S1 domain of the porcine epidemic diarrhea virus spike protein as a vaccine antigen

Makadiya, Niraj; Brownlie, Robert; van den Hurk, Jan; Berube, Nathalie; Allan, Brenda; Gerdts, Volker; Zakhartchouk, Alexander

The presence of PEDV-specific neutralizing antibodies in serum of sows and piglets was determined using a serum neutralizing (SN) test. Briefly, serum samples were diluted 2-fold and mixed with an equal volume of 200 TCID 50 of PEDV in each well. After a 1 h incubation at 37°C, 100 μL of virus-serum mix was added to 96-well microtiter plate with a confluent monolayer of Vero 76 cells. The cells were incubated for 3 h at 37°C in 5 % CO 2 and unbound virus particles were removed with two washes of DMEM. Then, 100 μL DMEM supplemented with trypsin (2 μg/mL) was added to the cells and incubated for 1 h at 37°C in 5 % CO 2 . Thereafter, 100 μL DMEM containing trypsin (2 μg/mL) and albumin (0.2 %) were added to each well and the cells were incubated for the period of 7 days at 37°C in 5 % CO 2 . The virus neutralizing antibody titers were expressed as the reciprocal of the highest serum dilution that showed no CPE in the cells. PEDV positive and negative control sera were also included in the tests.