Immunization against influenza by the ocular route. Brief report

The immunogenicity of influenza A strain A/Northern Territory/60/68 for mice when delivered by the ocular, nasal and sub-cutaneous routes was determined according to the dose of infectious virus required to induce inhibition of multiplication of a standard intransal challenge dose in 50 per cent of animals per group 3 weeks after vaccination. For mice inoculated by the ocular route, an immunizing dose of 10(2.89) TCID50 per animal was required. For anesthetised mice vaccinated intranasally and unanaesthetised mice vaccinated sub-cutaneously these figures are less than 10(2.0) and greater than 10(6.0) TCID50 per animal, respectively. The lower immunogenicity of virus delivered by the ocular route compared with the intranasal route can be correlated with a lowered capacity of ocularly administered virus to replicate in the murine respiratory tract.