107 TCID50 of FAdV-4 isolate SD2015 was used to immunize 6-week-old BALB/C mice four times every 10 days. At day 4 following the fourth immunization, the splenic cells from one immunized mouse were collected and fused with SP2/0 cells with PEG1500, as previously described . After culture with HAT-selective medium (Sigma), hybridoma cells secreting antibodies against the fiber-2 protein of FAdV-4 were screened using ELISA coating with purified GSTFiber2 (generated in our laboratory). After sub-cloning of the positive hybridoma cells, the characteristics of mAbs secreted by these positive clones were identified through immunofluorescence assay, ELISA, immunoprecipitation and neutralization testing. The isotype of mAb was determined with a mouse mAb isotyping kit according to the manufacturer’s protocol. The mAbs in ascites were generated as previously described and purified using protein G columns