Depression of contact sensitivity to oxazolone by the paramyxovirus of Newcastle disease. Impairment by infectious virus of effector T cells which mediate the response to contactant.

The paramyxovirus of Newcastle disease (NDV) impairs the contact sensitivity to oxazolone in CBA/J mice: in vitro treatment with the infectious virus inhibits the passive transfer of contact sensitivity. Experiments performed with three different virus preparations demonstrate that only the infectious virus is able to inhibit the hypersensitivity reaction while treatment of virus by heat or ultraviolet irradiation wipes out its inhibitory activity. These results suggest that I-NDV depresses the response to oxazolone by its action on T immunoblasts which mediate the response to contactant.