The invention relates to a freeze-
drying protective additive which is composed of 1 to 2% of NZ-Amine AS, 0.1 to 0.2% of
monosodium glutamate, 5 to 10% of saccharose, 1 to 2% of M199, 0.1 to 0.3% of
trehalose, 8 to 15% of hydrolyzed
gelatin, and the balance of water. The freeze-
drying protective additive is used for preparing a freeze-dried
pseudorabies vaccine. A heat-resisting protective agent can minimize the damage of various physical and chemical factors of a product to
virus activity during sub-packaging and freezing-
drying processes, greatly reduces the
titer loss of the
virus before and after freezing and drying and keeps the loss of being not greater than 0.2
titer. A heat-resisting protective agent live vaccine is high
in degree of resistance to aging, the loss ratio of the
virus kept for 10 days under a condition of 37 DEG C is not greater than 0.5
titer; the heat-resisting protective agent live vaccine can be stored for 24 months at 2 to 8 DEG C, the titer of the vaccine is reduced a little, so that the problem that the vaccine in general transporting and storing needs strict
cold chain condition, which leads to energy waste and inconvenient storage, can be solved effectively.