The Hitchner B1 strain of Newcastle disease virus induces high levels of IgA, IgG and IgM in newly hatched chicks.

Reaseheath line C chicks produced IgA, IgG and IgM in their serum, tears, spleen and Harderian gland (HG) as a consequence of oculotopical vaccination with the Hitchner B1 strain of Newcastle disease virus. The IgM response was seen first, at 5 days after vaccination, and antiviral IgM levels in the tears and serum were negatively correlated to the level of virus in HG over days 4 to 10 postinfection. The frequency of virus-specific IgM-antibody forming cells in the HG of 10-day-old birds that had been vaccinated at 1 day old could reach 1/30th of the total lymphoid cells prepared from the HG. Young chicks made an irregular or low response to inactivated virus by the intravenous route whereas 40-day-old birds made a high serum response to both live and inactivated virus. This emphasizes how day-old chicks respond well to live virus vaccination and that their IgM response is likely to have a role in the clearance of virus.