VIREMIA AND SEROLOGICAL RESPONSES IN ADULT CHICKENS INFECTED WITH WESTERN EQUINE ENCEPHALOMYELITIS AND ST-LOUIS ENCEPHALITIS VIRUSES

Adult hens, similar to those used for arbovirus surveillance, were exp erimentally infected with western equine encephalomyelitis (WEE) and S t. Louis encephalitis (SLE) viruses to describe the viremia response, to compare serological testing methods, and to evaluate a new method o f collecting whole blood onto filter paper strips from lancet pricks o f the chicken comb. Young (19 weeks), but not old (38 weeks), hens dev eloped a low-titer, transient viremia for a 1-day period. Immunoglobul in G (IgG) was detected by days 10 and 14 after infection with WEE and SLE viruses, respectively, by indirect fluorescent antibody tests, he magglutination inhibition tests, and plaque reduction neutralization t ests on sera and in direct enzyme immunoassays (EIA) on both sera and eluates from filter paper samples. Immunoglobulin M (IgM) was first de tected in sera 2 and 3 days before IgG, respectively, but IgM could no t be detected reliably in eluates from dried blood. Sera and dried blo od samples collected from naturally infected sentinel chickens gave co mparable results when tested by an EIA for IgG.