Induction of Systemic Delayed Hypersensitivity During Experimental Viral Infection of the Respiratory Tract with a Myxovirus or Paramyxovirus

Development of systemic delayed hypersensitivity was demonstrated in inbred strain 2 and strain 13 guinea pigs experimentally infected with influenza A/Hong Kong/1968(H3N2) virus or parainfluenza 3 virus. Groups of seronegative guinea pigs were inoculated intranasally with live influenza A virus or parainfluenza 3 virus, or ether-inactivated parainfluenza 3 virus, and nasal washings, sera, and suspensions of peritoneal exudate cells were collected at varying intervals. Animals receiving the live virus suspensions shed virus for 6 to 8 days, developed significant rises in serum neutralizing antibody titers, and demonstrated systemic delayed hypersensitivity 6 or 7 days after inoculation, which persisted 25 days after inoculation. The group inoculated with ether-inactivated parainfluenza 3 virus failed to shed virus or manifest a systemic delayed hypersensitivity response although one animal had a rise in serum antibody titer. The development of the delayed hypersensitivity correlates in time with the cessation of virus shedding and the appearance of circulating antibody. However, the role of delayed hypersensitivity in resolution of respiratory viral infections remains to be defined.