[Vaccination against bovine chlamydial abortion with a temperature-sensitive mutant of Chlamydia psittaci].

The safety of the vaccinal strain 1B was studied on cows during the pregnancy following the vaccination by recording complement fixing (CF) antibody titer, chlamydial excretion and calving performance. The immunity of vaccinated cows was challenged 19 months after vaccination by intradermal inoculation of 10(7) PFU of the virulent strain AV1 during the 7th month of pregnancy.