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Title: CATTLE RESPONSE TO FOOT-AND-MOUTH DISEASE VIRUS SNONSTRUCTURAL PROTEINS AS ANTIGENS WITHIN VACCINES PRODUCED USING DIFFERENT CONCENTRATIONS

Author
item LUBROTH, JUAN - USDA-APHIS, FADDL, PIADC
item LOPEZ, A - RIO DE JANEIRO, BRAZIL
item RAMALHO, A - RIO DE JANEIRO, BRAZIL
item MEYER, RICHARD - USDA-APHIS, FADDL, PIADC
item Brown, Fred
item DARSIE, G - RIO DE JANEIRO, BRAZIL

Submitted to: The Veterinary Quarterly
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/14/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: This paper was presented at a meeting of the European Community to discuss the results of a joint program to distinguish between animals infected with FMDV and those vaccinated against the disease. The results described in this paper review the work with baculovirus expressing proteins 2C and 3ABC, which have been identified as indicative of virus infection, and sera from vaccinated animals.

Technical Abstract: Four groups of ten 9-month-old Nelore heifers were used for this study. Each group received 1 of 4 FMD trivalent vaccines for the duration of the experiment. The 4 vaccine formulations (Normal 2X, 4X and 8X) differed in 140S content to determine the serological reactivities to FMDV nonstructural proteins 2C, 3ABC and 3D. Vaccination was by the intramuscular administration of vaccine on day 0, 180 and 360. Bleedings were done at 30 days post vaccination (dpv), 90 dpv, 30 dp revaccination (dpr), 90 dpr and 30 dp third administration. There was a general tendency to have higher mean 3D responses with increased vaccine application but not with increased concentration of antigen. With 2C and 3ABC this tendency was not seen, neither with repeated application of vaccine nor with increasedd antigen concentration. All individual animal observations to 2C and 3ABC remained within 3 standard deviations of the average observed for naive bovids. Percent of positive (PP) reactions was determined using an ELISA for nonstructural proteins 2C, 3ABC and 3D expressed in baculovirus as previously described. A value of > 25 PP to 2C or 3ABC could be considered as an indication of previous infection or of the presence of viral activity. PP results between 18 and 25 PP suggest viral activity and animals should be retested. Those responses below 15 PP are suggestive of vaccination or naive status. As diagnosis in the laboratory is not divorced from the field epidemiological scene, the intermediate zone between 10 and 20 PP should be considered and acted upon according to the overall zoosanitary situation of that country or region and the purposes of the ongoing FMD control efforts.