Use of adult chickens as arbovirus sentinels. I. Viremia and persistence of antibody in experimentally inoculated adult chickens.

Summary Three-month-old and 8-month-old chickens were inoculated subcutaneously with a single, small dose of WE virus calculated to represent that which could be inoculated by a naturally infected mosquito. Each chicken was bled for determination of the viremia and antibody pattern. A similar study was made with SLE virus. The viremia period for WE virus in the majority of adult chickens lasted only 2 days. SLE virus was present in the blood of about half of adult chickens on the 2nd and 3rd days after inoculation and persisted in a few individual birds for longer periods of time. Most of the chickens inoculated with WE virus had HI titers of 1:320 or greater by the 2nd week after inoculation. Although there was some decrease in HI-antibody titers to WE, this antibody persisted at detectable levels for at least 1 year. In these chickens strong neutralization indices developed by the 2nd week, and this type of antibody persisted for at least the 9-week observation period. In adult chickens inoculated with SLE virus HI antibody developed by the 2nd week, and although the titers declined during the next 9 months, every chicken tested had detectable antibody at the end of the observation period. Nineteen of these chickens had neutralization indices of 101.5 or greater during the 10-week observation period. Individual chickens showed considerable variation in their HI and neutralizing-antibody response to SLE infections. These data help to define the manner in which adult chickens may be used as sentinel animals to detect arbovirus activity, and they provide a basis for interpreting field data.