LAg-Avidity EIA Research Articles

An Assessment of Trends in HIV-1 Prevalence and Incidence and Spatio-Temporal Analyses of HIV-1 Recent Infection Among MSM During the Surveillance Period Between 2018 and 2022 in Sichuan, China.

Men who have sex with men (MSM) is one main type of high-risk activities facilitating HIV-1 transmission in Sichuan province. Previous works on HIV-1 incidence and prevalence among MSM only concentrated before 2018, the situation after that is unknown. In addition, the distribution of hot-spots related to current HIV-1 epidemic is also rarely known among MSM in Sichuan. To update trends of HIV-1 prevalence and incidence and to visualize hot-spots of ongoing transmission in Sichuan province during surveillance period among MSM between 2018 and 2022. Limiting Antigen Avidity assay was performed to detect recent infection within new HIV-1 diagnoses founded during surveillance period among MSM. The HIV-1 prevalence and incidence were calculated according to an extrapolation method proposed by publications and guidelines. Trend tests were performed using χ2 tests with linear-by-linear association. The spatial analysis was conducted with ArcGIS 10.7 to figure hot-spots of HIV-1 recent infections among MSM. Between 2018 and 2022, 16,697 individuals participated in HIV-1 MSM sentinel surveillance program, of which 449 samples (98.25%) were tested with LAg-Avidity EIA, and 230 samples were classified as recent infection. Respectively, the overall prevalence and incidence were 2.74% and 3.69% (95% CI: 3.21, 4.16) and both had significant declining trends (p < 0.001). Luzhou city had a highest HIV-1 incidence (10.74%, 95% CI: 8.39, 13.10) over the study period and was recognized as a hot-spot for recent HIV-1 infection among MSM. During the surveillance period, both HIV-1 prevalence and incidence were declining. However, Luzhou city had an unusually high HIV-1 incidence and became an emerging hot-spot of recent HIV-1 infection among MSM. This finding suggested focused attention, cross-regional intervention strategies, and prevention programs are urgently required to curb the spread of ongoing transmission.

Recent HIV infection and annualized HIV incidence rates among sexual and gender minorities in Brazil and Peru (ImPrEP seroincidence study): a cross-sectional, multicenter study

HIV incidence estimation is critical for monitoring the HIV epidemic dynamics and the effectiveness of public health prevention interventions. We aimed to identify sexual and gender minorities (SGM) with recent HIV infections, factors associated with recent HIV infection, and to estimate annualised HIV incidence rates. Cross-sectional multicentre study in HIV testing services in Brazil and Peru (15 cities). Inclusion criteria: 18+ years, SGM assigned male at birth, not using pre-/post-exposure prophylaxis. We identified recent HIV infection using the Maxim HIV-1 LAg-Avidity EIA assay as part of a recent infection testing algorithm (RITA). Annualized HIV incidence was calculated using the UNAIDS/WHO incidence estimator tool. Multivariable logistic regression models were used to estimate factors associated with recent HIV infection. Trial registration: NCT05674682. From 31-Jan-2021 to 29-May-2022, 6899 individuals participated [Brazil: 4586 (66.5%); Peru: 2313 (33.5%)]; 5946 (86.2%) cisgender men, 751 (10.9%) transgender women and 202 (2.9%) non-binary/gender diverse. Median age was 27 (IQR: 23-34) years. HIV prevalence was 11.4% (N=784/6899); 137 (2.0%) SGM were identified with recent HIV infection. The overall annualized HIV incidence rate was 3.88% (95% CI: 2.86-4.87); Brazil: 2.62% (95% CI: 1.78-3.43); Peru: 6.69% (95% CI: 4.62-8.69). Participants aged 18-24 years had higher odds of recent HIV infection compared to those aged 30+ years in both countries. Our results highlight the significant burden of HIV epidemic among SGM in large urban centres of Brazil and Peru. Public health policies and interventions to increase access to effective HIV prevention methods such as PrEP are urgently needed in Latin America. Unitaid, WHO (Switzerland), Ministry of Health from Brazil and Peru.

The Update of HIV-1 Prevalence and Incidence and Spatio-Temporal Analyses of HIV Recent Infection Among Four Sub-Groups in Sichuan, China During Surveillance Period Between 2016 and 2022.

Sichuan Province has gradually become a hot-spot for HIV/AIDS. Little is known about the HIV-1 incidence and prevalence among four sub-groups since 2015. Meanwhile, the distributions of hot-spot areas related to recent infection cases that indicate current transmission among the four subgroups are also rare. The main purpose of this study was to assess the HIV-1 prevalence and incidence and to visualize the distributions of hot-spot areas of current transmission among four subgroups (people who inject drugs, male STD clinic attendees, female sex workers and men who had sex with men) during the surveillance period in Sichuan province between 2016 and 2022. Of the 267,617 individuals, 2158 HIV-positive samples were tested with Lag-Avidity EIA, among which 493 samples were identified as recent infections. Among people who inject drugs (PWID), both HIV-1 prevalence (from 1.41% to 0.34%) and incidence (from 0.03% to 0.140%) showed a significant decreasing trend. Among men who had sex with men (MSM), female sex workers (FSWs), and male STD clinic attendees, HIV-1 prevalence indicated significant decreasing trends, whereas HIV-1 incidence showed no significant changes. Spatial analysis demonstrated the formation of hot-spots and clusters of current transmissions sharing regional differences, mainly concentrated in the southeast, and most of these were consecutive hot-spots. The prevention and control were efficacious and persistent. However, among the other three subgroups, there is a need for a regional cooperative in prevention and control approaches and collaborative research in many aspects.

Demographic Characteristics and Hot-Spot Areas of Recent Infections Among New HIV Diagnoses in Sichuan, China, Between 2018 and 2020.

Sichuan Province is severely affected by the HIV epidemic in China. Little is known about the characteristics of recent infections among new HIV diagnoses, which is critical to prevention strategies, evaluation of the HIV epidemic and health resource allocation. Meanwhile, individuals at primary stages of infection are related to the hot-spot areas of ongoing transmission in new HIV diagnoses, which is also rarely known. This article aimed to report the proportion of recent infections among new HIV diagnoses, and to reveal demographic characteristics associated with HIV recent infections, and finally, to indicate the hot-spot areas of ongoing transmission in Sichuan province between 2018 and 2020. Limiting Antigen (LAg)-Avidity assay was performed to detect recent infection within new HIV diagnoses reported in odd months between 2018 and 2020. Results were reclassified according to the data on CD4 cell count, antiretroviral treatment and the existence of an AIDS-defining illness. Logistic regression was used to determine characteristics associated with HIV recent infections. The spatial analysis was conducted with ArcGIS 10.7 to figure hot-spot areas of HIV recent infections. 42,089 newly diagnosed HIV-1 cases were tested using the LAg-Avidity EIA. In total, 5848 (13.89%) of those were classified as HIV recent infections. Female, age between 18-25 years and men who had sex with men were related to higher proportion of HIV recent infections. Logistic regression revealed that MSM aged between 18-25 years were more likely to be classified as recent infection. Spatial analysis demonstrated significant clustering in Chengdu, Yibin, Luzhou city between 2018 and 2020. Hot spots were mainly clustered in the center of Sichuan in 2018, but gradually spread to southwest and northwest between 2019 and 2020. Enhanced preventive measures among relevant risk groups and areas where the potential HIV-1 transmission is ongoing is urgently needed to curb further spread.

Evaluation of antiretroviral therapy effect and prognosis between HIV-1 recent and long-term infection based on a rapid recent infection testing algorithm.

Early diagnosis of HIV-1 infection and immediate initiation of combination antiretroviral therapy (cART) are important for achieving better virological suppression and quicker immune reconstitution. However, no serological HIV-1 recency testing assay has been approved for clinical use, and the real-world clinical outcomes remain to be explored for the subjects with HIV-1 recent infection (RI) or long-term infection (LI) when antiretroviral therapy is initiated. In this study, a HIV-1 rapid recent-infection testing strip (RRITS) was developed and incorporated into the recent infection testing algorithms (RITAs) to distinguish HIV-1 RI and LI and to assess their clinical outcomes including virological response, the recovery of CD4+ T-cell count and CD4/CD8 ratio and the probability of survival. We found that the concordance between our RRITS and the commercially available LAg-Avidity EIA was 97.13% and 90.63% when detecting the longitudinal and cross-sectional HIV-1 positive samples, respectively. Among the 200 HIV-1 patients analyzed, 22.5% (45/200) of them were RI patients and 77.5% (155/200) were chronically infected and 30% (60/200) of them were AIDS patients. After cART, 4.1% (5/155) of the LI patients showed virological rebound, but none in the RI group. The proportion of CD4+ T-cell count >500 cells/mm3 was significantly higher in RI patients than in LI after 2 years of cART with a hazard ratio (HR) of 2.6 (95% CI: 1.9, 3.6, p < 0.0001) while the probability of CD4/CD8 = 1 was higher in RI than in LI group with a HR of 3.6 (95% CI: 2.2, 5.7, p < 0.0001). Furthermore, the immunological recovery speed was 16 cells/mm3/month for CD4+ T-cell and 0.043/month for the ratio of CD4/CD8 in the RI group, and was bigger in the RI group than in the LI patients (p < 0.05) during the 1st year of cART. The survival probability for LI patients was significantly lower than that for RI patients (p < 0.001). Our results indicated that RRITS combined with RITAs could successfully distinguish HIV-1 RI and LI patients whose clinical outcomes were significantly different after cART. The rapid HIV-1 recency test provides a feasible assay for diagnosing HIV-1 recent infection and a useful tool for predicting the outcomes of HIV-1 patients.

Analysis of related factors of new-type drug use and recent HIV infection among men who have sex with men in Shandong province

Objective: To understand the related factors of new-type drug use and recent HIV infection among men who have sex with men (MSM), and provide a reference for formulating targeted strategies for HIV/AIDS prevention and control. Methods: MSM were recruited in sentinel surveillance sites of nine cities in Shandong province from April to July 2021, with a sample size of 400 in each city. A face-to-face questionnaire was conducted to collect demographic characteristics, high-risk behaviors, acceptance of HIV intervention services, etc. Blood samples were collected for HIV and syphilis antibodies detection. Limiting-antigen avidity enzyme immunoassay (LAg-Avidity EIA) was used to detect recent HIV infection, and the rate of recent HIV infection was calculated. Results: 3 624 MSM were under study with the following characteristics as: aged (32.70±9.33) years old, the aged 30 and above (59.52%, 2 157/3 624), with high school education or below (55.99%, 2 029/3 624), being unmarried/divorced/widowed (57.70%, 2 091/3 624) and as having homosexual orientation (86.26%, 3 126/3 624) accounted for the more mainly. Of 32.95% (1 194/3 624) had same-sex unprotected anal sex in recent six months; 27.48% (993/3 613) ever used new-type drugs, and the HIV antibody positive rate was 3.12% (113/3 624). The recent HIV infection rate appeared as 2.61% (95%CI: 1.73%-3.49%). The multivariable logistic regression analysis indicated that the related factors of new-type drug use were unmarried/divorced/widowed (compared with being married/cohabitating, aOR=1.43, 95%CI: 1.22-1.69), educational level of college or above (compared with educational level of high school or below, aOR=1.47, 95%CI: 1.25-1.72), mainly through the Internet/dating software to find male sex partners (compared with mainly through bars/baths/parks and other places to find male sex partners, aOR=1.76, 95%CI: 1.41-2.19). Those who had unprotected anal sex in the last six months (compared with no unprotected anal sex, aOR=1.33, 95%CI: 1.13-1.57), had sexually transmitted diseases in the past year (compared with no sexually transmitted disease, aOR=2.77, 95%CI: 2.04-3.76) were more likely to use new-type drugs. The multinominal logistic regression showed that MSM who had unprotected anal sex in the last six months (compared with no unprotected anal sex, aOR=2.51, 95%CI: 1.25-5.01) or did not receive HIV intervention services in the past year (compared with those who received HIV intervention services, aOR=3.89, 95%CI: 1.30-11.60), were syphilis positive (compared with syphilis negative, aOR=8.18, 95%CI: 2.98-22.48), used new-type drugs (compared with those who did not use new-type drugs, aOR=4.75, 95%CI: 2.32-9.70) had a higher risk of recent HIV infection. Conclusions: New-type drugs have been widely used in MSM in Shandong province. The abuse of new-type drugs increases the risk of recent HIV infection.

Characteristics of recent HIV infection among individuals newly diagnosed as HIV-positive in South Korea (2008–2015)

Most HIV-positive individuals diagnosed in Korea are infected through sexual contact, with the time of HIV infection therefore often being unknown. The aim of this study was to investigate the characteristics of diagnosed patients near the time of HIV seroconversion to establish useful HIV intervention strategies. Cross-sectional study. Newly diagnosed HIV cases based on the national HIV surveillance system in South Korea, 2008–2015. To distinguish recent from long-standing HIV infection among 5898 nationwide HIV-positive specimens, limiting antigen avidity assays (Sedia HIV-1 LAg-Avidity EIA, cut-off = 1.5) were performed. Data on CD4+ T cell count at HIV diagnosis and death from AIDS within one year after first HIV diagnosis were used to distinguish recent HIV infections. Acute HIV infection is characterized by detectable HIV RNA or HIV p24 antigen levels, along with a negative or indeterminate antibody western blot result, but with the subject subsequently testing positive after a predetermined period. We analyzed the characteristics of recent and acute HIV infections by sex, age, nationality, HIV testing site, region, and reason for HIV testing. Recent and acute HIV infections were described as the proportion of recent and acute HIV infections among newly-diagnosed cases in a given year. Recent and acute HIV infections over the 8-year study period were 20.5% (1210/5898) and 9.5% (562/5898), respectively. Both infections were generally higher in the following groups: males, younger age, Koreans, individuals who were tested due to disease, residents of smaller city or rural area, and individuals diagnosed in recent calendar years. Acute infections were significantly higher among individuals tested in hospitals and due to suspected HIV infection. The recent and acute HIV infection in younger age groups (< 30 years) has been increasing in a given year. There was an increase in the proportion of young individuals with recent HIV infection, and we identified risk groups more at risk of HIV infection recently in Korea. Therefore, our results could prove useful for the development and assessment of national HIV prevention strategies in Korea and provide valuable data for further HIV research.

Performance evaluation of the Asante Rapid Recency Assay for verification of HIV diagnosis and detection of recent HIV-1 infections: Implications for epidemic control.

We previously described development of a rapid test for recent infection (RTRI) that can diagnose HIV infection and detect HIV-1 recent infections in a single device. This technology was transferred to a commercial partner as Asante Rapid Recency Assay (ARRA). We evaluated performance of the ARRA kits in the laboratory using a well-characterized panel of specimens. The plasma specimen panel (N = 1500) included HIV-1 (N = 570), HIV-2 (N = 10), and HIV-negatives (N = 920) representing multiple subtypes and geographic locations. Reference diagnostic data were generated using the Bio-Rad HIV-1-2-O EIA/Western blot algorithm with further serotyping performed using the Multispot HIV-1/2 assay. The LAg-Avidity EIA was used to generate reference data on recent and long-term infection for HIV-1 positive specimens at a normalized optical density (ODn) cutoff of 2.0 corresponding to a mean duration of about 6 months. All specimens were tested with ARRA according to the manufacturer's recommendations. Test strips were also read for line intensities using a reader and results were correlated with visual interpretation. ARRA's positive verification line (PVL) correctly classified 575 of 580 HIV-positive and 910 of 920 negative specimens resulting in a sensitivity of 99.1% (95% CI: 98.0-99.6) and specificity of 98.9% (95% CI: 98.1-99.4), respectively. The reader-based classification was similar for PVL with sensitivity of 99.3% (576/580) and specificity of 98.8% (909/920). ARRA's long-term line (LTL) classified 109 of 565 HIV-1 specimens as recent and 456 as long-term compared to 98 as recent and 467 as long-term (LT) by LAg-Avidity EIA (cutoff ODn = 2.0), suggesting a mean duration of recent infection (MDRI) close to 6 months. Agreement of ARRA with LAg recent cases was 81.6% (80/98) and LT cases was 93.8% (438/467), with an overall agreement of 91.7% (kappa = 0.72). The reader (cutoff 2.9) classified 109/566 specimens as recent infections compared to 99 by the LAg-Avidity EIA for recency agreement of 81.8% (81/99), LT agreement of 9% (439/467) with overall agreement of 91.9% (kappa = 0.72). The agreement between visual interpretation and strip reader was 99.9% (95% CI: 99.6-99.9) for the PVL and 98.1% (95% CI: 96.6-98.9) for the LTL. ARRA performed well with HIV diagnostic sensitivity >99% and specificity >98%. Its ability to identify recent infections is comparable to the LA-Avidity EIA corresponding to an MDRI of about 6 months. This point-of-care assay has implications for real-time surveillance of new infections among newly diagnosed individuals for targeted prevention and interrupting ongoing transmission thus accelerating epidemic control.

Application of limiting antigen avidity enzyme immunoassay for estimating HIV-1 incidence in men who have sex with men

Objective: To estimate the incidence of HIV-1 infection in men who have sex with men (MSM) in key areas of China through HIV-1 limiting antigen avidity enzyme immunoassay (LAg-Avidity EIA), analyze the deviation from the actual results and identify influencing factors, and provided reference for improving the accuracy of estimation results. Methods: Based on the principle of the cohort randomized study design, 20 cities were selected in China based on population size and the number of HIV-positive MSM. The sample size was estimated to be 700 according to the HIV-1 infection rate in MSM. MSM mobile phone app. was used to establish a detection appointment and questionnaire system, and the baseline cross-sectional survey was conducted from April to November 2019. LAg-Avidity EIA was used to identify the recent infected samples. The incidence of HIV-1 infection was calculated and then adjusted based on the estimation formula designed by WHO. The influencing factors were identified by analyzing the sample collection and detection processes. Results: Among the 10 650 blood samples from the participants, 799 were HIV-positive in initial screening, in which 198 samples (24.78%) missed during confirmation test. Only 621 samples were received by the laboratory. After excluding misreported samples, 520 samples were qualified for testing. A total of 155 samples were eventually determined as recent infection through LAg-Avidity EIA; Based on the estimation formula , the incidence of HIV-1 infection in MSM in 20 cities was 4.06% (95%CI:3.27%-4.85%), it increased to 5.53% (95%CI: 4.45%-6.60%)after the adjusting for sample missing rate. When the sample missing rate and misreporting rate were both adjusted, the incidence of HIV-1 infection in the MSM increased to 5.66% (95%CI:4.67%-6.65%). The actual incidence of HIV-1 infection in MSM in the 20 cities might be between 4.06% and 5.66%. Conclusions: Sample missing and misreporting might cause the deviation of the estimation of HIV-1 infection incidence. It is important to ensure the sample source and the quality of sample collection and detection to reduce the deviation in the estimation of HIV-1 infection incidence.

Recent HIV infection and associated factors among men who have sex with men in Jiangsu province

Objective: To understand the incidence of HIV infections and associated factors among men who have sex with men (MSM) in Jiangsu province. Methods: Based on national AIDS sentinel surveillance in 2019, MSM from 13 cities in Jiangsu were recruited for questionnaire interview and laboratory testing during April to July, 2019. Seropositive samples were tested with Limiting-antigen avidity enzyme immunoassay to detect recent HIV infections. The incidence of HIV infection in MSM were calculated according to the formula and parameters from China CDC. Multivariable logistic regression analysis was used to identify factors associated with recent infection of HIV. Results: A total of 4 469 MSM were subjects and the incidence of HIV infection were 4.5% (95%CI: 3.4%-5.5%).Multivariate logistic regression analysis results showed that compared with these aged ≥40 years, recruitment ways from MSM venues, awareness of AIDS knowledge, non-unprotected anal sex in the past 6 months and non-syphilis infection, those who aged 18-24 years (aOR=2.083,95%CI:1.087-3.990), recruitment ways from VCT clinics (aOR=2.125,95%CI:1.175-3.843), unawareness of AIDS knowledge (aOR=2.456,95%CI:1.109-5.437), unprotected anal sex in the past 6 months (aOR=3.553,95%CI:2.143-5.889) and syphilis infection (aOR=2.414,95%CI:1.033-5.462) were higher risk of HIV infection. Conclusion: The new infection rates of HIV were high in MSM in Jiangsu province. Health education, condom use and HIV/syphilis screening promotions should therefore be top priority in the prevention and control of HIV infection in MSM.

Two-fold increase in the HIV viral load suppression rate along with decreased incidence over six years in Ndhiwa sub-county, Kenya.

BackgroundHIV‐positive individuals who maintain an undetectable viral load cannot transmit the virus to others. In 2012, an HIV population‐based survey was conducted in Ndhiwa sub‐county (Kenya) to provide information on the HIV local epidemic. We carried out a second survey 6 years after the first one, to assess progress in HIV diagnosis and care and differences in the HIV prevalence and incidence between the two surveys.MethodsA cross‐sectional, population‐based survey using cluster sampling and geospatial random selection was implemented in 2018, using the same design as 2012. Consenting participants aged 15–59 years were interviewed and tested for HIV at home. HIV‐positive individuals received viral load testing (viral suppression defined as <1000 copies/ml) and Lag‐Avidity EIA assay (to measure recent infection). The 90–90–90 UNAIDS indicators were also assessed.ResultsOverall, 6029 individuals were included in 2018. HIV prevalence was 16.9%. Viral suppression among all HIV‐positive was 88.3% in 2018 (vs. 39.9% in 2012, p < 0.001). HIV incidence was 0.75% in 2018 vs. 1.90% in 2012 (p = 0.07). In 2018, the 90–90–90 indicators were 93%–97%–95% (vs. 60%–68%–83% in 2012).ConclusionA two‐fold increase in the HIV viral load suppression rate along with a decreasing trend in incidence was observed over 6 years in Ndhiwa sub‐county. Achieving high rates of viral suppression in HIV populations that can lead to reducing HIV transmission in sub‐Saharan contexts is feasible. Nevertheless, we will need further efforts to sustain this progress.

The Recent HIV-1 Infections in Blood Donors of Fuzhou Zone

To investigate the recent HIV-1 infections of the blood donors in Fuzhou zone. The positive HIV antibody confirmatory samples in Fuzhou zone from 2012 to 2016 were collected and tested by LAg-Avidity EIA, and HIV long-term infections or recent infections were determined. 405 371 cases of blood donors were tested in the period from 2012 to 2016, and 94 HIV confirmatory positive samples were collected. 35 cases were recent infections determined by LAg-Avidity EIA, the annual HIV-1 incidences were 1.326‰, 0.845‰, 0.694‰, 1.148‰ and 0.364‰, the average incidences were 0.863‰. Among 94 cases of HIV confirmatory positive donors，58 cases were first donors and 36 cases were repeated donors, 17(29.3%) and 18 (50.0%) cases were recent infections respectively, which showed statistical significance（χ2=4.07，P＜0.05）. The HIV-1 incidences were stable among blood donors in Fuzhou zone. The percentage of HIV-1 recent infections in repeated donors were more higher than that in first donors.

Performance of limiting-antigen avidity enzyme immunoassay and pooling PCR in detection of recent HIV-1 infection among men who have sex with men in Yunnan province

Objective: To assess and compare the performance of limiting-antigen avidity enzyme immunoassay (LAg-Avidity EIA) and pooling PCR in the surveillance for recent infection rates of HIV-1 in men who have sex with men (MSM). Methods: Blood samples were collected from MSM selected through snowball sampling method in sentinel surveillance in 13 prefectures of Yunnan province from 2016 to 2017. The samples were tested for HIV-1 antibody. The confirmed positive samples were tested by LAg-Avidity EIA. The negative samples were tested by pooling PCR. The recent infection rates of HIV-1 were estimated by the algorithm based on LAg-Avidity EIA and pooling PCR respectively. The two results were compared. Results: During 2016-2017, a total of 5 363 blood samples were collected from MSM, in which 407 samples were HIV-1 positive (including 177 positive tested previously) and 4 956 samples were HIV-1 negative. A total of 211 samples(91.7%) were tested by LAg-Avidity EIA, 69 were confirmed to be recent infections. A total of 4 469 samples were tested by pooling PCR, 8 were confirmed to be acute infections. The recent infection rates of HIV-1 from 2016 to 2017 estimated by LAg-Avidity EIA were 3.36% and 4.84%, and the recent infection rates estimated by pooling PCR were 3.27% and 3.02% respectively. The differences in recent infection rates of HIV-1 estimated by the two algorithms were not significant. Conclusions: The recent infection rates of HIV-1 estimated by LAg-Avidity EIA and pooling PCR in sentinel surveillance in MSM in Yunnan had good consistency from 2016 to 2017. Using the two methods might have a better stability in continuous surveillance for recent infection rates of HIV-1.

Analysis of new HIV-1 infection in MSM with seroconversion determined by limiting antigen avidity enzyme immunoassay

Objective: To evaluate the applicability of limiting antigen avidity enzyme immunoassay (LAg-Avidity EIA, LAg for short) in determining the new HIV-1 infection status of MSM population with seroconversion and make correlation analysis of other biological indicators. Methods: The 15 cases with HIV seroconversion were found in a MSM observation cohort for calculating the HIV prevalence in Zhejiang.The subjects were conducted epidemiological investigation and sampled.The interval of infection time was estimated according to the exposure history and the time of HIV-positive confirmation.LAg, immunoblotting, CD4 cell counting and viral load test were applied in the testing of the related blood samples. McNermar test was conducted for consistency of the two methods. Results: Of 15 cases, the average age was (31.5±8.0) years old, ranging from 24 to 57 years old. The interval of infection time ranged from 40 days to 366 days, and the median was 134 days, with inter-quartile range from 89 to 180 days. A total of 7 cases were classified as new HIV-1 infection by LAg, and 8 cases were classified as chronic infection.The consistent rate was high to 86.67%, and kappa value was 0.73.The samples lacking at least two bands in p31, p51, p66 and gp120 by immunoblotting were determined as recent infection, of which the new infection proportion was significantly higher than that of other samples (P=0.029).There was no statistical difference in the distribution of CD4 counts (P=0.533) and viral loads (P=0.467) between the new infection and chronic infection groups that divided by LAg. Conclusion: By combining with exposure history, the limiting antigen avidity enzyme immunoassay can be used to estimate the new HIV-1 infection.The other biological indicators such as immunoblotting bands, CD4 cell counts and viral loads, can be used as accessory indicators in evaluating the status of new HIV-1 infection.

Incidence and Risk Factors of HIV-1 Infections among Pregnant Women in Burkina Faso from 2012 to 2016

Background: New cases of HIV/AIDS are still being reported and threaten the achievement of the HIV-1 elimination goal in Burkina Faso. An adequate assessment of the extent of this problem is key to redistributing available resources. HIV-1 incidence and associated risk factors among pregnant women estimated in Burkina Faso. Materials and Methods: We conducted a cross-sectional survey of pregnant women in all 13 administrative regions of Burkina Faso from 2012 to 2016. Collected sera analyzed by Vironostika HIV Uniform II Plus O, ImmunoComb II HIV-1 & 2 Bispot, HIV BLOT 2.2 assays to determine serological status. HIV-1 LAg-Avidity EIA performed on HIV-1 positive samples to differentiate between recent and old infections. Sociodemographic information collected for all participants. Data analysis performed using EPI Info and XLSTAT. Results: A total of 36,848 pregnant women included in the analyses. Serological testing showed 483 HIV-1 positive, 18 HIV-2 positive, 7 HIV-1 + 2 coinfection cases. Overall, 355 HIV-1 positive samples tested with HIV-1 LAg-Avidity EIA; the remaining samples had insufficient volume to be tested. The adjusted incidence rates were 0.17% and 0.09% (p=0.0919) in 2015 and 2016, respectively. Sociodemographic factors associated with recent infections included the 25-34 and ≥35 year age groups, high education level, household and secretary occupations, trader wife, civil servant wife, residence in urban sites, being married, a length of stay in the administrative region of <1 year. Conclusion: HIV-1 incidence is decreasing in Burkina Faso. However, women with certain risk factors should be targeted in prevention programs to reach the country’s HIV-1 elimination goal.

Incidence and Risk Factors of HIV-1 Infections among Pregnant Women in Burkina Faso from 2012 to 2016

Background: New cases of HIV/AIDS are still being reported and threaten the achievement of the HIV-1 elimination goal in Burkina Faso. An adequate assessment of the extent of this problem is key to redistributing available resources. HIV-1 incidence and associated risk factors among pregnant women estimated in Burkina Faso. Materials and Methods: We conducted a cross-sectional survey of pregnant women in all 13 administrative regions of Burkina Faso from 2012 to 2016. Collected sera analyzed by Vironostika HIV Uniform II Plus O, ImmunoComb II HIV-1 & 2 Bispot, HIV BLOT 2.2 assays to determine serological status. HIV-1 LAg-Avidity EIA performed on HIV-1 positive samples to differentiate between recent and old infections. Sociodemographic information collected for all participants. Data analysis performed using EPI Info and XLSTAT. Results: A total of 36,848 pregnant women included in the analyses. Serological testing showed 483 HIV-1 positive, 18 HIV-2 positive, 7 HIV-1 + 2 coinfection cases. Overall, 355 HIV-1 positive samples tested with HIV-1 LAg-Avidity EIA; the remaining samples had insufficient volume to be tested. The adjusted incidence rates were 0.17% and 0.09% (p=0.0919) in 2015 and 2016, respectively. Sociodemographic factors associated with recent infections included the 25-34 and ≥35 year age groups, high education level, household and secretary occupations, trader wife, civil servant wife, residence in urban sites, being married, a length of stay in the administrative region of <1 year. Conclusion: HIV-1 incidence is decreasing in Burkina Faso. However, women with certain risk factors should be targeted in prevention programs to reach the country’s HIV-1 elimination goal.

Performance of a Modified In-House HIV-1 Avidity Assay among a Cohort of Newly Diagnosed HIV-1 Infected Individuals and the Effect of ART on the Maturation of HIV-1 Specific Antibodies.

Viral kinetics impact humoral immune response to HIV; antibody avidity testing helps distinguish recent (<6 months) and long-term HIV infection. This study aims to determine the frequency of recent HIV-1 infection among clients attending ICTC (Integrated Counselling and Testing Centre) using a commercial EIA, to correlate it with a modified in-house avidity assay and to study the impact of ART on anti-HIV-1 antibody maturation. Commercial LAg Avidity EIA was used to detect antibody avidity among 117 treatment naïve HIV-1 infected individuals. A second-generation HIV ELISA was modified for in-house antibody avidity testing and cutoff was set based on Receiver Operating Characteristic (ROC) analysis. Archived paired samples from 25 HIV-1 infected individuals before ART and after successful ART; samples from 7 individuals responding to ART and during virological failure were also tested by LAg Avidity EIA. Six individuals (5.1%) were identified as recently infected by a combination of LAg avidity assay and HIV-1 viral load testing. The modified in-house avidity assay demonstrated sensitivity and specificity of 100% and 98.2%, respectively, at AI=0.69 by ROC analysis. Median ODn values of individuals when responding to ART were significantly lower than pre-ART [4.136 (IQR 3.437- 4.827) vs 4.455 (IQR 3.748-5.120), p=0.006] whereas ODn values were higher during virological failure [4.260 (IQR 3.665 - 4.515) vs 2.868 (IQR 2.247 - 3.921), p=0.16]. This modified in-house antibody avidity assay is an inexpensive method to detect recent HIV-1 infection. ART demonstrated significant effect on HIV-1 antibody avidity owing to changes in viral kinetics.

The concordance of the limiting antigen and the Bio-Rad avidity assays in persons from Estonia infected mainly with HIV-1 CRF06_cpx.

BackgroundSerological assays to determine HIV incidence have contributed to estimates of HIV incidence, monitoring of HIV spread, and evaluation of prevention strategies. Two frequently used incidence assays are the Sedia HIV-1 LAg-Avidity EIA (LAg) and the Bio-Rad avidity incidence (BRAI) assays with a mean duration of recent infection (MDRI) of 130 and 240 days for subtype B infections, respectively. Little is known about how these assays perform with recombinant HIV-1 strains. We evaluated the concordance of these assays in a population infected mainly with HIV-1 CRF06_cpx.Material/MethodsRemnant serum samples (n = 288) collected from confirmed, newly-diagnosed HIV-positive persons from Estonia in 2013 were tested. Demographic and clinical data were extracted from clinical databases. LAg was performed according to the manufacturer’s protocol and BRAI testing was done using a validated protocol. Samples with LAg-pending or BRAI-invalid results were reclassified as recent if they were from persons with viral loads <1000 copies/mL or were reclassified as long-term if presenting with AIDS.ResultsIn total 325 new HIV infections were diagnosed in 2013 in Estonia. Of those 276 persons were tested with both LAg and BRAI. Using assay results only, the recency rate was 44% and 70% by LAg and BRAI, respectively. The majority of samples (92%) recent by LAg were recent by BRAI. Similarly, 89% of samples long-term by BRAI were long-term by LAg. After clinical information was included in the analysis, the recency rate was 44% and 62% for LAg and BRAI, respectively. The majority of samples (86%) recent by LAg were recent by BRAI and 91% of long-term infections by BRAI were long-term by LAg.ConclusionsComparison of LAg and BRAI results in this mostly CRF06_cpx-infected population showed good concordance for incidence classification. Our finding of a higher recency rate with BRAI in this population is likely related to the longer MDRI for this assay.

Characterization of HIV-1 genotype specific antigens for the detection of recent and long-term HIV-1 infection in China

To characterize HIV-1 gp41 as an antigen for developing HIV-1 incidence assay and to investigate the impact of HIV-1 genetic diversity on the assay performance, a number of truncated peptides were synthesized to identify the immunodominant epitopes (IDEs) of HIV-1 gp41 protein. Subsequently, the mixed peptides (MP3) or the recombinant protein (MP4) containing HIV-1 gp41 IDEs of the major HIV-1 genotype CRF01_AE, CRF07_BC/ CRF08_BC and subtype B in China were used to verify the sensitivity and specificity of HIV-1 recency testing. We identified the QKFLG and GKIIC motifs located in the loop region of HIV-1 gp41 as the two major IDEs. The surrounding amino acids EAQQHLLQLT and WNSSWSN could block the binding of gp41 peptide and anti-HIV antibody with low avidity, making the gp41 peptide p57 suitable for distinguishing recent and long-term HIV-1 infections. Furthermore, MP3 or MP4-based immunoassay could significantly improve the assay sensitivity and showed 93.33% (140/150) vs. 94.59% (35/37) and 94.08% (143/152) vs. 94.59% (35/37) concordance with commercially available LAg-Avidity EIA test among the cross-sectional and longitudinal samples, respectively. The estimated mean duration of recent infection (MDRI) was 130 days (95% CI: 83–167) and 166 days (95% CI: 123–202) for MP3 and MP4 assays, respectively. Our preliminary results indicate that the HIV-1 gp41 peptide-based immunoassay specifically targeting the major HIV-1 genotype CRF01_AE, CRF07_BC/CRF08_BC and subtype B could serve as a simple incidence assay for differentiating recent and long-term HIV-1 infections in China.

Estimating HIV incidence among female sex workers and injection drug users in Dehong Prefecture, 2009-2017

Objective: To obtain HIV incidence among injection drug users (IDU) and female sex workers (FSW) in Dehong Prefecture, Yunnan Province during 2009-2017. Methods: We recruited drug users and female sex workers from all sentinel surveillance sites across Dehong Prefecture during 2009-2017. A total of 10 480 IDU and 18 126 FSW in Dehong Prefecture were recruited by fingerprint technique. Data about drug uses, commercial sexual behavior, sociodemographic characteristics was collected by structured questionnaire. HIV-positive patients who were long-term infected or with CD4(+) T cell count was ≤200 were not included for further HIV incidence testing. Also, those who self-identified as on antiretroviral treatment (ART) or AIDS cases were also excluded. A total of 841 and 157 plasma specimens from IDU and FSW that met the inclusion criterion were finally included, respectively. Limiting antigen avidity enzyme immunoassay(LAg-Avidity EIA) were performed to calculate the HIV incidence among these two sub-populations. Results: A total of 3 444 IDU were HIV-positive, among which 884 (25.7%) were Burmese with age of (30.4±7.7), and 2 560 were Chinese with age of (36.6±7.3). Among 228 HIV-positive FSW, 109 (47.8%) were Burmese with age of (27.1±6.3), 119 (52.5%) were Chinese with age of (29.9±11.1). For IDU, the estimated HIV incidence among Burmese in 2009-2010, 2011-2012, 2013-2014, 2015-2017 was 4.20% (95%CI: -0.55%-8.95%), 7.75% (95%CI: 2.95%-12.55%), 11.79% (95%CI: 5.38%-18.20%), 10.30% (95%CI: 5.67%-14.94%), respectively, while Chinese were 3.11% (95%CI: 1.59%-4.64%), 0.03% (95%CI: -0.03%-0.08%), 1.55% (95%CI: 0.54%-2.57%), 0.58% (95%CI: -0.06%-1.04%), respectively. In 2009-2011, 2012-2014, 2015-2017, estimated HIV incidence among Burmese FSW was 0.22% (95%CI: -0.21%-0.64%), 1.24%(95%CI: 0.15%-2.32%), 0.55%(95%CI: 0.01%-1.08%). Whereas, estimated HIV incidence among Chinese FSW was 0.62% (95%CI: 0.25%-0.98%), 0.11% (95%CI: -0.04%-0.26%), 0.22% (95%CI: 0-0.44%). Conclusion: HIV incidences among Chinese IDU and FSW are on the downward trend, while Burmese IDU and FSW seem to be gaining momentum.