Measurement of the effect of storage temperature and duration on the in vivo infectivity of Marek's disease virus in feather dust

A study was conducted to assess the in vivo infectivity of Marek's disease virus (MDV) in feather dust stored at various temperatures for a period of 90 days after collection. One-day old commercial chickens (10 per temperature group) were inoculated with MDV containing chicken dust by intra-tracheal insufflation. Spleen samples were collected at day 7 postinfection and MDV was quantified. The proportion of chicks infected was significantly greater at lower temperatures (-80, -20, 4°C) than higher temperatures (l0, 26 and 37°C) but there was no detectable decline in infectivity during storage at any temperature. There was no correlation between the copy number of MDV in the spleen of infected chicks at day 7 and the infectivity of dust (proportion of chickens infected).