Nucleic acid amplification testing for diagnosis of acute HIV infection: has the time come?

Real-world performance of HIV low viral load values in diagnosing acute HIV infection in a tertiary care hospital in Beijing, China

BACKGROUND

Early diagnosis of HIV infection decreases the time from HIV diagnosis to viral suppression and reduces further HIV transmission. The Chinese Guidelines for the Diagnosis and Treatment of HIV/AIDS (2021 edition) state that an HIV RNA level > 5,000 copies/mL is the threshold for diagnosing HIV infection. The impact of low viral load values on HIV diagnosis needs to be investigated.

METHODS

There were 3455 human immunodeficiency virus (HIV1 + 2) antibody results (immunoblotting method) and 65,129 HIV viral load values at Beijing Youan Hospital from 2019 to 2022. A total of 2434 patients had both antibody confirmatory results and viral load results. The confirmatory antibody results and HIV viral load results of 2434 patients were analyzed to investigate the impact of low viral load values on HIV diagnosis.

RESULTS

Of the 2434 patients who had both confirmatory antibody results and viral load results, the viral load values of 140 patients (5.8%) had viral loads ranging from 40 copies/mL to 5,000 copies/mL before positive confirmatory antibody result, and of these 140 patients, the sample receipt time for the viral load tests of 96 (66.7%) individuals was 1 to 6 days earlier than the corresponding sample receipt time for the confirmatory antibody test. In addition, 34 patients (1.4%) had low viral loads ranging from 40 copies/mL to 1,000 copies/mL before positive confirmatory antibody result.

CONCLUSION

This study revealed that there is a risk of missed diagnosis if a threshold of 5000 copies/mL is used for the diagnosis of HIV infection. These data provide valuable information for the early diagnosis of HIV infection, and our findings have potential benefits for decreasing HIV transmission.

HIV RNA levels in plasma and cervical-vaginal lavage fluid in elite controllers and HAART recipients

OBJECTIVES

The introduction of HAART leads to control of HIV replication to less than 50 copies/ml, similar to levels in 'elite controllers'. Low-level viral replication may be one of the contributing factors to persistent immune activation/inflammation in HAART-treated individuals. There are still gaps in our knowledge of whether low-level replication persists in systemic versus mucosal sites.

DESIGN AND METHODS

Participants for this study were recruited from the Women's Interagency HIV Study. We evaluated 33 'elite controllers' who naturally controlled HIV replication and 33 matched HAART-suppressed recipients. This study employed a sensitive target-capture transcription-mediated-amplification assay to compare low-level virus concentrations in plasma and cervical-vaginal lavage (CVL) samples from HIV-positive HAART recipients and 'elite controllers'.

RESULTS

The median (interquartile range) plasma viral load signal/cut-off (S/Co) for 'elite controllers' was 10.5 (3.9-21.1), which was significantly (P < 0.001) higher than the S/Co for HAART recipients [2.0 (1-4.9)]. The majority of CVL samples from both groups had undetectable HIV RNA and the proportion of CVL samples with a cut-off more than 1.0 was not different between 'elite controllers' and HAART-suppressed recipients.

CONCLUSION

This study demonstrated persistent low-level HIV replication in 'elite controllers', suggesting potential value of HAART treatment for these individuals. Absent or very low levels of HIV RNA in CVL indicate very low risk of secondary sexual transmission for both groups.

Prospective antiretroviral treatment of asymptomatic, HIV-1 infected controllers

The study of HIV-infected "controllers" who are able to maintain low levels of plasma HIV RNA in the absence of antiretroviral therapy (ART) may provide insights for HIV cure and vaccine strategies. Despite maintaining very low levels of plasma viremia, controllers have elevated immune activation and accelerated atherosclerosis. However, the degree to which low-level replication contributes to these phenomena is not known. Sixteen asymptomatic controllers were prospectively treated with ART for 24 weeks. Controllers had a statistically significant decrease in ultrasensitive plasma and rectal HIV RNA levels with ART. Markers of T cell activation/dysfunction in blood and gut mucosa also decreased substantially with ART. Similar reductions were observed in the subset of "elite" controllers with pre-ART plasma HIV RNA levels below conventional assays (<40 copies/mL). These data confirm that HIV replication persists in controllers and contributes to a chronic inflammatory state. ART should be considered for these individuals (ClinicalTrials.gov NCT01025427).

Finding those at risk: acute HIV infection in Newark, NJ

BACKGROUND

A screening strategy combining rapid HIV-1/2 (HIV) antibody testing with pooled HIV-1 RNA testing increases identification of HIV infections, but may have other limitations that restrict its usefulness to all but the highest incidence populations.

OBJECTIVE

By combining rapid antibody detection and pooled nucleic acid amplification testing (NAAT) testing, we sought to improve detection of early HIV-1 infections in an urban Newark, NJ hospital setting.

STUDY DESIGN

Pooled NAAT HIV-1 RNA testing was offered to emergency department patients and outpatients being screened for HIV antibodies by fingerstick-rapid HIV testing. For those negative by rapid HIV and agreeing to NAAT testing, pooled plasma samples were prepared and sent to the University of Washington where real-time reverse transcription-polymerase chain reaction (RT-PCR) amplification was performed.

RESULTS

Of 13,226 individuals screened, 6381 had rapid antibody testing alone, and 6845 agreed to add NAAT HIV screening. Rapid testing identified 115 antibody positive individuals. Pooled NAAT increased HIV-1 case detection by 7.0% identifying 8 additional cases. Overall, acute HIV infection yield was 0.12%. While males represent only 48.1% of those tested by NAAT, all samples that screened positive for HIV-1 RNA were obtained from men.

CONCLUSION

HIV-1 RNA testing of pooled, HIV antibody-negative specimens permits identification of recent infections. In Newark, pooled NAAT increased HIV-1 case detection and provided an opportunity to focus on treatment and prevention messages for those most at risk of transmitting infection. Although constrained by client willingness to participate in testing associated with a need to return to receive further results, use of pooled NAAT improved early infection sensitivity.

Screening for acute human immunodeficiency virus infection in Baltimore public testing sites

BACKGROUND

Human immunodeficiency virus (HIV) RNA testing of pooled HIV antibody-negative specimens can identify acute HIV infection (AHI) and trigger interventions to reduce transmission during this highly infectious period.

METHODS

A Baltimore, MD program serving sexually transmitted disease clinics and other high-risk sites combined HIV testing by third-generation enzyme immunoassay (EIA) with RNA testing of pooled antibody-negative specimens. Laboratory and Disease Intervention Specialists' records were reviewed for program evaluation. A cost analysis was performed.

RESULTS

In 22 months, we tested 60,695 specimens for HIV. Of these, 1766 (2.9%) tested positive by EIA. Pooled HIV RNA testing of 58,925 EIA-negative specimens detected 7 cases of AHI (0.01%). Reflex HIV RNA testing of EIA-reactive, Western blot-indeterminate specimens confirmed 4 additional AHI cases (total AHI, 0.02%). Contact tracing detected no additional previously unknown cases of HIV infection.

CONCLUSIONS

The utility of pooled HIV RNA testing may be limited by advances in HIV testing technology that reduce the seronegative window period and by characteristics of the local HIV epidemic.

Evaluation of an alternative HIV diagnostic algorithm using specimens from seroconversion panels and persons with established HIV infections

BACKGROUND

The current algorithm for HIV diagnosis in the US involves screening with an immunoassay (IA) and supplemental testing with Western blot (WB) or immunofluorescence assay. Because of existence of more sensitive and specific FDA-approved assays that would also reduce the cost and turn-around time of testing compared to WB, several alternative algorithms have been evaluated. Recently, an alternative algorithm using a sensitive 3rd or 4th generation IA followed by an HIV-1 and HIV-2 discriminatory supplemental test on the initial IA-positive specimens was proposed. Concordant positive results indicate HIV-positive specimens and discordant results are resolved by nucleic acid amplification testing (NAAT).

OBJECTIVES

To evaluate the sensitivity of assays during acute HIV infection and the performance of the current and an alternative algorithm using samples from HIV-1 seroconversion panels and persons with established HIV infections.

STUDY DESIGN

To evaluate the algorithms in early infections, 26 HIV-1 seroconverters from the US were tested with three 3rd generation and one 4th generation IA, six rapid tests (RTs), one NAAT, and WB. Sensitivity and specificity of the algorithms were calculated by testing an additional 416 HIV-positive and 414 uninfected control samples with one 3rd generation and one 4th generation IA, four RTs, one NAAT, and WB.

RESULTS

The individual assays evaluated became positive 5 (RT) to 26 days (NAAT) before WB was positive. Among seroconverters, the alternative algorithm detected significantly more infections than the current algorithm (103-134 versus 56, p<0.0001). Furthermore, the use of a 4th generation IA instead of a 3rd generation assay as the screen resulted in significantly higher detection of acute infections (p<0.0001). In contrast, the algorithms performed equally among specimens from established HIV-1 infections.

CONCLUSIONS

This study demonstrated improved sensitivity of the alternative algorithm for detecting acute HIV-1 infections, while maintaining the ability to accurately detect established HIV-1 infections. Early detection is important as individuals can be highly infectious during acute infection. In addition, the alternative algorithm should reduce turn-around time by using a RT as the supplemental test has the potential to increase the number of test results returned.

Performance of six commercial enzyme immunoassays and two alternative HIV-testing algorithms for the diagnosis of HIV-1 infection in Kisumu, Western Kenya

Performances of serological parallel and serial testing algorithms were analyzed using a combination of three ELISA and three rapid tests for the confirmation of HIV infection. Each was assessed individually for their sensitivity and specificity on a blinded panel of 769 retrospective sera of known HIV status. Western blot was used as a confirmatory assay for discordant results. Subsequently, one parallel and one serial testing algorithm were assessed on a new panel of 912 HIV-positive and negative samples. Individual evaluation of the ELISAs and rapid tests indicated a sensitivity of 100% for all assays except Uni-Gold with 99.7%. The specificities ranged from 99.1% to 99.4% for rapid assays and from 97.5% to 99.1% for ELISAs. A parallel and serial testing algorithms using Enzygnost and Vironostika, and Determine followed by Uni-Gold respectively, showed 100% sensitivity and specificity. The cost for testing 912 samples was US$4.74 and US$ 1.9 per sample in parallel and serial testing respectively. Parallel or serial testing algorithm yielded a sensitivity and specificity of 100%. This alternative algorithm is reliable and reduces the occurrence of both false negatives and positives. The serial testing algorithm was more cost effective for diagnosing HIV infections in this population.

Evidence of persistent low-level viremia in long-term HAART-suppressed, HIV-infected individuals

BACKGROUND

HAART can effectively reduce plasma HIV RNA levels to below the level of detection in most HIV-infected patients. The degree to which residual low-level viremia persists during HAART remains unclear.

METHODS

We identified 180 individuals (median duration of HIV infection 12 years) who had at least two consecutive plasma HIV-1 RNA levels below the level of detection (<50-75 copies/ml) while taking antiretroviral drugs; 36 of 180 had been virologically suppressed for more than 5 years. Longitudinal plasma samples that were taken from these individuals during periods of viral load suppression were selected and analyzed. The isothermal transcription-mediated amplification (TMA) (limit of detection <3.5 copies RNA/ml) assay was used to measure persistent viremia. A 'detuned' EIA assay was used to obtain quantitative HIV antibody levels.

RESULTS

A total of 1606 TMA assays were performed on 438 specimens in 180 HAART-suppressed individuals (median 3 replicates per specimen). In the first year of viral suppression, plasma RNA levels declined significantly (P = 0.001), but after month 12 there was no evidence for a continued decline (P = 0.383). In the first year of viral suppression, HIV antibody levels also declined (P = 0.054), but after month 12 there was no evidence for a continued decline (P = 0.988).

CONCLUSION

Viremia continued to decline during the first 12 months after viremia became undetectable using conventional methods, and then remained stable. HIV antibody levels also decreased in the first year of viral suppression and then remained stable. Viremia and the HIV-associated host response appear to achieve a steady-state 'set-point' during long-term combination therapy.

A rapid real-time PCR assay for the detection of HIV-1 proviral DNA using double-stranded primer

In this study, a rapid real-time PCR assay to detect HIV-1 proviral DNA in whole blood was developed using a novel double-stranded primer that does not require a target-specific fluorescent probe or intercalating dye systems. Co-amplification of a human gene RNase P served as the internal control to monitor the efficiency of the DNA extraction and PCR amplification. The HIV-1 amplification efficiency was 100% and could amplify 1 copy of HIV-1 DNA 64% of the time and all attempts to amplify 4 copies were successful in less than 51 min. All 22 HIV-1 sero-positive and 20 sero-negative whole blood specimens tested were classified correctly by this assay. In addition, 22 cultured PBMC specimens infected with various HIV-1 subtypes or CRF (A=2, AC=1, B=4, C=3, D=3, AE=2, F=1, BF=2, G=4) were amplified equally well with a similar threshold cycle (C(t)) number (22.9+/-1.2). The high amplification efficiency and short PCR cycles were in part due to the short target sequence amplified by eliminating the probe-binding sequence between the primers. This assay may be useful as an alternative confirmation test in a variety of HIV testing venues.

Lessons learned about behavioral science and acute/early HIV infection. The NIMH Multisite Acute HIV Infection Study: V

Acute/early HIV infection is a period of heightened HIV transmission and a window of opportunity for intervention to prevent onward disease transmission. The NIMH Multisite Acute HIV Infection (AHI) Study was an exploratory initiative aimed at determining the feasibility of recruiting persons with AHI into research, assessing their psychosocial and behavioral characteristics, and examining short-term changes in these characteristics. This paper reports on lessons learned in the study, including: (1) the need to establish the cost-effectiveness of AHI testing; (2) challenges to identifying persons with AHI; (3) the need to increase awareness of acute-phase HIV transmission risks; (4) determining the goals of behavioral interventions following AHI diagnosis; and (5) the need for "rapid response" public health systems that can move quickly enough to intervene while persons are still in the AHI stage. There are untapped opportunities for behavioral and medical science collaborations in these areas that could reduce the incidence of HIV infection.

Monitoring HIV vaccine trial participants for primary infection: studies in the SIV/macaque model

OBJECTIVES

The ability to detect and quantify acute HIV-1 infection prior to seroconversion would be an important tool for use in HIV vaccine clinical efficacy trials. We have utilized the SIV/rhesus monkey model to evaluate whether samples more easily obtained than peripheral blood might be used for intensive monitoring of vaccine trial participants.

METHODS

We have evaluated viral loads in peripheral blood, saliva, feces, and urine of five rhesus monkeys during primary SIVmac251 infection by quantitative real-time PCR. As an alternative to the direct monitoring of frozen samples, we have also developed a fully quantitative viral load assay utilizing dried blood spots.

RESULTS

Although all compartments were found to harbor viral RNA during primary infection, viral RNA could be detected in the peripheral compartments only when levels of plasma viremia exceed a threshold value of 10 RNA copies/ml. We found no direct correlation between viral burden in plasma and saliva, feces, or urine viral loads. Importantly, both dried saliva and whole blood spots can be used for viral detection. Quantitative whole blood or plasma spotting correlated well with viral burden in plasma during both the acute and set point phase of infection.

CONCLUSION

Dried blood spots are amenable to rapid quantitative viral load testing. Whole blood spotting has a significant logistical benefit as it requires low blood volumes and no blood processing. Saliva or dried saliva spots or both are potential candidates for acute phase diagnostic screening. These studies indicate the feasibility of intensive monitoring of HIV-1 vaccine trial participants for virus acquisition in resource-limited settings.

Targeted testing for acute HIV infection in North Carolina

BACKGROUND

Persons with acute HIV infection contribute disproportionately to HIV transmission. The identification of these persons is a critical public health challenge. We developed targeted approaches for detecting HIV RNA in persons with negative serological tests.

METHODS

Persons undergoing publicly funded HIV testing in North Carolina between October 2002 and April 2005 were included in this cross-sectional study. We used logistic regression to develop targeted testing approaches. We also assessed simple approaches based on clinic type and geography. Algorithm development used persons with recent HIV infection, determined by a detuned enzyme-linked immunosorbent assay. Validation used persons with acute HIV infection, identified with an HIV RNA pooling procedure.

RESULTS

Among 215 528 eligible persons, 232 persons had recent HIV infection and 44 had acute HIV infection. A combination of five indicators (testing site, sexual preference, sex with a person with HIV infection, county HIV incidence, and race) identified 92% of recent infections when testing 50% of the population. In validation among persons with acute HIV infection, this indicator combination had sensitivities of 98% in years 1 and 2 and 88% in year 3. A simple combination of testing site and county performed nearly as well [development (recent infections): sensitivity = 95%; validation (acute infections): sensitivity = 86% in years 1 and 2; 81% in year 3; cut-off established for testing 50% of population.]

CONCLUSION

Acute HIV infection can be identified accurately using targeted testing. Simple approaches for identifying the types of clinics and geographical areas where infections are concentrated may be logistically feasible and cost-efficient.

Alternative algorithms for human immunodeficiency virus infection diagnosis using tests that are licensed in the United States

Serodiagnosis of human immunodeficiency virus (HIV) infection in the United States has traditionally relied on a sequential two-test algorithm: an initial screen with an enzyme immunoassay (EIA) and reflex testing of EIA-reactive specimens with a more specific supplemental test such as Western blotting or immunofluorescence. The supplemental tests are tedious, subjective, and expensive. In addition, there have been major improvements in the performance and accuracy of the EIA tests as well as the introduction of rapid serologic tests (RT) and HIV nucleic acid amplification tests (NAAT). Related to these improvements is the possibility that alternative algorithms using combinations of currently approved HIV tests may function as well as if not better than the current algorithm, with more flexibility, improved accuracy, and lower cost. To this end, we evaluated the performance of 12 currently licensed tests and 1 in-house HIV test (6 EIA, 4 RT, and 3 NAAT) on panels of plasma samples from HIV-infected (n = 621 HIV type 1 [HIV-1] and 34 HIV-2) and uninfected (n = 513) people and of sequential specimens from people early in seroconversion (183 specimens from 15 patients). Test combinations were analyzed in two dual-test (sensitivity-optimized and specificity-optimized) algorithms and in a three-test (tie-breaking) algorithm, and performance was compared to the conventional algorithm. The results indicate that alternative algorithm strategies with currently licensed tests compare favorably with the conventional algorithm in detecting and confirming established HIV infection. Furthermore, there was a lower frequency of discordant or indeterminate results that require follow-up testing, and there was improved detection of early infection.

Performance of a transcription-mediated-amplification HIV-1 RNA assay in pooled specimens

BACKGROUND

Very limited data exist on the comparative performance of nucleic acid amplification tests (NATs) for the screening of pooled specimens for acute human immunodeficiency virus (HIV) infection.

STUDY DESIGN

In this study, we compared a transcription-mediated-amplification assay (Procleix HIV-1 Discriminatory Assay, [TMA]) with a branched DNA assay (Bayer Versant HIV-1 RNA 3.0 assay, [bDNA]).

RESULTS

After re-testing 1552 samples that were negative for HIV RNA by bDNA, we found one additional positive sample with the TMA assay.

CONCLUSION

Our results suggest that TMA could potentially detect acute HIV infections missed by other technologies.

Postexposure prophylaxis after sexual exposure to HIV

Increasing numbers of international, national and state/provincial health organizations in the developed and developing world recommend postexposure prophylaxis (PEP) following potential sexual exposure to HIV. The evidence for these policies is extrapolated from occupational healthcare worker, perinatal prophylaxis and animal studies. There is no direct evidence of PEP efficacy after sexual exposures. Studies addressing potential increases in risk behavior, toxicities and cost–effectiveness are encouraging. Considerations for offering PEP include the timing and characteristics of the exposure and the HIV status of the source and exposed individuals. PEP includes 28 days of a combination antiretroviral drug regimen containing two or more drugs and associated laboratory testing, counseling and referrals. PEP service delivery challenges include ensuring adequate access to services, optimizing PEP adherence and facilitating follow-up HIV testing and counseling. Men who have sex with men, sexual assault survivors, children and adolescents, and individuals in resource-limited settings present unique needs and challenges.

Testing for HIV infection in the United States

The process by which HIV-infected individuals are tested and identified has changed with the evolving HIV epidemic and public health response. In this review, we discuss the rationale for increased HIV testing as well as the current standards in HIV diagnostics and their inherent limitations. Current policy guidelines for routine HIV testing from the U.S. Preventive Services Task Force and the U.S. Centers for Disease Control and Prevention are divergent. However, national momentum toward the implementation of routine HIV testing programs continues based on the efficacy and feasibility of these programs in terms of HIV case identification and on recent reports of their cost-effectiveness. As routine, voluntary HIV screening programs are established, issues surrounding consent, reporting, and stigma still persist, as does the challenge of effectively linking detected HIV cases to care.

Postexposure prophylaxis after sexual exposure to HIV

PURPOSE OF REVIEW

HIV postexposure prophylaxis is often recommended following potential sexual exposure to HIV. Recent data address the effectiveness of postexposure prophylaxis and prevention counseling, cost-effectiveness, antiretroviral options, challenges with nonoccupational postexposure prophylaxis among adolescents and children and following sexual assault in high HIV prevalence areas, and a successful program in Amsterdam.

RECENT FINDINGS

Postexposure prophylaxis is not completely protective. Seroconversion may result from antiretroviral failure or from ongoing exposures. Postexposure prophylaxis associated risk reduction counseling results in reductions in subsequent risk behavior. Programs that target outreach and limit prescriptions to those with exposure sources who are at risk of being HIV infected are cost-effective. Less restrictive guidelines result in more prescriptions for low-risk exposures; this practice is not cost-effective. The ideal antiretrovirals for postexposure prophylaxis use have not been established. Tenofovir has several attractive properties. Developing systems to support the effective delivery of postexposure prophylaxis among children and adolescents and following sexual assault in high HIV prevalence, resource limited settings is challenging.

SUMMARY

Numerous national and international guidelines recommend postexposure prophylaxis following potential sexual exposure to HIV. Maximizing adherence and minimizing subsequent HIV exposures will be critical to enhancing the effectiveness of this HIV prevention intervention.