Aug
17
Written by:
Emily Sherman
8/17/2010 8:04 AM
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Source PDF with Charts: http://www.seracare.com/Portals/0/Papers/Tech%20Bulletin902_r8.pdf
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SeraCare Technical Bulletin 0902: HIV Antibody Test Sensitivity
Q: Why do seroconversion panels provide the best measure for evaluating HIV sensitivity?
A:Many laboratories are interested in using the “most sensitive” HIV antibody screening
assay to avoid false negative test results. It is well known that HIV antibody is at its lowest level early in seroconversion, and thus most difficult to detect within two to four weeks after HIV infection when the immune response is just beginning.
Once an infected person begins to produce antibodies, the titer rises quickly and remains high, even in later stages of the disease.
Early seroconversion samples differ in several ways from those obtained many months after infection:
• Early samples may contain HIV p24 antigen and IgM or IgA antibodies in addition to IgG; later samples most often contain only IgG antibodies
• Some HIV antibodies appear earlier than others: for instance, Western blot patterns indicate that p24 appears first, followed by gp120/160, and then other antibodies, with p31 usually coming up last
• The binding properties of early vs. late antibodies also differ; low affinity antibodies are produced early and high affinity antibodies are produced later in infection Antibodies present in high titer samples (from later in infection) represent a much different mixture of high and low affinity antibodies to different viral protein epitopes than those from early infection. Thus, testing diluted samples from later in infection will yield a different estimate of test kit sensitivity than from testing naturally-occurring low titer samples from early seroconversion.1
ACCURUN® 1 Positive Control, and other ACCURUN HIV controls, are prepared in part by diluting a pool of high titer, anti-HIV samples with fully developed Western blot patterns, most likely collected many months or years after seroconversion. ACCURUN 1 is designed tomonitor your test methods for changes in performance.
For evaluation of assay sensitivity to HIV antibodies, SeraCare recommends use of samples from a seroconversion series, or, naturallyoccurring low titer, anti-HIV samples.
These samples are available from SeraCare as HIV Seroconversion Panels and Low Titer HIV Performance Panels.
See Table 2, page 3.
Naturally-occurring, low titer, anti-HIV samples may also be found by analyzing HIV test results according to the Fiebig classification, as shown in Table 1 on the following page.2 Samples that can be classified as Fiebig III, IV or V are generally accepted as low titer anti-HIV.
Table 1
Laboratory Stages of Primary HIV Infection Based on the Emergence of Viral Markers in 51 Seroconverting Plasma Donors
a Calculations are based on a parametric Markov model
b Without p31 band
CI = Confidence interval
I = Indeterminate
NS = Not sensitive, refers to second-generation, not IgM-sensitive enzyme immunoassay (EIA)
S = Sensitive, refers to IgM-sensitive, third-generation EIA
References
1. Thorn RM et al. Assessment of HIV-1 screening test sensitivities using serially diluted positive sera can give misleading results.
Transfusion 1989, 29(1): 78-80
2. Fiebig EW et al. Dynamics of HIV viremia and antibody seroconversion in plasma donors: implications for diagnosis and staging of primary HIV infection. AIDS 2003, 17:1871–1879
Members/ Product Volume* Cat No HIV Seroconversion Panels
HIV-1 Panel D 5 x 0.25 mL PRB904-00-0.25
5 x 1.0 mL PRB904-00-1.0
HIV-1 Panel H 6 x 1.0 mL PRB908-00-1.0
HIV-1 Panel J 7 x 0.25 mL PRB910-00-0.25
HIV-1 Panel L 6 x 0.25 mL PRB912-00-0.25
HIV-1 Panel N 5 x 1.0 mL PRB914-00-1.0
HIV-1 Panel P 6 x 1.0 mL PRB916-00-1.0
HIV-1 Panel Q 5 x 0.25 mL PRB917-00-0.25 (M)
HIV-1 Panel S 3 x 0.25 mL PRB919-00-0.25
3 x 1.0 mL PRB919-00-1.0
HIV-1 Panel V 4 x 1.0 mL PRB922-00-1.0
HIV-1 Panel X 8 x 0.25 mL PRB924-00-0.25
8 x 1.0 mL PRB924-00-1.0
HIV-1 Panel Y 6 x 0.25 mL PRB925-00-0.25
6 x 1.0 mL PRB925-00-1.0
HIV-1 Panel Z 6 x 0.25 mL PRB926-00-0.25
6 x 1.0 mL PRB926-00-1.0
HIV-1 Panel AD 7 x 0.25 mL PRB929-00-0.25
HIV-1 Panel AE 4 x 1.0 mL PRB930-00-1.0
HIV-1 Panel AF 9 x 0.25 mL PRB931-00-0.25
9 x 1.0 mL PRB931-00-1.0
HIV-1 Panel AH 3 x 1.0 mL PRB933-00-1.0
HIV-1 Panel AI 3 x 1.0 mL PRB934-00-1.0
HIV-1 Panel AJ 7 x 0.25 mL PRB935-00-0.25
HIV-1 Panel AL 6 x 1.0 mL PRB937-00-1.0
HIV-1 Panel AN 9 x 1.0 mL PRB939-00-1.0 (E)
HIV-1 Panel AP 8 x 1.0 mL PRB940-00-1.0
HIV-1 Panel AR 4 x 0.25 mL PRB942-00-0.25
4 x 1.0 mL PRB942-00-1.0
HIV-1 Panel AS 7 x 1.0 mL PRB943-00-1.0
HIV-1 Panel AT 6 x 1.0 mL PRB944-00-1.0
HIV-1 Panel AU 6 x 1.0 mL PRB945-00-1.0
HIV-1 Panel AV 4 x 0.25 mL PRB946-00-0.25
4 x 1.0 mL PRB946-00-1.0
For more information or to place an order, contact SeraCare customer service at 800.676.1881 or visit our eCatalog at www.seracarecatalog.com
Members/ Product Volume* Cat No
HIV-1 Panel AW 4 x 1.0 mL PRB947-00-1.0
HIV-1 Panel AX 4 x 0.25 mL PRB948-00-0.25
4 x 1.0 mL PRB948-00-1.0
HIV-1 Panel AY 4 x 1.0 mL PRB949(M)-1.0
HIV-1 Panel AZ 4 x 0.25 mL PRB950-00-0.25
4 x 1.0 mL PRB950-00-1.0
HIV-1 Panel BA 6 x 0.25 mL PRB951-00-0.25
6 x 1.0 mL PRB951-00-1.0
HIV-1 Panel BB 6 x 1.0 mL PRB952-00-1.0
HIV-1 Panel BC 4 x 1.0 mL PRB953-00-1.0
HIV-1 Panel BD 7 x 1.0 mL PRB954-1.0
HIV-1 Panel BE 5 x 1.0 mL PRB955-1.0
HIV-1 Panel BF 5 x 1.0 mL PRB956-1.0
HIV-1 Panel BG 7 x 1.0 mL PRB957-1.0
HIV-1 Panel BH 6 x 1.0 mL PRB958-1.0
HIV-1 Panel BI 7 x 1.0 mL PRB959-1.0
HIV-1 Panel 9 x 1.0 mL PRB960-1.0
HIV-1 Panel 9 x 1.0 mL PRB961-1.0
HIV-1 Panel 6 x 1.0 mL PRB962-1.0
HIV-1 Panel 7 x 1.0 mL PRB963-1.0
HIV-1 Panel 6 x 1.0 mL PRB964-1.0
HIV-1 Panel 6 x 1.0 mL PRB965-1.0
HIV-1 Panel 10 x 1.0 mL PRB966-1.0
HIV Performance Panels
Anti-HIV-1 Low Titer 10 x 1.0 mL PRB108(M)-1.0
Anti-HIV-1 Mixed Titer 25 x 0.25 mL PRB204-0.25
Anti-HIV-1 Mixed Titer 21 x 1.0 mL PRB204(M)-1.0
HIV-1 15 x 1.0 mL PRB601-1.0
Incidence/Prevalence
HIV-1 Group O 5 x 1.1 mL PRD301-1.1
HIV Subtype 20 x 1.0 mL PRD320-1.0
Infectivity Panel
HIV RNA Genotype 10 x 1.1 mL PRD202-1.1
Worldwide HIV 18 x 1.0 mL WWRB350-1.0
[M] = Modified
[E] = Extended
* Unless otherwise noted, configuration includes one set of members
For research use only. Not for use in diagnostic procedures