Recent and Local HIV Infections among Newly Diagnosed Cases in Two Districts of Chongqing, China (2019-2021).

Newly diagnosed HIV cases often do not clearly indicate whether they are recent or long-standing infections. We collected the history of HIV antibody testing, sexual behavior and initial CD4 + T cell (CD4) count of newly diagnosed HIV/AIDS to determine the time and location of HIV infections. Of the included 612 cases, 17.3% were classified as recent HIV infection. Recent HIV infections were higher in cases aged < 30 (adjusted odds ratio [AOR] = 4.267, 95% Confidence Interval [CI] 1.856-9.813) and 30-49 (AOR = 2.847, 95%CI 1.356-5.977) vs. ≥50, and the transmission mode was men who have sex with men (MSM) (AOR = 4.130, 95%CI 1.815-9.399) was higher than heterosexual contact. Of the 582 cases, 80.8% were classified as local HIV infection (An infection occurred in the two survey districts). Local HIV infections were higher in cases being single and divorced/widowed (AOR = 2.511, 95% CI 1.271-4.962) vs. being married, residing in the survey districts ≥ 5 years (AOR = 168.962, 95%CI 64.942-439.593) vs. < 1 year, transmission mode was MSM (AOR = 8.669, 95%CI 2.668-28.163) vs. heterosexual contact, and acquired infections through spouses or steady partners (AOR = 11.493, 95%CI 3.236-40.819) vs. commercial partners. Both recent and local HIV infections were higher in cases whose transmission mode was MSM, we recommended using internet platforms and MSM dating apps for HIV education and intervention, promoting internet intervention tools to raise awareness about HIV and facilitate early detection.

Programmatic Implications of National Recent HIV Infection Surveillance in Cambodia.

We compared characteristics of HIV diagnosis and recent HIV infection (ie, likely acquired within the last year) in Cambodia. We included individuals ≥ 15 years old accessing HIV testing. From August 2020 to August 2022, 53 031 people were tested for HIV, 6868 were newly diagnosed, and 192 were recently infected. We found differences in geographical burden and risk behaviors with diagnosis and recency (eg, men who have sex with men, transgender women, and entertainment workers had a nearly 2-fold increased odds of testing positive for recent infection compared to being diagnosed with HIV). Recent infection surveillance may provide unique insights into ongoing HIV acquisition to inform programs.

Latency to initiation of antiretroviral therapy in people living with HIV in Japan.

Rapid initiation of antiretroviral therapy (ART) in HIV infection is recommended because it increases care retention rate and reduces the time to viral suppression. In Japan, although ART initiation is delayed, there is little information on the latency to ART initiation (time from HIV diagnosis to ART initiation). The present study was designed to obtain information on the latency to ART initiation in individuals with 1) acute or recent HIV infection (ARH), and with 2) advanced HIV diseases. Questionnaires were sent to 379 regional AIDS facilities requesting information on the people living with HIV (PLWH) who visited their facilities during 2020. Among 1098 new PLWH visitors, 706 were treatment-naïve patients, including 111 (15.7%) with ARH and 304 (43.1%) with advanced HIV diseases. Among those with ARH, only 8.2% received rapid ART initiation (latency to ART <2 weeks) and the time from diagnosis to virological suppression was longer than 14 weeks in 40.4%. Among those with advanced HIV diseases, 36.2% received late ART initiation (latency to ART ≧6 weeks). Our data showed that only a small proportion of PLWH with ARH in Japan received rapid ART. Furthermore, in PLWH with advanced HIV diseases in Japan, current latency to ART seems too long, though the timing of ART commencement should be tailored according to the presence/lack of opportunistic infections and accessibility to medical care. Further investigation is required to identify barriers to rapid ART initiation in Japan.

Prevalence, recent infection and predictors of HIV infection in fishing community along the shore of Lake Victoria in Tanzania.

BACKGROUND: Fishing communities are a subpopulation burdened by human immunodeficiency virus (HIV), mainly due to their mobility and cash income access. Strategies to mitigate the spread of HIV in fishing communities have varying outcomes. We conducted a study to determine the prevalence of HIV, recent infection and associated factors among fishing communities at Lake Victoria in Tanzania. METHODS: We conducted a cross-sectional study in the first quarter of 2019. The participants' information was collected using a structured questionnaire. Blood samples were screened for HIV infection; the positive samples were tested for avidity and viral load to determine the recent infection. Logistic regression analysis was used to determine the factors associated with HIV infection. RESULTS: A total of 1048 individuals were included with a mean age of 34 years (SD ± 11.5). The overall prevalence of HIV was 9.1%, while 7.4% had a recent infection. Lack of formal education, being separated/divorced/widowed, transactional sex, history of sexually transmitted infections, not tested for HIV in the last 12 months had 1.7 to three times more odds of contracting HIV. CONCLUSION: A proportion of HIV recent infection among the fisherfolks was relatively high, signifying the continuous spread, which is predisposed by some demographic and behavioural characteristics.

Acceptability and feasibility of HIV recent infection surveillance by healthcare workers using a rapid test for recent infection at HIV testing sites - Malawi, 2019.

BACKGROUND: The Malawi Ministry of Health implemented a new surveillance activity in April 2019 to detect recent HIV infections using a rapid test for recent infection (RTRI) to identify areas of ongoing transmission and guide response activities. SETTING: At 23 health facilities in Blantyre District, healthcare workers (HCWs) were trained to conduct recent infection testing. In September 2019, we conducted a cross-sectional survey at these sites to explore the acceptability and feasibility of integrating this activity into routine HIV testing services (HTS). METHODS: Research assistants interviewed HCWs using a semi-structured survey. Descriptive statistics were used to summarize quantitative responses and thematic analysis was used to group open-ended text. RESULTS: We interviewed 119 HCWs. Eighty-two percent of participants reported the RTRI was easy-to-use. HCWs perceived high client acceptability; 100% reported clients as 'somewhat' or 'very accepting'. Challenges included 68% of HCWs estimating they spend ≥20 min beyond routine HTS per client for this activity and 51% performing at least two additional finger pricks to complete the testing algorithm. HCWs differed in their perceptions of whether results should be returned to clients. CONCLUSION: This study assessed HCW experiences using point-of-care RTRIs for HIV recent infection surveillance. Overall, HCWs perceived RTRIs to be acceptable, easy-to-use, and valuable. Though only clients with new HIV diagnoses are tested for recent infection, additional time may be substantial at high-volume health service delivery points. Providing response plans or aggregated recent infection results to HCWs and/or clients may support motivation and sustainability of this novel surveillance activity.

Antibody avidity-based approach to estimate population-level incidence of hepatitis C.

BACKGROUND & AIMS: Accurate HCV incidence estimates are critical for monitoring progress towards HCV elimination goals, including an 80% reduction in HCV incidence by 2030. Moreover, incidence estimates can help guide prevention and treatment programming, particularly in the context of the US opioid epidemic. METHODS: An inexpensive, Genedia-based HCV IgG antibody avidity assay was evaluated as a platform to estimate cross-sectional, population-level primary HCV incidence using 1,840 HCV antibody and RNA-positive samples from 875 individuals enrolled in 5 cohort studies in the US and India. Using samples collected <2 years following HCV seroconversion, the mean duration of recent infection (MDRI) was calculated by fitting a maximum likelihood binomial regression model to the probability of appearing recent. Among samples collected ≥2 years post-HCV seroconversion, an individual-level false recent ratio (FRR) was calculated by estimating the probability of appearing recent using an exact binomial test. Factors associated with falsely appearing recent among samples collected ≥2 years post seroconversion were determined by Poisson regression with generalized estimating equations and robust variance estimators. RESULTS: An avidity index cut-off of <40% resulted in an MDRI of 113 days (95% CI 84-146), and FRRs of 0.4% (95% CI 0.0-1.2), 4.6% (95% CI 2.2-8.3), and 9.5% (95% CI 3.6-19.6) among individuals who were HIV-uninfected, HIV-infected, and HIV-infected with a CD4 count <200/µl, respectively. No variation was seen between HCV genotypes 1 and 3. In hypothetical scenarios of high-risk settings, a sample size of <1,000 individuals could reliably estimate primary HCV incidence. CONCLUSIONS: This cross-sectional approach can estimate primary HCV incidence for the most common genotypes. This tool can serve as a valuable resource for program and policy planners seeking to monitor and reduce HCV burden. LAY SUMMARY: Determining the rate of new hepatitis C virus (HCV) infections in a population is critical to monitoring progress toward HCV elimination and to appropriately guide control efforts. However, since HCV infections are most often initially asymptomatic, it is difficult to estimate the rate of new HCV infections without following HCV-uninfected people over time and repeatedly testing them for HCV infection. Here, we present a novel, resource-efficient method to estimate the rate of new HCV infections in a population using data from a single timepoint.

Determining the Origins of Human Immunodeficiency Virus Type 1 Drug-resistant Minority Variants in People Who Are Recently Infected Using Phylogenetic Reconstruction.

BACKGROUND: Drug-resistant minority variants (DRMinVs) detected in patients who recently acquired human immunodeficiency virus type 1 (HIV-1) can be transmitted, generated de novo through virus replication, or technical errors. The first form is likely to persist and result in treatment failure, while the latter two could be stochastic and transient. METHODS: Ultradeep sequencing of plasma samples from 835 individuals with recent HIV-1 infection in the United Kingdom was performed to detect DRMinVs at a mutation frequency between 2% and 20%. Sequence alignments including >110 000 HIV-1 partial pol consensus sequences from the UK HIV Drug Resistance Database (UK-HDRD), linked to epidemiological and clinical data from the HIV and AIDS Reporting System, were used for transmission cluster analysis. Transmission clusters were identified using Cluster Picker with a clade support of >90% and maximum genetic distances of 4.5% or 1.5%, the latter to limit detection to likely direct transmission events. RESULTS: Drug-resistant majority variants (DRMajVs) were detected in 66 (7.9%) and DRMinVs in 84 (10.1%) of the recently infected individuals. High levels of clustering to sequences in UK-HDRD were observed for both DRMajV (n = 48; 72.7%) and DRMinV (n = 63; 75.0%) sequences. Of these, 43 (65.2%) with DRMajVs were in a transmission cluster with sequences that harbored the same DR mutation compared to only 3 (3.6%) sequences with DRMinVs (P < .00001, Fisher exact test). Evidence of likely direct transmission of DRMajVs was observed for 25/66 (37.9%), whereas none were observed for the DRMinVs (P < .00001). CONCLUSIONS: Using a densely sampled HIV-infected population, we show no evidence of DRMinV transmission among recently infected individuals.

Interpretation of very low avidity indices acquired with the Liaison XL Toxo IgG avidity assay in dating toxoplasmosis infection.

Congenital toxoplasmosis is an important cause of complications in pregnancy. Toxoplasmosis is often asymptomatic and thus serological tests are usually performed to screen for it. A first serum which exhibit both IgG and IgM may be due to nascent toxoplasmosis seroconversion, non-specific IgM reaction, or residual IgM. The IgG avidity test has been proposed to identify latent infections. A high index excludes recent toxoplasmosis whereas an intermediate or low index only suggests a recent infection, the caveats being that some people with latent Toxoplasma gondii infection show IgG with low or intermediate avidity. In this study, we investigated the ability of the Liaison XL Toxo IgG avidity (DiaSorin, Saluggia, Italy) assay to confirm recent infection when IgG avidity index is very low (≤ 0.1). Four thousand two hundred ninety-seven sera exhibiting both IgG and IgM were included and avidity was performed on the Liaison device according to the manufacturer's recommendations. One hundred twenty-six sera on the 297 sera which exhibited very low IgG avidity indices (≤ 0.1) could be exploited: 97% of sera with IgG avidity indices < 0.05 actually corresponded to recent infection (less than 3 months). A similar but less pronounced trend was observed for the sera exhibiting indices between 0.05 and 0.1 (69% corresponded to recent infections). The IgG avidity index data we obtained with the Liaison XL Toxo device are similar to those obtained with other devices. This body of consistent results underlines the interest of very low IgG avidity indices as a sign of probable recent toxoplasmosis.

Characteristics of Persons Who Inject Drugs with Recent HIV Infection in the United States: National HIV Behavioral Surveillance, 2012.

We evaluated characteristics associated with recent HIV infection among persons who inject drugs (PWID) from 19 U.S. cities who participated in 2012 National HIV Behavioral Surveillance. Recent infection was defined as having a reactive HIV test, a Bio-Rad Avidity index cutoff ≤ 30%, no reported HIV diagnosis ≥ 12 months before interview, and no evidence of viral suppression. Of 8667 PWID, 50 (0.6%) were recently HIV infected. Having a greater number of sex partners (≥ 2 partners vs. 0) [prevalence ratio (PR) 4.7, 95% confidence interval (CI) 1.3-17.8], injecting heroin and other drugs (PR 3.0, 95% CI 1.3-6.6) or exclusively non-heroin drugs (PR 5.9, 95% CI 1.7-20.7) compared to injecting only heroin, and having male-male sex in the past year (PR 7.1, 95% CI 3.0-16.6) were associated with recent infection. Promoting not only safe injection practices but also safe sex practices will be key to preventing new HIV infections.

Integration of a recent infection testing algorithm into HIV surveillance in Ireland: improving HIV knowledge to target prevention.

Recent infection testing algorithms (RITA) for HIV combine serological assays with epidemiological data to determine likely recent infections, indicators of ongoing transmission. In 2016, we integrated RITA into national HIV surveillance in Ireland to better inform HIV prevention interventions. We determined the avidity index (AI) of new HIV diagnoses and linked the results with data captured in the national infectious disease reporting system. RITA classified a diagnosis as recent based on an AI < 1.5, unless epidemiological criteria (CD4 count <200 cells/mm3; viral load <400 copies/ml; the presence of AIDS-defining illness; prior antiretroviral therapy use) indicated a potential false-recent result. Of 508 diagnoses in 2016, we linked 448 (88.1%) to an avidity test result. RITA classified 12.5% of diagnoses as recent, with the highest proportion (26.3%) amongst people who inject drugs. On multivariable logistic regression recent infection was more likely with a concurrent sexually transmitted infection (aOR 2.59; 95% CI 1.04-6.45). Data were incomplete for at least one RITA criterion in 48% of cases. The study demonstrated the feasibility of integrating RITA into routine surveillance and showed some ongoing HIV transmission. To improve the interpretation of RITA, further efforts are required to improve completeness of the required epidemiological data.

Demographic characteristics and spatial clusters of recent HIV-1 infections among newly diagnosed HIV-1 cases in Yunnan, China, 2015.

BACKGROUND: The characteristics of recent HIV infections can provide the information about the dynamics of HIV transmission. Yunnan is one of the provinces hardest-hit by HIV-1 in China. To further understand the characteristics of the HIV-1 epidemic in Yunnan, we analyzed the prevalence of recent HIV-1 infections among newly diagnosed cases, identified the associated factors and explored the spatial distribution of recent HIV-1 infections. METHODS: Residual plasma samples from HIV-1 diagnostic tests were preserved. The associated information was collected from China HIV/AIDS case reporting system. Recent HIV-1 infections were estimated by combining the information about disease progression and BED- capture enzyme immunoassay (CEIA). The proportions of recent HIV-1 infections among newly diagnosed cases stratified by demographic characteristics were analyzed. The spatial clusters of recent HIV-1 infections were investigated by spatial scan statistics. RESULTS: Among 6119 HIV/AIDS cases were newly reported between January 2015 and June 2015 in Yunnan Province, 9.3% (570/6119) were estimated as recent infections. Female, aged below 25 years and homosexual contact were more associated with the higher proportion of recent HIV-1 infections. Among the different demographic sub-groups, men who have sex with men (MSM) aged < 25 years and ≥ 50 years had a higher chance of being diagnosed as recent infections, heterosexually infected men aged ≥25 years had a lower chance of being diagnosed as recent infections. In the sub-groups with different screening approaches, the highest proportion of recent infections (16.1%) was found among women diagnosed by testing during pregnancy and childbirth. In the sub-groups with different contact histories, the higher proportion of recent infections was found among the female cases having commercial heterosexual contacts (16.4%) and MSM (19.7%). The statistically significant spatial clusters of recent infections attributed to heterosexual contact, homosexual contact and intravenous drug injection were identified, respectively. CONCLUSIONS: The investigation of recent HIV infections among newly diagnosed cases supplements the routine HIV surveillance, and reveals the characteristics of ongoing HIV transmission. Our finding identified the potential sub-populations and geographic areas in need of services or improved interventions.

[The characteristics of recent HIV-1 infection and associated factors in Tianjin].

The newly reported HIV infected cases was collected, and HIV blood samples were detected to identify recent HIV infection in Tianjin during 2008-2015. Factors associated with HIV-1 infection were analyzed by the univariate and multivariate unconditional logistic regression. The recent HIV-1 infection proportion of homosexuals increased from 37.70% in 2008 to 83.68% in 2015. Those cases who aged ≤30 years (OR=1.53, 95%CI: 1.30-1.79), in han ethnic group (OR=1.40, 95%CI: 1.02-1.91), students (OR=1.79, 95%CI: 1.28-2.51) were more likely to be recent infected. The cases who had a high school education (OR=1.28, 95%CI: 1.05-1.56) or collage education (OR=1.23, 95%CI: 1.00-1.50) were more likely to be recent infected than those who had a primary school education. Compared with patients identified by hospitals, the recent HIV infections were more likely to be found through voluntary counseling and testing (VCT), STD outpatients, men who have sex with men (MSM) investigation and unpaid blood donors. Homosexual transmission has become the major route of HIV-1 recent infection in Tianjin.

Peripheral Th17 cells expressing ß7 intestinal homing receptor in recent and chronic HIV infections.

The objective of this study was to conduct an analysis of peripheral blood Th17 cells with the ability to home to gut mucosa (CD4+ Th17+ ß7+ ) during recent or chronic human immunodeficiency virus (HIV) infections. The relationship between HIV load and systemic inflammation markers was studied. Twenty-five patients with recent (n = 10) or chronic (n = 15) untreated HIV infections; 30 treated HIV-infected patients with undetectable HIV load at the time of inclusion and 30 healthy controls were included. Bacterial translocation markers (16S rDNA), soluble CD14 (sCD14) and interleukin (IL)-6 monocyte activation parameters, CD4/CD8 ratio and T helper type 17 (Th17) subpopulations [CD4+ Th17+ expressing the IL-23 receptor (IL-23R) or ß7] were analysed at baseline and after 6 and 12 months of anti-retroviral therapy (ART). 16S rDNA was detected in all patients. Significantly increased serum levels of sCD14 and IL-6 and a decreased CD4/CD8 ratio were observed in patients. Similar percentages of CD4+ IL-23R+ and CD4+ Th17+ ß7+ cells were observed in healthy controls and patients at baseline. After 12 months of therapy, patients with a recent HIV infection showed significant increases of CD4+ IL-23R+ and CD4+ Th17+ ß7+ cell percentages and a decrease in IL-6 levels, although 16S rDNA continued to be detectable in all patients. No significant differences were observed in Th17 subpopulations in patients with chronic HIV infection after therapy. Early initiation of ART helps to increase the number of Th17 cells with the ability to home to the intestinal mucosa and to partially restore gut mucosal homeostasis. These results provide a rationale for initiating ART during the acute phase of HIV infection.

HIV incidence in the Estonian population in 2013 determined using the HIV-1 limiting antigen avidity assay.

OBJECTIVES: Estonia has one the highest number of new HIV diagnoses in the European Union, mainly among injecting drug users and heterosexuals. Little is known of HIV incidence, which is crucial for limiting the epidemic. Using a recent HIV infection testing algorithm (RITA) assay, we aimed to estimate HIV incidence in 2013. METHODS: All individuals aged ≥18 years newly-diagnosed with HIV in Estonia January- December 2013, except blood donors and those undergoing antenatal screening, were included. Demographic and clinical data were obtained from the Estonian Health Board and the Estonian HIV-positive patient database. Serum samples were tested for recent infection using the LAg-avidity EIA assay. HIV incidence was estimated based on previously published methods. RESULTS: Of 69,115 tested subjects, 286 (0.41%) were newly-diagnosed with HIV with median age of 33 years (IQR: 28-42) and 65% male. Self-reported routes of HIV transmission were mostly heterosexual contact (n = 157, 53%) and injecting drug use (n = 62, 21%); 64 (22%) were with unknown risk group. Eighty two (36%) were assigned recent, resulting in estimated HIV incidence of 0.06%, corresponding to 642 new infections in 2013 among the non-screened population. Incidence was highest (1.48%) among people who inject drugs. CONCLUSIONS: These high HIV incidence estimates in Estonia call for urgent action of renewed targeted public health promotion and HIV testing campaigns.

HCV avidity as a tool for detection of recent HCV infection: Sensitivity depends on HCV genotype.

Accurate detection of incident hepatitis C virus (HCV) infection is required to target and evaluate public health interventions, but acute infection is largely asymptomatic and difficult to detect using traditional methods. Our aim was to evaluate a previously developed HCV avidity assay to distinguish acute from chronic HCV infection. Plasma samples collected from recent seroconversion subjects in two large Australian cohorts were tested using the avidity assay, and the avidity index (AI) was calculated. Demographic and clinical characteristics of patients with low/high AI were compared via logistic regression. Sensitivity and specificity of the assay for recent infection and the mean duration of recent infection (MDRI) were estimated stratified by HCV genotype. Avidity was assessed in 567 samples (from 215 participants), including 304 with viraemia (defined as ≥250 IU/mL). An inverse relationship between AI and infection duration was found in viraemic samples only. The adjusted odds of a low AI (<30%) decreased with infection duration (odds ratio [OR] per week of 0.93; 95% CI:0.89-0.97), and were lower for G1 compared with G3 samples (OR = 0.14; 95% CI:0.05-0.39). Defining recent infection as <26 weeks, sensitivity (at AI cut-off of 20%) was estimated at 48% (95% CI:39-56%), 36% (95% CI:20-52%), and 65% (95% CI:54-75%) and MDRI was 116, 83, and 152 days for all genotypes, G1, and G3, respectively. Specificity (≥52 weeks infection duration, all genotypes) was 96% (95% CI:90-98%). HCV avidity testing has utility for detecting recent HCV infection in patients, and for assessing progress in reaching incidence targets for eliminating transmission, but variation in assay performance across genotype should be recognized.

Characterization of HIV Recent Infection Among High-Risk Men at Public STI Clinics in Mumbai.

We examined associations with HIV recent infection and estimated transmitted drug resistance (TDR) prevalence among 3345 men at sexually transmitted infection clinics in Mumbai (2002-2005). HIV seroincidence was 7.92% by the BED-CEIA and was higher at a clinic located near brothels (12.39%) than at a hospital-based clinic (3.94%). HIV recent infection was associated with a lifetime history of female sex worker (FSW) partners, HSV-2, genital warts, and gonorrhea. TDR prevalence among recent infection cases was 5.7%. HIV testing services near sex venues may enhance case detection among high-risk men who represent a bridging population between FSWs and the men's other sexual partners.

Detection of IgG3 antibodies specific to the human immunodeficiency virus type 1 (HIV-1) p24 protein as marker for recently acquired infection.

Reducing the risk of human immunodeficiency virus type 1 (HIV-1) transmission is still a public health priority. The development of effective control strategies relies on the quantification of the effects of prophylactic and therapeutic measures in disease incidence. Although several assays can be used to estimate HIV incidence, these estimates are limited by the poor performance of these assays in distinguishing recent from long-standing infections. To address such limitation, we have developed an assay to titrate p24-specific IgG3 antibodies as a marker of recent infection. The assay is based on a recombinant p24 protein capable to detect total IgG antibodies in sera using a liquid micro array and enzyme-linked immunosorbent assay. Subsequently, the assay was optimised to detect and titrate anti-p24 IgG3 responses in a panel of sequential specimens from seroconverters over 24 months. The kinetics of p24-specific IgG3 titres revealed a transient peak in the 4 to 5-month period after seroconversion. It was followed by a sharp decline, allowing infections with less than 6 months to be distinguished from older ones. The developed assay exhibited a mean duration of recent infection of 144 days and a false-recent rate of ca. 14%. Our findings show that HIV-1 p24-specific IgG3 titres can be used as a tool to evaluate HIV incidence in serosurveys and to monitor the efficacy of vaccines and other transmission control strategies.

Assessment of HIV Screening Tests for Use in Preexposure Prophylaxis Programs.

Preexposure prophylaxis programs involve frequent human immunodeficiency virus (HIV) testing. We evaluated the sensitivity of 2 antigen/antibody immunoassays (Architect and Bioplex), 2 antibody-based rapid tests (Vikia-HIV-1/2 and Autotest-VIH), and 1 antigen/antibody rapid test (Alere HIV Combo) for the diagnosis of HIV infection. Among the 31 HIV-1-infected participants in the ANRS-IPERGAY trial, HIV-1 RNA was detected alone in only 2. The sensitivities of the Architect and Bioplex assays were 83% (95% confidence interval [CI], 76%-99%) and 82% (95% CI, 63%-94%), respectively. The sensitivities of the Vikia, Autotest, and Alere tests were 54% (95% CI, 34%-72%), 50% (95% CI, 31%-69%), and 78% (95% CI, 58%-91%), respectively. Antigen/antibody tests should be preferred to avoid missing cases of acute HIV infection and to decrease the related risks of viral transmission and emergence of drug resistance.

Evaluation of the limiting antigen avidity EIA (LAg) in people who inject drugs in Greece.

This analysis assessed the utility of the limiting antigen avidity assay (LAg). Samples of people who inject drugs (PWID) in Greece with documented duration of HIV-1 infection were tested by LAg. A LAg-normalized optical density (ODn) ⩽1·5 corresponds to a recency window period of 130 days. The proportion true recent (PTR) and proportion false recent (PFR) were estimated in 28 seroconverters and in 366 samples collected >6 months after HIV diagnosis, respectively. The association between LAg ODn and HIV RNA level was evaluated in 232 persons. The PTR was 85·7%. The PFR was 20·8% but fell to 5·9% in samples from treatment-naive individuals with long-standing infection (>1 year), and to 0 in samples with the circulating recombinant form CRF35 AD. A LAg-based algorithm with a PFR of 3·3% estimated a similar incidence trend to that calculated by analyses based on HIV-1 seroconversions. In recently infected persons indicated by LAg, the median log10 HIV RNA level was high (5·30, interquartile range 4·56-5·90). LAg can help identify highly infectious HIV(+) individuals as it accurately identifies recent infections and is correlated with the HIV RNA level. It can also produce reliable estimates of HIV-1 incidence.

HIV avidity index performance using a modified fourth-generation immunoassay to detect recent HIV infections.

BACKGROUND: Detecting recent HIV infections is important to evaluate incidence and monitor epidemic trends. We aimed to evaluate the diagnostic performance and accuracy of the avidity index (AI) for discriminating for recent HIV infections. METHODS: We collected serum samples from HIV-1 positive individuals: A) with known date of infection (midpoint in time between last HIV-negative and first HIV-positive test); B) infected for >1 year. Samples were divided into two aliquots: one diluted with phosphate buffered saline (PBS) and the other with 1 M guanidine. Both aliquots were assayed by the Architect HIV Ag/Ab Combo 4th generation assay (Abbott). We compared AI found in recent (RI=<6 months from seroconversion) and established (EI) infections. The diagnostic accuracy was evaluated by receiver operating characteristic (ROC) curve analysis. The proportion of samples misclassified as recent (FRR) was calculated. RESULTS: In total, 647 samples were collected: 455 in group A (51.6% RI and 48.4% EI) and 192 in group B. Among these, sixteen samples were from elite controllers, 294 from treated patients, 328 from patients infected with non-B subtypes. Samples before antiretroviral initiation showed a mean AI significantly lower among RI compared to EI (0.66+0.28 vs. 1.00±0.12; p<0.000). The FRR was 0% using a cut-off of ≤0.70. An extremely low FRR was observed among elite controllers, samples with low VL or CD4. HIV subtype had no impact on AI misclassifications. All individuals in group A reached the AI threshold of 0.80 within 24 months after seroconversion. CONCLUSIONS: The AI is an accurate serological marker for discriminating recent from established HIV infections and meets WHO requirements for HIV incidence assays.