Fowlpox vaccination: routes of inoculation and pathological effects.

Chickens were vaccinated against fowlpox via the wing web, oral route, drinking water or by aerosol. Using two inoculations of virus, at 5 and 26 days of age, protective immunity was induced in chickens which resisted challenge with a pathogenic fowlpox virus given either via the wing web or intravenously at 46 days of age. Aerosol and wing web vaccination induced slightly better protective immunity than drinking water or oral vaccination. Virus was detected in lung cells of chicks vaccinated by either oral, drinking water or aerosol routes. Virus was also recovered from the lungs of these chicks, maximum titre being obtained 6 days post vaccination. Although a marked histological reaction was present in the lung no clinical signs were observed in the chicks.