The neutralization assays are considered the gold-standard being capable of evaluating and detecting, functional antibodies. To date, many different protocols exist for micro-neutralization (MN) assay which varies in several steps: cell number and seeding conditions, virus amount used in the infection step, virus-serum-cells incubation time and read out.

The aim of the present preliminary study was to carry out SARS-CoV-2 wild type MN assay in order to investigate which optimal tissue culture infective dose 50 (TCID₅₀) infective dose in use is the most adequate choice for implementation in terms of reproducibility, standardization possibilities and comparability of results. Therefore, we assessed the MN by using two viral infective doses: the “standard” dose of 100 TCID₅₀/well and a reduced dose of 25 TCID₅₀/well. The results obtained, yielded by MN on using the lower infective dose (25 TCID50), were higher respect to those obtained with the standard infective dose. This suggests that the lower dose can potentially have a positive impact on the detection and estimation of real amount of neutralizing antibodies present in a given sample, showing higher sensitivity maintaining high specificity.

中和试验被认为是能够评估和检测功能性抗体的金标准。迄今为止，微中和 (MN) 测定存在许多不同的协议，这些协议在几个步骤中有所不同：细胞数量和播种条件、感染步骤中使用的病毒量、病毒-血清-细胞孵育时间和读出。

本初步研究的目的是进行 SARS-CoV-2 野生型 MN 测定，以研究使用中的最佳组织培养感染剂量 50 (TCID ₅₀ ) 感染剂量是最适合实施的选择。 ，标准化的可能性和结果的可比性。因此，我们通过使用两种病毒感染剂量评估 MN：“标准”剂量为 100 TCID ₅₀ /孔和减少剂量 25 TCID ₅₀/出色地。MN 使用较低感染剂量 (25 TCID50) 获得的结果比使用标准感染剂量获得的结果更高。这表明较低剂量可能对检测和估计给定样品中存在的中和抗体的实际量产生积极影响，显示出保持高特异性的更高灵敏度。