Journal of Clinical Virology 58S (2013) e76–e78
Contents lists available at ScienceDirect
Journal of Clinical Virology journal homepage: www.elsevier.com/locate/jcv
Short Communication
Use of the Abbott Architect HIV antigen/antibody assay in a low incidence population Terry Dubravac, Thomas F. Gahan, Michael A. Pentella ∗ State Hygienic Laboratory at the University of Iowa, 2490 Crosspark Road, Coralville, IA 52241, United States
a r t i c l e
i n f o
Article history: Received 24 September 2013 Received in revised form 12 October 2013 Accepted 16 October 2013 Keyword: HIV diagnostic testing
a b s t r a c t Background: With the availability of 4th generation HIV diagnostic tests which are capable of detecting acute infection, Iowa evaluated the 3rd and 4th generation HIV test and compared the performance of these products in a low incidence population. Objective: This study was conducted to evaluate the performance of an HIV antigen/antibody combination (4th generation) assay compared to an EIA 3rd generation assay. Study design: Over a 4 month period, 2037 specimens submitted for HIV screening were tested by BioRad GS HIV-1/HIV-2 Plus O EIA and the Abbott Architect i1000SR HIV Ag/Ab Combo. The performance characteristics of sensitivity, specificity, positive predictive value and negative predictive value were determined. Results: Of the 2037 specimens tested, there were 13 (0.64%) true positives detected. None of the positive specimens were from patients in the acute phase of infection. The Abbott antigen/antibody combo assay had a sensitivity, specificity, positive-predictive value and negative predictive value of 100%, 99.85%, 81.25%, and 100% respectively. The Bio-Rad EIA assay had a sensitivity, specificity, positive-predictive value and negative predictive value of 100%, 99.80%, 76.47% and 100%, respectively. The EIA had four false positive results which tested negative by the antigen/antibody assay and western blot. Conclusion: In a low-incidence state where early infections are less commonly encountered, the EIA assay and the antigen/antibody assay performed with near equivalency. The antigen/antibody assay had one less false positive result. While no patients were detected in the acute stage of infection, the use of the antigen/antibody assay presents the opportunity to detect an infected patient sooner and prevent transmission to others. © 2013 Elsevier B.V. All rights reserved.
1. Background Detection of patients infected with HIV is the first step in accessing care and treatment services and preventing future cases of HIV infection. When a patient is initially infected with HIV, the patient has a large number of HIV virus particles in their blood and body fluids but has not mounted a detectable antibody response to the infection. Acute infection is described as the period between the appearance of HIV RNA and p24 antigen in plasma and the detection of HIV antibodies [1]. The acute phase of the infection is also known as the “window period” of the HIV infection because HIV tests that detect antibodies are negative while the patient is infectious. Detectable levels of antibody can take from two to eight weeks to develop. The acute phase plays a significant role in transmission of HIV to others since the levels of virus in the body are at their highest during the acute phase of infection. A person in
∗ Corresponding author. Tel.: +1 617 983 4362; fax: +1 617 983 6211. E-mail address: [email protected] (M.A. Pentella). 1386-6532/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jcv.2013.10.020
the acute HIV infection phase has an opportunity to begin treatment and to prevent transmission to others [2]. When HIV antibody tests were first available only immunoglobulin G (IgG) class antibodies to HIV could be detected. With the 3rd generation of HIV antibody tests, HIV immunoassays detected both IgG class antibodies and immunoglobulin M (IgM) class antibodies to HIV. The fourth generation immunoassay is further improved because it couples HIV-1/HIV-2 antibody tests that detect both IgG and IgM class antibodies with the p24 antigen detection assay. The p24 antigen test is generally able to be detected in serum from about 14 days to 22 days [3] after infection with HIV, yet this is before HIV antibody is detectable. Therefore, with the 4th generation test the window period in which a person is highly infectious, yet would not be identified by only antibody testing, is further shortened. In March 2010, the Centers for Disease Control and Prevention (CDC, Atlanta, GA) and the Association of Public Health Laboratories (APHL, Silver Spring, MD), proposed a new HIV diagnostic testing algorithm that would replace the current algorithm first introduced in 1989 [4]. The new algorithm was acknowledged by the Clinical and Laboratory Standards Institute (CLSI, Wayne, PA)
T. Dubravac et al. / Journal of Clinical Virology 58S (2013) e76–e78 Table 1 Results of Abbott Architect antigen/antibody assay and Bio-Rad GS HIV-1/2 Plus O on 2037 specimens submitted for HIV screening. N = 2037
HIV positive
HIV negative
Positive by Abbott Architect antigen/antibody Negative by Abbott Architect antigen/antibody Positive by Bio-Rad GS HIV-1/2 Plus O Negative by Bio-Rad GS HIV-1/2 Plus O
13 0 13 0
3 2021 4 2020
in 2011 [3]. The need for a new algorithm was recognized because the 1989 HIV diagnostics algorithm detects HIV antibody using a screening immunoassay followed by confirmation using western blot (WB) which only detects HIV-1 IgG class antibodies. This testing algorithm was no longer adequate due to the introduction of more sensitive assays that detect the presence of both IgG and IgM antibodies earlier in the course of the disease [2,5]. The first test in the new algorithm is a fourth generation HIV antigen/antibody screening test [6]. A reactive specimen is followed by a supplemental test with an HIV immunoassay that differentiates antibodies to HIV-1 from HIV-2. If the specimen is negative or indeterminate for HIV-1 and HIV-2 antibodies on the second or supplemental test it is then tested for HIV-1 RNA. In using this algorithm, there are very few specimens which will require HIV-1 RNA testing [7]. The algorithm is structured to have a high predictive value for positive results with the minimum number of tests. The supplemental test provides the necessary specificity to limit false positives [5]. Of importance is that the supplemental test can be performed within a short time of the initial screening tests allowing for completion of both tests on the same day [6]. In 2010, Iowa reported 3.6 HIV diagnoses per 100,000 compared to the national average of 16.1. Iowa has a much lower incidence of HIV illness than other areas of the nation. While incidence is low, the need to quickly identify and treat infected individuals, and prevent transmission to others is the same. The 4th generation testing is beneficial in all incidence settings. The performance of the algorithm in a high incidence population has been studied [7]. 2. Objective This study was conducted to evaluate the performance of an HIV antigen/antibody combo (4th generation) assay compared to an EIA 3rd generation assay, for routine screening in a low HIV incidence population. 3. Study design Over the period from March 2, 2012 to August 3, 2012, 2037 specimens submitted for HIV screening were tested by GS HIV1/HIV-2 Plus O EIA (Bio-Rad Laboratories, Hercules, CA) and the Architect i1000SR HIV Ag/Ab Combo (Abbott Diagnostics, Lake Forest, IL). Other testing included western blot (Bio-Rad Laboratories, Hercules, CA) and the NAAT assay (Gen-Probe APTIMA HIV-1 RNA Assay, Hologic, Inc., Bedford, MA). The performance characteristics of sensitivity, specificity, positive predictive value and negative predictive value were determined.
e77
Table 2 Performance characteristics of Abbott Architect antigen/antibody assay and Bio-Rad GS HIV-1/2 Plus O on 2037 specimens submitted for HIV screening. Performance (%) Abbott Architect antigen/antibody Sensitivity 100 Specificity 99.85 81.25 Predictive value positive Predictive value negative 100 Bio-Rad GS HIV-1/2 Plus O 100 Sensitivity 99.80 Specificity Predictive value positive 76.47 100 Predictive value negative
(95% CI: 75.12–100%) (95% CI: 99.57–99.97%) (95% CI: 54.34–95.73%) (95% CI: 99.82–100%) (95% CI: 75.12–100%) (95% CI: 99.49–99.94%) (95% CI: 50.10–93.04%) (95% CI: 99.82–100%)
three false positives detected by the antigen/antibody assay tested negative by Bio-Rad EIA, western blot and HIV NAAT testing. For the three false positive tests by the antigen/antibody assay, the signal to cut off ratio was low at 1.86, 2.03 and 1.59 respectively. 4.2. BioRad HIV-1/2 Plus O EIA performance characteristics Of the 2037 patient samples tested by the Bio-Rad HIV-1/2 Plus O assay, 17 were positive. Of those 17, 13 were true positives, 4 were false positives, and 2020 were true negatives. This calculates to a sensitivity of 100%, specificity of 99.80%, predictive value positive of 76.47%, and predictive value negative of 100% (Table 2). The 4 false positives detected by the Bio-Rad EIA assay were negative by the Abbott Architect and western blot assay. 5. Discussion At the time of this study, our laboratory had not adopted the new algorithm using the 4th generation assay for routine use. While no additional positives were detected by the Abbott Architect in this small sample low incidence study, the premise that adopting the algorithm provides for the detection of infected individuals in the highly viremic, acute phase and acts as an effective tool in reducing transmission still holds. The Abbott Architect 4th generation assay is demonstrated to be a highly sensitive and specific HIV serologic assay. This meets the strategy of the algorithm which is to screen with a highly sensitive test so that as many positives as possible can be detected [5]. The Bio-Rad HIV 1/2 Plus O performed as expected consistent with prior results [5]. In this study of a low incidence population the 3rd and 4th generation assays performed essentially the same with the exception of one additional false positive for the 3rd generation assay. The HIV-1 NAAT test resolved the false positives, all were HIV RNA negative, there were no acute stage infections detected. The new algorithm is less labor intensive than the 1989 algorithm and provides a more rapid turnaround time since the supplemental test can be performed and resulted on the same day as the initial screening assay [8]. Additionally, the algorithm provides for detection of HIV-2, which can incorrectly be identified as HIV-1 if the WB is used [5]. 6. Conclusions
4. Results 4.1. Abbott Architect performance characteristics Of the 2037 patient samples tested by the 4th generation Abbott Architect assay 16 were positive. Of those 16, 13 were true positives, 3 were false positives, and 2021 were true negatives. This calculates to a sensitivity of 100%, specificity of 99.85%, predictive value positive of 81.25%, and predictive value negative of 100% (Table 1). The
The performance characteristics of the 4th generation Abbott HIV-1/2 antigen/antibody assay and the 3rd generation Bio-Rad HIV-1/2 EIA assay are essentially equivalent when used in a low HIV-1/2 prevalence population. The Abbott assay detected one less false positive result. Although no persons in our study were identified in the acute phase of HIV infection, the use of 4th generation antigen/antibody assays should be standard. The additional value to laboratories who adopt the new testing algorithm is the
e78
T. Dubravac et al. / Journal of Clinical Virology 58S (2013) e76–e78
replacement of the relatively insensitive WB with the more sensitive and rapid HIV-1/2 differentiation assays. Funding Testing supplies for this project were provided by Abbott Diagnostics. Competing interests The authors have no competing interests to report. Ethical approval The design for this study was reviewed by the Institutional Review Board of the University of Iowa. References [1] CDC. Detection of acute HIV infection in two evaluations of a new HIV diagnostic testing algorithm – United States, 2011–2013. Morbidity and Mortality Weekly Report (MMWR) 2013;62:489–94.
[2] Branson BM, Mermin J. Establishing the diagnosis of HIV infection: new tests and a new algorithm for the United States. Journal of Clinical Virology 2011;52(Suppl. 1):S3–4. [3] CLSI. Criteria for laboratory testing and diagnosis of human immunodeficiency virus infection: approved guideline. CLSI Document M53A. Wayne, PA: Clinical and Laboratory Standards Institute; 2011. [4] CDC. Interpretation and use of the Western blot assay for serodiagnosis of human immunodeficiency virus type 1 infections. MMWR – Recommendations and Reports 1989;38:7. [5] Owen SM, Yang C, Spira T, Ou CY, Pau CP, Parekh BS, et al. Alternative algorithms for human immunodeficiency virus infection diagnosis using tests that are licensed in the United States. Journal of Clinical Microbiology 2008;46: 1588–95. [6] Wesolowski L, Delaney KP, Hart C, Dawson C, Owen SM, Candal D, et al. Performance of an alternative laboratory-based algorithm for diagnosis of HIV infection utilizing a third generation immunoassay, a rapid HIV-1/HIV-2 differentiation test and a DNA or RNA-based nucleic acid amplification test in persons with established HIV-1 infection and blood donors. Journal of Clinical Virology 2011;52(Suppl. 1):S45–9. [7] Delaney KP, Heffelfinger JD, Wesolowski LG, Owen MS, Meyer WA, Kennedy S, et al. Performance of an alternative laboratory-based algorithm for HIV diagnosis in a high-risk population. Journal of Clinical Virology 2011;52(Suppl. 1): S5–10. [8] Masciotra S, McDougal SJ, Feldman J, Sprinkle P, Wesolowski L, Owen SM. Evaluation of an alternative HIV diagnostic algorithm using specimens from seroconversion panels and persons with established HIV infections. Journal of Clinical Virology 2011;52(Suppl. 1):S17–22.
Contents lists available at ScienceDirect
Journal of Clinical Virology journal homepage: www.elsevier.com/locate/jcv
Short Communication
Use of the Abbott Architect HIV antigen/antibody assay in a low incidence population Terry Dubravac, Thomas F. Gahan, Michael A. Pentella ∗ State Hygienic Laboratory at the University of Iowa, 2490 Crosspark Road, Coralville, IA 52241, United States
a r t i c l e
i n f o
Article history: Received 24 September 2013 Received in revised form 12 October 2013 Accepted 16 October 2013 Keyword: HIV diagnostic testing
a b s t r a c t Background: With the availability of 4th generation HIV diagnostic tests which are capable of detecting acute infection, Iowa evaluated the 3rd and 4th generation HIV test and compared the performance of these products in a low incidence population. Objective: This study was conducted to evaluate the performance of an HIV antigen/antibody combination (4th generation) assay compared to an EIA 3rd generation assay. Study design: Over a 4 month period, 2037 specimens submitted for HIV screening were tested by BioRad GS HIV-1/HIV-2 Plus O EIA and the Abbott Architect i1000SR HIV Ag/Ab Combo. The performance characteristics of sensitivity, specificity, positive predictive value and negative predictive value were determined. Results: Of the 2037 specimens tested, there were 13 (0.64%) true positives detected. None of the positive specimens were from patients in the acute phase of infection. The Abbott antigen/antibody combo assay had a sensitivity, specificity, positive-predictive value and negative predictive value of 100%, 99.85%, 81.25%, and 100% respectively. The Bio-Rad EIA assay had a sensitivity, specificity, positive-predictive value and negative predictive value of 100%, 99.80%, 76.47% and 100%, respectively. The EIA had four false positive results which tested negative by the antigen/antibody assay and western blot. Conclusion: In a low-incidence state where early infections are less commonly encountered, the EIA assay and the antigen/antibody assay performed with near equivalency. The antigen/antibody assay had one less false positive result. While no patients were detected in the acute stage of infection, the use of the antigen/antibody assay presents the opportunity to detect an infected patient sooner and prevent transmission to others. © 2013 Elsevier B.V. All rights reserved.
1. Background Detection of patients infected with HIV is the first step in accessing care and treatment services and preventing future cases of HIV infection. When a patient is initially infected with HIV, the patient has a large number of HIV virus particles in their blood and body fluids but has not mounted a detectable antibody response to the infection. Acute infection is described as the period between the appearance of HIV RNA and p24 antigen in plasma and the detection of HIV antibodies [1]. The acute phase of the infection is also known as the “window period” of the HIV infection because HIV tests that detect antibodies are negative while the patient is infectious. Detectable levels of antibody can take from two to eight weeks to develop. The acute phase plays a significant role in transmission of HIV to others since the levels of virus in the body are at their highest during the acute phase of infection. A person in
∗ Corresponding author. Tel.: +1 617 983 4362; fax: +1 617 983 6211. E-mail address: [email protected] (M.A. Pentella). 1386-6532/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jcv.2013.10.020
the acute HIV infection phase has an opportunity to begin treatment and to prevent transmission to others [2]. When HIV antibody tests were first available only immunoglobulin G (IgG) class antibodies to HIV could be detected. With the 3rd generation of HIV antibody tests, HIV immunoassays detected both IgG class antibodies and immunoglobulin M (IgM) class antibodies to HIV. The fourth generation immunoassay is further improved because it couples HIV-1/HIV-2 antibody tests that detect both IgG and IgM class antibodies with the p24 antigen detection assay. The p24 antigen test is generally able to be detected in serum from about 14 days to 22 days [3] after infection with HIV, yet this is before HIV antibody is detectable. Therefore, with the 4th generation test the window period in which a person is highly infectious, yet would not be identified by only antibody testing, is further shortened. In March 2010, the Centers for Disease Control and Prevention (CDC, Atlanta, GA) and the Association of Public Health Laboratories (APHL, Silver Spring, MD), proposed a new HIV diagnostic testing algorithm that would replace the current algorithm first introduced in 1989 [4]. The new algorithm was acknowledged by the Clinical and Laboratory Standards Institute (CLSI, Wayne, PA)
T. Dubravac et al. / Journal of Clinical Virology 58S (2013) e76–e78 Table 1 Results of Abbott Architect antigen/antibody assay and Bio-Rad GS HIV-1/2 Plus O on 2037 specimens submitted for HIV screening. N = 2037
HIV positive
HIV negative
Positive by Abbott Architect antigen/antibody Negative by Abbott Architect antigen/antibody Positive by Bio-Rad GS HIV-1/2 Plus O Negative by Bio-Rad GS HIV-1/2 Plus O
13 0 13 0
3 2021 4 2020
in 2011 [3]. The need for a new algorithm was recognized because the 1989 HIV diagnostics algorithm detects HIV antibody using a screening immunoassay followed by confirmation using western blot (WB) which only detects HIV-1 IgG class antibodies. This testing algorithm was no longer adequate due to the introduction of more sensitive assays that detect the presence of both IgG and IgM antibodies earlier in the course of the disease [2,5]. The first test in the new algorithm is a fourth generation HIV antigen/antibody screening test [6]. A reactive specimen is followed by a supplemental test with an HIV immunoassay that differentiates antibodies to HIV-1 from HIV-2. If the specimen is negative or indeterminate for HIV-1 and HIV-2 antibodies on the second or supplemental test it is then tested for HIV-1 RNA. In using this algorithm, there are very few specimens which will require HIV-1 RNA testing [7]. The algorithm is structured to have a high predictive value for positive results with the minimum number of tests. The supplemental test provides the necessary specificity to limit false positives [5]. Of importance is that the supplemental test can be performed within a short time of the initial screening tests allowing for completion of both tests on the same day [6]. In 2010, Iowa reported 3.6 HIV diagnoses per 100,000 compared to the national average of 16.1. Iowa has a much lower incidence of HIV illness than other areas of the nation. While incidence is low, the need to quickly identify and treat infected individuals, and prevent transmission to others is the same. The 4th generation testing is beneficial in all incidence settings. The performance of the algorithm in a high incidence population has been studied [7]. 2. Objective This study was conducted to evaluate the performance of an HIV antigen/antibody combo (4th generation) assay compared to an EIA 3rd generation assay, for routine screening in a low HIV incidence population. 3. Study design Over the period from March 2, 2012 to August 3, 2012, 2037 specimens submitted for HIV screening were tested by GS HIV1/HIV-2 Plus O EIA (Bio-Rad Laboratories, Hercules, CA) and the Architect i1000SR HIV Ag/Ab Combo (Abbott Diagnostics, Lake Forest, IL). Other testing included western blot (Bio-Rad Laboratories, Hercules, CA) and the NAAT assay (Gen-Probe APTIMA HIV-1 RNA Assay, Hologic, Inc., Bedford, MA). The performance characteristics of sensitivity, specificity, positive predictive value and negative predictive value were determined.
e77
Table 2 Performance characteristics of Abbott Architect antigen/antibody assay and Bio-Rad GS HIV-1/2 Plus O on 2037 specimens submitted for HIV screening. Performance (%) Abbott Architect antigen/antibody Sensitivity 100 Specificity 99.85 81.25 Predictive value positive Predictive value negative 100 Bio-Rad GS HIV-1/2 Plus O 100 Sensitivity 99.80 Specificity Predictive value positive 76.47 100 Predictive value negative
(95% CI: 75.12–100%) (95% CI: 99.57–99.97%) (95% CI: 54.34–95.73%) (95% CI: 99.82–100%) (95% CI: 75.12–100%) (95% CI: 99.49–99.94%) (95% CI: 50.10–93.04%) (95% CI: 99.82–100%)
three false positives detected by the antigen/antibody assay tested negative by Bio-Rad EIA, western blot and HIV NAAT testing. For the three false positive tests by the antigen/antibody assay, the signal to cut off ratio was low at 1.86, 2.03 and 1.59 respectively. 4.2. BioRad HIV-1/2 Plus O EIA performance characteristics Of the 2037 patient samples tested by the Bio-Rad HIV-1/2 Plus O assay, 17 were positive. Of those 17, 13 were true positives, 4 were false positives, and 2020 were true negatives. This calculates to a sensitivity of 100%, specificity of 99.80%, predictive value positive of 76.47%, and predictive value negative of 100% (Table 2). The 4 false positives detected by the Bio-Rad EIA assay were negative by the Abbott Architect and western blot assay. 5. Discussion At the time of this study, our laboratory had not adopted the new algorithm using the 4th generation assay for routine use. While no additional positives were detected by the Abbott Architect in this small sample low incidence study, the premise that adopting the algorithm provides for the detection of infected individuals in the highly viremic, acute phase and acts as an effective tool in reducing transmission still holds. The Abbott Architect 4th generation assay is demonstrated to be a highly sensitive and specific HIV serologic assay. This meets the strategy of the algorithm which is to screen with a highly sensitive test so that as many positives as possible can be detected [5]. The Bio-Rad HIV 1/2 Plus O performed as expected consistent with prior results [5]. In this study of a low incidence population the 3rd and 4th generation assays performed essentially the same with the exception of one additional false positive for the 3rd generation assay. The HIV-1 NAAT test resolved the false positives, all were HIV RNA negative, there were no acute stage infections detected. The new algorithm is less labor intensive than the 1989 algorithm and provides a more rapid turnaround time since the supplemental test can be performed and resulted on the same day as the initial screening assay [8]. Additionally, the algorithm provides for detection of HIV-2, which can incorrectly be identified as HIV-1 if the WB is used [5]. 6. Conclusions
4. Results 4.1. Abbott Architect performance characteristics Of the 2037 patient samples tested by the 4th generation Abbott Architect assay 16 were positive. Of those 16, 13 were true positives, 3 were false positives, and 2021 were true negatives. This calculates to a sensitivity of 100%, specificity of 99.85%, predictive value positive of 81.25%, and predictive value negative of 100% (Table 1). The
The performance characteristics of the 4th generation Abbott HIV-1/2 antigen/antibody assay and the 3rd generation Bio-Rad HIV-1/2 EIA assay are essentially equivalent when used in a low HIV-1/2 prevalence population. The Abbott assay detected one less false positive result. Although no persons in our study were identified in the acute phase of HIV infection, the use of 4th generation antigen/antibody assays should be standard. The additional value to laboratories who adopt the new testing algorithm is the
e78
T. Dubravac et al. / Journal of Clinical Virology 58S (2013) e76–e78
replacement of the relatively insensitive WB with the more sensitive and rapid HIV-1/2 differentiation assays. Funding Testing supplies for this project were provided by Abbott Diagnostics. Competing interests The authors have no competing interests to report. Ethical approval The design for this study was reviewed by the Institutional Review Board of the University of Iowa. References [1] CDC. Detection of acute HIV infection in two evaluations of a new HIV diagnostic testing algorithm – United States, 2011–2013. Morbidity and Mortality Weekly Report (MMWR) 2013;62:489–94.
[2] Branson BM, Mermin J. Establishing the diagnosis of HIV infection: new tests and a new algorithm for the United States. Journal of Clinical Virology 2011;52(Suppl. 1):S3–4. [3] CLSI. Criteria for laboratory testing and diagnosis of human immunodeficiency virus infection: approved guideline. CLSI Document M53A. Wayne, PA: Clinical and Laboratory Standards Institute; 2011. [4] CDC. Interpretation and use of the Western blot assay for serodiagnosis of human immunodeficiency virus type 1 infections. MMWR – Recommendations and Reports 1989;38:7. [5] Owen SM, Yang C, Spira T, Ou CY, Pau CP, Parekh BS, et al. Alternative algorithms for human immunodeficiency virus infection diagnosis using tests that are licensed in the United States. Journal of Clinical Microbiology 2008;46: 1588–95. [6] Wesolowski L, Delaney KP, Hart C, Dawson C, Owen SM, Candal D, et al. Performance of an alternative laboratory-based algorithm for diagnosis of HIV infection utilizing a third generation immunoassay, a rapid HIV-1/HIV-2 differentiation test and a DNA or RNA-based nucleic acid amplification test in persons with established HIV-1 infection and blood donors. Journal of Clinical Virology 2011;52(Suppl. 1):S45–9. [7] Delaney KP, Heffelfinger JD, Wesolowski LG, Owen MS, Meyer WA, Kennedy S, et al. Performance of an alternative laboratory-based algorithm for HIV diagnosis in a high-risk population. Journal of Clinical Virology 2011;52(Suppl. 1): S5–10. [8] Masciotra S, McDougal SJ, Feldman J, Sprinkle P, Wesolowski L, Owen SM. Evaluation of an alternative HIV diagnostic algorithm using specimens from seroconversion panels and persons with established HIV infections. Journal of Clinical Virology 2011;52(Suppl. 1):S17–22.
