Indeterminate human immunodeficiency virus type 1 western blots: seroconversion risk, specificity of supplemental tests, and an algorithm for evaluation

Article Abstract:

The human immunodeficiency virus type 1 (HIV-1) is the virus that causes AIDS. HIV-1 infections are diagnosed by testing a sample of blood to see if it contains HIV-1 antigens (pieces of virus) or HIV-1 antibodies (proteins made by the body to attack the virus). This report describes the laboratory diagnosis of HIV infection and presents an algorithm for evaluating uncertain results. Routine screening of blood samples is performed using a simple test called the enzyme immunoassay (EIA). In this test, HIV-1 antigens are firmly attached to a small plate or a dip stick. The blood sample is added to the plate or stick and after a short incubation period the plate or stick is rinsed with several different solutions. If HIV-1 antibodies were present in the blood, indicating an HIV-1 infection, the plate or dip stick will change color. When a person has a positive EIA test, a second EIA test is performed. If the second test is negative and the person does not engage in high-risk behaviors (intravenous drug use or homosexual relationships), no further testing is conducted. If the second EIA test is positive, then the Western blot test is performed. This test is more difficult to do than the EIA and requires a fully equipped laboratory. Approximately 80 to 90 percent of the blood samples that test positive in the EIA also test positive in the Western blot. The remaining 10 to 20 percent of blood samples with unclear results and are called indeterminate Western blots (IWB). If a person has two positive EIA tests and one positive Western blot, the person is considered to have an HIV-1 infection. If a person has two positive EIA tests and an IWB, then another Western blot test should be performed one month later. If a person who has an IWB engages in high-risk behaviors, repeat testing should be performed at three to six month intervals. In most cases of HIV-1 infection with an initial IWB result, the second Western blot (performed one month after an IWB result) is positive. However, if the second Western blot is negative then the person is not considered to have HIV-1 infection. Risk of HIV infection is an important consideration in monitoring patients who have a second negative EIA or an IWB. (Consumer Summary produced by Reliance Medical Information, Inc.)

Research, Methods, Enzyme-linked immunosorbent assay, HIV seropositivity, HIV positive, Western immunoblotting, Western blot

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Prevalence of antibodies to human immunodeficiency virus and to human T cell leukemia virus type 1 in transfused sickle cell disease patients

Article Abstract:

In recent years, several cases of human immunodeficiency virus (HIV) infection have been reported in patients with sickle cell disease at the Howard University Center for Sickle Cell Disease. Patients with sickle cell disease require multiple blood transfusions during the course of their illness. Consequently, they are at risk for contracting HIV infection and human T cell leukemia virus type 1 (HTLV-1) infection from transfused blood products. Currently, the predicted risk of developing HIV infection after receiving a blood transfusion is approximately 1:40,000. Patients with sickle cell disease who received transfusions between 1978 and 1985 were examined for the presence of HIV and HTLV-1 antibodies. A total of 116 patients with sickle cell disease were identified. During the period under study, 88 of the patients had received an average of 18.6 blood transfusions. Antibodies to HIV were not detected in any of the patients. HTLV-1 antibodies were detected in 9 of the 116 patients. Three of the nine patients with HTLV-1 antibodies came from the Caribbean or West Africa. It is not possible to determine if the patients acquired HTLV-1 from the blood transfusions. The authors recommended screening blood donors for HTLV-1 infection. These results indicate that sickle cell disease patients have a low risk for developing HIV infection from blood transfusions received at a time when blood donors were not screened for HIV antibodies. (Consumer Summary produced by Reliance Medical Information, Inc.)

Complications and side effects, Sickle cell anemia, HIV (Viruses), HIV, Disease transmission, HTLV-I infections, Blood transfusion, HTLV-I (Virus)

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Absence of chronic human immunodeficiency virus infection without seroconversion in intravenous drug users: a prospective and retrospective study

Article Abstract:

The human immunodeficiency virus type-1 (HIV-1) is the virus that causes AIDS. During infection with HIV-1, the immune system produces substances called antibodies to fend off the virus. The routine method for diagnosing an HIV-1 infection involves testing a sample of blood for the presence of HIV-1 antibodies. If HIV-1 antibodies are present, the person is said to be HIV-seropositive and to have an HIV-1 infection. In a recent study, the virus itself was reported to be present in people who were seronegative. The diagnosis was made using viral cultures or by testing for viral DNA (the genetic material). Based on these findings it has been suggested that the HIV may be present in a silent form or carrier state for several years without causing HIV-1 antibodies to be made. To determine if this is true, 124 intravenous drug users who tested seronegative for HIV-1 were studied. Blood samples were taken at six-month intervals and tested for viral DNA using a method called the polymerase chain reaction (PCR). Only 2 of the 124 subjects tested positive for viral DNA. These findings indicate that long-term infection with HIV-1 in an individual who tests seronegative is rare. Thus, testing blood samples for the presence of HIV-1 antibodies is sufficient to determine if a person does not have HIV-1 infection. (Consumer Summary produced by Reliance Medical Information, Inc.)

Evaluation, Measurement, Polymerase chain reaction, Blood chemical analysis, Intravenous drug abuse, blood, HIV antibodies, HIV seroprevalence

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