E2 and E rns isotype-specific antibody responses in serum and oral fluid after infection with classical swine fever virus (CSFV).

•Infection of pigs with the Paderborn CSFV isolate resulted in acute, chronic and recovered outcomes.•Each outcome group was unique in terms of CSFV infection and immunological responses.•E2-specific IgM in serum was an early indicator of infection.•Oral fluid was a source of CSFV nucleic acid and E2-reactive IgG.•Combinations of molecular and immunologically-based tests of serum and oral fluid provide a means to surveil acute and chronic CSFV infections.