Characterization of acute HIV-1 infection in high-risk Nigerian populations

Differences in neutralizing antibody sensitivities and envelope characteristics indicate distinct antigenic properties of Nigerian HIV-1 subtype G and CRF02_AG

The magnitude of the HIV-1 epidemic in Nigeria is second only to the subtype C epidemic in South Africa, yet the subtypes prevalent in Nigeria require further characterization. A panel of 50 subtype G and 18 CRF02_AG Nigerian HIV-1 pseudoviruses (PSV) was developed and envelope coreceptor usage, neutralization sensitivity and cross-clade reactivity were characterized. These PSV were neutralized by some antibodies targeting major neutralizing determinants, but potentially important differences were observed in specific sensitivities (eg. to sCD4, MPER and V2/V3 monoclonal antibodies), as well as in properties such as variable loop lengths, number of potential N-linked glycans and charge, demonstrating distinct antigenic characteristics of CRF02_AG and subtype G. There was preferential neutralization of the matched CRF/subtype when PSV from subtype G or CRF02_AG were tested using pooled plasma. These novel Nigerian PSV will be useful to study HIV-1 CRF- or subtype-specific humoral immune responses for subtype G and CRF02_AG.

Characterization of a novel HIV-1 circulating recombinant form, CRF91_cpx, comprising CRF02_AG, G, J, and U, mostly among men who have sex with men

Prospective molecular studies of HIV-1 pol region (2253-5250 in HXB2 genome) sequences from sequenced samples of 269 HIV-1-infected patients in Cyprus (2017-2021) revealed a transmission cluster of 14 unknown HIV-1 recombinants that were not classified as previously established CRFs. The earliest recombinant was collected in September 2017, and the transmission cluster continued to grow until November 2020. Near full-length HIV-1 genome sequences of the 11 of the 14 recombinants were successfully obtained (790-8795 in HXB2 genome) and aligned against a reference dataset of HIV-1 subtypes and CRFs. We employed MEGAX for maximum-likelihood tree construction (GTR model, 1000 bootstrap replicates), Cluster-Picker for phylogenetic clustering analysis (genetic distance ≤0.045, bootstrap support value ≥70%), and REGA-3.0 for subtype determination. Bootscan and similarity plot analyses (sliding window of 400 nucleotides overlapped by 40 nucleotides) were conducted using SimPlot-v3.5.1, and subregion confirmatory neighbour-joining tree analyses were conducted using MEGAX (Kimura two-parameter model, 1000 bootstrap replicates, ≥70% bootstrap-support value). Exclusive clustering of the HIV-1 recombinants revealed their uniqueness. The recombination analyses illustrated the same unique mosaic pattern with six putative intersubtype recombination breakpoints, seven fragments of subtypes CRF02_AG, G, J and an unclassified fragment. We conclusively characterized the mosaic structure of the novel HIV-1 CRF, named CRF91_cpx, by the Los Alamos HIV Sequence Database. Additionally, we identified a URF of CRF91_cpx with two additional recombination sites, generated by a recombination event between subtype B and CRF91_cpx. Since the identification of CRF91_cpx, two additional patient samples have been entered into the CRF91_cpx transmission cluster, demonstrating active growth.

HIV-1 drug resistance and genetic diversity in a cohort of people with HIV-1 in Nigeria

OBJECTIVE

This study was designed to provide information on the genetic diversity of HIV-1 and drug resistance mutations in Nigeria, as there is limited understanding of variants circulating in the country.

METHODS

We used an advanced next-generation sequencing platform, Primer ID, to: investigate the presence of high and low abundance drug resistance mutations; characterize preexisting Integrase Strand Transfer Inhibitor (INSTI) mutations in antiretroviral therapy (ART)-experienced but dolutegravir-naive individuals; detect recent HIV-1 infections and characterize subtype diversity from a cohort of people with HIV-1 (PWH).

RESULTS

HIV-1 subtype analysis revealed the predominance of CRF02_AG and subtype G in our study population. At detection sensitivity of 30% abundance, drug resistance mutations (DRMs) were identified in 3% of samples. At a sensitivity level of 10%, DRMs were identified in 27.3% of samples. We did not detect any major INSTI mutation associated with dolutegravir-resistance. Only one recent infection was detected in our study population.

CONCLUSION

Our study suggests that dolutegravir-containing antiretroviral regimens will be effective in Nigeria. Our study also further emphasizes the high genetic diversity of HIV-1 in Nigeria and that CRF02_AG and subtype G are the dominant circulating forms of HIV-1 in Nigeria. These two circulating forms of the virus are largely driving the epidemic in the country.

New infections and HIV-1 subtypes among febrile persons and blood donors in Oyo State, Nigeria

PURPOSE

There were approximately 37.9 million persons infected with HIV in 2018 globally, resulting in 770,000 deaths annually. Over 50% of this infection and deaths occur in sub-Saharan Africa, with countries like Nigeria being seriously affected. Nigeria has one of the highest rates of new infections globally. To control HIV infection in Nigeria, there is a need to continually screen high-risk groups for early HIV infection and subtypes using very sensitive methods. In this study, new HIV-1 infection and circulating HIV-1 subtypes among febrile persons and blood donors were determined. Performance characteristics of three commercial EIA kits were also evaluated.

METHODS

In total, 1028 participants were recruited for the study. New HIV-1 infection and subtypes were determined using enzyme immunoassays and molecular techniques, respectively. Sensitivity, specificity, predictive values, and agreements were compared among the EIA kits using PCR-confirmed HIV-positive and negative samples.

RESULTS

The overall prevalence of HIV infection in this study was 5.35%. The rate of new HIV infection was significantly different (p < .03674) among 1028 febrile persons (Ibadan: 2.22%; Saki: 1.36%) and blood donors (5.07%) studied. Three subtypes, CRF02_AG, A, and G, were found among those with new HIV infection. Whereas the commercial ELISA kits had very high specificities (94.12%, 100%, and 100%) for HIV-1 detection, Alere Determine HIV-1 antibody rapid kit had the lowest sensitivity score (50%).

CONCLUSION

Genetic diversity of HIV-1 strains among infected individuals in Oyo State, Nigeria, is still relatively high. This high level of diversity of HIV-1 strains may impact the reliability of diagnosis of the virus in Nigeria and other African countries where many of the virus strains co-circulate.

New Subtype B Containing HIV-1 Circulating Recombinant of sub-Saharan Africa Origin in Nigerian Men Who Have Sex With Men

BACKGROUND

HIV-1 circulating recombinant forms (CRF) containing subtype B are uncommon in sub-Saharan Africa. Prevalent infections observed during enrollment of a prospective study of men who have sex with men (MSM) from Lagos, Nigeria, revealed the presence of a family of subtype B and CRF02_AG recombinants. This report describes the HIV-1 genetic diversity within a high-risk, high-prevalence, and previously undersampled cohort of Nigerian MSM.

METHODS

Between 2013 and 2016, 672 MSM were enrolled at the Lagos site of the TRUST/RV368 study. Prevalent HIV-1 infections were initially characterized by pol sequencing and phylogenetic subtyping analysis. Samples demonstrating the presence of subtype B were further characterized by near full-length sequencing, phylogenetic, and Bayesian analyses.

RESULTS

Within this cohort, HIV-1 prevalence was 59%. The major subtype was CRF02_AG (57%), followed by CRF02/B recombinants (15%), subtype G (13%), and smaller amounts of A1, B, and other recombinants. Nine clusters of closely related pol sequences indicate ongoing transmission events within this cohort. Among the CRF02_AG/B, a new CRF was identified and termed CRF95_02B. Shared risk factors and Bayesian phylogenetic inference of the new CRF95_02B and the similarly structured CRF56_cpx indicate a Nigerian or West African origin of CRF56_cpx before its observation in France.

CONCLUSION

With high HIV-1 prevalence, new strains, and multiple transmission networks, this cohort of Nigerian MSM represents a previously hidden reservoir of HIV-1 strains, including the newly identified CRF95_02B and closely related CRF56_cpx. These strains will need to be considered during vaccine selection and development to optimize the design of a globally effective HIV-1 vaccine.

Characterisation of HIV-1 Molecular Epidemiology in Nigeria: Origin, Diversity, Demography and Geographic Spread

Nigeria has the highest number of AIDS-related deaths in the world. In this study, we characterised the HIV-1 molecular epidemiology by analysing 1442 HIV-1 pol sequences collected 1999-2014 from four geopolitical zones in Nigeria using state-of-the-art maximum-likelihood and Bayesian phylogenetic analyses. The main circulating forms were the circulating recombinant form (CRF) 02_AG (44% of the analysed sequences), CRF43_02G (16%), and subtype G (8%). Twenty-three percent of the sequences represented unique recombinant forms (URFs), whereof 37 (11%) could be grouped into seven potentially novel CRFs. Bayesian phylodynamic analysis suggested that five major Nigerian HIV-1 sub-epidemics were introduced in the 1960s and 1970s, close to the Nigerian Civil War. The analysis also indicated that the number of effective infections decreased in Nigeria after the introduction of free antiretroviral treatment in 2006. Finally, Bayesian phylogeographic analysis suggested gravity-like dynamics in which virus lineages first emerge and expand within large urban centers such as Abuja and Lagos, before migrating towards smaller rural areas. This study provides novel insight into the Nigerian HIV-1 epidemic and may have implications for future HIV-1 prevention strategies in Nigeria and other severely affected countries.

Cognitive Function Among Antiretroviral Treatment-Naive Individuals Infected With Human Immunodeficiency Virus Type 1 Subtype G Versus CRF02_AG in Nigeria

Background

Human immunodeficiency virus type 1 (HIV-1) subtype has been shown to be associated with disease progression. We compared cognitive function between individuals infected with HIV-1 subtype G and CRF02_AG in Nigeria.

Methods

For this cross-sectional study, samples were analyzed from 146 antiretroviral-naive participants. Genotypic analysis of plasma HIV RNA was performed by nested polymerase chain reaction of protease and reverse transcriptase genes, and sequences were aligned with curated HIV-1 subtype references. Cognitive status was determined using demographically adjusted T scores and global deficit score (GDS) obtained from a comprehensive neuropsychological test battery.

Results

A total of 76 (52.1%) participants were infected with CRF02_AG, 48 (32.8%) with subtype G, and 22 (15.1%) with other HIV-1 strains. In a multivariable linear regression adjusting for plasma HIV RNA, CD4 count, and depression score, mean global T score was lower among subtype G-infected compared with CRF02_AG-infected participants (mean difference, -3.0 [95% confidence interval {CI}, -5.2, to -.7]; P = .011). Also, T scores were significantly lower among subtype G- than CRF02_AG-infected participants for the speed of information processing, executive function, and verbal fluency ability domains. Adjusting for similar variables in a logistic regression, the odds of global cognitive impairment (GDS ≥0.5) were 2.2 times higher among subtype G compared with CRF02_AG-infected participants (odds ratio, 2.2 [95% CI, .9-5.4]; P = .078).

Conclusions

Cognitive performance was significantly worse among antiretroviral-naive individuals with HIV-1 subtype G vs CRF02_AG infection. Further studies are required to characterize the mechanistic basis for these differences.

Early HIV infection among persons referred for malaria parasite testing in Nigeria

Persons in the early stages of HIV infection are the major drivers of new infections. These individuals may also develop renal dysfunctions at this time. Nigeria, as other African countries, has one of the highest prevalence of newly diagnosed HIV infections. Despite this, limited information exists on early HIV detection in the continent. This may be related to difficulties in providing early HIV diagnosis and treatment. Patients referred for malaria testing may provide a unique opportunity for early HIV detection. In this study, a method for identifying early HIV-infected individuals was assessed. HIV-1 subtype and renal function biomarkers were also analyzed in these persons. To identify early HIV infection, over a period of 18 months blood samples were collected from persons referred by clinicians for malaria parasite tests in Nigeria. A total of 671 samples were collected and analyzed for HIV antigen/antibody and subtypes. 101 of these samples were categorized into one of four groups: early HIV, chronic HIV, malaria infection and control groups for renal function analysis. 29% of HIV infected individuals were at the early stages of infection. The predominant subtype detected was CRF02_AG (57.14%). The early HIV group had the highest mean serum creatinine (95 µmol/L) and urea (5.7 mmol/L) values across all groups with the difference significant at P < 0.05. There was no significant difference between the circulating subtype and the stage of HIV infection. Our results show the feasibility of screening persons referred for malaria tests for early HIV. This can be used to control new HIV infections in sub-Saharan Africa.

Discordant rapid HIV tests: lessons from a low-resource community

OBJECTIVES

HIV rapid antibody tests are widely used in Africa, but dual testing sometimes produces discordant results. It is not clear if discordant rapid HIV tests should always heighten suspicion by frontline health workers that early HIV infection is present. Some studies have reported that discordant rapid tests have value for identifying early HIV infection in high HIV prevalence populations. It is not known if rapid test performance influenced this conclusion, or if this observation will hold true for low HIV prevalence populations. We therefore explored the occurrence of discordant rapid HIV tests in a low-resource community.

METHODS

A cross-sectional sample of HIV status-unaware adults with recent exposure to unsafe sex was assessed using a validated risk-based tool (University of North Carolina (UNC)-Malawi Risk Screening Score) for acute HIV infection. Participants received rapid testing with Determine™ HIV 1/2 and Uni-Gold™ HIV assays, plus plasma HIV-1 antigen testing with the COBAS^® Ampliprep/COBAS^® Taqman^® HIV-1 assay, followed by western blot in those with detected HIV-1 antigen.

RESULTS

Of 408 participants, 1.0% were confirmed to have established HIV infection. The discordance between rapid tests at initial screening was 2.45 and 2.94% when the two assays were used sequentially and simultaneously, respectively. Discordant rapid tests were strongly associated with risk scores > 2 [odds ratio (OR) 10.88; 95% confidence interval (CI) 2.35-50.43], and with detected HIV-1 RNA (OR 26.06; 95% CI 3.91-173.60).

CONCLUSIONS

When the sample occurrence of discordance between the first and second tests is below 5%, discordant rapid tests in an adult with sexual risk behaviour should trigger strong suspicion of early HIV infection in low HIV prevalence populations.

An Evaluation of Selected Populations for HIV-1 Vaccine Cohort Development in Nigeria

Development of a globally effective HIV-1 vaccine will need to encompass Nigeria, one of the hardest hit areas, with an estimated 3.2 million people living with HIV. This cross-sectional Institutional Review Board (IRB) approved study was conducted in 2009-12 at four market sites and two highway settlements sites in Nigeria to identify and characterize populations at high risk for HIV; engage support of local stakeholders; and assess the level of interest in future vaccine studies. Demographic, HIV risk data were collected by structured interviewer-administered questionnaires. Blood samples were tested on site by HIV rapid diagnostic tests, followed by rigorous confirmatory testing, subtype evaluation and testing for HBV and HCV markers in a clinical reference laboratory. Of 3229 study participants, 326 were HIV infected as confirmed by Western Blot or RNA, with a HIV prevalence of 15.4%-23.9% at highway settlements and 3.1%-9.1% at market sites. There was no observable correlation of prevalence of HIV-1 (10.1%) with HBV (10.9%) or HCV (2.9%). Major HIV-1 subtypes included CRF02_AG (37.5%); G (27.5%); G/CRF02_AG (25.9%); and non-typeable (8.9%), with 0.3% HIV-2. Univariate analysis found age, gender, marital status, level of education, and sex under substance influence as significant risk factors for HIV (p<0.001). Educating and winning the trust of local community leadership ensured high level of participation (53.3-77.9%) and willingness to participate in future studies (95%). The high HIV prevalence and high risk of HIV infection at highway settlement and mammy markets make them well suited for targeting future vaccine trials in Nigeria.

Significant contribution of subtype G to HIV-1 genetic complexity in Nigeria identified by a newly developed subtyping assay specific for subtype G and CRF02_AG

While abundant sequence information is available from human immunodeficiency virus type 1 (HIV-1) subtypes A, B, C and CRF01_AE for HIV-1 vaccine design, sequences from West Africa are less represented. We sought to augment our understanding of HIV-1 variants circulating in 6 Nigerian cities as a step to subsequent HIV-1 vaccine development.The G/CRF02_AG multi-region hybridization assay (MHA) was developed to differentiate subtype G, CRF02_AG and their recombinants from other subtypes based on 7 HIV-1 segments. Plasma from 224 HIV-1 infected volunteers enrolled in a cohort examining HIV-1 prevalence, risk factor, and subtype from Makurdi (30), Abuja (18), Enugu (11), Kaduna (12), Tafa (95), and Ojo/Lagos (58) was analyzed using MHA. HIV-1 genomes from 42 samples were sequenced to validate the MHA and fully explore the recombinant structure of G and CRF02_AG variants.The sensitivity and specificity of MHA varied between 73-100% and 90-100%, respectively. The subtype distribution as identified by MHA among 224 samples revealed 38% CRF02_AG, 28% G, and 26% G/CRF02_AG recombinants while 8% remained nontypeable strains. In envelope (env) gp120, 38.84% of the samples reacted to a G probe while 31.25% reacted to a CRF02 (subtype A) probe. Full genome characterization of 42 sequences revealed the complexity of Nigerian HIV-1 variants.CRF02_AG, subtype G, and their recombinants were the major circulating HIV-1 variants in 6 Nigerian cities. High proportions of samples reacted to a G probe in env gp120 confirms that subtype G infections are abundant and should be considered in strategies for global HIV-1 vaccine development.

Sensitivity of HIV rapid tests compared with fourth-generation enzyme immunoassays or HIV RNA tests

OBJECTIVE

Determine the sensitivity of HIV rapid tests compared with fourth-generation enzyme immunoassays (EIA) or nucleic acid amplification tests (NAAT) in clinical settings.

DESIGN

Systematic review and meta-analysis.

METHODS

Medline, PubMed, Embase, Cochrane Controlled Trials Register, Cochrane reviews and Cumulative Index to Nursing and Allied Health Literature were searched until 14 July 2015 for studies of adults comparing point-of-care HIV rapid tests to fourth-generation HIV EIA antibody/p24 antigen or HIV NAAT.

RESULTS

From 953 titles, 18 studies were included, involving 110 122 HIV rapid test results. Compared with EIA, the estimated sensitivity (random effects) of HIV rapid tests was 94.5% [95% confidence interval (CI): 87.4-97.7]. Compared with NAAT, the sensitivity of HIV rapid tests was 93.7% (95% CI: 88.7-96.5). The sensitivity of HIV rapid tests in high-income countries was 85.7% (95% CI: 81.9-88.9) and in low-income countries was 97.7% (95% CI: 95.2-98.9) compared with either EIA or NAAT (P < 0.01 for difference between settings). Proportions of antibody negative acute infections were 13.6 (95% CI: 10.1-18.0) and 4.7% (95% CI: 2.8-7.7) in studies from high-income and low-income countries, respectively (P < 0.01).

CONCLUSION

In clinical settings, HIV rapid tests were less sensitive in high-income countries compared with low-income countries, missing about one in seven infections, possibly because of the larger proportion of acute infections in targeted populations. This suggests that in high-income countries, HIV rapid tests should be used in combination with fourth-generation EIA or NAAT tests, except in special circumstances. Prospective Registration of Systematic Reviews registration number CRD42015020154.Supplementary video link: http://links.lww.com/QAD/A924.

λ Light Chain Bias Associated With Enhanced Binding and Function of Anti-HIV Env Glycoprotein Antibodies

The humoral response to human immunodeficiency virus (HIV) remains incompletely understood. In this report, we describe biased λ light chain use during the HIV Env glycoprotein (Env) response in HIV infection and vaccination. We examined HIV Env binding (and neutralization) in the context of light chain use in subjects with acute HIV infection, chronic HIV infection, and among HIV vaccinees. In all populations tested, there was a λ chain bias for HIV Env binding antibodies, compared with other HIV antigens (such as p24) or tetanus toxoid. In subjects with chronic HIV infection, a λ bias was noted for neutralization, with λ antibodies accounting for up to 90% of all neutralization activity observed. This is the first report of antibody function in a human infection being tied to light chain use. In HIV infection, antibodies expressing λ light chains tended to have longer CDRL3s, increased light chain contact with HIV Env, and less hypermutation in the heavy chain, compared with antibodies using the κ light chain. These data also support an evolutionary model for the understanding the various κ to λ light chain ratios observed across species and suggest that the λ light chain bias against HIV provides the host an advantage in developing a more efficient humoral response.

Evaluation of nine HIV rapid test kits to develop a national HIV testing algorithm in Nigeria

Background: Non-cold chain-dependent HIV rapid testing has been adopted in many resource-constrained nations as a strategy for reaching out to populations. HIV rapid test kits (RTKs) have the advantage of ease of use, low operational cost and short turnaround times. Before 2005, different RTKs had been used in Nigeria without formal evaluation. Between 2005 and 2007, a study was conducted to formally evaluate a number of RTKs and construct HIV testing algorithms. Objectives: The objectives of this study were to assess and select HIV RTKs and develop national testing algorithms. Method: Nine RTKs were evaluated using 528 well-characterised plasma samples. These comprised 198 HIV-positive specimens (37.5%) and 330 HIV-negative specimens (62.5%), collected nationally. Sensitivity and specificity were calculated with 95% confidence intervals for all nine RTKs singly and for serial and parallel combinations of six RTKs; and relative costs were estimated. Results: Six of the nine RTKs met the selection criteria, including minimum sensitivity and specificity (both ≥ 99.0%) requirements. There were no significant differences in sensitivities or specificities of RTKs in the serial and parallel algorithms, but the cost of RTKs in parallel algorithms was twice that in serial algorithms. Consequently, three serial algorithms, comprising four test kits (BundiTM, DetermineTM, Stat-Pak® and Uni-GoldTM) with 100.0% sensitivity and 99.1% - 100.0% specificity, were recommended and adopted as national interim testing algorithms in 2007. Conclusion: This evaluation provides the first evidence for reliable combinations of RTKs for HIV testing in Nigeria. However, these RTKs need further evaluation in the field (Phase II) to re-validate their performance.

Longitudinal analysis of HIV-1-specific antibody responses

Laboratory assays for determining recent HIV-1 infection are of great public health importance for aiding in the estimation of HIV incidence. Concerns have been raised about the potential for misclassification with serology-based assays due to fluctuations in the antibody response, particularly following progression to AIDS. We characterized longitudinal antibody responses to HIV using a cohort of men who have sex with men (MSM) sampled for up to 17 years, in which 57% of the 65 study subjects included in the current analyses progressed to AIDS during the study period. Envelope-specific total IgG antibody levels, avidity, and p24-specific IgG3 levels were evaluated using a multiplexed Bio-Plex assay. For the majority of the analytes, no significant difference in IgG reactivity was observed between AIDS and non-AIDS specimens. Although a slight decline in gp120 reactivity was noted with decreasing CD4(+) T cell count, the drop in assay values was relatively minimal and would likely not lead to an increase in the misclassification rate of the assay. A peak in HIV-1 p24 IgG3 levels was observed during early infection, as confirmed by testing 1,216 specimens from 342 recent seroconverters with the Bio-Plex assay. As expected, IgG3 reactivity declined with disease progression and decreasing CD4(+) T cell count in the MSM cohort; however, 37% of the study subjects exhibited relatively high IgG3 levels late in the course of infection.

Comparison of HIV oral fluid and plasma antibody results during early infection in a longitudinal Nigerian cohort

BACKGROUND

Oral fluid (OF) testing is a less-invasive alternative to blood-based testing for HIV. The performance of HIV OF tests has not been extensively evaluated in serially collected paired specimens from seroconverters.

OBJECTIVE

To compare paired OF and plasma test performance in a cohort of HIV-1 seroconverters from Nigeria.

STUDY DESIGN

Paired plasma and OF specimens from 14 seroconverters collected during 24 months of longitudinal follow up were included in the study. Plasma and OF were tested using Avioq HIV-1 Microelisa System, and first reactivity in plasma and OF specimens was compared. OF specimens reactive by Avioq were subsequently tested by OraSure HIV-1 Western blot. Genetic Systems HIV-1 Western blot was also performed on the corresponding plasma of the first 2 Avioq-OF positive time-points.

RESULTS

Of the 14 seroconverters, 5 (35.7%) had concordant results between plasma and OF for all time points tested, whereas 9 (64.3%) showed reactivity on plasma before OF specimens early in infection. The median delay between plasma and OF reactivity was 29 days (range: 0 day-20 months) (p<0.0039); the median overall delay for OF compared to RNA testing was 69.5 days. Delayed antibody response with OF was observed in both males and females regardless of viral load or HIV subtypes.

CONCLUSIONS

Results demonstrate decreased sensitivity of OF testing compared to blood-based testing with specimens obtained early after HIV infection. Programs that utilize OF testing in populations with increased risk of incident HIV infection should understand these limitations of OF testing.

Evaluation of a multiplex assay for estimation of HIV-1 incidence

Objectives

Accurate methods of estimating HIV-1 incidence are critical for monitoring the status of the epidemic and the impact of prevention strategies. Although several laboratory-based tests have been developed strictly for this purpose, several limitations exist and improved methods or technologies are needed. We sought to further optimize a previously described bead-based, HIV-1-specific multiplex assay with the capability of measuring multiple immune responses for determining recent infection.

Methods

We refined the customized HIV-1 Bio-Plex assay by determining cutoffs and mean durations of recency (MDR), based on the reactivity to longitudinal seroconversion specimens (n = 1347) from 311 ART-naïve, HIV-1-infected subjects. False-recent rates (FRRs) were calculated for various long-term cohorts, including AIDS patients, individuals on ART, and subtype C specimens. Incidence was estimated for each individual assay analyte from a simulated population with a known incidence of 1%. For improved incidence estimates, multi-analyte algorithms based on combinations of 3 to 6 analytes were evaluated and compared to the performance of each individual analyte.

Results

The MDR for the six analytes varied from 164.2 to 279.4 days, while the multi-analyte algorithm MDRs were less variable with a minimum and maximum value of 228.4 and 277.9 days, respectively. The FRRs for the 7 multi-analyte algorithms evaluated in this study varied from 0.3% to 3.1%, in a population of ART-naïve, long-term individuals. All algorithms yielded improved incidence estimates as compared to the individual analytes, predicting an incidence of 0.95% to 1.02%.

Conclusions

The HIV-specific multiplex assay described here measures several distinct immune responses in a single assay, allowing for the consideration of multi-analyte algorithms for improved HIV incidence estimates.

May viral (antigen) load be the real crucial tool leading to anergy in a "micro-evolutionary" model of host/virus interaction?

HYPOTHESIS

The hypothesis in the present work is that in host/virus/tumor (antigens) interactions, leading to anergy of the immune system, the Viral (antigen) load plays a crucial and central role, which all interactions turn around.

BACKGROUND

Notwithstanding apparent strong favorable evidences, the still prevailing concept of "active virus strategies to escape" may be misleading, since it might hide the cited pivotal role in a wide number of researches. This concept could be easily substituted by a microevolutionary model explaining many unresolved questions and allowing to emerge the role of antigen load conditioned reactions of the host's immune system as motivated choices. EVIDENCES: An anergy induced condition can be detected not only in HCV, but also in the course of persistent viral (e.g. HBV, HIV) and non viral parasitic infections (e.g. Leishmania and Helminths) which share the same host's reactions leading to anergy, independently on the infecting agents. The starting point of those reactions is always time elapsing from the primary infection after a short early (often undetected) period of high viral(antigen) load in the lack of clearance. This latter seems then the only conceivable link between such so different infections determining, as far as HBV and HCV are concerned, also Hepatocarcinoma under indirect facilitating conditions. In a wide majority of studies it seems clearly evident that viral load exerts a main role which contributes to determine host chosen reactions aimed at avoiding dangerous outcomes while controlling viral load. Strong clinical (i.e. both HIV infected patients treated with HAART, and helminths infected people with deworming drugs acting directly on viral and parasitic loads) and experimental studies (i.e. chimpanzees (the only animal model of HCV infection) infected with HBV inocula of different size) are here reported or cited to highlight the crucial role of antigen load also on HIV infection transmission, seroconversion, disease progression, treatment initiation and efficacy.

CONCLUDING SUGGESTIONS

The new era for antiviral drugs like protease and polymerase inhibitors that seem to be more efficacious and less toxic than Ribavirin, may open the possibility to verify, when administered during the early phase of HCV infection (eventually helped by an immune-stimulant cytokine as IL-2), whether a precocious significant reduction of viral load (threshold) may allow the host to sustain his strong reactions and clear the virus within the due time, confirming the hypothesis about the crucial role of this tool which may be extended to all the cited infections.