A systematic review of limiting antigen avidity enzyme immunoassay for detection of recent HIV-1 infection to expand supported applications

Low CD4 count was characterized in recent HIV CRF01_AE infection and it rapidly increased to reach a peak in the first year since ART initiation

BACKGROUND

Currently, most people living with HIV (PLWH) in China have a strong awareness of diagnosis and treatment in the early stage of HIV infection. Subtype-specific virological and immunological features of recently infected PLWH have not yet been elucidated.

METHODS

Data including CD4 count and viral load (VL) of 1508 anti-retroviral therapy (ART) -naïve PLWH were obtained from the HIV Database and comparatively analyzed among PLWH with different HIV subtypes. The infection status of 402 newly diagnosed and ART-naïve PLWH from a cohort of men who have sex with men (MSM) in China was evaluated using diagnosis records and LAg-Avidity EIA. Based on partial pol genes, HIV genotypes in 120 recent, 68 long-term, and 54 chronic infections were identified. The CD4 count, CD8 count, and VL, as well as trajectories of dynamic CD4 counts during ART of local PLWH with different HIV subtypes, were compared using non-parametric tests.

RESULTS

For the HIV database, the CD4 count in PLWH with CRF01_AE was lower than that in PLWH with CRF07_BC or subtype B. For the recently infected local PLWH, CRF01_AE was the dominant HIV subtype (65.83%), followed by CRF07_BC (18.33%) and subtype B (15.83%). Recent CRF01_AE infections showed a lower baseline CD4 count than CRF07_BC infections. During ART for recently infected PLWH, the CD4 count in the CRF01_AE group rapidly increased to reach a peak at the end of the first year post-ART, while the CD4 count in the CRF07_BC group increased slowly to reach a plateau at the end of the third year. The CD4 count in the subtype B group increased significantly to reach a plateau within the first two years and then its trajectory overlapped with that of the CRF07_BC group at the end of the third year post-ART.

CONCLUSIONS

CRF01_AE rapidly reduced CD4 count during the recent HIV infection. The CD4 count of the recently infected individuals with CRF01_AE increased sharply and reached its highest level of recovery within the first year of ART initiation. This study revealed an important time point for estimating CD4 count recovery post-ART in individuals with different HIV subtypes.

Analysis of HIV-1 recent infections and hotspot areas in a bordering area in Yunnan Province, China

BACKGROUND

Honghe Prefecture, located on the China-Vietnam border, has long suffered from HIV-1. To accurately assess the HIV-1 prevalence situation and promote precise prevention and treatment of AIDS, a recent infection surveillance was conducted to explore the at-risk subpopulations and hotspot areas of HIV-1 transmission in Honghe Prefecture.

METHODS

Combined with the recent infection testing algorithm, HIV-1 recency assay was used to differentiate recent HIV-1 infections among newly reported HIV-1 cases in Honghe Prefecture from 2021 to 2022. Factors associated with recent HIV-1 infection were analyzed by logistic regression. The hotspot areas of recent infections were analyzed by spatial scanning statistics.

RESULTS

Of the 2698 HIV-1-infected individuals enrolled in this study (no HIV-2 cases reported), 297 HIV-1 cases were classified as recent HIV-1 infection, and the proportion of recent infection was 11.0%. Females (AOR = 2.61, 95% CI: 1.98-3.43), young people (15-34 years old) (AOR = 1.71, 95% CI: 1.21-2.43), highly educated people (AOR = 2.04, 95% CI: 1.24-3.37), men who have sex with men (MSM) (AOR = 3.08, 95% CI: 1.74-5.46), and spouses/regular sexual partners of HIV-1-positive individuals (AOR = 1.96, 95% CI: 1.15-3.33) were more likely to be detected as recent infections. Among the subpopulations by sex, age and transmission route, heterosexually exposed women aged 15-34 years (OR = 1.85, 95% CI: 1.07-3.19) and 35-49 years (OR = 1.65, 95% CI: 1.05-2.58) and MSM aged 15-34 years (OR = 5.11, 95% CI: 2.73-9.59) had a higher proportion of recent infections. Among the subpopulations by mode of exposure and sex, men infected through homosexual contact (OR = 5.59, 95% CI: 3.30-9.47) and women infected through non-marital non-commercial heterosexual contact (OR = 2.10, 95% CI: 1.50-2.95) and positive spousal exposure (OR = 3.03, 95% CI: 1.96-4.69) had a higher proportion of recent infections. With regard to detection methods, women detected by provider-initiated HIV testing counseling (PITC) (OR = 2.03, 95% CI: 1.50-2.76) and spouse/sexual partner testing (OR = 4.10, 95% CI: 2.19-7.67) had a higher proportion of recent infections. A statistically significant spatial cluster of recent infections was found in one county, Yuanyang.

CONCLUSIONS

This study investigated the use of HIV-1 recency testing in combination with HIV-1 case report surveillance. Correlation factor analysis revealed the presence of distinct risk subpopulations. The spatial distribution of recent infections showed differences. These findings were important for assessing the transmission risk and developing the targeted measures for interventions.

CLINICAL TRIAL NUMBER

Not applicable.

Determination of the mean duration of recent infection and false recency rate for the HIV triplex multiplex bead assay

BACKGROUND

We developed the HIV Triplex multiplex bead assay to identify and serotype HIV infection with high sensitivity and specificity; and distinguish recent from long-term HIV-1 infections. It can facilitate accurate incidence estimation, while reducing the number of tests and blood collected, which is highly desirable for use in future studies and surveys. Using previously collected, treatment-naive longitudinal seroconversion HIV-1 positive panels and specimens from individuals infected for >12 months, we determined the assay's mean duration of recent infection (MDRI) and false-recency rate (FRR) respectively, at various mean fluorescent intensity (MFI) cutoffs.

METHODS

We tested seroconversion specimens (N = 814) from 142 individuals infected with HIV-1 subtypes B, C, or AE, and 1341 cross-sectional specimens from individuals infected >12 months. The MFI cutoffs of 1000 to 2000 were evaluated for recency classification, including an MFI of 1250 corresponding to the limiting antigen avidity enzyme immunoassay (LAg-EIA) cutoff of 1.5 normalized optical density for MDRI and FRR. We used four statistical methods: Methods 1 and 2 used the empirically balanced observation time approach. Method 2 MFI values were raised to power = 1.33, based on a repeated measures model to linearize the relationship between MFI and time points, whereas Method 1 was not linearized. Methods 3 and 4 employed quadratic and linear interpolations for each seroconversion panel. FRR was calculated by dividing the number of specimens misclassified as recent by the total number of specimens tested.

RESULTS

MDRI values ranged from 135-146 days at MFI = 1000 to 229-279 days at MFI = 2000 by the 4 methods. FRR varied from 0.15%-1.27% with increasing MFI cutoff. At MFI = 1250, the average MDRI of 4 methods was 169 days and ranged from 159-183 with overlapping 95% CIs and FRR = 0.52%.

CONCLUSION

The HIV Triplex assay demonstrates a longer dynamic range compared to current HIV recency assays with a low FRR for cutoffs examined. With a longer dynamic range and low FRR, the MDRI for recent infection can be extended as appropriate to detect more recent infections, increasing the value of incidence assays benefiting public health surveillance and future surveys.

Sustained high HIV incidence among men who have sex with men in Jiangsu province, China: based on the limiting-antigen avidity EIA method and six consecutive surveys, 2016-2021

Background

The epidemic of HIV infection among men who have sex with men (MSM) is a major public health concern in some parts of China, but data on trends in HIV incidence are limited. This study aimed to examine the trends in HIV incidence and factors associated with recent HIV infection among MSM in Jiangsu province, China, based on the limiting-antigen avidity enzyme immunoassay (LAg-Avidity-EIA) method.

Methods

Six consecutive surveys were implemented among MSM throughout Jiangsu province from 2016 to 2021. Participants were recruited in three ways. Socio-demographic and behavioral information were collected through face-to-face interviews. Venous blood samples were taken to test for HIV and syphilis. HIV incidence was estimated using the LAg-Avidity-EIA method. Chi-square trend tests were used to observe trends over the years. Multivariate regression analyses were used to identify factors associated with recent HIV infection.

Results

A total of 15,401 participants were enrolled in the study. The prevalence of HIV infection ranged from 8.0 to 9.8%, with no consistent rise or fall over the years (P = 0.189). HIV incidence ranged from 5.0 to 9.0%, and no uptrend or downtrend was shown (P = 0.418). MSM who lived locally for more than 2 years (aOR = 1.366, P = 0.019), had a lack of comprehensive HIV knowledge (aOR = 1.643, P = 0.031), had engaged in unprotected anal intercourse (UAI) in the past 6 months (aOR = 7.373, P < 0.001), had been tested for HIV within 12 months (aOR = 1.292, P = 0.035), and tested positive for syphilis (aOR = 2.840, P < 0.001) were likely to be recently infected with HIV.

Conclusions

HIV incidence among MSM has remained at a high level in Jiangsu province. In China, health education, condom use, and HIV/syphilis testing should continue to be top priorities for HIV prevention among MSM to reduce HIV transmission.

Rapid and visual identification of HIV-1 using reverse transcription loop-mediated isothermal amplification integrated with a gold nanoparticle-based lateral flow assay platform

Human immunodeficiency virus type one (HIV-1) infection remains a major public health problem worldwide. Early diagnosis of HIV-1 is crucial to treat and control this infection effectively. Here, for the first time, we reported a novel molecular diagnostic assay called reverse transcription loop-mediated isothermal amplification combined with a visual gold nanoparticle-based lateral flow assay (RT-LAMP-AuNPs-LFA), which we devised for rapid, specific, sensitive, and visual identification of HIV-1. The unique LAMP primers were successfully designed based on the pol gene from the major HIV-1 genotypes CRF01_AE, CRF07_BC, CRF08_BC, and subtype B, which are prevalent in China. The optimal HIV-1-RT-LAMP-AuNPs-LFA reaction conditions were determined to be 68°C for 35 min. The detection procedure, including crude genomic RNA isolation (approximately 5 min), RT-LAMP amplification (35 min), and visual result readout (<2 min), can be completed within 45 min. Our assay has a detection limit of 20 copies per test, and we did not observe any cross-reactivity with any other pathogen in our testing. Hence, our preliminary results indicated that the HIV-1-RT-LAMP-AuNPs-LFA assay can potentially serve as a useful point-of-care diagnostic tool for HIV-1 detection in a clinical setting.

Facilitating Next-Generation Pre-Exposure Prophylaxis Clinical Trials Using HIV Recent Infection Assays: A Consensus Statement from the Forum HIV Prevention Trial Design Project

Standard-of-care HIV pre-exposure prophylaxis (PrEP) is highly efficacious, but uptake of and persistence on a daily oral pill is low in many settings. Evaluation of alternate PrEP products will require innovation to avoid the unpractically large sample sizes in noninferiority trials. We propose estimating HIV incidence in people not on PrEP as an external counterfactual to which on-PrEP incidence in trial subjects can be compared. HIV recent infection testing algorithms (RITAs), such as the limiting antigen avidity assay plus viral load used on specimens from untreated HIV positive people identified during screening, is one possible approach. Its feasibility is partly dependent on the sample size needed to ensure adequate power, which is impacted by RITA performance, the number of recent infections identified, the expected efficacy of the intervention, and other factors. Screening sample sizes to support detection of an 80% reduction in incidence for 3 key populations are more modest, and comparable to the number of participants in recent phase III PrEP trials. Sample sizes would be significantly larger in populations with lower incidence, where the false recency rate is higher or if PrEP efficacy is expected to be lower. Our proposed counterfactual approach appears to be feasible, offers high statistical power, and is nearly contemporaneous with the on-PrEP population. It will be important to monitor the performance of this approach during new product development for HIV prevention. If successful, it could be a model for preventive HIV vaccines and prevention of other infectious diseases.