Use of interferon-gamma release assays in a health care worker screening program: Experience from a tertiary care centre in the United States

BACKGROUND:

Interferon-gamma release assays including the QuantiFERON-TB Gold In-Tube test (QFT-GIT [Cellestis Ltd, Australia]) may be used in place of the tuberculin skin test (TST) in surveillance programs for Mycobacterium tuberculosis infection control. However, data on performance and practicality of the QFT-GIT in such programs for health care workers (HCWs) are limited.

OBJECTIVES:

To assess the performance, practicality and reversion rate of the QFT-GIT among HCWs at a tertiary health care institution in the United States.

METHODS:

Retrospective chart review of HCWs at Central Arkansas Veterans Healthcare System (Arkansas, USA) who underwent QFT-GIT testing as a part of their employee screening between November 1, 2008 and October 31, 2009.

RESULTS:

QFT-GIT was used to screen 3290 HCWs. The initial QFT-GIT was interpreted as positive for 129 (3.9%) HCWs, negative for 3155 (95.9%) and indeterminate for six (0.2%). Testing with QFT-GIT was repeated in 45 HCWs who had positive results on the initial test. The QFT-GIT reverted to negative in 18 (40.0%) HCWs, all of whom had negative TST status and initial interferon-gamma values of 0.35 IU/mL to 2.0 IU/mL.

CONCLUSIONS:

The QFT-GIT test is feasible in large health care setting as an alternative to TST for M tuberculosis infection screening in HCWs but is not free from challenges. The major concerns are the high number of positive test results and high reversion rates on repeat testing, illustrating poor short-term reproducibility of positive QFT-GIT test results. These results suggest adopting a borderline zone between interferon-gamma values of 0.35 IU/mL to 2.0 IU/mL, and cautious clinical interpretation of values in this range.     

Construction of a High Titer Infectious HIV-1 Subtype C Proviral Clone from South Africa

The Human Immunodeficiency Virus type 1 (HIV-1) subtype C is currently the predominant subtype worldwide. Cell culture studies of Sub-Saharan African subtype C proviral plasmids are hampered by the low replication capacity of the resulting viruses, although viral loads in subtype C infected patients are as high as those from patients with subtype B. Here, we describe the sequencing and construction of a new HIV-1 subtype C proviral clone (pZAC), replicating more than one order of magnitude better than the previous subtype C plasmids. We identify the env-region for being the determinant for the higher viral titers and the pZAC Env to be M-tropic. This higher replication capacity does not lead to a higher cytotoxicity compared to previously described subtype C viruses. In addition, the pZAC Vpu is also shown to be able to down-regulate CD4, but fails to fully counteract CD317.     

HLA antibodies in pediatric heart transplantation

We have analyzed the impact of anti-HLA antibodies present in the patients' circulation prior and/or following heart transplantation in a population of 108 pediatric recipients. Anti-HLA class I and class II antibodies were monitored by traditional CDC using donor and panel T and B lymphocytes and by SPA for detection of DSA. There was a highly significant correlation between the development of AMR and presence of CDC- or SPA-detected DSA. However, the fraction of the transplant population which remained AMR-free was much higher among patients with SPA-detected compared to CDC-detected DSA. Furthermore, long-term graft survival was negatively affected only by cytotoxic, complement-fixing anti-HLA class I antibodies developing following transplantation. Anti-HLA class I or class II antibodies detected by SPA had no effect on long-term survival rates.     

Urine protein concentration estimation for biomarker discovery

Recent advances have been made in the study of urinary proteomics as a diagnostic tool for renal disease and pre-eclampsia which requires accurate measurement of urinary protein. We compared different protein assays (Bicinchoninic acid (BCA), Lowry and Bradford) against the ‘gold standard’ amino-acid assay in urine from 43 women (8 non-pregnant, 34 pregnant, including 8 with pre-eclampsia). BCA assay was superior to both Lowry and Bradford assays (Bland Altman bias: 0.08) compared to amino-acid assay, which performed particularly poorly at higher protein concentrations. These data highlight the need to use amino-acid or BCA assays for unprocessed urine protein estimation.     

Carotenoid and flavonoid profile and antioxidant activity in “Pomodorino Vesuviano” tomatoes

Tomatoes are one of the most widely consumed vegetables in the Mediterranean Diet. They are a rich source of antioxidant compounds and their consumption is linked with a reduction of various types of pathologies. In addition to geographical and seasonal variables, cultivar is an important factor affecting the profile and the concentration of antioxidant compounds. “Pomodorino Vesuviano” is a Protected Designation of Origin (PDO) tomato cultivar traditionally grown in Campania (southern Italy), which to the best of our knowledge has never been analyzed for bioactive compounds before. Here we present a study conducted to investigate the carotenoid and flavonoid content in tomatoes from this cultivar. Results indicate that Pomodorino Vesuviano is a rich source of antioxidants, with lycopene (78.6 mg/kg fresh weight (fw)) and quercetin (8.52 mg/kg fw) are the major components. Moreover, cell-based studies have suggested that a synergistic effect among phytochemicals in tomatoes is responsible for their antioxidant activity, since the combination of low concentrations of carotenoids and polyphenols (i.e. per se inactive concentrations) resulted in a significant reduction of reactive oxygen species (ROS) formation. .     

Quantitative high throughput analytics to support polysaccharide production process development

The rapid development of purification processes for polysaccharide vaccines is constrained by a lack of analytical tools current technologies for the measurement of polysaccharide recovery and process-related impurity clearance are complex, time-consuming, and generally not amenable to high throughput process development (HTPD). HTPD is envisioned to be central to the improvement of existing polysaccharide manufacturing processes through the identification of critical process parameters that potentially impact the quality attributes of the vaccine and to the development of de novo processes for clinical candidates, across the spectrum of downstream processing. The availability of a fast and automated analytics platform will expand the scope, robustness, and evolution of Design of Experiment (DOE) studies.     

γ-干扰素释放试验对HIV感染者合并菌阴肺结核辅助诊断价值的探讨

目的探讨γ-干扰素释放试验(IGRAs)对人类免疫缺陷病毒(HIV)感染者合并菌阴肺结核(HIV/菌阴肺结核)的辅助诊断价值。方法对128例于2014年5月至2016年4月在河南省鹤壁市传染病医院感染科住院期间行IGRAs检测的HIV/菌阴肺结核、人类免疫缺陷病毒感染/获得性免疫缺陷综合征(HIV/AIDS)、菌阴肺结核患者的IGRAs测定结果和相关临床资料进行回顾性分析。组内及组间构成比或率的比较采用χ~2检验,计量资料采用t检验,以P0.05的因素作为自变量,以IGRAs结果为阳性或阴性作为因变量,行Logistic回归(基于条件参数估计的后退法)分析。结果 (1)HIV/菌阴肺结核患者血γ-干扰素水平和阳性检出率高于HIV/AIDS患者(U=7.813,P=0.005;χ~2=8.486,P=0.004),但与菌阴肺结核患者相接近(U=1.109,P=0.292;χ~2=2.459,P=0.117)。(2)与IGRAs阴性的HIV/菌阴肺结核患者相比较,IGRAs阳性的HIV/菌阴肺结核患者的CD_4~+计数(t=5.349,P=0.002)、CD_4~+/CD_8~+(t=2.834,P=0.009)、淋巴细胞计数(t=5.576,P0.001)增高,血沉(t=-2.317,P=0.029)降低。(3)logistic回归分析显示,仅CD_4~+计数是影响HIV/菌阴肺结核患者IGRAs结果的独立因素(Wald X2=4.434,P=0.035,OR=13.5,95%CI=1.197-152.211)。(4)不同检测方法比较,HIV/菌阴肺结核患者IGRAs检测的敏感度(35.7%)和诊断正确率(72.7%)高于结核抗体(21.4%,63.6%)和PPD(14.2%,67.0%)检测,其特异度(90.0%)与PPD相接近(91.7%),略高于结核抗体(83.3%)。IGRAs联合PPD和结核抗体检测可提高敏感度至60.7%。结论IGRAS检测有助于从HIV患者中早期筛出或发现HIV/结核病患者。HIV/菌阴肺结核患者CD_4~+200/μL影响IGRAs的检测结果。IGRAs检测对HIV/菌阴肺结核的辅助诊断价值优于PPD和结核抗体,而三项联合检测也有助于HIV/菌阴肺结核的早期发现。