Serologic testing for human immunodeficiency virus antibodies

A serological screening assay of human immunodeficiency virus type 1 antibodies based on recombinant protein p24-gp41 as a fusion protein expressed in Escherichia coli

The objective of this study was expression of a recombinant fusion protein p24-gp41 to gain a proper folding pattern of the proteins which could be recognized by specific antibodies against human immunodeficiency virus type 1 (HIV-1) for development of a reliable serodiagnostic kit. Serodiagnostic method using enzyme-linked immunosorbent assay (ELISA) with the expressed recombinant fusion protein p24-gp41 was carried out to test the sensitivity and specificity of the protein using human sera and various reference panels from Boston Biomedica Inc. (BBI). The level of the expression was determined to be 30% and the final recovery from fermentation and purification process was calculated as 80 mg/L with more than 98% purity. The developed ELISA assay was demonstrated to have 100 and 99.5% sensitivity and specificity, respectively, detecting anti-HIV-1 antibody using 900 positive and 10,000 negative human sera. The developed assay showed reliable results in comparison with other reference HIV ELISA kits using various BBI panels as well. In conclusion, the recombinant fusion protein p24-gp41 was expressed and used to develop a serodiagnostic kit for screening of the HIV-1 with high sensitivity (100%) and specificity (99.5%) which could be useful for screening large groups of blood donors.

When risk is low: primary care physicians' counseling about HIV prevention

To explore the conceptualization of risk by primary care physicians about behaviors associated with a relatively low risk of HIV transmission, we performed open-ended telephone interviews with 59 primary care physicians throughout the United States. During the interviews, physicians were asked to respond to a series of clinical vignettes presenting situations where the risk of HIV transmission is relatively low or unknown. We performed a qualitative content analysis of physicians' responses to these clinical vignettes. We found that relatively few information-gathering statements were made in an effort to elicit the patient's perspective regarding risk, and that risk counseling by physicians often followed an 'all or nothing' heuristic that manifested itself as the advice to take maximum precautions under situations of any perceived risk, no matter how small. In addition, HIV testing was often incompletely explained. When combined with the all or nothing heuristic, this created advice that was potentially harmful by using testing as a means to achieve zero risk and forgo protective strategies in settings where patients may potentially be in the HIV negative 'window' phase of infection.

[Intestinal lymphoma. A long diagnostic path]

CASE REPORT

We describe the case of a 43-year-old patient with a Burkitt lymphoma in the small intestine, who initially presented with abdominal discomfort, weight loss, constipation and neurological symptoms.

DIAGNOSIS

In terms of differential diagnosis other inflammatory and tumorous diseases had to be considered. Non-Hodgkin lymphomas are common malignant afflictions of the GI-tract. The total body tumor burden is the principal determinant of prognosis. Serum lactate dehydrogenase (LDH) level is one parameter that reflects the tumor burden. On the other hand abdominal mass, bone marrow and central nervous system involvement are negative prognostic factors. Lymphomas can invade in the CNS at any time during the course of disease. This is generally associated with a poor prognosis if not treated immediately.

TREATMENT

High doses of cyclophosphamid and MTX have been shown successful in the treatment of Burkitt lymphoma. Almost all relapses occur on therapy or shortly after termination of treatment. Therefore, criteria are needed to select patients of higher and lesser risk to protect the latter from the further intensification of therapy.

Pediatric human immunodeficiency virus infection

In the past decade, an increase in pediatric human immunodeficiency virus (HIV) infection has had a substantial impact on childhood morbidity and mortality worldwide. The vertical transmission of HIV from mother to infant accounts for the vast majority of these cases. Identification of HIV-infected pregnant women needs to be impoved so that appropriate therapy can be initiated for both mothers and infants. While recent data demonstrate a dramatic decrease in HIV transmission from a subset of women treated with zidovudine during pregnancy, further efforts at reducing transmission are desperately needed. This review focuses on vertically transmitted HIV infection in children, its epidemiology, diagnostic criteria, natural history, and clinical manifestations including infectious and noninfectious complications. An overview of the complex medical management of these children ensues, including the use of antiretroviral therapy. Opportunistic infection prophylaxis is reviewed, along with the important role of other supportive therapies.

Multicentre study for diagnostic evaluation of an assay for simultaneous detection of antibodies to HIV-1, HIV-2 and HIV-1 subtype 0 (HIV-0)

The aim of the study was to evaluate a new ELISA for detection of HIV-1, HIV-2 and HIV-1 subtype 0 (HIV-0) antibodies. The assay format is based on the antigen sandwich principle. To enable specific detection of HIV-0 antibodies, in addition to HIV-1 and HIV-2 antigens HIV-0 antigen is used for coating the solid phase and for the conjugate. The results show that all 12 HIV-0 samples tested were detected with a high degree of reactivity, as were all the 1,144 anti-HIV-1 and 424 anti-HIV-2 positive samples. The capacity of the test to enable early detection of seroconversions is equivalent to that of other sandwich ELISAs. The specificity of the assay was determined to be 99.89/99.94% (initial/after retest) using 58,366 samples, which is superior to the other ELISAs used for comparison. Even with difficult samples (i.e. samples of African origin, samples known to cause false-positive reactivity in different ELISAs, or samples containing potential interference factors) there were very few false-positive reactions. Therefore, the new assay is well suited for screening blood donations as well as for evaluating samples from patients of different geographic origin.

Lack of relationship between human immunodeficiency virus infection and systemic lupus erythematosus

The objective of this work was to determine whether HIV-1 and HIV-2 could be involved in the pathogenesis of systemic lupus erythematosus (SLE). Seventy-five consecutive Caucasian patients with SLE presenting at one institution over a 2-year period were studied. Serum samples were surveyed for anti-HIV-1 antibodies by a commercial ELISA coated with HIV-1-p24. For confirmation, conventional immunoblots were performed with the following antigens: HIV-1-gp41, p31, p24 and p17 (recombinant) and HIV-2-gp36 (synthetic peptide). Additionally, Western blots with HIV-1-gp160, gp120, gp41, p65, p51, p24 and p18 bands were applied. Seventeen (23%) patients exhibited reactivity with HIV-1-p24 in the ELISA, but in the immunoblots and Western blots these sera samples were negative. Patients with SLE may exhibit a reactivity with HIV-1-p24 in the ELISA for HIV infection screening but not in the confirmatory blots. This false-positive reactivity is probably due to molecular mimicry between autoantigens and retroviruses or a contaminant or artefacts in the antigen preparation procedure.

The diagnostic challenge of the child born "at risk" for HIV infection

Standard serologic tests for human immunodeficiency (HIV)-specific antibodies are difficult to interpret in young infants born "at risk" for HIV infection owing to transplacentally acquired maternal IgG. This article reviews the treatment advantages of early diagnosis of HIV infection, the indications for HIV testing in children, the general principles and use of individual HIV assays, and an idealized evaluation schedule for infants born "at risk" for HIV infection.

Utility of quantitative enzyme immunoassay reactivity for predicting human immunodeficiency virus seropositivity in low- and high-prevalence populations

To assess the utility of quantitative enzyme immunoassay (EIA) reactivity for predicting human immunodeficiency virus seropositivity, we evaluated 22,823 serum samples from homo- and bisexual men, heterosexual intravenous drug users, and other heterosexuals with initial screening by EIA, retesting of reactive samples in duplicate, and confirmatory Western blot (immunoblot) testing. Quantitative EIA reactivity was determined by a mean of the optical density ratio of the three assays performed for each reactive specimen. A total of 1,773 samples (7.8%) were repeatedly reactive, and 1,747 (7.7%) were confirmed Western blot positive. All 26 EIA-reactive-Western blot-negative samples had low-level EIA reactivity (ratio < 2.2), while most (86%) of the Western blot-positive samples had high-level reactivity (ratio, > 3.0). The positive predictive value for samples with moderate-to-high-level EIA reactivity (ratio, > 2.2) was 100% for all risk groups. These results support the value of quantitative EIA reactivity in predicting human immunodeficiency virus seropositivity and suggest that confirmatory testing of specimens with high-level reactivity is not necessary in all situations.

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.

Comparison of a radioimmunoprecipitation assay to immunoblotting and ELISA for detection of antibody to African swine fever virus

A radioimmunoprecipitation assay (RIPA) has been developed for detection of antibody to African swine fever virus (ASFV) and compared with the immunoblot assay with regard to sensitivity and specificity. Two hundred seven field sera, obtained from pigs in Spain from different geographic areas between 1975 and 1986, that were positive by ASFV enzyme-linked immunosorbent assay (ELISA) were also analysed by immunoblot assay and RIPA. By serum dilution experiments, the RIPA appeared at least as sensitive as the ELISA and immunoblotting tests, although ELISA and RIPA detected antibodies to ASFV earlier in natural infection than did the immunoblot assay, as disclosed by animal inoculation studies. The most antigenic ASFV-induced proteins in natural infection detected by RIPA were the viral proteins p243, p172, p73, p25.5, p15, and p12 and the infection proteins p30 and p23.5. In the immunoblot assay, the proteins that were most reactive with the same sera were the viral protein p25.5 and the infection proteins p30, p25, and p21.5. Only 1 serum, from an animal infected with ASFV, was negative by immunoblot assay but showed a positive result by RIPA. A modification of conventional RIPA was performed using a dot transference of immunoprecipitated proteins to a nitrocellulose filter. This modification simplified the conventional RIPA procedures by eliminating the electrophoresis of immunoprecipitated proteins without affecting sensitivity and specificity. The ease of use, specificity, and the sensitivity comparable to that of the immunoblot assay make the RIPA a useful confirmatory assay for sera that yield conflicting results in other ASFV antibody assays.

Antigen detection for human immunodeficiency virus

The recent development of enzyme immunoassay procedures for the direct determination of human immunodeficiency virus (HIV) antigens has been of significant benefit in both clinical and research applications. The historical development of HIV antigen assays as well as their current and future applications for use in the clinical microbiology laboratory are reviewed. A detailed description of selected commercially available assays is presented, and a comparison is made of various parameters, including sensitivity, specificity, and cost. The use of the HIV antigen assay as an alternative to the reverse transcriptase assay in virus culture applications is also discussed. In addition, the diagnostic and prognostic utility of the HIV antigen assay is considered for various patient groups, including neonatal, high-risk asymptomatic, seronegative, and seropositive patient populations. The use of the HIV antigen assay as an adjunct to anti-HIV antibody testing, as well as its utility in assessing the therapeutic efficacy of antiviral drug therapy, is discussed. The biology of HIV antigen expression and modulation of anti-HIV antibody titers during infection are also discussed in terms of two possible models.