Analysis of the NDV-specific antibody titer in chicken antisera through ELISA. The anti-NDV antibody titer and standard deviations (SD) among serum samples collected from chickens of different poultry farms are shown along with controls. Serum samples from NDV-infected chickens displayed a significanlty higher anti-NDV antibody titer than negative controls, confirming that the recombinant M protein can be used for detection of anti-NDV antibodies and/or NDV infection in chickens.