Role of Harderian glands in resistance against Mycoplasma gallisepticum challenge

Harderian glands of one-day-old chickens were surgically removed. At one week old, these chickens and controls from which these tissues were not removed, were vaccinated intranasally with a temperature-sensitive mutant of Mycoplasma gallisepticum. Humoral and local immunity were measured by means of antibody in sera and tracheal washings, respectively. Protection was measured by resistance to intra-air-sac challenge with the S6 strain of M gallisepticum. There was no discernible difference in either humoral or local antibody response between vaccinated chickens from which the glands had been removed and control birds. In addition, both groups were significantly protected against air-sac challenge compared with unvaccinated controls. These results indicate that removal of the Harderian glands neither affects the production of antibody to M gallisepticum , nor alters the effectiveness of temperature-sensitive M gallisepticum vaccination. The role that the Harderian glands play in resistance to M gallisepticum is therefore questioned.