[1] Univ Illinois, Dept Pathobiol, Coll Vet Med, Urbana, IL 61802 USA
[2] Univ Connecticut, Dept Pathobiol & Vet Sci, Storrs, CT 06269 USA
[3] Univ Connecticut, Ctr Excellence Vaccine Res, Storrs, CT 06269 USA
[4] Natl Vet Res & Quarantine Serv, Anyang 430016, Kyonggi Do, South Korea