ISOTYPE PROFILES INDUCED IN BALB C MICE DURING FOOT-AND-MOUTH-DISEASE(FMD) VIRUS-INFECTION OR IMMUNIZATION WITH DIFFERENT FMD VACCINE FORMULATIONS/

The IgG isotype response in Balb/c mice infected with E;MD I/ or immun ized with different vaccine formulations using inactivated virus parti cles as antigen was analyzed at various times post-inoculation. For th is purpose an ELISA based on polyclonal antibodies for detection and q uantification of mouse IgG isotypes with FMD virus (FMDV) specificity was developed. Three immunomodulators, which have been shown to be ver y effective in inducing strong and long-lasting antibody responses (Ba hnemann, Arch. Virol. 1975, 47, 47-56; Polatnik and Bachrach, Appl. Mi crobiol. 1964, 12, 368-376), were employed to formulate different vacc ines using aqueous and oil vehicles: a water-soluble fraction of the c ell wall of Mycobacterium sp., a purified extract of lipopolysacharide from Brucella ovis and a synthetic lipoamide, Avridine. Infected anim als between 14 and 60 days postinoculation (d.p.i.) showed responses d ominated by IgG2b, followed by IgG1, IgG2a and IgG3, respectively. The IgG3 isotype was the first, together with IgG1, to be elicited during the first 7 days after infection, whereas no IgG3 activity was detect ed in vaccinated animals at any time. With formulations including immu nomodulators, persisting high levels of IgG2b (similar to those of inf ected animals) were detected until 180 d.p.i., while with conventional vaccines IgG2b responses were detected up to 60 dp.i. Animals vaccina ted with formulations including these immunomodulators presented an au gmented resistance to viral challenge at 210 d.p.i. in relation with t hose immunized with conventional vaccines. The possible relationship o f these differences in the isotype response and protection is discusse d