No abstract

An immunoassay (IA) that simultaneously detects both antibody to human immunodeficiency virus (HIV) and HIV p24 antigen (Architect HIV Ag/Ab Combo) was evaluated for its ability to detect HIV infection by using a panel of specimens collected from individuals recently infected with HIV type 1 (HIV-1). This IA was found to be capable of detecting the majority (89%) of infections, including 80% of those considered acute infections based on the presence of HIV RNA and the lack of detectable antibody to HIV. Substantial improvements in detection of recent infections by the Architect HIV Ag/Ab Combo relative to previous generations of IAs as well as the capacity to detect acute infections have important implications for HIV prevention strategies.

Background It is hypothesized that sexually transmitted diseases (STDs) increase the risk of HIV acquisition. Yet, difficulties establishing an accurate temporal relation and controlling confounders have obscured this relationship. In an attempt to overcome prior methodologic shortcomings, we explored the use of different study designs to examine the relationship between STDs and HIV acquisition. Methods Acutely HIV-infected patients were included as cases and compared to 1) HIV-uninfected patients (matched case-control), 2) newly diagnosed, chronically HIV-infected patients (infected analysis), and 3) themselves at prior clinic visits when they tested HIV-negative (case-crossover). We used t-tests to compare the average number of STDs and logistic regression to determine independent correlates and the odds of acute HIV infection. Results Between October 2003 and March 2007, 13,662 male patients who had sex with men were tested for HIV infection at San Francisco's municipal STD clinic and 350 (2.56%) HIV infections were diagnosed. Among the HIV-infected patients, 36 (10.3%) cases were identified as acute. We found consistently higher odds of having had an STD within the 12 months (matched case-control, OR 5.2 [2.2-12.6]; infected analysis, OR 1.4 [1.0-2.0]; case-crossover, OR 1.3 [0.5-3.1]) and 3 months (matched case-control, OR 34.5 [4.1-291.3]; infected analysis, OR 2.3 [1.1-4.8]; case-crossover OR 1.8 [0.6-5.6]) prior to HIV testing among acutely HIV-infected patients. We found higher odds of acute HIV infection among patients with concurrent rectal gonorrhea (17.0 [2.6 - 111.4], p<0.01) or syphilis (5.8 [1.1 - 32.3], p=0.04) when compared to those HIV-uninfected. Conclusions Acute HIV infection was associated with a recent or concurrent STD, particularly rectal gonorrhea, among men at San Francisco's municipal STD clinic. Given the complex relationship between STDs and HIV infection, no single design will appropriately control for all the possible confounders; studies using complementary designs are required.

The integration of HIV nucleic acid amplification, recent infection, and antiretroviral resistance testing enhanced HIV/STD surveillance. The high proportion of NNRTI mutations detected suggests they may be more common in source partners or more fit for transmission than other forms of drug-resistant HIV-1. Primary antiretroviral resistance monitoring in STD clinic patients may guide the selection of treatment and post-exposure prophylaxis regimens active against viruses being transmitted in the community, and provide health departments with surveillance data in a sentinel population at risk of HIV transmission.

We have evaluated four current Food and Drug Administration-cleared rapid tests for human immunodeficiency virus (HIV)-specific antibodies with a panel of specimens from recently infected individuals. Recent infection was detected by RNA-based screening coupled with enzyme immunoassay-based testing. We found that the sensitivities of the various rapid tests vary greatly with regard to their ability to detect HIV-specific antibodies in recently infected individuals.The persistence of the human immunodeficiency virus (HIV) pandemic is in part the result of the inability to comprehensively test all at-risk individuals. Even when at-risk individuals submit to laboratory testing, the inherent limitations of laboratory-based testing can lead to the failure to identify or inform infected individuals. Such limitations include the window periods associated with antibody-based testing (the time between infection and the generation of detectable antibodies in the blood) and the limited sensitivities of certain antibody tests (2,3,11,22). Moreover, the turnaround time associated with the logistics of laboratory-based testing can result in patients not obtaining their test results (6,7,9,17,20). Point-ofcare testing (rapid testing) for HIV infection seeks to broaden the capacity of the public health and medical communities to identify and to inform infected individuals. Rapid tests are easy to perform and can give conclusive results within minutes, making them amenable for use in outreach centers, emergency rooms, doctor's offices, and clinics.

BackgroundCurrent laboratory and point-of-care tests for HIV detect different analytes and use different sample types. Some have fast turnaround times (<1 hour). We investigated how HIV test choice could impact case finding by testing programs.MethodsWe analyzed 21,234 consecutive HIV tests with venous blood obtained by San Francisco HIV testing programs from 2003 to 2008. For a subset, oral fluid (n = 6446) or fingerstick blood (n = 8127) samples were also obtained for rapid testing. In all cases, HIV status was determined using an HIV antibody-plus-RNA test algorithm. We assessed how the screening antibody tests performed individually versus the gold standard of the full algorithm. We then evaluated the potential ability of other tests (including new tests) to detect more cases, by re-testing all specimens that had negative/discrepant antibody results on initial screening.FindingsThe antibody-RNA algorithm identified 58 acute and 703 established HIV infection cases. 1st-generation (Vironostika) and 3rd-generation (Genetic Systems) immunoassays had 92 and 96 percent sensitivity, respectively. The Oraquick rapid test had clinical sensitivity of only 86 percent on oral fluid samples, but 92 percent on finger-stick blood. Newer 4th-generation, antigen-antibody combo rapid immunoassay (ARCHITECT) detected HIV in 87 percent of all the acute cases that had been missed by one of the previous screening assays. A point-of-care 4th generation antigen-antibody combo rapid test (Determine) detected about 54 percent of such acute cases.ConclusionsOur study suggests that some rapid antibody blood tests will give similar case detection to laboratory antibody tests, but that oral fluid testing greatly reduces ability to detect HIV. New 4th-generation combo tests can detect the majority of acute infections detectable by HIV RNA but with rapid results. Using these tests as a primary screening assay in high-risk HIV testing programs could reduce or eliminate the need for HIV RNA testing.

The authors compared temporal trends in the prevalence and incidence of human immunodeficiency virus (HIV) infection based upon 34,866 specimens from patients who attended the San Francisco, California, municipal sexually transmitted disease clinic between 1989 and 1998. HIV infection data were collected during annual blinded HIV serologic surveys. Incidence was determined by applying a serologic testing algorithm for recent HIV seroconversion that uses both a sensitive and a less sensitive enzyme immunoassay to stored HIV positive sera. The HIV seroprevalence declined from 15.2% in 1989 to 7.2% in 1998 (odds ratio per year = 0.92, 95% confidence interval (CI): 0.91, 0.94). Among homosexual men, the HIV prevalence declined from 50.9% in 1989 to 19.9% in 1998 (odds ratio per year = 0.86, 95% CI: 0.85, 0.88). The pooled seroincidence was 1.6% and did not change significantly over time (odds ratio per year = 1.0, 95% CI: 0.98, 1.1). The pooled seroincidence among homosexual men was 6.6% per year and remained steady between 1989 and 1998 (odds ratio per year = 0.99, 95% CI: 0.92, 1.1). During a dramatic, 10-year decline in seroprevalence of HIV infection, the incidence of HIV infection remained remarkably stable.

The absence of new HCV infections in this sample supports the hypothesis that the risk of sexual transmission of HCV is low.