In vitro Effects of Some Steroidal Hormones on the Replication of Avian Pneumovirus

The effects of testosterone, oestradiol, progesterone and cortisone on the in vitro replication of avian pneumovirus in tracheal organ cultures (TOC) were investigated. Samples of cell‐associated and cell‐free virus from TOC, grown in medium containing these hormones, were taken at selected intervals. Progesterone and cortisone caused a slight increase in cell‐associated virus. Testosterone and oestradiol caused a slight delay and decrease in virus replication when compared with the controls. All groups shared the same time interval to reach peak cell‐free virus titre, 96 h post inoculation. In comparison with the controls, only a small drop (0.25–0.50 log10) in the peak of virus titre was observed in the hormone treated groups.