A pseudovirus-based hemagglutination-inhibition assay as a rapid, highly sensitive, and specific assay for detecting avian influenza A (H7N9) antibodies

Background Increased surveillance of avian-origin influenza A (H7N9) virus infection is critical to assess the risk of new outbreaks in China. A high-throughput assay with a good safety profile, sensitivity, and specificity is urgently needed. Methods We used a hemagglutination-inhibition (HI) assay based on an H7N9-enveloped pseudovirus to assess serum neutralization antibodies level in 40 H7N9 positive sera and 40 H7N9 negative sera and compared the efficacy of the assay with traditional HI test and micro-neutralization (MN) test. Results Spearman’s rank correlation coefficient analysis showed pseudovirus HI (PHI) titers correlated well with both HI titers and MN titers. Receiver operating characteristic (ROC) curves test revealed using a PHI cut-off titer of 10, the sensitivity and specificity reached 1.0. Conclusions PHI can be used in H7N9-related serological studies. This assay is high-throughput, very sensitive and specific, and cost effective