Suligoi Barbara, Regine Vincenza, Raimondo Mariangela, Rodella Anna, Terlenghi Luigina, Caruso Arnaldo, Bagnarelli Patrizia, Capobianchi Maria Rosaria, Zanchetta Nadia, Ghisetti Valeria, Galli Claudio
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Clin Chem Lab Med. 2017 Oct 26;55(12):2010-2019. doi: 10.1515/cclm-2016-1192.
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.
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.
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.
The AI is an accurate serological marker for discriminating recent from established HIV infections and meets WHO requirements for HIV incidence assays.
检测近期HIV感染对于评估发病率和监测流行趋势至关重要。我们旨在评估亲和力指数（AI）鉴别近期HIV感染的诊断性能和准确性。
我们收集了HIV-1阳性个体的血清样本：A）已知感染日期（最后一次HIV阴性和首次HIV阳性检测之间的时间中点）；B）感染超过1年。样本分为两份：一份用磷酸盐缓冲盐水（PBS）稀释，另一份用1 M胍稀释。两份样本均采用Architect HIV Ag/Ab Combo第4代检测法（雅培）进行检测。我们比较了近期感染（RI =血清转换后<6个月）和已确诊感染（EI）中发现的AI。通过受试者工作特征（ROC）曲线分析评估诊断准确性。计算被错误分类为近期感染的样本比例（FRR）。
总共收集了647份样本：A组455份（51.6%为RI，48.4%为EI），B组192份。其中，16份样本来自精英控制者，294份来自接受治疗的患者，328份来自感染非B亚型的患者。抗逆转录病毒治疗开始前的样本显示，RI组的平均AI显著低于EI组（0.66 + 0.28 vs. 1.00±0.12；p<0.000）。使用≤0.70的临界值，FRR为0%。在精英控制者、病毒载量低或CD4低的样本中观察到极低的FRR。HIV亚型对AI错误分类没有影响。A组的所有个体在血清转换后24个月内达到了0.80的AI阈值。
AI是鉴别近期HIV感染与已确诊感染的准确血清学标志物，符合WHO对HIV发病率检测的要求。
