HIV treatment during acute infection can lead to false negative HIV antibody tests

Initiation of antiretroviral therapy during acute HIV-1 infection leads to a high rate of nonreactive HIV serology.

de Souza MS, Pinyakorn S, Akapirat S, Pattanachaiwit S, Fletcher JL, Chomchey N, Kroon ED, Ubolyam S, Michael NL, Robb ML, Phanuphak P, Kim JH, Phanuphak N, Ananworanich J. Clin Infect Dis. 2016 Aug 15;63(4):555-61. doi: 10.1093/cid/ciw365. Epub 2016 Jun 17.

Background: Third- and fourth-generation immunoassays (IAs) are widely used in the diagnosis of human immunodeficiency virus (HIV) infection. Antiretroviral therapy (ART) during acute HIV infection (AHI) may impact HIV-specific antibodies, with failure to develop antibody or seroreversion. We report on the ability of diagnostic tests to detect HIV-specific antibodies in Thai participants initiating ART during AHI.

Methods: Participants with detectable plasma HIV RNA but nonreactive HIV-specific immunoglobulin G, enrolled in an AHI study, were offered immediate initiation of ART. Participants were tested at initiation and at 12 and 24 weeks following treatment using standard second-, third-, and fourth-generation IAs and Western blot (WB).

Results: Participants (N = 234) initiating ART at a median of 19 days (range, 1-62 days) from HIV exposure demonstrated different frequencies of reactivity prior to and following 24 weeks of ART depending on the IA. Third-generation IA nonreactivity prior to ART was 48%, which decreased to 4% following ART (P < .001). Fourth-generation IA nonreactivity was 18% prior to ART and 17% following ART (P = .720). Negative WB results were observed in 89% and 12% of participants prior to and following 24 weeks of ART, respectively (P < .001). Seroreversion to nonreactivity during ART was observed to at least one of the tests in 20% of participants, with fourth-generation IA demonstrating the highest frequency (11%) of seroreversion.

Conclusions: HIV-specific antibodies may fail to develop and, when detected, may decline when ART is initiated during AHI. Although fourth-generation IA was the most sensitive at detecting AHI prior to ART, third-generation IA was the most sensitive during treatment.

Clinical trials registration: NCT00796146 and NCT00796263.

Abstract access   [1]

Editor’s notes: Antibodies to HIV become detectable around three weeks after HIV infection. Fourth generation HIV tests detect both HIV antibodies and the p24 HIV antigen, and can therefore detect HIV infection earlier than second and third-generation tests, which are based on detection of antibodies. Fourth generation tests therefore allow for earlier initiation of antiretroviral therapy (ART) relative to second- and third-generation HIV tests.

There have been sporadic reports of seroreversion from being HIV antibody positive to negative, or failure to seroconvert to being HIV antibody positive, following initiation of ART, particularly from paediatric populations. This study examined the impact of ART initiation during acute HIV infection on HIV diagnostic test results. Although the fourth-generation HIV test was the most sensitive at detecting acute HIV infection, it also had the highest frequency of seroreversion. Conversely, third generation HIV tests were positive prior to the start of ART in just over half of participants, compared to nearly all by 12 weeks after ART initiation. Notably, the Western blot, which was historically used as a confirmatory test for HIV, had high rates of non-reactivity in acute infection and 12% of tests were negative at 24 weeks after treatment, demonstrating that this test is not informative as a confirmatory assay in the context of acutely-treated HIV infection.   

The recent WHO guidelines recommend ART for all HIV-positive people regardless of age and disease stage.  Initiating ART as early as possible following HIV infection has also been recommended as a means to limit the size of the viral reservoir and improve prognosis. It is therefore likely that increasing numbers of individuals will start ART during early infection. There may be instances where individuals on ART may retest either due to doubts about results, or when they relocate to other HIV services. Clinicians need to be aware of the possibility of false-negative HIV antibody tests among people taking ART, particularly among individuals who initiated treatment during acute infection.    

Asia [7]
Thailand [8]
  • [9]