Estimating HIV incidence in the Akwa Ibom AIDS indicator survey (AKAIS), Nigeria using the limiting antigen avidity recency assay

IntroductionHIV incidence estimates are important to characterize the status of an epidemic, identify locations and populations at high risk and to guide and evaluate HIV prevention interventions. We used the limiting antigen avidity assay (LAg) as part of a recent infection testing algorithm to estimate HIV incidence in the Akwa Ibom AIDS Indicator Survey (AKAIS), Nigeria.MethodsIn 2017, AKAIS, a cross‐sectional population‐based study was conducted at the household (HH) level in 31 local government areas (LGAs) of Akwa Ibom state. Of the 8963 participants aged ≥15 years who were administered questionnaires for demographic and behavioural data, 8306 consented to HIV rapid testing. Whole‐blood specimens were collected from 394 preliminary HIV‐seropositive individuals for CD4+ cell count determination and plasma storage. Samples were shipped to a central quality laboratory for HIV confirmatory testing and viral load determination. A total of 370 HIV‐positive specimens were tested for the recent HIV infection using the LAg assay.ResultsOf the 8306 consenting adults, the HIV prevalence was 4.8%. Of the 370 HIV‐positive samples tested for HIV recency, the median age was 35 years, 48.8% had CD4+ cell count >500/mm³ and 81.3% was not virally suppressed. Viral suppression was greater among females (21%) than for males (13%). A total of 11 specimens were classified as recent based on the LAg assay and HIV viral load ≥1000 copies/mL. The weighted, adjusted HIV‐1 incidence was 0.41/100 person‐years (95% CI 0.16 to 0.66); translating to 13,000 new cases of HIV infections annually in Akwa Ibom, a state with a population of 5.5 million. The HIV incidence rate was similar in females and males (0.41% and 0.42% respectively). The incidence rate was the highest among participants aged 15 to 49 years (0.44%, 95% CI 0.15 to 0.74) translating to 11,000 new infections annually, about 85% of all new infections in the state.ConclusionsThe finding of the high HIV incidence among the 15 to 49‐year age group calls for renewed and innovative efforts to prevent HIV infection among young adults in Akwa Ibom state.     

Humoral and cellular immune response to tick-borne-encephalitis (TBE) vaccination depends on booster doses in patients with Juvenile Idiopathic Arthritis (JIA)

Juvenile Idiopathic Arthritis (JIA) patients living in areas with high prevalence of tick-borne-encephalitis-virus-(TBEV)-infection are recommended for administration of inactivated TBE-vaccination. However, there are serious concerns regarding protective vaccine-induced immune responses against TBEV in immunocompromised patients.The present study aimed to analyze the humoral and cellular immune response to TBE-vaccination in previously TBE-vaccinated JIA patients compared to healthy controls (HC) including investigation of IgG-anti-TBEV avidity, neutralization capacity, cellular reactivity by IFNgamma-ELISPOT and cytokine secretion assays.Similar IgG-anti-TBEV antibody concentrations, neutralization titers and cellular reactivity were found between JIA and HC. The number and the early timing of booster vaccinations after primary vaccination had the most prominent effect on neutralizing antibodies in JIA and on IgG-anti-TBEV concentrations in both JIA and HC. Administration of booster vaccinations made it more likely for JIA patients to have IgG-anti-TBEV concentrations ≥165 VIEU/ml and avidities >60%. TNF-alpha inhibitors had a positive and MTX administration a negative effect on humoral immune responses.In conclusion, irrespective of having JIA or not, vaccinated children showed similar humoral and cellular immunity against TBEV several years after primary TBE-vaccination. However, in JIA, booster vaccinations mounted a significantly higher humoral immune response than in JIA without boosters. Our results highlight the need for timely administration of boosters particularly in JIA. Although immunosuppressive treatment at vaccinations in diagnosed JIA had a negative effect mainly on TBEV-specific cellular immunity, most JIA patients mounted a favorable humoral immune response which was maintained over time. Thus, successful TBE-vaccination seems highly feasible in JIA patients with immunosuppressive regimens.     

Prognostic markers in well differentiated papillary and follicular thyroid cancer (WDTC)

Objectives

WDTC (papillary and follicular thyroid cancer) make up around 90% of all thyroid tumours. Overall, the prognosis in patients with WDTC is excellent. However, there are small cohorts of patients who experience a more aggressive form of disease which is often associated with certain poor prognostic factors. Identifying these patients at an early stage is imperative for guiding treatment decisions. With recent developments in this area we plan to discuss the current evidence surrounding prognostic markers.

Evaluating the population measles susceptibility in Tianjin,China

BackgroundMeasles is a highly infectious illness requiring herd immunity of 95% to interrupt transmission. China has not reached elimination goals despite high vaccination coverage. We estimated the population susceptibility against measles in Tianjin, China and to tailor awareness raising activities in the measles elimination plan.MethodsAge-specific measles seroprevalence was evaluated by Enzyme-Linked Immunosorbent Assay (ELISA) on 12,164 individual aged 0–44 years in 2009–2018. Measles IgG avidity testing was performed to confirm the relationship of the waning immunity after vaccination and secondary vaccination failures (SVF) on 324 confirmed measles cases in 2013–2018.Results11,108 samples (91.32%) tested positive for measles IgG, 239 (1.96%) tested as equivocal and 817 (6.72%) were negative. The age distribution of measles cases in Tianjin followed a U-shaped curve and was highest for those at <8 months and again at 20–39 years which correlated closely with the age distribution of measles susceptibility based on measles IgG antibody status (r = 0.72, P < 0.001). The seropositivity rate and antibody geometric mean concentration (GMC) for the 2018 study population were significantly lower (χ² = 7.45, P = 0.006 and t = 12.01, P < 0.001) compared to 2009. The multivariate stepwise logistic regression analysis showed that age and region were the risk factors for both measles seropositivity rate and GMC after vaccination. The proportion of high avidity cases increased with age, being significantly higher in 75.31% of cases in patients aged 30–34 years (χ² = 18.04, P = 0.003).ConclusionsHigh immunization coverage in children alone will not be adequate to realizing sufficient levels of population herd immunity, particularly given that the potential susceptibility window in adult. Implementation of supplemental immunization activity (SIA) targeted to appropriate group aged 30–34 years is recommended.     

风疹病毒特异性IgG抗体亲和力测定的临床意义

目的区分风疹病毒原发性感染、继发性感染的病毒活化或再感染。方法对12 y以下患儿的风疹病毒IgG抗体(RV-IgG)阳性血清,采用尿素变性酶联免疫吸附实验(ELISA法)测定RV-IgG抗体亲和力指数(AI)。结果1~12 y的患儿中,只有4.8%(3/63)的病例有低亲和力抗体(AI<30%)。1 y以内患儿中高达56.2%(18/32)的病例有低亲和力抗体,明显高于1~12 y患儿。1 y以内患儿中,1~3 mo和4~6 mo患儿低亲和力抗体比例低(分别为36.4%和44.4%),而7~12mo患儿有83.3%为低亲和力抗体。结论RV的早期感染大都发生在1y以内。IgG抗体亲和力测定是鉴别初次感染和体内病毒活化及再感染的有效方法。     

轻链替换提高抗HBsAg噬菌体抗体的结合力

通过轻链替换,提高抗ＨＢＳＡｄｅ菌体抗体的结合力。方法将ＰＣＲ扩增的人抗体轻链基因,插至已克隆有人源抗乙肝表面抗原（ＨＢｓＡｇ）抗体重链Ｆｄ基因的噬菌粒中,构建成轻链替换文库,通过亲和淘洗,筛选与Ｆｄ相匹配的轻链基因。结果经亲和淘洗后,筛选出了与Ｆｄ相匹配的轻链基因,链替换后,噬菌体抗体（ＰｈＡｂ）的ＥＬＩＳＡ光吸收值（Ａ）从０．４３±０．０９提高到最高为１．２４±０．１０。抑制实验证实所筛选出来的ｎｈａｂ具有抗ＨＢｓＡｚ的特异性。分析了ＥＬＩＳＡ光吸收值（Ａ）最高的５株噬菌体抗体的轻链基因序列,结果表明,３株ｋ链的碱基序列一致,属ＶｋⅢ亚群;２株链的基因序列相同,均属ＶＩ亚群。结论结果表明经链替换的噬菌体抗体结合力得到了较大提高,并具有与ＨＢｓＡｇ合的特异性。     

An Optimized FI-RSV Vaccine Effectively Protects Cotton Rats and BALB/c Mice without Causing Enhanced Respiratory Disease

Background: Despite considerable efforts toward vaccine development in past decades, no effective vaccines against respiratory syncytial virus (RSV) are available. Recently, we showed that an optimized formalin concentration can preserve prefusion protein (pre-F) on RSV-infected cells and protect mice against RSV infection without causing enhanced respiratory disease (ERD). Here, we sought to further stabilize pre-F on RSV virions by optimizing the production of FI-RSV. Methods: Freshly produced RSV virions were treated with formalin under different concentrations to obtained an opti-FI-RSV vaccine with high pre-F level. Immunogenicity and safety of opti-FI-RSV were evaluated in Balb/c mice and cotton rats. Results: Using 0.0156–0.1778% formalin, we successfully preserved pre-F on virions. This opti-FI-RSV exhibited improved immunogenicity and efficacy without causing ERD. Surprisingly, opti-FI-RSV, with a pre-F-dominant immunogen, still caused ERD after immunization with a suboptimal dose or when the neutralizing antibody titers declined. ERD was avoided by coadministering opti-FI-RSV with CpG + MPLA adjuvant, which subsequently induced a Th1-biasing immune response and, more importantly, significantly improved antibody avidity. Conclusions: Our study provides a new method to obtain a novel FI-RSV vaccine with a high pre-F level and may provide a reference for developing other inactivated vaccines. Our findings also emphasize that appropriate adjuvants are critical for nonreplicating vaccines.     

The use of semi-automated EBV IgG avidity determination for the diagnosis of infectious mononucleosis

The diagnosis of acute Epstein-Barr virus (EBV) infection is based frequently on the combination of positive viral capsid antigen (VCA) IgM antibodies and negative EB viral nuclear antigen 1 (EBNA-1) IgG antibodies. However, both VCA IgM and EBNA-1 IgG can provide false positive and false negative results. Therefore, situations in which the EBV serology remains unclear are not uncommon. Determination of EBV IgG avidity can clarify the EBV status in these patients. So far, mainly immunofluorescence assays have been used for this purpose. These tests are laborious, their evaluation is subjective, and automation is difficult. Therefore, two commercially available microtiter plate enzyme immunoassays (EIA) were compared for their usefulness for semi-automated EBV IgG avidity determination. One assay is based on a mixture of EBV antigens, the other assay uses a synthetic peptide of the VCA-complex. Patient sera of confirmed acute and past EBV infections were tested for avidity by both assays. The results with the antigen mixture assay proved to be highly sensitive (100%) and specific (100%). Avidity index calculations on the basis of one-point-quantification titers gave better results than calculations using OD values. Determination of EBV IgG avidity by the peptide assay was complicated by the fact that it was less sensitive than the antigen mixture assay for IgG detection in acute EBV infections. On the other hand, about 30% of the samples had to be retested with the peptide assay in a higher dilution because the IgG units in initial testing fell outside the range covered by the standard curve. Using OD values of the peptide EIA, the sensitivity was 99% but the specificity of detection of acute EBV infections was only 86%. Thus, while the peptide EBV avidity assay is unsuitable as a confirmatory assay, avidity testing with the antigen mixture assay is a useful tool to resolve equivocal EBV serologies. Avidity assays on the basis of EIA can be automated which should lead to wider use of this methodology. J. Med. Virol. 54:145–153, 1998. © 1998 Wiley-Liss,Inc.     

Detection,phenotyping, and quantification of antigen-specific T cells using a peptide-MHC dodecamer

Here we report a peptide-MHC (pMHC) dodecamer as a “next generation” technology that is a significantly more sensitive and versatile alternative to pMHC tetramers for the detection, isolation, and phenotypic analysis of antigen-specific T cells. In particular, dodecamers are able to detect two- to fivefold more antigen-specific T cells in both human and murine CD4⁺ and CD8⁺ αβ T-cell compartments compared with the equivalent tetramers. The low-affinity, tetramer-negative, dodecamer-positive T cells showed comparable effector cytokine responses as those of high-affinity, tetramer-positive T cells. Dodecamers are able to detect early stage CD4⁺CD8⁺ double-positive thymocytes on which T-cell receptors are 10- to 30-fold less dense than mature T cells. Dodecamers also show utility in the analysis of γδ T cells and in cytometry by time-of-flight applications. This construct has a simple structure with a central scaffold protein linked to four streptavidin molecules, each having three pMHC ligands or other molecules. The dodecamer is straightforward and inexpensive to produce and is compatible with current tetramer technology and commercially available streptavidin conjugates.T-cell receptors (TCRs) detect antigens in the form of peptides bound to peptide-major histocompatibility complex (pMHC) molecules on the surface of antigen-presenting cells. TCR–pMHC interactions determine the selection, development, differentiation, fate, and function of a T cell. However, TCRs bind monomeric pMHCs with very low binding affinities (K_d, ∼1–200 μM, 1,000- to 200,000-fold weaker than a typical antibody–antigen interaction) and with fast dissociation rates (k_off, ∼0.05 s⁻¹) in solution (1). To increase the binding avidity and circumvent the problem of fast dissociation, we previously engineered a pMHC tetramer to detect antigen-specific T cells by conjugating four biotinylated pMHC monomers to a single fluorescent-labeled streptavidin (2). This fulfilled a critical need in both basic and clinical immunology to be able to identify and characterize often very rare specific T cells in a population. Subsequent improvements in sensitivity, manufacture, and combinatorial labeling have made this methodology even more useful (3–7). However, there is a sharp drop-off in tetramer binding in the lower affinity range (∼150 μM) (8) so there have been a number of higher valency alternatives including pentamers (ProImmune), lipid vesicles (9), octamers (10), dextramers (11), and quantum dot (QD)-based multimers (12). Some of these clearly have improved sensitivity, and this is important in detecting T cells with especially low affinities (13, 14). For example, naive T cells and thymocytes, which express low-level and/or low-affinity TCRs, show little-to-no tetramer staining. Furthermore, αβ T cells and γδ T cells that do not bind antigen-specific tetramers can still produce significant antigen-specific cytokine responses (15, 16). MHC class II tetramers are also problematic in cytometry by time-of-flight mass spectrometry (CyTOF), which is an advanced version of flow cytometry that can simultaneously measure more than 40 parameters on single cells (17). The extensive washing steps, harsh fixation conditions, complicated sample injection process, and sensitivity of the time-of-flight mass spectrometry make the low-avidity MHC class II tetramers unsuitable for CyTOF studies.To augment the avidity of the tetramer, we have engineered a biotinylated scaffold protein linked to four streptavidin tetramers, each capable of binding three biotinylated pMHC monomers. We then used the resulting dodecamer (Greek for “12”) to detect low-affinity αβ and γδ T cells in blood and tissue samples from humans and mice. Compared with tetramers and at least some multimers, this construct has better sensitivity, stronger signal strength, higher binding avidity, and a much slower dissociation rate. For the various specificities that we have analyzed, it can identify two- to fivefold more specific T cells than an equivalent tetrameric reagent.