MUCOSAL AND SYSTEMIC IMMUNE-RESPONSES TO MEASLES-VIRUS HEMAGGLUTININ IN MICE IMMUNIZED WITH A RECOMBINANT VACCINIA VIRUS

The immune response to a vaccinia virus recombinant expressing the mea sles virus haemagglutinin (VV-HA) was compared after parenteral or muc osal immunizations in mice, Parenteral immunizations with 10(6) p.f.u. VV-HA induced HA-specific antibody-producing cells (IgG > IgA) and HA -specific class I-restricted cytotoxic T lymphocytes (CTL) in the sple en, In contrast, intranasal administrations of 10(6) p.f.u. of VV-HA i nduced HA-specific spot-forming cells in the spleen (IgG > IgA) and th e lungs (IgA > IgG), and HA-specific CTL in the spleen. Co-immunizatio n by the nasal route with VV-HA and cholera toxin enhanced HA-specific immune responses, Oral immunizations with 10(8) p.f.u. of VV-HA gener ated low numbers of HA-specific IgA-producing cells in the lamina prop ria of the gut, and a weak HA-specific CTL activity in the spleen and mesenteric lymph nodes. Oral co-immunization with W-HA and cholera tox in greatly enhanced the level of HA-specific spot-forming cells in the lamina propria (IgA much greater than IgG). Interestingly, intrajejun al immunizations with 10(8) p.f.u. W-HA alone induced high levels of a nti-HA IgG-producing cells in the spleen and anti-HA IgA-secreting cel ls in the lamina propria of the gut, These data show that (i) VV-HA by the nasal route is immunogenic and generates a measles-specific mucos al immune response in the lung, which represents the primary site of r eplication of measles virus and that (ii) VV-HA can also induce measle s-specific immunity in the intestine provided that it is protected fro m degradation in the gastrointestinal tract, or that cholera toxin is used as an adjuvant.