Antibody titres to influenza A/PR/8/34 (H1N1) in sheep immunized with either whole inactivated or split PR8 virus.

aSheep were immunized with inactivated whole influenza A PR8/34 virus (n = 3) or purified split PR8 virus (n = 2) with adjuvant (Titermax Gold) at weeks 0, 2 and 3–4 and samples collected at weeks 6 and 8, respectively.
bH1-specific antibody titres in sera and whey determined by HI assay using homologous virus as antigen. Data expressed as reciprocal endpoint dilution of sample from individual sheep.
cMicroneutralization titres in sera and whey determined by microneutralization assay using homologous virus. Data expressed as reciprocal endpoint dilution of sample from individual sheep.
dN1-specific antibody reactivity in sera determined by NI assay using homologous virus as antigen and expressed as (+) positive or (-) negative for individual sheep.