Suligoi Barbara, Massi Mario, Galli Claudio, Sciandra Mauro, Di Sora Fiorella, Pezzotti Patrizio, Recchia Olga, Montella Francesco, Sinicco Alessandro, Rezza Giovanni
Reparto AIDS e MSTl, Istituto Superiore di Sanità, Rome, Italy.
J Acquir Immune Defic Syndr. 2003 Apr 1;32(4):424-8. doi: 10.1097/00126334-200304010-00012.
We evaluated a procedure for identifying recent HIV infections, using sequential serum samples from 47 HIV-positive persons for whom the seroconversion date could be accurately estimated. Each serum sample was divided into two aliquots: one diluted with phosphate-buffered saline and the other diluted with 1 M guanidine. We assayed the aliquots with the automated AxSYM HIV1/2gO test (Abbott Diagnostics Division), without modifying the manufacturer's protocol. We then calculated the avidity index (AI): the ratio of the sample/cutoff value for the guanidine aliquot to that of the phosphate-buffered saline aliquot. We analyzed 216 serum samples: 34 samples were collected within 6 months of seroconversion (recent seroconversions), and 182 were collected after 6 months. The mean AIs, by time from seroconversion, were 0.68 +/- 0.16 (within 6 months) and 0.98 +/- 0.10 (after 6 months) (P < 0.0001). AI of <0.90 correctly identified 88.2% of recent infections but misclassified as recent infections 13.2% of serum samples collected afterward. The probability of an infection being classified as recent and having AI of > or = 0.90 would be 0.7% in a population with 5% recent infections. AI can identify with a certain degree of accuracy recent HIV infections, and being a quantitative index, it provides different levels of sensitivity and specificity, depending on the selected cutoff value. The standard assay procedure is not modified. This test is simple and inexpensive and could be used for surveillance, decision-making in treatment, and prevention.
我们评估了一种识别近期HIV感染的方法，使用来自47名HIV阳性者的序贯血清样本，这些人的血清转化日期能够被准确估计。每个血清样本被分成两份：一份用磷酸盐缓冲盐水稀释，另一份用1M胍稀释。我们使用自动AxSYM HIV1/2gO检测（雅培诊断部）对这些样本进行检测，未修改制造商的方案。然后我们计算亲和力指数（AI）：胍稀释样本的样本/临界值与磷酸盐缓冲盐水稀释样本的样本/临界值之比。我们分析了216份血清样本：34份样本在血清转化后6个月内采集（近期血清转化），182份在6个月后采集。根据血清转化后的时间，平均AI分别为0.68±0.16（6个月内）和0.98±0.10（6个月后）（P<0.0001）。AI<0.90能正确识别88.2%的近期感染，但将13.2%的后续采集血清样本误分类为近期感染。在近期感染率为5%的人群中，感染被分类为近期感染且AI≥0.90的概率为0.7%。AI能够以一定程度的准确性识别近期HIV感染，并且作为一个定量指标，根据所选临界值，它提供不同水平的敏感性和特异性。标准检测程序未被修改。该检测简单且成本低廉，可用于监测、治疗决策和预防。
