source patient at the time of health-care worker exposure. Acknowledgement The authors thank F. Simon from the Virology Unit of the Hôpital Bichat, Paris, for performing nucleic acid analysis.

Use of pooled residual laboratory sera to assess human immunodeficiency virus prevalence among patients in Italy

An anonymous unlinked seroprevalence study of human immunodeficiency virus (HIV) infection was performed by testing pools of ten sera remaining from specimens submitted consecutively to clinical pathology laboratories at 18 Italian public hospitals during four consecutive days in April 1991. Sera from positive pools were retested individually by three different enzyme immunoassays (EIAs) and considered positive if reactive by all three assays. Only the sera with discordant EIA results were retested by Western blot. Of a total of 22,590 sera, 278 were HIV positive (1.2%). The highest rates were seen in hospitals located in metropolitan areas (1.5%), in infectious disease departments (28%) and in drug addiction treatment units (28%); among men aged 21-30 (4.6%) and 31-40 years (4%); and among women aged 21-30 years (1.6%). The distribution of seropositive patients by gender and age group suggests an increasing role of heterosexual transmissions of the infection. The presence of anti-HIV antibodies in sera from patients of both sexes, in all age groups, and from all clinical settings reinforces the need for health care workers to adhere to universal precautions issued to prevent occupational bloodborne infections.

Two-colour combination enzyme-linked immunosorbent assay for the simultaneous detection of HBV and HIV infection

To reduce the cost, time and waste in screening for HIV and HBV infections a combined assay for HIV-1 and -2 antibodies and HBsAg has been developed. Monoclonal anti-HBs antibodies were co-immobilized with synthetic peptides representing immunodominant regions of HIV-1 and -2. The presence of anti-HIV antibodies in the samples was detected with alkaline phosphatase-labelled anti-human IgG and of HBsAg with horseradish peroxidase-labelled monoclonal anti-HBs antibodies by a sequential substrate reaction. In this assay, HBsAg was detectable in a concentration range between 0.25 and 0.30 U/ml and the results were available within 3 h. The specificity, tested on 5000 serum samples from blood donors after confirmation, was 99.8% for HBsAg and 99.5% for anti-HIV antibody detection. All serum samples taken from 600 HIV-1- and 115 HIV-2-infected individuals were correctly classified as reactive. The two-colour HBsAg-anti-HIV-1/-2 combination ELISA meets all the requirements of single parameter assays with regard to precision, stability and robustness.

Antibody-dependent cellular cytotoxicity against HIV-coated target cells by peripheral blood monocytes from HIV seropositive asymptomatic patients.

Cytotoxic effector cells like cytotoxic T cells, NK cells, monocytes/macrophages, and neutrophils can lyse directly HIV-infected or HIV-coated cells in the absence or presence of anti-HIV antibodies. Therefore, these cytotoxic mechanisms can be invoked either in the control of HIV infection at early stages of the disease or in the generalized immunosuppression observed at later stages of the disease. The relationship between anti-HIV effector mechanisms and disease, however, remains elusive. The present study investigates in HIV+ seropositive asymptomatic patients peripheral blood monocytes (PBM)-mediated antibody dependent cellular cytotoxicity (ADCC) against HIV-coated target cells in the presence of heterologous or autologous anti-HIV serum. To test for specific ADCC against HIV Ag, a T4+ CEM.TR line resistant to TNF and macrophage-mediated cytotoxicity was selected in vitro. ADCC was performed in an 18-h 51Cr-release assay using CEM.TR cells coated with inactivated HIV. Unlike PBM from normal controls, significant ADCC was observed by PBM from HIV+ seropositive patients in the presence of pooled HIV+ antiserum. The ADCC activity was specific for HIV and was dependent on the E:T ratio and the antiserum dilution used. Upon activation of PBM with rIFN-gamma, both normal and HIV+ PBM-mediated ADCC against HIV-coated CEM.TR. Furthermore, ADCC activity by PBM from HIV+ seropositive patients in the presence of their autologous serum was examined. Significant ADCC activity was observed and was dependent on the E:T ratio and serum dilution used. The findings demonstrating anti-HIV ADCC activity by PBM from HIV+ seropositive individuals and their autologous sera support the notion that monocyte-mediated ADCC may be operative in vivo.

Anonymous HIV Testing on Newborns

To the Editor.— We read with interest the report by Novick et al 1 regarding the prevalence of human immunodeficiency virus (HIV) infection in parturient women in New York State. In Italy, where cases of acquired immunodeficiency syndrome (AIDS) among women and children represent 17.7% and 3.2%, respectively, of all patients with AIDS reported, we carried out a program similar to that described by Novick et al. Using blood samples collected on adsorbent paper during June through December 1988 for the routine detection of hereditary metabolic disorders, we examined for the presence of anti-HIV antibodies (HIV-Ab) 23 492 consecutive newborn babies from 63 hospital nurseries in nine Italian regions. At the National Blood Transfusion Center of the Italian Red Cross, one blood-saturated disk was punched out from each collection paper, without identification of the patient. The sample was eluted in phosphate-buffered saline as described previously 2 and screened for HIV-Ab

AIDS in a Hemophiliac Child Transmitted by Cryoprecipitate and with Negative HIV Antibodies by Western Blot

We report a 3-year-old hemophiliac child who became infected with human immunodeficiency virus (HIV) from cryoprecipitate treatments and subsequently developed acquired immunodeficiency syndrome (AIDS). Though evidence of HIV infection was suggested by the presence of anti-HIV antibodies by enzyme-linked immunosorbent assay, the Western blot assay was negative. A second confirmatory test for HIV antibodies, flow cytometric immunofluorescence assay (FIFA), was performed demonstrating specific anti-HIV antibodies. This patient with clinical and immunological manifestations of AIDS illustrated that the diagnosis should not be discounted because of the failure to demonstrate anti-HIV antibodies by the Western blot assay and also demonstrated the utility of the FIFA as a more sensitive confirmatory assay of specific anti-HIV antibodies.