Evaluation of United States-licensed human immunodeficiency virus immunoassays for detection of group M viral variants.

Six Food and Drug Administration (FDA)-licensed human immunodeficiency virus type 1 (HIV-1) and HIV-1/2 immunoassays, including five enzyme immunoassays and one rapid test, were challenged with up to 250 serum samples collected from various global sites. The serum samples were from individuals known to be infected with variants of HIV-1 including group M subtypes A, B, B', C, D, E, F, and G and group O. All immunoassays detected the vast majority of samples tested. Three samples produced low signal over cutoff values in one or more tests: a clade B sample, an untypeable sample with a low antibody titer, and a group O sample. It is concluded that HIV-1 immunoassays used in the United States are capable of detecting most HIV-1 group M variants.

Phylogenetic analysis of protease and transmembrane region of HIV type 1 group O.

The molecular diversity and phylogenetic relationship of 22 HIV-1 group O strains were examined on the basis of the protease gene and the N-terminal region of gp41env. Analysis of the newly characterized protease sequences with 12 reference sequences revealed no specific clustering patterns, despite the distinct geographic locations of the specimens. In contrast, analysis of the newly sequenced gp41 sequences with 34 published sequences revealed two distinct clusters, each represented by one full-length sequence (MVP5180 and ANT-70). Further, four of the specimens classified as group O in the protease region clustered with group M in the gp41 region (three subtype A and one subtype G, respectively), suggesting dual and/or recombinant infections with HIV-1 groups M and O. The presence of two distinct clusters in the gp41 region indicates at least two possible subtypes within group O viruses, and this may provide useful information regarding molecular epidemiological studies of group O infections.

Human immunodeficiency virus (HIV) subtype surveillance of African-born persons at risk for group O and group N HIV infections in the United States.

A population-based surveillance registry was used to identify human immunodeficiency virus (HIV)-infected persons in the United States at increased risk for group O and group N infections (those born in or near African countries where group O infection has been reported). Of 155 eligible subjects, 37 gave samples. By phylogenetic and serologic analysis, 32 were infected with group M (16 with subtype A, 5 with B, 7 with C, and 1 each with subtypes D, F2, G, and recombinant A/J) and 2 with group O but none with group N virus. For 3, samples could not be typed by serology or amplified by polymerase chain reaction using group M-, O-, or N-specific primers. In the United States, group O HIV infection is uncommon; no case of group N infection was found. African-born persons may have HIV strains typical of their birth country. Ongoing subtype surveillance may allow early identification of novel or emerging HIV strains.

Presence of human immunodeficiency virus (HIV) type 1, group M, non-B subtypes, Bronx, New York: a sentinel site for monitoring HIV genetic diversity in the United States.

In the United States, human immunodeficiency virus (HIV) type 1, group M, subtype B is the predominant subtype. A cross-sectional study of HIV-infected patients at the Bronx-Lebanon Hospital Center, Bronx, NY, between September 1997 and February 1998 identified 3 (1. 2%) of 252 persons infected with non-B subtypes: subtypes A and F, 1 each, and 1 potential recombinant subtype B(env)/F(prt). All 3 persons were born in the United States and tested positive for HIV antibodies between 1988 and 1997 while living in the Bronx. None reported travel to other countries, receipt of blood products, or drug injection. This study is among the first to indicate probable transmission of non-B HIV-1 subtypes in the United States. The occurrence of non-B HIV-1 subtypes in long-term US residents without a history of foreign travel may have implications for the evaluation and development of antiretroviral drugs, vaccines, and tests intended for use in the United States to diagnose HIV infection and screen blood.

Viral and immunologic examination of human immunodeficiency virus type 1-infected, persistently seronegative persons.

Persons who were human immunodeficiency virus type 1 (HIV-1)-infected but who remained persistently seronegative (HIPS) on HIV-1 antibody tests were examined through AIDS case surveillance. Six such individuals (HIPS-1 to -4, -7, and -9) were examined to determine whether their persistent seronegativity was attributable to immune dysfunction or infection with atypical HIV. Of the 6, 4 had antibody titers to at least 1 other common pathogen. In vitro stimulation of peripheral blood mononuclear cells from HIPS-4 and HIPS-7 with pokeweed mitogen or phosphorothioate oligodeoxynucleotide (direct B cell mitogen) did not produce HIV-1-specific antibody. Reconstitution experiments with recombinant interleukin (rIL)-4 and rIL-12 also had no impact on antibody production. Virus isolates from HIPS-4 and -9 were R5X4-tropic, whereas HIPS-7 was CCR5-tropic only. Sequence analysis of long terminal repeat, p24, and env gp41 did not reveal any specific mutation, and phylogenetic analysis confirmed that all 6 virus specimens were HIV-1 subtype B. These data suggest that the lack of a detectable antibody response in these patients may be the result of immune dysfunction.

Persistently negative HIV-1 antibody enzyme immunoassay screening results for patients with HIV-1 infection and AIDS: serologic, clinical, and virologic results. Seronegative AIDS Clinical Study Group.

OBJECTIVE: To describe persons with HIV infection and AIDS but with persistently negative HIV antibody enzyme immunoassay (EIA) results. DESIGN: Surveillance for persons meeting a case definition for HIV-1-seronegative AIDS. SETTING: United States and Canada. PATIENTS: A total of eight patients with seronegative AIDS identified from July 1995 through September 1997. MAIN OUTCOME MEASURES: Clinical history of HIV disease, history of HIV test results, and CD4 cell counts from medical record review; results of testing with a panel of EIA for antibodies to HIV-1, and HIV-1 p24 antigen; and viral subtype. RESULTS: Negative HIV EIA results occurred at CD4 cell counts of 0-230 x 10(6)/l, and at HIV RNA concentrations of 105,000-7,943,000 copies/ml. Using a panel of HIV EIA on sera from three patients, none of the HIV EIA detected infection with HIV-1, and signal-to-cut-off ratios were < or = 0.8 or all test kits evaluated. Sera from five patients showed weak reactivity in some HIV EIA, but were non-reactive in other HIV EIA. All patients were infected with HIV-1 subtype B. CONCLUSIONS: Rarely, results of EIA tests for antibodies to HIV-1 may be persistently negative in some HIV-1 subtype B-infected persons with AIDS. Physicians treating patients with illnesses or CD4 cell counts suggestive of HIV infection, but for whom results of HIV EIA are negative, should consider p24 antigen, nucleic acid amplification, or viral culture testing to document the presence of HIV.

HIV-1 subtypes among blood donors from Rio de Janeiro, Brazil.

The prevalence of HIV infection in Brazil is one of the highest in the world. In addition, transfusion-transmitted HIV accounts for 2.3% of all AIDS cases in Brazil. The objective of this study was to evaluate genetic diversity and distribution of HIV-1 strains circulating in the blood-donor population. We characterized 43 seropositive blood units collected from volunteer blood donors residing throughout Rio de Janeiro, Brazil. Viral RNA was extracted from plasma, reverse transcribed, and amplified by nested polymerase chain reaction (PCR) using HIV group M degenerate primers. Genetic heterogeneity was evaluated by direct automated cycle sequencing of the following gene fragments: gag p24 (399 bp), env C2V3 (345 bp), and env gp41 (369 bp). Phylogenetic analysis reflected the complexity of the Brazilian HIV epidemic: the majority of specimens, 33 of 43 (76.7%) were subtype B, and 6 of 43 (14%) were subtype F. The remaining 4 samples (9.3%) involved potential mosaic viruses of subtypes B and F or B and D. This survey is the first to document HIV-1 genetic variation in the Brazilian blood-donor population.

PIP: Brazil has the highest prevalence of HIV infection in Latin America and one of the highest such prevalences in the world. By 1996, 110,000 AIDS cases had been cumulatively reported by the Brazil National AIDS Program. HIV-1 subtypes B and F have previously been described in Brazil, accounting for 85% and 15% of infections, respectively. Findings are presented from a study conducted to evaluate the genetic diversity and distribution of HIV-1 strains circulating in the blood donor population. The authors characterized 43 HIV-seropositive blood units collected from volunteer blood donors living throughout Rio de Janeiro. Viral RNA was extracted from plasma, reverse transcribed, and amplified by nested polymerase chain reaction using HIV group M degenerate primers. Genetic heterogeneity was assessed through the direct automated cycle sequencing of gene fragments gag p24 (399 bp), env C2V3 (345 bp), and env gp41 (369 bp). 33 of the 43 (76.7%) specimens were of subtype B and 6 (14%) of subtype F, while the remaining 4 (9.3%) involved potential mosaic viruses of subtypes B and F or B and D.

Introduction of HIV-2 and multiple HIV-1 subtypes to Lebanon.

HIV genetic variability, phylogenetic relationships, and transmission dynamics were analyzed in 26 HIV-infected patients from Lebanon. Twenty-five specimens were identified as HIV-1 and one as HIV-2 subtype B. The 25 strains were classified into six env-C2-V3 HIV-1 subtypes: B (n = 10), A (n = 11), C (n = 1), D (n = 1), G (n = 1), and unclassifiable. Potential recombinants combining parts of viral regions from different subtypes Aenv/Dpol/Agag, Genv/Apol, and the unclassifiable-subtype(env)/unclassifiable-subtype(pol)/Agag were found in three patients. Epidemiologic analysis of travel histories and behavioral risks indicated that HIV-1 and HIV-2 subtypes reflected HIV strains prevalent in countries visited by patients or their sex partners. Spread of complex HIV-subtype distribution patterns to regions where HIV is not endemic may be more common than previously thought. Blood screening for both HIV-1 and HIV-2 in Lebanon is recommended to protect the blood supply. HIV subtype data provide information for vaccine development.

Identification of a human population infected with simian foamy viruses.

Studying the transmission of simian retroviruses to humans can help define the importance of these infections to public health. We identified a substantial prevalence (4/231, 1.8%) of infection with simian foamy viruses (SFV) among humans occupationally exposed to nonhuman primates. Evidence of SFV infection included seropositivity, proviral DNA detection and isolation of foamy virus. The infecting SFV originated from an African green monkey (one person) and baboons (three people). These infections have not as yet resulted in either disease or sexual transmission, and may represent benign endpoint infections.

Identification and characterization of an HIV-2 antibody-positive blood donor in the United States.

BACKGROUND: As of June 1, 1992, the Food and Drug Administration recommended that all donated blood be screened for antibodies specific to HIV-2. Despite broad serologic surveillance, only two cases of HIV-2 infection had been detected among potential blood and plasma donors since the implementation of the test. CASE REPORT: The identification of a third HIV-2 antibody-positive blood donor is reported. The first-time donor was identified by routine screening procedures as anti-HIV-1/HIV-2-reactive, and that status was confirmed by licensed HIV-1 Western blot. Concurrent whole-virus lysate enzyme immunoassay and Western blot for HIV-2 were strongly positive, but the possibility of HIV-1 cross-reactivity could not be eliminated. The donor was notified, counseled, and deferred from future donation. He subsequently enrolled in a Centers for Disease Control and Prevention-sponsored epidemiologic study of HIV-positive former donors. When it was revealed during the standardized interview that he was a native of an HIV-2-endemic region, follow-up samples were submitted to the Centers for Disease Control and Prevention. Investigational HIV-1 and HIV-2 peptide enzyme immunoassays indicated that this infection was due to HIV-2 only. CONCLUSION: Enzyme immunoassays for antibodies to synthetic peptides of HIV-1 and HIV-2 may be useful in differentiating the two viruses in individuals with ambiguous Western blot results and risk factors for HIV-2 infection.

Use of human immunodeficiency virus (HIV) type 1 and 2 recombinant strip immunoblot assay to resolve enzyme immunoassay anti-HIV-2-repeatably reactive samples after anti-HIV-1/2 combination enzyme immunoassay screening.

BACKGROUND: With the implementation of combination human immunodeficiency virus types 1 and 2 (HIV-1/2) antibody enzyme immunoassay (EIA) in donor screening in 1992, the supplemental testing algorithm changed to require the use of a Food and Drug Administration (FDA)-licensed HIV-1 Western blot (WB) or immunofluorescence assay, as well as an FDA-licensed HIV-2 EIA. When HIV-2 EIA-reactive specimens are identified, further testing to confirm HIV-2 infection is recommended. Currently, a licensed HIV-2 supplemental assay is not available. STUDY DESIGN AND METHODS: The sensitivity of an HIV-1/2 recombinant strip immunoblot assay (SIA) for HIV-2 was determined on the basis of the analysis of 65 HIV-2-positive samples identified by the Centers for Disease Control and Prevention (CDC). Anti-HIV-1/2 combination EIA-repeatably reactive (RR) specimens from seven blood centers and their affiliated hospitals were tested in parallel by HIV-1 WB and HIV-2 EIA. Anti-HIV-2 EIA-RR specimens were further tested by HIV-1/2 SIA. Specimens interpreted as positive for HIV-2 or HIV-1/2 were referred to the CDC for final resolution of antibody status. RESULTS: Ninety-seven percent (63/65) of known HIV-2-positive samples tested positive for HIV-2 only or HIV-1/2 on the HIV-1/2 SIA. A total of 1048 anti-HIV-1/2 combination-EIA-RR specimens were evaluated. Sixty-nine percent (75/109) of the WB-positive specimens were HIV-2 EIA-RR, while only 9 percent (84/939) of WB-indeterminate or WB-negative specimens tested HIV-2 EIA-RR. The HIV-1/2 SIA resolved 91 percent of HIV-2 EIA-RR samples as negative. Four HIV-2 EIA-RR specimens (all HIV-1 WB-positive) were classified as positive for HIV-1 and HIV-2 in the HIV-1/2 SIA. Final interpretation of these specimens by CDC was that they were reactive for HIV-1 with cross-reactivity to HIV-2. CONCLUSION: No confirmed HIV-2-positive specimens were detected. The HIV-1/2 SIA is currently useful for resolving HIV-2 EIA-RR specimens.

Absence of detectable antibody in a patient infected with human immunodeficiency virus.

Infection with human immunodeficiency virus (HIV) is routinely and easily diagnosed with use of enzyme immunoassay (EIA) test kits. We describe an unusual patient who developed AIDS despite testing negative for antibodies to HIV 35 times over a 4-year period. HIV infection was confirmed by the results of p24-antigen assays and polymerase chain reaction amplification of proviral DNA. Sequence analysis of the virus demonstrated that it was closely related to a strain obtained from the patient's sexual partner. The explanation for this patient's persistently negative EIA results is unclear. However, this case does suggest that physicians who treat patients with AIDS-defining conditions but for whom standard HIV antibody testing is negative should consider the possibility that HIV infection is present and may be identified by additional testing procedures.

Update on the seroepidemiology of human immunodeficiency virus in the United States household population: NHANES III, 1988-1994.

To update the estimate of seroprevalence of HIV from the third National Health and Nutrition Examination Survey (NHANES III), data from the second phase of the survey were combined with previously published data to produce a more precise estimate. The testing was performed anonymously on 11,203 individuals 18-59 years of age examined from 1988 to 1994. Fifty-nine individuals were HIV positive, for an overall prevalence of 0.32%. The number of individuals living in households with HIV infection based on this estimate was 461,000, with a 95% confidence interval of 290,000-733,000. Analysis of nonresponse demonstrated that white and black men 40-59 years of age were least likely to participate in the survey. A sensitivity analysis demonstrated that this nonresponse may have biased the NHANES III estimate downward by 190,000 persons. Data from the second phase of the survey were used to analyze the association between drug use and HIV infection. Black women who used cocaine were 12 times more likely to be HIV positive compared with all tested black women (6.5% vs. 0.55%). This survey provides an estimate of HIV prevalence for individuals who reside in households but excludes some persons who are at higher risk for HIV infection, including prisoners and the homeless not residing in shelters.

Risk of occupational exposure to potentially infectious nonhuman primate materials and to simian immunodeficiency virus.

Five hundred fifty persons who worked with nonhuman primates (NHP) or with NHP material in 13 North American research institutions were surveyed for potential occupational exposures and tested for antibodies to simian immunodeficiency virus (SIV). Needlesticks and mucocutaneous exposures were reported more frequently among persons who handled SIV-negative or SIV-status-unknown (SIV-N/U) animals (36% and 35%) or who worked with SIV-N/U material in the laboratory (18% and 17%) than among persons who handled SIV-positive NHP (SIV-P) (9% and 4%) or worked with SIV-P material (6% and 8%). The risk for needlesticks when working with both SIV-N/U and SIV-P animals and the risk for mucocutaneous exposures from SIV-N/U animals increased with the number of years working with NHP. Persons who performed invasive tasks (e.g., obtaining blood samples, performing surgery/autopsies) were more likely than others to sustain needlesticks (adjusted OR = 3.55, 95%CI = 1.40-9.02). Two (0.4%) of 550 persons had antibodies to SIV. One appears to be infected with SIV, as previously reported. These data suggest that persons who work with NHP or with NHP material are at risk for occupational exposure to potentially infectious materials including SIV. Prevention strategies are needed to reduce the risk for needlesticks and mucocutaneous exposures around all NHP, and safety guidelines should emphasize prevention options for invasive tasks performed with animals.

Performance characteristics of a rapid HIV antibody assay in a hospital with a high prevalence of HIV infection. CDC-Bronx-Lebanon HIV Serosurvey Team.

BACKGROUND: The delay between collection of blood samples and availability of test results may be as long as 3 weeks and is one barrier to the acceptance of voluntary testing for human immunodeficiency virus (HIV) infection. Serologic tests that provide results rapidly could overcome this barrier, but the accuracy and reliability of rapid tests have not been well characterized in the United States. OBJECTIVE: To evaluate, in a "real world" setting, the performance characteristics of a rapid HIV assay that reduces the need for patients to return for counseling after the test. DESIGN: Testing of HIV antibodies by rapid and nonrapid assays and survey about risk behaviors for HIV. SETTING: A hospital in Bronx, New York, with a high prevalence of HIV-seropositive patients. PATIENTS: 837 patients who were not known to be infected with HIV, had not been admitted for conditions related to the acquired immunodeficiency syndrome, and agreed to participate in HIV testing and an interview. MEASUREMENTS: Sensitivity and specificity of a rapid HIV antibody assay based on comparisons with nonrapid assay and Western blot assay. RESULTS: According to nonrapid assays, 5.4% of patients were infected with HIV. The rapid assay was highly accurate in this sample overall: its sensitivity was 1.00, its specificity was 0.991, its positive predictive value was 0.865, and its negative predictive value was 1.00. The assay was also highly accurate in various subgroups. CONCLUSIONS: Accurate, rapid tests for HIV infection may enhance testing programs by preventing the need for delayed counseling of seronegative patients and by providing preliminary results to seropositive patients. These preliminary results may encourage patients to return for confirmatory test results and to adopt risk-reducing behaviors sooner.

Absence of human immunodeficiency virus type 2 infection among patients in a hospital serving a New York community at high risk for infection. Centers for Disease Control and Prevention/Bronx-Lebanon Hospital Center HIV Serosurvey Team.

BACKGROUND: Although human immunodeficiency virus type 2 (HIV-2) infection among United States residents is considered rare, there are US populations at high risk. Few studies have surveyed these populations with a high likelihood of infection, that is, those with high percentages of persons from HIV-2-endemic areas and high prevalences of behaviors that would allow for transmission. STUDY DESIGN AND METHODS: Patients (n = 832) enrolled in a confidential HIV serosurvey at a hospital that serves a community with a relatively high percentage of West African immigrants, drug injectors, and persons who practice high-risk sexual activity were evaluated. Sera were tested for HIV type 1 (HIV-1) and HIV-2 by rapid enzyme immunoassays, standard enzyme immunoassays and Western blots. RESULTS: Eight of 832 patients were weakly reactive to HIV-2 on rapid assay, but none was confirmed to be infected when tested by standard immunoassay and Western blot. Five of these eight were reactive to HIV-1. CONCLUSION: Weak reactivity to HIV-2 antibody on the rapid assay is best explained by cross-reactivity with HIV-1 antibody; thus, even in this population at high risk for infection, false-positive reactions are more likely than true infections. The finding that HIV-2 is absent in this population at potentially high risk for infection corroborates the findings of other studies that HIV-2 infection is rare among US residents. These results support previous recommendations that, in settings other than blood collection facilities, HIV-2 testing should be selectively offered to persons with epidemiologic risk factors.

Surveillance for human immunodeficiency virus type 1 group O infections in the United States.

BACKGROUND: Reports that the human immunodeficiency virus type 1 (HIV-1) group O variants are not reliably detected by some commercial diagnostic tests have raised concerns about the sensitivity of existing screening tests, especially with regard to blood safety. Although it is unlikely that these divergent strains are prevalent in North America, systematic, continuous surveillance is needed to monitor the potential spread of HIV variants into that region. STUDY DESIGN AND METHODS: Stored serum samples (n = 1072) from both high- and low-risk population groups at several sites in the United States and Puerto Rico were tested by peptide enzyme immunoassays specific for the prototypic HIV-1 group O strains, MVP5180 and ANT70. RESULTS: None of the 1072 samples examined had peptide reactivity that was consistent with HIV-1 group O infection. CONCLUSION: While no evidence of specific HIV-1 group O (MVP5180 or ANT70) infection was found in this study, the sensitivity of current tests has not been fully evaluated against the wide range of genetic variation of HIV. Therefore, it is important to continue active surveillance for HIV-1 and HIV type 2 strains, to characterize any divergent strains, and to judiciously modify tests to correct for any deficiencies in sensitivity.