Abstract

The correlation between quantities of pigeon paramyxovirus type 1 (PPMV1)-Haemagglutination Inhibition (HI) antibodies exhibited by sera of Specific
Pathogen Free (SPF) chicks and susceptible pigeon squabs at 7, 14, 21 and 28
days after inoculation with one and two pigeon doses of three batches of
commercial inactivated PPMV-1vaccine was assessed throughout the present
study to declare the reasonability of using SPF-chicken for evaluating the
immunogenicity of inactivated PPMV-1 vaccine instead of pigeon in case of
difficulty to find susceptible pigeon squabs in the market. Three groups of
each susceptible pigeon squabs and SPF-chicks were used for
immunogenicity assay of each batch of the tested vaccine. Blood samples
were collected weekly from ten individuals of each inoculated and control
group, and PPMV-1 HI antibodies were measured in each individual serum
sample by HI test using PPMV-1HA antigen containing 4 HA units, and
geometric mean titer of each group was calculated. SPF-chickens were
reacted serologically with the test vaccine batches; PPMV-1-HI antibody
GMTs of range 6.0 log2 – 7.1 log2 and mean 6.4 log2, and 6.0 log2 – 7.4 log2
and 6.6 log2 were determined in sera of chickens by the third and fourth weeks
after inoculation with the pigeon dose respectively, while PPMV-1-HI
antibody GMTs of range 7.0 log2 – 8.8 log2 and mean 7.6 log2, and 7.1 log2 -
8.9 log2 and mean 7.8 log2 and 8.1 log2 - 9.5 log2 and mean 8.8 log2 were
determined in sera of pigeons by the third and fourth weeks after inoculation
respectively. The obtained Relative Potencies of the test vaccine batches in
chickens were ranged between 0.84 and 0.86, and the minimum required
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PPMV-1-HI antibody GMT in sera of SPF-chicks collected between the third
and fourth weeks after inoculation with the pigeon dose should be equal or
more than 6.0 log2 X 85/ 100 = 5.1 log2.
In-conclusion, the present study data suggest that SPF-chickens represent the
reasonable alternative host for immunogenicity assay with one recommended
dose of pigeon by inactivated PPMV-1 vaccine instead of susceptible
pigeon.

Key words: pigeon ,paramyxovirus ,vaccine