Incidence of Human Immunodeficiency Virus Antibody in a Prenatal Population at a Community Hospital

Prenatal human immunodeficiency virus (HIV) screening may reduce vertical HIV transmission. We screened 4,419 prenatal sera and found 38 repeatedly reactive specimens with an HIV-1–HIV-2 enzyme-linked immunosorbent assay. Western blot analysis confirmed four of these specimens as positive for HIV-1 antibodies. Screening detects previously unidentified HIV infections, but false-positive results may also occur.     

Evaluation of an ultrasensitive p24 antigen assay as a potential alternative to human immunodeficiency virus type 1 RNA viral load assay in resource-limited settings

An inexpensive enzyme-linked immunosorbent assay method for human immunodeficiency virus type 1 quantitation, ultrasensitive p24 antigen assay (Up24), was compared with RNA viral load assay (VL). Up24 had 100% sensitivity of detection at a viral load of >/=30,000, with sensitivity of 46.4% at a viral load of <30,000 (232 specimens from 65 seropositive subjects). The assay was highly reproducible, with excellent correlation between duplicates and among three laboratories.     

Evaluation of human immunodeficiency virus seroprevalence in population surveys using pooled sera.

The pooling of individual serum samples to determine human immunodeficiency virus (HIV) seropositivity was examined to assess whether testing pooled sera was technically feasible, cost-effective, and accurate for estimating seroprevalence in large population surveys. The sensitivities and specificities of three commercially available HIV enzyme-linked immunosorbent assay (ELISA) kits were tested using 65 serum pools of 15 individual serum samples each (975 total serum samples) at two different dilutions. With pooled sera, the Organon Teknika Bio-EnzaBead ELISA at half the dilution recommended by the manufacturer showed the best agreement with ELISA and Western blot results of individual sera. In subsequently testing 92 pools, each containing 15 individual serum samples from a population of American patients attending a sexually transmitted diseases clinic, the estimated seroprevalence was 5.27 compared with 4.93% in a test of 1,380 individual serum samples and 5.19% in a test of 4,028 individual serum samples from the same population. In an evaluation of 1,380 African patients using 10 serum samples per pool, the estimated seroprevalence was 5.79 compared with 6.16% in a test of individual sera. These results indicate that ELISA testing with pooled sera is highly sensitive and specific and appears to be a cost-effective means for estimating HIV seroprevalence in large population-based surveys.     

Detection of human immunodeficiency virus antigen in vitreous humor.

The vitreous humor from 11 patients with acquired immunodeficiency syndrome was obtained at postmortem examination and tested for human immunodeficiency virus antigen and antibody by using the Abbott enzyme-linked immunosorbent assay procedures. Five patients had detectable antigen, supporting the recent observation that the virus may directly infect the retina.     

Evaluation of a 2-minute anti-human immunodeficiency virus (HIV) test using the autologous erythrocyte agglutination technique with populations differing in HIV prevalence.

A total of 1,800 blood specimens (1,000 from healthy blood donors, 300 from patients with sexually transmitted disease, and 500 from intravenous drug users) were simultaneously tested with anti-human immunodeficiency virus enzyme-linked immunosorbent assay (ELISA) kits and a newly developed 2-min test for anti-human immunodeficiency virus based on the principle of autologous erythrocyte agglutination (AGEN Biomedical Limited). We found that AGEN's rapid test was as sensitive and specific as the other ELISA kits.     

Detection of respiratory syncytial virus in nasopharyngeal secretions by inhibition of enzyme-linked immunosorbent assay.

An enzyme-linked immunosorbent assay developed for the demonstration of respiratory syncytial (RS) virus immunoglobulin G antibodies was used for the detection of RS virus in specimens of nasopharyngeal secretions (NPS) obtained from children with acute respiratory disease. Samples of NPS were incubated with a fixed amount of standard serum (human serum antibodies to RS virus) before being added to the enzyme-linked immunosorbent assay test plate. A decrease in the optical density value determined for this standard serum was seen with majority of NPS specimens from which RS virus had been isolated in tissue culture. The reliability and the specificity of this inhibiton test were supported by experiments with purified RS virus and by tests with NPS specimens containing other respiratory viruses.     

Enzyme-linked immunosorbent assay for detection and typing of herpes simplex virus

An enzyme-linked immunosorbent assay for herpes simplex virus was tested using commercially available peroxidase-conjugated and unconjugated rabbit antibodies to herpes simplex virus type 1 and type 2 (DAKO immunoglobulins A/S, Copenhagen, Denmark). One hundred and thirty-seven clinical specimens from vesicles and superficial cutaneous lesions were tested and the results compared with virus isolation. In addition 210 herpes simplex virus isolates were typed. Forty-four specimens yielded herpes simplex virus both in the enzyme-linked immunosorbent assay and in tissue culture and 79 were negative in both tests. Fourteen were positive in isolation but negative in the enzyme-linked immunosorbent assay. Seventy-three isolates were typed as herpes simplex virus type 1 and 137 as herpes simplex virus type 2. The enzyme-linked immunosorbent assay was found to be rapid and easy to perform but less sensitive than conventional isolation in routine diagnostic work. For typing of isolates it was found to be a useful method for distinguishing herpes simplex virus type 1 and type 2.     

Detection of hepatitis A virus and antibody by solid-phase radioimmunoassay and enzyme-linked immunosorbent assay with monoclonal antibodies.

Monoclonal antibodies (K3-2F2 and K3-4C8) raised against hepatitis A virus were used to develop a solid-phase radioimmunoassay and enzyme-linked immunosorbent assay for the detection of hepatitis A virus and antibody. Assays with this pair of monoclonal antibodies were compared in parallel with similarly constructed solid-phase radioimmunoassays and enzyme-linked immunosorbent assays in which human polyclonal serum was used. The monoclonal antibody assay proved to be more sensitive for the detection of hepatitis A virus from fecal specimens as well as for anti-hepatitis A virus immunoglobulin G (IgG) and IgM in sera.     

Performance of a commercial, type-specific enzyme-linked immunosorbent assay for detection of herpes simplex virus type 2-specific antibodies in Ugandans

Two hundred forty-eight human immunodeficiency virus (HIV)-positive and 496 HIV-negative subjects in Uganda were tested by HerpeSelect herpes simplex virus type 2 enzyme-linked immunosorbent assay (ELISA) and Western blotting to optimize the ELISA for use in this population. A higher index cutoff value was required for optimal sensitivity and specificity, and overall performance of the assay was not affected by HIV status.     

Detection and differentiation by sandwich enzyme-linked immunosorbent assay of human T-cell lymphotropic virus type III/lymphadenopathy-associated virus- and acquired immunodeficiency syndrome-associated retroviruslike clinical isolates.

Monoclonal antibodies can be used in sandwich enzyme-linked immunosorbent assays to measure viral antigens. Such an assay was developed to detect the core protein, p24, of human T-cell lymphotropic virus type III and lymphadenopathy-associated virus, etiologic agents of the acquired immunodeficiency syndrome (AIDS). Another AIDS-associated virus, AIDS-associated retrovirus type 2 (ARV-2) could not be detected in this assay because of the low affinity of one of the monoclonal antibodies to ARV-2 p24. Detection of ARV-2 was accomplished with a monoclonal antibody-rabbit polyclonal antibody sandwich enzyme-linked immunosorbent assay. These two assays were used to efficiently detect AIDS-related viruses in lymphocyte cell cultures and to distinguish strains of the viruses.     

Detection of Breda virus antigen and antibody in humans and animals by enzyme immunoassay.

Enzyme immunoassays were developed for the detection of Breda virus antibody and antigen. Cattle sera collected in the United Kingdom were found to have a high prevalence of antibody (55%) to Breda virus when examined in a competitive enzyme-linked immunosorbent assay. A low prevalence of antibody was found in pigs (2.2%), and no antibody was found in sheep or goat sera. No antibody to either Breda virus or Berne virus was detected in human sera collected from veterinarians and farm workers. Only 1 of 430 human fecal specimens (0.2%) contained Breda virus antigen detectable by enzyme-linked immunosorbent assay.     

A Luminescence Western blot with enhanced sensitivity for antibodies to human immunodeficiency virus

A luminescence assay was adapted for detection of peroxidase-labelled secondary antibodies, which react specifically with antibodies to human immunodeficiency virus on Western blots. This method is about one hundred times more sensitive than either commercial enzyme-linked immunosorbent assay or the chromogenic peroxidase assay on Western blots and detects seroconversion earlier than any other technique currently available.     

High Human Herpesvirus 8 Seroprevalence in the Homosexual Population in Switzerland

The seroprevalence of human herpesvirus 8 (HHV-8) in the Swiss population was investigated. By enzyme-linked immunosorbent assay, sera reactive to the recombinant HHV-8 antigen orf 65.2 were found in 24% of human immunodeficiency virus (HIV)-positive patients without and in 92% of HIV-positive patients with Kaposi’s sarcoma. Surprisingly, 20% of homosexual HIV-negative men, versus only 7% of heterosexual HIV-negative individuals and 5% of blood donors, had antibodies to HHV-8.     

Comparison of ortho respiratory syncytial virus enzyme-linked immunosorbent assay and HEp-2 cell culture.

Two hundred seventy nasopharyngeal aspirates were tested in duplicate with the Ortho Diagnostics, Inc. (Raritan, N.J.), respiratory syncytial virus antigen enzyme-linked immunosorbent assay. The test was sensitive (80 to 82%) and specific (96%) when compared with cell culture. The enzyme-linked immunosorbent assay detected seven antigen-positive specimens not among the 71 specimens that were positive for respiratory syncytial virus in cell culture. A blocking test confirmed those specimens as true positives (specificity, 100%).     

Development and evaluation of immunoassay for detection of antibodies to the feline T-lymphotropic lentivirus (feline immunodeficiency virus).

The feline T-cell lymphotropic lentivirus (feline immunodeficiency virus) is a recently described feline-specific retrovirus that can produce chronic immunodeficiency-like disorders in cats. A microdilution plate format enzyme-linked immunosorbent assay has been developed to detect the presence of antibody to the virus in feline serum or plasma. Temporal studies performed with experimentally infected animals show that seroconversion can be demonstrated 3 to 4 weeks after exposure to the virus. Results of a serosurvey (n = 1,556 samples) indicate that infection is fairly common in both clinic (5.2%) and sick cat (15.2%) populations. Western blot (immunoblot) and sodium dodecyl sulfate radioimmunoprecipitation assays were developed to confirm microdilution plate test results and to identify peptides specific for the feline immunodeficiency virus. All microdilution plate test positive results and selected negative results were confirmed by one or both of these procedures. These data demonstrate that this microassay plate enzyme-linked immunosorbent assay is a very sensitive and specific test for detection of antibody to the feline immunodeficiency virus.     

Comparison of the human immunodeficiency virus (HIV) type 1-specific immunoglobulin G capture enzyme-linked immunosorbent assay and the avidity index method for identification of recent HIV infections

The sensitivity and specificity of the human immunodeficiency virus (HIV) type 1-specific immunoglobulin G capture enzyme-linked immunosorbent assay (BED-CEIA) were compared with those of the avidity index method to identify recent HIV infection using a panel of 148 samples (81 patients) representing durations of infection ranging from 0 to 222 weeks. The results from the two tests were similar (sensitivity of 80% versus 74% [P = 0.53]; specificity of 86% versus 82% [P = 0.67]).     

Potential of a simplified p24 assay for early diagnosis of infant human immunodeficiency virus type 1 infection in Haiti

With global efforts to scale up the prevention of mother-to-child transmission services and pediatric antiretroviral therapy, there is an urgent need to introduce a simple, low-cost infant human immunodeficiency virus test in the field. We postulated that the p24 antigen capture enzyme-linked immunosorbent assay could be simplified by eliminating signal amplification without compromising diagnostic accuracy.     

Antibody to a synthetic oligopeptide in subjects at risk for human immunodeficiency virus infection.

Detection of antibodies to human immunodeficiency virus (HIV) by enzyme-linked immunosorbent assay (ELISA) is the accepted method to screen blood products at risk to transmit infection. The presence of antibodies to HIV in 565 serum specimens from 274 patients with acquired immunodeficiency syndrome (AIDS) or AIDS-related complex, symptomatic and asymptomatic subjects at risk for AIDS, and controls was determined with an ELISA that incorporates synthetic peptides (designated E32/E34) representing sequences in the envelope glycoprotein gp41. Of 105 specimens from patients with AIDS or AIDS-related complex, 3 specimens that were negative by commercially licensed ELISA and immunoblot test were similarly unreactive in the E32/E34 ELISA. For homosexual men with generalized lymphadenopathy, 186 specimens were positive by the E32/E34 ELISA and 63 specimens were negative. In comparison, with the licensed ELISA, 184 of these samples were positive and 65 samples were negative. The two samples that were positive in the E32/E34 ELISA but not the commercial kit were also positive by immunoblotting. Sequential sera from one individual who apparently underwent seroconversion according to the commercial assays were all positive by E32/E34 ELISA and immunoblotting. Thus, the ELISA with synthetic peptides is an extremely sensitive and specific test of antibody response to HIV and has not yet yielded a negative result with a Western blot (immunoblot)-confirmed antibody-positive serum.     

Rapid diagnosis of herpes simplex virus infections by enzyme-linked immunosorbent assay.

A total of 457 clinical specimens were tested for the presence of herpes simplex virus (HSV) by isolation in cell culture and by enzyme-linked immunosorbent assay. HSV antigen was detected by enzyme-linked immunosorbent assay in 94% of the clinical specimens from which the virus was isolated. The detection rate was improved to 100% when specimens were either assayed within 24 h or stored frozen at a constant temperature (-20 degrees C) for up to 14 days. Type-specific HSV antigen was also detected in 6% of culture-negative specimens. The assay can be completed in 5 h or less, and commercially available immunoglobulins are used. Enzyme-linked immunosorbent assay is a rapid and sensitive method for the diagnosis of HSV infection and can be used to improve the management of pregnant women with a history of genital herpes and of neonates and others with serious HSV infection which may require specific antiviral therapy. It also offers an alternative to cell culture for routine diagnosis of HSV infections.