In recent years, with the advancement of single B-cell antibody technology, the development of native neutralizing antibodies has gradually increased. For example, HIV(Walker et al., 2009, Wu et al., 2010, Scheid et al., 2011, Walker et al., 2011, Huang et al., 2016, Sok et al., 2016), Ebola virus(Corti et al., 2016), respiratory syncytial virus(Kwakkenbos et al., 2010), and the novel coronavirus that emerged in recent years have led to the development of human neutralizing antibodies(Pinto et al., 2020, Zost et al., 2020, Cao et al., 2022, Westendorf et al., 2022), which has important implications for treatment and emergency immunization.

First, randomly clone B cell sequences, then randomly express a large number of antibodies, and finally verify the neutralizing ability of the expressed antibodies. This early development strategy is costly, conveys a heavy workload, and has low efficiency. If before cloning B cell sequences, add a microneutralizing activity screening experiment, B-cell samples containing neutralizing activity can be purposefully selected for subsequent cloning and expression, which reduces the cost and workload in subsequent experiments. For example, Walker, L. M, et al. established a high-throughput HIV microneutralizing activity screening method(Walker et al., 2009) that greatly improved the development efficiency of HIV neutralizing antibodies. Therefore, establishing a microneutralizing activity screening method is of great significance to the development of native neutralizing antibodies based on single B-cell technology.

Therefore, in order to develop native CDV neutralizing antibodies. This study is based on the principle of whether a fixed amount of live CDV (neutralizing solution of this method) can still infect cells after neutralizing it with the test sample. Using IFA technology established an economical, stable, and easy-to-operate screening method for CDV microneutralizing activity. This method lays a methodological foundation for the development of native CDV neutralizing antibodies based on single B cells.