HIV Insight: Spectrum of False Positivity for the Fourth Generation Human Immunodeficiency Virus Diagnostic Tests

Novel fourth generation screening and confirmatory human immunodeficiency virus (HIV) assays are now commercially available and incorporated into new diagnostic algorithms. We report two cases involving a total of three patients which highlight the spectrum of false positivity for both the Abbott Architect p24 antigen/antibody assay and the confirmatory Multispot antibody differentiation test. We then discuss the mechanisms for falsepositivity and the associated clinical conditions or laboratory scenarios that may predispose to inaccurate interpretation.

..We report the cautionary spectrum of false positive HIV diagnostics in three patients (Table 1). In case one, a false positive fourth generation test was not confirmed by antibody differentiation or by nucleic acid amplification testing, representing a common scenario often observed with prior generations of HIV diagnostics. Yet, in case two, we report one likely and one confirmed false positive result which occurred with both the antigen/antibody assay and with a confirmatory HIV antibody differentiation test.

Table 1

Summary of diagnostic test results and proposed mechanisms of false positivity

	Abbott p24 antigen/antibody	MultiSpot HIV-1/HIV-2 differentiation	HIV proviral DNA	HIV RNA viral load	Alternative diagnosis/mechanism of false positivity	Other explanatory studies/reports
Case 1	Positive	Non-reactive	Not done	Negative	EBV infection and reactive lymphocytosis	[7–13]
Case 2 patient	Positive	Reactive to HIV-1	Negative	Negative	Metastatic cancer	[18]
Case 2 exposed health care provider	Positive	Reactive to HIV-1	Negative	Negative	Healthy/query poor specificity of individual test kit	[16]
Case 2 exposed health care provider (6 month follow up)	Negative		Negative	Negative

Full article at: http://goo.gl/g14uCS

By: Liu P1, Jackson P2, Shaw N3, Heysell S2.

1Department of Internal Medicine, University of Virginia, 1215 Lee Street, Charlottesville, VA 22908 USA.
2Division of Infectious Diseases and International Health, University of Virginia, 345 Crispell Drive, Carter Harrison Building, Room 1523, Charlottesville, VA 22908 USA.
3University of Virginia School of Medicine, 1215 Lee Street, Charlottesville, VA 22908 USA.
AIDS Res Ther. 2016 Jan 5;13:1. doi: 10.1186/s12981-015-0086-3. eCollection 2016.