Immunisation against Panleucopenia: Early development of immunity

The time necessary to obtain the immunity of cats against Panleucopenia has been studied by means of a modified live vaccine.

This vaccine makes it possible to obtain a very early post-vaccinal immunity: the full immunity is reached 72 hr after the inoculation of the vaccine by the subcutaneous route.

Furthermore, we have demonstrated that a sensitive kitten can be admitted in a contaminated environment immediately after vaccination without showing any clinical evidence of the disease.     

Freeze-dried vaccine against Rinderpest: Stability and activity study

A freeze-dried vaccine against Rinderpest was prepared from modified virus multiplied in calf kidney cell cutlure. Characteristics of the vaccine are as follows:

• —high titre after freeze-drying (10⁴ CCID₅₀/dose),

• —well-adapted freeze-drying stabiliser which ensures maintenance of the infective titre of the vaccinal virus, even under severe conditions (3.5 days at +45°C),

• —use of an appropriate solvent: magnesium sulphate molar solution or more simply physiological saline (for stability after reconstitution even at high temperatures—up to 4 h at +45°C).

The activity of the vaccine, tested in cattle by antibody titration and resistance to specific challenge perfectly satisfies requirements set by the WHO and OIE.     

A new freeze-dried living virus vaccine against sheep-pox

A sheep-pox virus strain has been adapted and multiplied in primary lamb kidney cell cultures. The main characteristics of the strain have been verified in vitro after clones were isolated, and the results confirmed its identity. The safety and the potency of the strain have been investigated in sheep.

The inoculation of the strain to sheep was followed by a post-vaccinal reaction materialised by a nodule at the site of inoculation and an increase of temperature by about 1°C. No reactions adversely affecting pregnancy have been noted. Immunisation was demonstrated by an increase in the level of neutralising serous antibodies and protection against the pathogenic virus. The immunity tended to decrease during the second year after primovaccination and a yearly booster vaccination appeared to be necessary. Primovaccination of lambs over 2 months of age produced a better immunity, especially when the lambs were born from vaccinated ewes.

This strain forms the active principle of a freeze-dried vaccine containing no adjuvant of the immunity.