FIG. 1.

Baculovirus-expressed H5 antigen from A/Vietnam/1203/04 purified by affinity chromatography columns (Protein Sciences Corporation, Meridian, CT). One microgram of H5 protein per lane was separated on a 10% sodium dodecyl sulfate-polyacrylamide gel and immunoblotted with pig sera at a dilution of 1/200. Horseradish peroxidase-conjugated anti-pig immunoglobulin (DakoCytomatron, Glostrup, Denmark) was used at a dilution of 1/10,000 as recommended by the manufacturer. All the sera giving positive neutralization test reactions and a random selection of sera giving negative neutralization test results were tested by Western blotting. A representative result is shown.