Diagnostic challenges for rapid human immunodeficiency virus assays. Performance using HIV-1 group O, HIV-1 group M, and HIV-2 samples

OBJECTIVE: We sought to determine the ability of seven rapid assays for human immunodeficiency virus (HIV) to detect antibodies in a panel of sera from individuals infected with different types and groups of HIV. STUDY DESIGN/METHODS: Sixty-eight well-characterized samples, including HIV-1 group O (24), several HIV-1 group M clades (21), HIV-1/2 (10), HIV-2 (10), and samples with indeterminate results (3), were tested by the following rapid HIV assays: HIV-Spot, HIVCHEK System 3, A/Q Rapid HIV, Genie II HIV-1/HIV-2, Quix HIV-1-2-O, ImmunoComb II HIV-1+2 BiSpot, and the Serodia HIV-1+2. RESULTS: All tests successfully detected the HIV-1 group M clades and the HIV-1/2-positive samples. Of the HIV-2 stand-alone samples, four tests missed the same sample, and three tests missed another sample. Of the HIV-1 group O samples, four samples were missed by at least one test, and another sample was missed by three tests. The sensitivity of the seven rapid assays in detecting each group of sera was between 83% and 100%, with only one test having a sensitivity of 100% for all groups of sera. Three samples proved to be problematic because they were misclassified by more than one assay. CONCLUSIONS: The performance of rapid HIV assays is variable when testing sera from individuals infected with HIV-1 group O and HIV-2.     

Field evaluation of a rapid human immunodeficiency virus (HIV) serial serologic testing algorithm for diagnosis and differentiation of HIV type 1 (HIV-1), HIV-2, and dual HIV-1-HIV-2 infections in West African pregnant women

We evaluated a two-rapid-test serial algorithm using the Determine and Genie II rapid assays, performed on-site in four peripheral laboratories during the French Agence Nationale de Recherches sur le SIDA (ANRS) 1201/1202 Ditrame Plus cohort developed for prevention of mother-to-child transmission of human immunodeficiency virus (HIV) infection in Côte d'Ivoire. A total of 1,039 specimens were retested by two commercial enzyme-linked immunosorbent assays (ELISAs). The following specimens were tested: 315 specimens found on-site to be infected with HIV type 1 (HIV-1), 8 specimens found on-site to be infected with HIV-2, 71 specimens found on-site to be infected with both HIV-1 and HIV-2, 40 specimens found on-site to have indeterminate results for HIV infection, and 605 specimens taken during a quality assurance program. For HIV discrimination, 99 positive serum samples (20 with HIV-1, 8 with HIV-2, and 71 with HIV-1 and HIV-2 on the basis of our rapid test algorithm) were retested by the Peptilav test, Western blot (WB) assays, and homemade monospecific ELISAs. Real-time DNA PCRs for the detection of HIV-1 and HIV-2 were performed with peripheral blood mononuclear cells from 35 women diagnosed on-site with HIV-1 and HIV-2 infections. Compared to the results of the ELISAs, the sensitivities of the Determine and Genie II assays were 100% (95% lower limit [95% LL], 99.1%) and 99.5% (95% confidence interval [95% CI], 98.2 to 99.9%), respectively. The specificities were 98.4% (95% CI, 96.9 to 99.3%) and 100% (95% LL, 99.3%), respectively. All serological assays gave concordant results for infections with single types. By contrast, for samples found to be infected with dual HIV types by the Genie II assay, dual reactivity was detected for only 37 samples (52.1%) by WB assays, 34 samples (47.9%) by the Peptilav assay, and 23 samples (32.4%) by the monospecific ELISAs. For specimens with dual reactivity by the Genie II assay, the rates of concordance between the real-time PCR assays and the serological assays were 25.7% for the Genie II assay, 82.9% for the Peptilav assay, 74.3% for WB assays, and 80% for the homemade ELISAs. Our algorithm provided high degrees of sensitivity and specificity comparable to those of ELISAs. Even if they are rare, women identified by the Genie II assay as being infected with HIV-1 and HIV-2 mostly appeared to be infected only with HIV-2.     

Evaluation of supplemental testing with the Multispot HIV-1/HIV-2 Rapid Test and APTIMA HIV-1 RNA Qualitative Assay to resolve specimens with indeterminate or negative HIV-1 Western blots

BackgroundThe use of Western blot (WB) as a supplemental test after reactive sensitive initial assays can lead to inconclusive or misclassified HIV test results, delaying diagnosis.ObjectiveTo determine the proportion of specimens reactive by immunoassay (IA) but indeterminate or negative by WB that could be resolved by alternative supplemental tests recommended under a new HIV diagnostic testing algorithm.Study designRemnant HIV diagnostic specimens that were reactive on 3rd generation HIV-1/2 IA and either negative or indeterminate by HIV-1 WB from 11 health departments were tested with the Bio-Rad Multispot HIV-1/HIV-2 Rapid Test (Multispot) and the Gen-Probe APTIMA HIV-1 RNA Qualitative Assay (APTIMA).ResultsAccording to the new testing algorithm, 512 (89.8%) specimens were HIV-negative, 55 (9.6%) were HIV-1 positive (including 19 [3.3%] that were acute HIV-1 and 9 [1.6%] that were positive for HIV-1 by Multispot but APTIMA-negative), 2 (0.4%) were HIV-2 positive, and 1 (0.2%) was HIV-positive, type undifferentiated. 47 (21.4%) of the 220 WB-indeterminate and 8 (2.3%) of the 350 WB-negative specimens were HIV-1 positive.ConclusionApplying the new HIV diagnostic algorithm retrospectively to WB-negative and indeterminate specimens, the HIV infection status could be established for nearly all of the specimens. IA-reactive HIV-infected persons with WB-negative results had been previously misclassified as uninfected, and HIV diagnosis was delayed for those with WB-indeterminate specimens. These findings underscore the limitations of the WB to confirm HIV infection after reactive results from contemporary 3rd or 4th generation IAs that can detect HIV antibodies several weeks sooner than the WB.     

Genetic diversity of HIV type 1 in rural eastern Cameroon

To monitor the presence of genotypic HIV-1 variants circulating in eastern Cameroon, blood samples from 57 HIV-1-infected individuals attending 3 local health centers in the bordering rural villages with Central African Republic (CAR) were collected and analyzed phylogenetically. Out of the 40 HIV-1 strains with positive polymerase chain reaction (PCR) profile for both gag and env-C2V3,12 (30.0%) had discordant subtype or CRF designation: 2 subtype B/A (gag/env), 1 B/CRF01, 2 B/CRF02, 1 CRF01/CRF01.A, 2 CRF11/CRF01, 1 CRF13/A, 1 CRF13/CRF01, 1 CRF13/CRF11, and 1 G/U (unclassified). Twenty-eight strains (70.0%) had concordant subtypes or CRF designation between gag and env: 27 subtype A and 1 F2. Out of the remaining 17HIV-1 strains negative for PCR with the env-C2V3 primers used, 10 (58.8%) had discordant subtype or CRF, and 7 (41.2%) had concordant one based on gag/pol/env-gp41 analysis. Altogether, a high proportion (22/57, 38.6%) of the isolates were found to be recombinant strains. In addition, an emergence of new forms of HIV-1 strains, such as subtype B/A (gag/env), B/CRF01 and B/CRF02, was identified. The epidemiologic pattern of HIV-1 in eastern Cameroon, relatively low and high prevalence of CRF02 and CRF11, respectively, was more closely related to those of CAR and Chad than that of other regions of Cameroon, where CRF02 is the most predominant HIV-1 strain. These findings strongly suggest that this part of Cameroon is a potential hotspot of HIV-1 recombination, with a likelihood of an active generation of new forms of HIV-1 variants, though epidemiologic significance of new HIV-1 forms is unknown.     

Low Prevalence Rate of Indeterminate Serological Human Immunodeficiency Virus Results among Pregnant Women from Burkina Faso,West Africa

Rapid human immunodeficiency virus (HIV) antibody tests have been adopted into national guidelines for HIV testing in many countries in sub-Saharan Africa. One goal of HIV rapid testing is to minimize the occurrence of indeterminate results. From January 2005 to December 2007, plasma (or serum) samples from pregnant women in Bobo-Dioulasso (Burkina Faso, West Africa) were screened for HIV by using two rapid tests (the Determine HIV1/2 test [Abbott] and Genie II HIV-1/HIV-2 [Bio-Rad]) through a sequential algorithm prior to enrollment of HIV-1-infected women in a prevention of mother-to-child transmission (PMTCT) trial (WHO/ANRS 1289 Kesho Bora trial). Samples exhibiting indeterminate results (Determine positive and Genie II negative) were further tested with a fourth-generation HIV enzyme immunoassay (EIA) (Murex HIV Ag/Ab combination in 2005 and 2006 and Vironostika HIV Uni-Form II Ag/Ab in 2007). If positive, they were finally assessed for HIV-1 RNA (Generic HIV-1 RNA viral load assay; Biocentric). From a total of 44,653 samples tested, 597 (1.3%) showed indeterminate results. Of these, 367 could be analyzed by EIA. Only 15 (15/367, 4.1%) samples were found EIA reactive. Of these, 11 could be tested for HIV-1 RNA. All were HIV-1 RNA negative. In our clinical practice, pregnant women with such indeterminate results are now reassured during posttest counseling that they are very unlikely to be infected with HIV-1. As a consequence, such women with indeterminate results can reliably be considered negative when urgent clinical decisions (such as providing PMTCT prophylaxis) need to be taken.In sub-Saharan Africa, rapid testing for human immunodeficiency virus (HIV) is the most efficient and sometimes the only feasible way to quickly provide information about HIV status among adults and children ≥18 months of age (6, 29). In contrast to enzyme immunoassays (EIAs) and Western blot assays (WBs), HIV rapid tests are relatively cheap, easy to use, and fast to perform. Most of them do not require refrigeration, sophisticated laboratory equipment, skilled technicians, and an electricity supply. Results from serum, plasma, whole-blood, urine, or saliva samples are obtained by visual reading after a few minutes. Some of the rapid tests can distinguish HIV type 1 (HIV-1) from HIV type 2 (HIV-2). They are also accurate and reliable as a result of applying a quality system approach recommended by the World Health Organization (WHO) (36). Due to their low cost and technical advantages, they have been adopted into national HIV voluntary counseling and testing (VCT) guidelines in many African countries. Their sensitivity and specificity have been studied in Kenya (12), Tanzania (22), Uganda (15), Zambia (30), South Africa (25), Cameroon (1), Central African Republic (24), Democratic Republic of Congo (19), Ghana (2), Ivory Coast (32), and Burkina Faso (23, 28).One objective for rapid HIV testing is to minimize the occurrence of indeterminate results (i.e., discordant results when using at least two different rapid tests). It is often quite difficult for HIV counselors and health care providers to disclose such indeterminate results. In the context of interventions for prevention of mother-to-child transmission (PMTCT) of HIV-1 (which can require immediate decisions, notably during labor), medical staff need to know rapidly the HIV status of the woman from the laboratory in order to provide her, or not, antiretroviral (ARV) prophylaxis (5, 26, 27). The prolonged delay in the decision (by performing additional tests or by retesting women 14 days later) can be inappropriate in the clinical routine since women may deliver before obtaining definitive results.The aims of this study conducted among pregnant women from Burkina Faso (West Africa) with a low risk of early HIV-1 seroconversion were (i) to determine the prevalence rates of indeterminate results by using two rapid tests in a sequential algorithm, as recommended in Burkina Faso, and (ii) to assess, using additional tests, the biological significance of indeterminate results in order to define a more rational strategy at the individual and public health levels.(This work was presented in part at the 15th Conference on AIDS and STDs in Africa, Dakar, Senegal, 3 to 7 December 2008 [17].)     

HIV type 1 group M clades infecting subjects from rural villages in equatorial rain forests of Cameroon

Though the HIV-1 subtypes infecting patients living in urban and semi-urban areas in Cameroon have been reported, information on the subtypes infecting patients in rural villages is lacking. To begin to understand the diversity of the HIV-1 group M subtypes infecting persons living in rural villages in the equatorial rain forest regions of Cameroon, 49 plasma samples from 14 rural villages in four provinces of Cameroon were analyzed using heteroduplex mobility analysis (HMA), DNA sequencing, and phylogenetic tree analysis on the basis of env C2V5, gag, or pol regions. Sixty-one percent of the group M infections were clade A or CRF02_AG-like as subtyped by env and gag. Of the remaining group M infections, 12% were either A or CRF02_AG-like or CRF01_AE-like in recombination with other clades; 25% were infections that were entirely non-A or non-CRF02_AG-like; and 2% were CRF11_cpx. The HIV-1 group M clades identified included A, D, F (F2), G, and H. The CRF strains identified were CRF02_AG-like, CRF01_AE-like, and CRF11_cpx. Two new intersubtype recombinant infections, H/G and A/F2, were identified. This study suggests that the HIV-1 diversity in rural villages in the equatorial rain forest of Cameroon is at least as broad as has been observed in major cities of Cameroon and that multiple HIV-1 group M subtypes are infecting persons living in the countryside of Cameroon.     

Prospective evaluation of the new chromogenic medium Candida ID, in comparison with Candiselect, for isolation of molds and isolation and presumptive identification of yeast species

We conducted a prospective evaluation of Candida ID chromogenic medium (bioMérieux, Marcy l'Etoile, France) with 786 clinical specimens in comparison with Candiselect medium (Bio-Rad, Marnes la Coquette, France). Candida ID chromogenic medium identified 97.7% of Candida albicans strains; enabled presumptive identification of C. tropicalis, C. lusitaniae, C. guillermondii, and C. kefyr and better detection of yeast combinations (11.4% more often); and was more sensitive for the isolation of filamentous fungi (17.7% more often). However, Candida ID chromogenic medium appeared to be less selective vis-à-vis bacteria, with bacterial colonies sometimes pigmented blue.     

Comparison of five commercial enzyme-linked immunosorbent assays and Western immunoblotting for human immunodeficiency virus antibody detection in serum samples from Central Africa.

Detection by five different enzyme-linked immunosorbent assays (ELISAs) of antibody to human immunodeficiency virus (HIV) in sera from three Zairian populations consisting of 1,998 individuals with various risks for HIV infection was evaluated. Sera that were reactive by at least one assay and 10% of the nonreactive serum samples were analyzed by Western blot (immunoblot) by using U.S. Public Health Service interpretation criteria. Sera which were positive by ELISA for detection of antibody to HIV-1 and HIV-2 and negative or indeterminate by HIV-1 Western blot were also analyzed by HIV-2 Western blot. Overall, 443 (22.2%) serum specimens were HIV-1 Western blot positive, 390 (19.5%) had indeterminate HIV-1 Western blot patterns, and no samples were HIV-2 Western blot positive. The sensitivity of the ELISAs ranged from 97.5 to 99.8%, and the specificity ranged from 51.7 to 98.4%. By population group, the negative predictive value ranged from 97.1 to 100%, in contrast to the positive predictive value, which varied from 6.6 to 100%. Follow-up results for sera which were indeterminate for antibody to HIV-1 documented only four seroconversions (6.0%) among 67 individuals at high risk for HIV-1 infection and no seroconversions among 202 individuals at relatively low risk for HIV-1 infection. This study demonstrates the importance of evaluating commercial ELISAs with sera from appropriate geographical regions in order to select the most cost-effective and practical assay for use in that region. Furthermore, the high frequency of indeterminate Western blots for African sera emphasizes the continual need for improved confirmatory assays and interpretation criteria.     

Comparison of the performance of rapid HIV tests using samples collected for surveillance in Mozambique

Mozambique had low HIV prevalence until the mid‐1990s, but recent data indicate increasing rates. There is little information on HIV‐2. Therefore, HIV seroprevalence was assessed among pregnant women and field‐ready HIV diagnostic strategies were evaluated. A total of 6,930 samples collected by three health centers from 2002 to 2005 were tested on site by nurses with two simple/rapid tests, Determine HIV‐1/2 (Abbott Laboratories; screening) and Uni‐Gold HIV (Trinity Biotech; confirmation), which is the national HIV testing strategy. The prevalence of HIV was 14.0% (2002), 17.8% (2003), 16.5% (2004), and 20.2% (2005). A subset of 888 samples collected 2003 was sent to the Central Microbiology Laboratory, Maputo for evaluation of tests and testing strategies. The assays included for comparison were Capillus HIV‐1/HIV‐2 (Trinity Biotech), DoubleCheckGold HIV‐1&2 (Orgenics) and Enzygnost Anti‐HIV‐1/2 Plus (Behringwerke, reference ELISA). Confirmation of reactive samples was done by Uni‐Gold HIV and ImmunoComb II HIV‐1&2 BiSpot (for HIV type differentiation). The Capillus HIV‐1/ HIV‐2 + ImmunoComb II HIV‐1&2 BiSpot combination was the gold standard. The sensitivity of the rapid/simple screening assays (Determine HIV‐1/2, DoubleCheckGold HIV‐1&2) was 100% (N = 160) and their (initial) specificities were 99.6% and 99.7%, respectively. Repeated testing and combinations of assays increased the specificity. Four suspected cases of recent seroconversion were found. Together with the increasing prevalence rates, this may indicate that Mozambique is a high‐incidence area, although further studies are needed to confirm this. Testing strategies for on‐site screening and confirmation based on the combination of Determine HIV‐1/2, Uni‐Gold HIV and DoubleCheckGold HIV‐1&2 are well suited for local field use. J. Med. Virol. 81:1991–1998, 2009. © 2009 Wiley‐Liss, Inc.     

Detection of antibodies to HIV-1 in serum and saliva

In this study we report the detection of antibodies to HIV-1 in paired serum and saliva collected from 118 HIV-1 infected patients and 80 normal controls in Madras, South India. Saliva was collected using Omnisal (R) collection device. All the reactive samples were confirmed by Western blot test (WB), while all the control serum and saliva were negative for HIV-1 antibodies. 107 (90.6%) HIV individual's serum and saliva contained antibodies to HIV-1. When these reactive samples were tested by WB test for confirmation the following results were obtained; 68% HIV individuals' paired serum and saliva were positive; while 9% of serum samples were positive and the saliva specimens were negative on WB. 3% of paired samples showed indeterminate Western blot pattern in contrast to 10% of serum showed full WB pattern while the saliva result was indeterminate. It is suggested that saliva testing may be appropriate for surveillance and epidemiological studies. However, if used for individual HIV diagnosis it is imperative to use a confirmatory test.     

Performance evaluation of Elecsys HIV Duo on cobas e 801 using clinical samples in China

The prevalence and incidence of human immunodeficiency viruses (HIV) infection are rapidly increasing, and novel HIV genotypes are emerging. This study evaluated the sensitivity and specificity of Elecsys HIV Duo assay in population with the epidemic of multiple genotypes of HIV-1 infection. Specificity of the Elecsys HIV Duo assay was determined using 3039 serum samples from patients receiving routine HIV-1 screening tests in China. Sensitivity was assessed with seroconversion panels. Additional 67 positive from newly diagnosed HIV-1 infected samples were also included to test assay performance on various HIV-1 genotypes. The assay performance was compared with that of the Elecsys HIV Combi PT assay. The genotypes of all HIV-1 positive samples were determined with phylogenetic analyses on the 1.1 kb Pro-RT region of pol gene for drug resistance tests. The Elecsys HIV Duo assay had a slightly higher specificity (99.93% vs 99.84%) and equivalent sensitivity to Elecsys HIV Combi PT assay. Seventy-two HIV-1 positive samples, including 12 antigens positive samples, were distinguished by Elecsys HIV Duo. Among them, 43 samples were circulating recombinant form (CRF)01_AE, followed by 13 of CRF07_BC, 10 of subtype B, 4 of URF_0107, 1 of URF_01B and 1 of CRF02_AG. The Elecsys HIV Duo assay showed good performance for the Chinese population with an epidemic of multiple HIV genotypes.     

A cost-effective algorithm for the diagnosis of Hepatitis C virus infection and prediction of HCV viremia in Cameroon

Conventional tests for antibody to Hepatitis C virus (HCV) and HCV RNA require considerable time before results are available, remain very expensive and are not adapted to many sub-Saharan African countries where HCV is endemic. The aim of this study was to evaluate the accuracy of an algorithm consisting of two HCV rapid tests to diagnose and predict HCV viremia in patients in Cameroon. Three hundred and twenty nine plasma samples were screened by two HCV rapid tests (ImmunoComb II HCV, PBS Orgenics and Hexagon HCV, Human). Previous evaluation of these samples for HCV antibodies (anti-HCV) by conventional third generation ELISA, considered as a reference test, indicated that 168 were anti-HCV negative and 161 positive. Among the 161 anti-HCV positive plasma, 114 (71%) were HCV RNA-positive by RT-PCR assay. The ImmunoComb II HCV test provided the more sensitive detection of anti-HCV (sensitivity: 99.4% with a 95% CI = 96-100%). Surprisingly, the second HCV rapid test, Hexagon HCV, showed a high capacity to identify non-viremic subjects amongst anti-HCV positive cases (93.6% [95% CI: 82-99%]). These results suggest an algorithm using ImmunoComb II HCV as a first test to screen anti-HCV positive subjects, and Hexagon HCV as a second test to discriminate between viremic and non-viremic HCV seropositive subjects.     

New Automated Chemiluminescence Immunoassay for Simultaneous but Separate Detection of Human Immunodeficiency Virus Antigens and Antibodies

The recently launched Liaison XL Murex HIV Ab/Ag assay (DiaSorin S.p.A) uses chemiluminescence immunoassay technology for the combined qualitative determination of p24 antigen of HIV-1 and specific antibodies to both HIV-1 and HIV-2. We studied 571 serum samples from those submitted to our laboratory for HIV screening. The samples were divided into 3 subsets: subset A, 365 samples collected prospectively during 1 week; subset B, 158 samples from confirmed HIV-positive patients; and subset C, 48 samples with a positive screening result but a negative or indeterminate confirmatory test result. Our standard screening/confirmatory algorithm was used as a reference. In subset A (prospective), 5 samples were positive and 360 negative by the standard procedure. Liaison XL Murex HIV Ab/Ag correctly identified all 5 positive samples (100%) and 357 negative samples (99.2%). In subset B (confirmed positive), all 158 positive samples were in total agreement in both procedures. In subset C (screen positive only), Liaison XL Murex HIV Ab/Ag yielded accurate results in 42 out of 48 samples (87.5%). Global sensitivity and specificity for Liaison XL Murex HIV Ab/Ag (all subsets included) were 98.3% and 98.5%, respectively. Considering only nonselected prospective samples and confirmed positive samples (subsets A and B), the corresponding sensitivity and specificity values were 100% and 99.2%, respectively. The new fully automated HIV screening test showed high sensitivity and specificity compared to our standard algorithm. Its added advantage of being able to detect HIV-1 and HIV-2 antibodies and p24 antigen separately could prove useful in the diagnosis of early infections.     

Evaluation of the Bio-Rad Geenius HIV 1/2 Assay as an Alternative to the INNO-LIA HIV 1/2 Assay for Confirmation of HIV Infection

The Bio-Rad Geenius HIV 1/2 assay was evaluated as an alternative to the INNO-LIA HIV 1/2 assay for the confirmation of HIV infection in 198 serum samples reactive to 4th-generation HIV enzyme immunoassays (EIAs). The Geenius assay correctly identified 85% of the samples, compared to 75% identified by the INNO-LIA assay, reduced the number of indeterminate results, and shortened the overall turnaround time.     

Sensitivity and specificity of human immunodeficiency virus rapid serologic assays and testing algorithms in an antenatal clinic in Abidjan, Ivory Coast

To evaluate serologic testing algorithms for human immunodeficiency virus (HIV) based on a combination of rapid assays among persons with HIV-1 (non-B subtypes) infection, HIV-2 infection, and HIV-1-HIV-2 dual infections in Abidjan, Ivory Coast, a total of 1,216 sera with known HIV serologic status were used to evaluate the sensitivity and specificity of four rapid assays: Determine HIV-1/2, Capillus HIV-1/HIV-2, HIV-SPOT, and Genie II HIV-1/HIV-2. Two serum panels obtained from patients recently infected with HIV-1 subtypes B and non-B were also included. Based on sensitivity and specificity, three of the four rapid assays were evaluated prospectively in parallel (serum samples tested by two simultaneous rapid assays) and serial (serum samples tested by two consecutive rapid assays) testing algorithms. All assays were 100% sensitive, and specificities ranged from 99.4 to 100%. In the prospective evaluation, both the parallel and serial algorithms were 100% sensitive and specific. Our results suggest that rapid assays have high sensitivity and specificity and, when used in parallel or serial testing algorithms, yield results similar to those of enzyme-linked immunosorbent assay-based testing strategies. HIV serodiagnosis based on rapid assays may be a valuable alternative in implementing HIV prevention and surveillance programs in areas where sophisticated laboratories are difficult to establish.     

CRF22_01A1 is involved in the emergence of new HIV-1 recombinants in Cameroon

Cameroon is a West African country where high genetic diversity of HIV-1 has been reported. The predominant CRF02_AG is involved in the emergence of more complex intersubtype recombinants. In this study, we sequenced the full-length genome of a novel unique recombinant form of HIV-1, 02CAMLT04 isolated in blood donors in urban Cameroon. Phylogenetic tree and bootscan analysis showed that 02CAMLT04 was complex and seemed to be a secondary recombinant derived from CRF02_AG and CRF22_01A1. The genomic composition of 02CAMLT04 strain showed that it is composed of 3 segments; 24% of the genome is classified as CRF02_AG, spanning most of the envelope gene. The remaining 76% of the genome is classified as CRF22_01A1. In addition, the sequence analysis of 13 full-length sequences from HIV-1-positive specimens received from Cameroon between 2002 and 2010 indicated that 5 specimens are pure CRF22_01A1 viruses, and 6 others have homology with CRF22_01A1 sequences in either gag, pol, or env region, whereas 6% of strains contain portions of CRF22_01A1. Further study demonstrated that CRF22_01A1 is a primary prevalence strain co-circulating in Cameroon and is involved in complex intersubtype recombination events with subtypes (D or F), subsubtypes (A1 or F2), and CRFs (CRF01_AE or CRF02_AG). Our studies show that novel recombinants between CRF22_01A1 and other clades and recombinant forms may be emerging in Cameroon that could contribute to the future global diversity of HIV-1 in this region and worldwide.     

Evaluation of Chiron HIV-1/HIV-2 recombinant immunoblot assay.

In a study to determine the reliability, sensitivity, and specificity of the Chiron RIBA HIV-1/HIV-2 Strip Immunoblot Assay (RIBA HIV-1/2 SIA) for confirmation of human immunodeficiency virus type 1 (HIV-1) and HIV-2 antibodies, 1,263 serum samples from various populations in the United States, Caribbean, Africa, India, and Thailand were evaluated by RIBA HIV-1/2 SIA, and the results were compared with those obtained by an HIV-1 Western blot (immunoblot) assay. All sera were tested by HIV enzyme immunoassay, RIBA HIV-1/2 SIA, and Western blotting. Samples with discrepant results were further tested by an HIV-1 and/or HIV-2 immunofluorescent-antibody assay and HIV-1 p24 antigen assay. The RIBA HIV-1/2 SIA detected all 17 HIV-1 and HIV-2 dually reactive serum samples, all 215 HIV-2-positive serum samples, and 480 of 481 HIV-1-positive serum samples for a sensitivity of 99.8%. Of 548 negative samples, 523 were RIBA HIV-1/2 SIA negative, for a specificity of 95.4%, with 22 (4%) samples interpreted as indeterminate and 3 (0.6%) interpreted as falsely positive. Western blotting detected 391 of 548 negative samples (specificity, 71.4%), with 152 (27.7%) samples interpreted as indeterminate and 5 (0.9%) interpreted as falsely positive. In conclusion, the RIBA HIV-1/2 SIA had a sensitivity comparable to that of Western blotting and could discriminate HIV-1 from HIV-2 in one blot, providing a cost advantage. Because of its high degree of specificity, the RIBA HIV-1/2 SIA further reduced the number of indeterminate results found by Western blotting, providing a more accurate means of assessing seronegative individuals.     

淮安市经异性性传播的HIV感染者中HIV-1病毒基因亚型特征分析

目的 了解淮安市经异性性传播HIV感染者中HIV-1病毒基因亚型分布及其流行特征.方法 从60名异性性传播HIV-1感染者血液中提取DNA或RNA,用巢式PCR或RT-PCR方法扩增gag、env基因区片段,测定序列并分析.结果 60份标本中,确定了48份标本的基因亚型,发现有4种HIV-1亚型和重组型.其中CRF01_AE亚型占62.5％,CRF07_BC亚型占22.9％,CRF08_BC亚型占6.3％,B亚型占6.3％.结论淮安市异性性传播感染HIV者中,流行着CRF01_AE、CRF07_BC、CRF08_BC、B亚型这4种亚型病毒株,CRF01_AE为主要流行亚型.