Susan Phillips

Maternal Virus Load and Perinatal Human Immunodeficiency Virus Type 1 Subtype E Transmission, Thailand

To determine the rate and risk factors for human immunodeficiency virus (HIV)-1 subtype E perinatal transmission, with focus on virus load, pregnant HIV-infected women and their formula-fed infants were followed prospectively in Bangkok. Of 281 infants with known outcome, 68 were infected (transmission rate, 24.2%; 95% confidence interval, 19.3%-29.6%). Transmitting mothers had a 4.3-fold higher median plasma HIV RNA level at delivery than did nontransmitters (P<.001). No transmission occurred at <2000 copies/mL. On multivariate analysis, prematurity (adjusted odds ratio [AOR], 4.5), vaginal delivery (AOR, 2.9), low NK cell percentage (AOR, 2.4), and maternal virus load were associated with transmission. As RNA quintiles increased, the AOR for transmission increased linearly from 4.5 to 24.8. Two-thirds of transmission was attributed to virus load>10,000 copies/mL. Although risk is multifactorial, high maternal virus load at delivery strongly predicts transmission. This may have important implications for interventions designed to reduce perinatal transmission.

Evaluation of the Performance Characteristics of 6 Rapid HIV Antibody Tests

BACKGROUND Since 2002, the US Food and Drug Administration has approved 6 rapid human immunodeficiency virus (HIV) tests for use in the United States. To date, there has been no direct comparison of the performance of all 6 tests. METHODS Persons known to be HIV-infected and persons who sought HIV testing at 2 clinical sites in Los Angeles, California, were recruited for evaluation of 6 rapid HIV tests with whole blood, oral fluid, serum, and plasma specimens. Sensitivity and specificity of the rapid tests were compared with viral lysate and immunoglobulin (Ig) M-sensitive peptide HIV enzyme immunoassays (EIAs). RESULTS A total of 6282 specimens were tested. Sensitivity was >95% and specificity was >99% for all rapid tests. Compared with the IgM-sensitive EIA, rapid tests gave false-negative results with an additional 2-5 specimens. All rapid tests had statistically equivalent performance characteristics, based on overlapping confidence intervals for sensitivity and specificity, compared with either conventional EIA. CONCLUSIONS All 6 rapid tests have high sensitivity and specificity, compared with that of conventional EIAs. Because performance was similar for all tests and specimen types, other characteristics, such as convenience, time to result, shelf life, and cost will likely be determining factors for selection of a rapid HIV screening test for a specific application.

Diagnosis of Human Immunodeficiency Virus Type 1 Infection with Different Subtypes Using Rapid Tests

ABSTRACT We evaluated six rapid tests for their sensitivity and specificity in diagnosing human immunodeficiency virus type 1 (HIV-1) infection using 241 specimens (172 HIV-1 positive, 69 HIV-1 negative) representing different HIV-1 subtypes (A [n = 40], B [n = 47], C [n = 28], E [n = 42], and F [n = 7]). HIVCHEK, Multispot, RTD and SeroStrip were 100% sensitive and specific. Capillus failed to identify two of eight subtype C specimens (overall sensitivity of 98.85%), while the SUDS test (the only test approved by the Food and Drug Administration) gave false-positive results for 5 of 69 seronegative specimens (specificity of 93.24%). Our results suggest that although rapid tests perform well in general, it may be prudent to evaluate a rapid test for sensitivity and specificity in a local population prior to its widespread use.

HIV-Specific IgG in Cervicovaginal Secretions of Exposed HIV-Uninfected Female Sexual Partners of HIV-Infected Men

The presence of human immunodeficiency virus (HIV)-specific antibodies was examined in plasma and cervicovaginal (mucosal) samples of 24 HIV-exposed uninfected (EU) female sexual partners of HIV-infected men, and compared with findings in 18 HIV-infected and 15 low-risk HIV-uninfected women. Only HIV-infected women had detectable HIV-specific immunoglobulin G (IgG) (18 of 18) or HIV-IgA (6 of 18) in cervicovaginal samples by enzyme immunoassay (EIA). However, 3 of 24 EU women had positive Western blot (WB) for HIV-IgG in cervicovaginal secretions, while 2 of 24 EU women and 1 of 15 low-risk controls had indeterminate IgG-WB. EU women with positive or indeterminate IgG-WB in the cervicovaginal samples were similar in risk to the remaining EU women. None of the HIV-uninfected women had mucosal HIV-IgA. The findings suggest that some sexually or parenterally exposed HIV-uninfected women might develop low-level mucosal IgG responses. However, it appears unlikely that HIV-specific cervicovaginal antibodies play a major role in protection from HIV infection in this EU population.

Influence of Host Factors on Immunoglobulin G Concentration in Oral Fluid Specimens

ABSTRACT The influence of host factors (tobacco use, dentition, bleeding gums, oral rinsing, nasal medications, and time since the last meal) on immunoglobulin G (IgG) concentration in oral fluids (OF) was determined by univariate and multivariate analysis. Significant differences in IgG concentration were found to be associated with human immunodeficiency virus (HIV) status (HIV antibody positive, +16.60 μg/ml, P = 0.0001), sex (female, +1.23 μg/ml, P = 0.004), dentition (+2.83 μg/ml, edentulous versus dentulous, P = 0.0001), bleeding gums (+6.35 μg/ml, P = 0.0001), and time since the last meal (+3.55 μg/ml, >6 h, P = 0.0001). These factors could impact diagnostic methods that rely on the immunoglobulin concentration in OF specimens.

Factors influencing HIV-1 banding patterns in miniaturized Western blot testing of dried blood spot specimens

In the HIV Seroprevalence Survey among Childbearing Women (SCBW), antibodies to human immunodeficiency virus type 1 are detected using enzyme immunoassays (EIA) and Western blot (WB) methods modified to accommodate samples of blood dried on special collection paper. Dried blood spot (DBS) eluates positive by EIA are tested by one of two WB methods, the miniblot technique using equipment from Immunetics Corporation and the PBS Integra assay (pageblot) from Genetic Systems. In this report we compared the performance of the two WB methods. The identity and position of the viral proteins on the WB were identified using monoclonal antibodies and monospecific antisera. The blots differed substantially in their composition and concentration of viral glycoproteins. Performance of the WB assays with DBS elution buffers from different EIA kits was equivalent except for samples eluted in the Abbott buffer, which reduced detection of antibodies to the p31, p51, p55, and p66 viral proteins. Case classification of DBS, positive sera, dilution curve samples, and seroconversion panels was equivalent by both tests in the presence of all elution buffers. Proficiency evaluation panels sent to SCBW participating laboratories over a 3-year period were used to note the differences between the two WB methods in detection of antibodies to the viral glycoproteins.