Immune response of chicks to oral vaccination with combined extra- and intracellular fowl pox viruses.

The immune response of chicks to oral vaccination with HP1-strain of fowl pox virus was studied using intracellular virus alone or a combination of intra and extracellular viruses. The first and second vaccinations were done at four days and 25 days of age, respectively. In both groups the birds showed 50% protection against challenge virus at 32 days of age while no immunity was recorded at 95 days of age. The serum IgG concentration in both the vaccinated groups was comparable and it was significantly higher (P less than 0.05) than the control birds one week after revaccination. The serum haemolytic complement activity in both the vaccinated groups was significantly lower (P less than 0.05) than the control birds.