Assessment of the proportion of recent HIV-1 infections in newly-diagnosed cases in Ghana

Accurate monitoring of epidemics is a key strategy for the control of human immunodeficiency virus type-1 (HIV-1) infection. To delineate the characteristic of newly-diagnosed cases of HIV-1 infection, we assessed the proportion of recent HIV-1 infections using a recent infection testing algorithm (RITA). In 2015, 248 cases were newly diagnosed with HIV infection in Reginal Hospital Koforidua, Ghana. Of these, 234 cases (94.4%) were infected with HIV-1 only, four (1.6%) were infected with HIV-2 only, and 10 (4.0%) were co-infected with HIV-1 and HIV-2. All the HIV-1 single seropositive samples were applied to HIV-1 LAg avidity assay for RITA. Our analysis revealed that 18 cases (7.7%) were determined as recent infections, indicating that early diagnosis has not been achieved in Ghana. This is the first report assessing the proportion of recent infections in Ghana using a biomarker approach. Accumulation of these data would contribute to accurate estimation of HIV-1 incidence and prevalence in Ghana.

Immune profiling of Mycobacterium tuberculosis-specific T cells in recent and remote infection

BACKGROUND

Recent Mycobacterium tuberculosis (M.tb) infection is associated with a higher risk of progression to tuberculosis disease, compared to persistent infection after remote exposure. However, current immunodiagnostic tools fail to distinguish between recent and remote infection. We aimed to characterise the immunobiology associated with acquisition of M.tb infection and identify a biomarker that can distinguish recent from remote infection.

METHODS

Healthy South African adolescents were serially tested with QuantiFERON-TB Gold to define recent (QuantiFERON-TB conversion <6 months) and persistent (QuantiFERON-TB+ for >1.5 year) infection. We characterised M.tb-specific CD4 T cell functional (IFN-γ, TNF, IL-2, CD107, CD154), memory (CD45RA, CCR7, CD27, KLRG-1) and activation (HLA-DR) profiles by flow cytometry after CFP-10/ESAT-6 peptide pool or M.tb lysate stimulation. We then assessed the diagnostic performance of immune profiles that were differentially expressed between individuals with recent or persistent QuantiFERON-TB+.

FINDINGS

CFP-10/ESAT-6-specific CD4 T cell activation but not functional or memory phenotypes distinguished between individuals with recent and persistent QuantiFERON-TB+. In response to M.tb lysate, recent QuantiFERON-TB+ individuals had lower proportions of highly differentiated IFN-γ+TNF+ CD4 T cells expressing a KLRG-1+ effector phenotype and higher proportions of early differentiated IFN-γ-TNF+IL-2+ and activated CD4 T cells compared to persistent QuantiFERON-TB+ individuals. Among all differentially expressed T cell features CFP-10/ESAT-6-specific CD4 T cell activation was the best performing diagnostic biomarker of recent infection.

INTERPRETATION

Recent M.tb infection is associated with highly activated and moderately differentiated functional M.tb-specific T cell subsets, that can be used as biomarkers to distinguish between recent and remote infection.

FUNDING

US National Institutes of Health (NIH), Bill and Melinda Gates Foundation, South African National Research Foundation, South African Medical Research Council, and Aeras.

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.

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.

Modeling based response guided therapy in subjects with recent hepatitis C infection

BACKGROUND & AIMS

Mathematical modeling of viral kinetics has been shown to identify patients with chronic hepatitis C virus (HCV) infection who could be cured with a shorter duration of direct-acting antiviral (DAA) treatment. However, modeling therapy duration has yet to be evaluated in recently infected individuals. The aim of this study was to retrospectively examine whether modeling can predict outcomes of six-week sofosbuvir (SOF) and weight-based ribavirin (R) therapy in individuals with recent HCV infection.

METHODS

Modeling was used to estimate viral host parameters and to predict time to cure for 12 adults with recent HCV infection (<12 months of infection) who received six weeks of treatment with SOF + R.

RESULTS

Modeling results yielded a 100% negative predictive value for SOF + R treatment response in nine participants and suggested that a median of 13 [interquartile range: 8-16] weeks of therapy would be required for these patients to achieve cure. Modeling predicted cure after 5 weeks of therapy in the only modeled participant who achieved a sustained virological response. However, cure was also predicted for two participants who relapsed following treatment.

CONCLUSIONS

The modeling results confirm that longer than 6 weeks of SOF + R is needed to reach cure in individuals with recent HCV infection. Prospective real-time modeling under current potent DAA regimens is needed to validate the potential of response-guided therapy in the management of recent HCV infection.

Establishment of an anti-hepatitis C virus IgG avidity test for dried serum/plasma spots

Monitoring recency of infection helps to identify current transmission in vulnerable populations for effective disease control. We have established an in-house avidity based hepatitis C virus (HCV) recency assay based on the Monolisa Anti-HCV PLUS Version 3 ELISA kit for use of dried serum/plasma spots (DS/PS) in order to distinguish recent and long-term infections. A first panel of DS/PS (n = 218; genotype 1 n = 170 and non-genotype 1 n = 48) consisting of primary and at least one follow up sample was used to analyze the temporal changes of the Avidity Index (AI) over time. Sub-panels of longitudinal DS/PS (n = 66) and acute cases (<26 weeks; n = 34) were taken to calculate the Mean Duration of Recent Infection (MDRI) and the False Long-term Rate (FLTR), respectively. A second panel of DS/PS >104 weeks (n = 132) and a third panel of DS/PS prepared from resolved infections (≥180 days since last positive; n = 32) were used to calculate the False Recent Rate (FRR). For all genotypes, the optimal AI cut-off was determined to be 40% resulting in an MDRI of 364 days (95% CI: 223-485). FLTR was 5.9% (95% CI: 0.7-19.7), 8.3% (95% CI: 1-27), and 0% (-) and FRR was 13.6% (95% CI: 8.3-20.7), 11.7% (95% CI: 6.6-19), and 30.6% (95% CI: 9.1-61.4) for all genotypes, genotype 1, and non-genotype 1 infections, respectively. For resolved infections, the FRR was 53.1% (95% CI: 35.8-70.4). Thus, this assay performs particularly well for genotype 1 reaching a high rate of correct discriminations between infections acquired less than a year before diagnosis and those acquired earlier by applying an AI cut-off of 40%. Due to a rapid decline in avidity post resolution of an HCV infection this assay is not recommended to be used in HCV RNA negative patients.

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.

Knowledge, Normative Beliefs and Attitudes Related to Recent HIV Infection among People who Inject Drugs in Athens, Greece

BACKGROUND

Despite great improvements in prevention over the last years, much has to be done to reduce new human immunodeficiency virus (HIV) infections. Substantial evidence shows that the six-month period of recent HIV infection contributes disproportionately to HIV transmission.

OBJECTIVE

This study aims to investigate knowledge, normative beliefs, and attitudes of people who inject drugs (PWID) regarding recent HIV infection.

METHODS

People who inject drugs in Athens, Greece were recruited in the fifth round of a respondent- driven sampling program (ARISTOTLE). The participants were tested for HIV and answered a structured questionnaire, which also included items on knowledge, normative beliefs, and attitudes regarding recent infection to address needs of the social network-based Transmission Reduction Intervention Project. The multivariable analyses included logistic regression models, which produced odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

In total, 1,407 people (mean age: 36.3 ± 7.9 years old; males: 81.9%) took part in the fifth round of ARISTOTLE. Of these, 61.5% knew that HIV-infected people who are not on treatment are more likely to transmit HIV during the first six months of their infection and 58.4% reported that people in their network would react positively towards a recently HIV-infected person. People who inject drugs who were knowledgeable of recent HIV infection were more likely to disagree with statements such as that one should avoid all contact with a person recently infected by HIV (adjusted OR: 1.510, 95% CI: 1.090, 2.091) or more likely to agree with statements such as that an HIV+ person is much less likely to transmit HIV when h/she is on combination antiretroviral treatment (adjusted OR: 2.083, 95% CI: 1.231, 3.523).

CONCLUSION

A considerable proportion of PWID in Athens, Greece, were aware of the high HIV transmission risk of recent HIV infection, although improvement is needed for some population segments. People who inject drugs who were knowledgeable of the role of recent HIV infection were more likely to have normative beliefs and attitudes that favor behaviors that could help rather than harm or stigmatize people who have recently been infected with HIV. Interventions that are based on the role of recent HIV infection in HIV transmission could be important to HIV prevention.

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.

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.

Development of antibody biomarkers of long term and recent dengue virus infections

Dengue virus (DENV) infections elicit antibody responses to the non-structural protein 1 (NS1) that are associated with protection against disease. However, the antibody isotypes and subclasses involved, and their kinetics have not been extensively studied. We characterized the antibody responses to DENV NS1 by enzyme-linked immunosorbent assay (ELISA) in a longitudinal cohort of 266 confirmed dengue cases in Recife, Northeast Brazil. Samples were collected during the febrile phase and up to over 3 years after onset of symptoms. The antibodies investigated [IgA, IgM, total IgG (all subclasses measured together) and each subclass (IgG2, IgG3 and IgG4) measured separately] had distinct kinetic profiles following primary or secondary DENV infections. Of interest, most of these antibodies were consistently detected greater than 6 months after onset of symptoms, except for IgG3. Anti-dengue NS1-specific IgG was consistently detected from the acute phase to beyond 3 years after symptom onset. In contrast, anti-dengue NS1-specific IgG3 was detected within the first week, peaked at week 2-3, and disappeared within 4-6 months after onset of symptoms. The mean duration of the IgG3 positive signal was 149 days (ranging from 126 to 172 days). In conclusion, anti-dengue NS1-specific IgG and IgG3 are potential biomarkers of long-term and recent (less than 6 months) DENV infections, respectively.

[HIV infection and associated factors in HIV-antibody positive clients of female sex workers recently reported in Shaanxi province]

Objective: To investigate the current status of HIV infection and the related factors in HIV antibody positive clients of female sex workers (FSWs) recently reported in Shaanxi province. Methods: The HIV/AIDS cases newly diagnosed in males living in Shaanxi from January 1th of 2013 to June 30th of 2014 were selected and those infected through " commercial heterosexual behavior" were identified. The information about their demographic characteristics, previous unprotected heterosexual sex and the sample sources were collected, and serum or plasma samples were collected from them and tested with BED-CEIA. The proportion of recent HIV infections and associated factors were investigated. Results: The proportion of recent HIV infection and HIV-antibody detection rate in 212 HIV antibody positive male clients of FSWs were 25.5% and 6.6% respectively. The cases who had the educational level of junior middle school or high middle school were wore likely to have long term HIV infections than those with lower educational level (aOR=0.28, 95% CI: 0.08-0.93). Compared with patients identified by hospitals or sexually transmitted diseases clinics, recent HIV infections were more likely to be found through preoperative test or blood transfusion test (aOR=3.14, 95% CI: 1.06-9.30) and blood donation test (aOR=4.19, 95% CI:1.01-17.42). Compared with the cases who had commercial sex only in Xi' an or other province or both in Xi' an and other province, the cases who had commercial sex in other cities in Shaanxi were more likely to be infected recently (aOR=0.19, 95%CI: 0.07-0.57). Compared with the cases had temporary heterosexual sex partner, those who had no temporary sex partners were more likely to be infected recently (aOR=9.03, 95% CI: 3.00-27.18) (P<0.05). Conclusions: The proportion of recent HIV infections among HIV antibody positive clients of FSWs was high and the HIV-antibody detection rate among them was low. The educational level, sample source, geographic area and temporary heterosexual partner were related factors for recent HIV infection. The HIV infection in the clients of FSWs, especially those with lower educational level, was serious in Shaanxi. It is necessary to strengthen behavior intervention and improve HIV defection according to the characteristics of this population.

Toxocara canis: Analysis of the kinetics of antigen release and antibody production in an in vivo model for the detection of past or present infection

Worldwide, Toxocara canis is an important zoonotic nematode of public health concern. This soil-transmitted helminth causes visceral larva and ocular larva migrans in paratenic hosts. The detection of T. canis larva migrans is complicated because current immunological tests detect only IgG antibodies, which can cross-react with antigens from other parasites and cannot distinguish between the past and present infection. Analysis of antigen release and antibody production could help improve the detection of larva migrans. Here, we report the kinetics of antigen release, IgM and IgG production in an in vivo model for the detection of past or present infection. We used four groups of seven mice: two groups infected orally with 50 or 100 embryonated eggs, and the other two infected intraperitoneally with 50 or 100 live larvae. We obtained blood samples at 0, 3, 7, and 14days and, then, every two weeks until day 140. Sandwich ELISA and indirect ELISA were performed for antigen capture and the detection of immunoglobulins, respectively. Mice inoculated with larvae developed an immune response faster than those inoculated with eggs. In all groups, antigen capture was positive starting at 3days until 140days post-inoculation (dpi). Detection of immunoglobulins was at 14 or 28dpi in mice inoculated with larvae or eggs, respectively. Negative IgM values were detected at days 98 and 112. The samples remained positive for IgG until the last day of the experiment. Data suggest that in mice inoculated with T canis eggs, some larvae did not hatch, others died or never reached the bloodstream. Based on our model, we propose that there is early infection when only antigens are present, and active larva migrans when antigen and immunoglobulins are detected, implying an immune response of the host against the antigen. Our study offers a view into the parasite-host relationship and enables us to infer if there are live larvae. Additionally, these findings provide a foundation for the diagnosis and differentiation of recent infection and active larva migrans.

Resistance to linezolid in Staphylococcus spp. clinical isolates associated with ribosomal binding site modifications: novel mutation in domain V of 23S rRNA

Linezolid is the main representative of the oxazolidinones, introduced in 2000 in clinical practice to treat severe Gram-positive infections. This compound inhibits protein synthesis by binding to the peptidyl transferase centre of the 50S bacterial ribosomal subunit. The aim of this study was to characterize 12 clinical strains of linezolid-resistant Staphylococcus spp. isolated in Northern Italy. All isolates of Staphylococcus spp. studied showed a multi-antibiotic resistance phenotype. In particular, all isolates showed the presence of the mecA gene associated with SSCmec types IVa, V or I. Mutations in domain V of 23S rRNA were shown to be the most prevalent mechanism of linezolid resistance: among these a new C2551T mutation was found in S. aureus, whilst the G2576T mutation was shown to be the most prevalent overall. Moreover, three S. epidermidis isolates were shown to have linezolid resistance associated only with alterations in both L3 and L4 ribosomal proteins. No strain was shown to harbor the previously described cfr gene. These results have shown how the clinical use of linezolid in Northern Italy has resulted in the selection of multiple antibiotic-resistant clinical isolates of Staphylococcus spp., with linezolid resistance in these strains being associated with mutations in 23S rRNA or ribosomal proteins L3 and L4.

HIV-1 early and late diagnosis in the Emilia Romagna Region (Italy): a three year study

It is crucial to establish the timing of infection and distinguish between early and long-lasting HIV-1 infections not only for partner notification and epidemiological surveillance, but also to offer early drug treatment and contain the spread of infection. This study analyzed serum and/or plasma samples with a first positive HIV antibody/antigen result coming from different Medical Centers in the Emilia Romagna Region, North East Italy, using the avidity assay, Western Blotting, RNA viral load, CD4 cell counts and genotyping assay. From May 2013 to May 2016, we certified 845 new HIV-1 infections, 18.7% of which were classified on the basis of avidity index as recent infections and 81.3% as long-lasting infections, with an estimated conversion time exceeding six months at the time of study. Western Blotting showed reactivity to only one or two HIV-1 proteins in recently infected patients (RIPs), while a complete pattern to gag, env and pol proteins was observed in most long-lasting infected patients (LLIPs). The median age, gender, nationality and risk transmission factors were comparable in RIPs and LLIPs. Phylogenetic analysis performed in available plasma disclosed B strains, non-B subtypes and circulating recombinant forms (CRFs) in both groups of patients, with a major presence of CRFs in non-Italian HIV subjects. The large number of patients unaware of their HIV status makes it crucial to discover hidden epidemics and implement appropriate targeted public health interventions.

Evaluation of an antibody avidity index method for detecting recent human immunodeficiency virus type 1 infection using an automated chemiluminescence immunoassay

BACKGROUND

Recent infection testing algorithms (RITAs) are used in public health surveillance to estimate the incidence of recently acquired HIV-1 infection.

OBJECTIVES

Our aims were (i) to evaluate the precision of the VITROS® Anti-HIV 1+2 automated antibody avidity assay for qualitative detection of antibodies to HIV 1+2 virus; (ii) to validate the accuracy of an automated guanidine-based antibody avidity assay to discriminate between recent and long standing infections using the VITROS 3600 platform; (iii) to compare this method with BED-CEIA assay; and (iv) to evaluate the occurrence of false recent misclassifications by the VITROS antibody avidity assay in patients with a CD4 count <200 cells/μL and in patients on combination antiretroviral therapy (cART).

RESULTS

The VITROS® antibody avidity assay is highly reproducible. The ROC curve analysis of the accuracy of this assay, optimized for sensitivity and specificity, had an AI cut off of ≤0.51, with sensitivity and specificity values of 86.67% (95% CI: 72.51-94.46) and 86.24% (95% CI: 78.00-91.84), respectively. The agreement between VITROS antibody avidity and BED-CEIA assays was good. Misclassifications of long standing infections as recent infection occurred in 8.2% of patients with CD4 <200 cell/μL and 8.7% in patients on combination antiretroviral therapy.

CONCLUSIONS

The VITROS antibody avidity assay is a reliable serological method to detect recent HIV-1 infections and it could be incorporated into a RITA to estimate HIV incidence.