Study of the One-Step Growth Curve of Equine Infectious Anemia Virus by Immunofluorescence

Abstract

Primary horse leukocyte cultures were inoculated with 2 or 10 50% tissue culture infective doses (TCID 50 ) of equine infectious anemia (EIA) virus per cell, and the titer of cell-associated and fluid-phase virus was determined from 1 to 72 hr postinoculation (PI). Cover slips were collected from 4 to 72 hr PI and stained for EIA viral antigen by the indirect immunofluorescent (FA) technique. Viral replication was detected after a latent period of approximately 18 to 24 hr and reached peak titers of approximately 10 4.5 to 10 6 TCID 50 /0.5 ml from 48 to 72 hr PI. The fluid phase contained 10 1 to 10 2 TCID 50 /0.5 ml more virus than the cells. Viral antigen was first detected by FA from 18 to 24 hr PI. Approximately 75% of the cells contained antigen in their cytoplasm 72 hr PI. The FA technique is a sensitive method for detecting EIA virus in horse leukocyte cultures.