..::Veterinary Serum and Vaccine Research Institute::..

J. Egypt. Vet.Med. Ass. 62,No.5 27-34 (2002)

Some studies of Antigenic Viriations between recent Isolated FMD
Field Strain and Vaccinal Strain Egypt.

FATMA A. MOUSSA; SAIMRA EL-KILANY; ABD EL-ATY, M.M. AND DAOUD, A.M.

Veterinary Serum and Vaccine Research Institute,
Abbassia, Cairo , Egypt.

Summary

	Some studies of antigenic variations between vaccinal strain (O 1 /93) and field isolate during year 2001 from El-Haraky, Sharkia Governorate, from cattle where clinical signs of foot and mouth disease were supected in twelve animals out of sixty seven cattle.

	The isolates samples were tested and diagnosed by CFT (Complement Fixation Test) against the seven serotypes of FMD and the results revealed that the isolates showed positive FMDV type “ O 1 ” one sample of them was taken to study the variation between the new field samples and the vaccinal strain. Vaccinal strain (O 1 /93) and field isolate (O/2001) were passaged on tissue culture (bovine embryo cell kidney, BEK) to obtain a good infective titre which giving (6.8 and 6.3) Iog 10 TCID50 and complement fixing titers (3.01 and 2.5 ) Iog 10 CFU /ml for O 1 /93 and O/2001, respectively. The two isolates were inoculated also in Guinea pigs to obtain hyperimmune sera for them.

	The study of antigenic relationship and dominating factor between the field strain and the vaccinal one have shown little variation and had a percentage of 49.2, that meaning the two strains are under class ( subtype is similar but still different in which the percentage is between 32 –7 % ) while the vaccinal strain is dominating the field strain. The conclusion of this study shows that there is no need to change the vaccinal strain at the time being in the current vaccination program.