Local antibody forming cell responses to the Hitchner B1 and Ulster strains of Newcastle disease virus.

The Hitchner B1 and Ulster strains of Newcastle disease virus (NDV) replicated to high titre in the Harderian gland (HG) after eye-drop infection. The Harderian gland then became the major site of antiviral IgA-antibody-forming cells (AFC) in the body and their number correlated to the level of antiviral IgA antibody in the tears. The spleen, HG and femoral bone marrow all contained comparable levels of antiviral IgG-AFC and IgM-AFC after two intra-ocular inoculations of virus, whereas the caecal tonsil and bursa contained few AFC despite the local replication of the Ulster strain of NDV leading to high titres of virus in the faeces. Vaccines of the Hitchner B1 strain of NDV were much less effective at inducing antibody by the intranasal compared with intra-ocular route and no virus was re-isolated after intranasal vaccination. The intravenous inoculation of inactivated Iscoms of NDV could stimulate the spleen, but not the Harderian gland to the same extent as a live virus.