Absence of an immune response after oral administration of attenuated feline panleukopenia virus.

Cats were orally vaccinated with attenuated feline panleukopenia virus to compare this route with parenteral immunization. Cats receiving vaccine virus by mouth did not produce a systemic or local antibody response to the virus. Intranasal and subcutaneous vaccination produced high levels of neutralizing antibodies and provided protection from challenge with virulent virus. The results suggest that virus does not initially infect the tissue of the oral pharynx or gastrointestinal tract as previously suspected.