This study measured total serum
immunoglobulin A (
IgA),
immunoglobulin G (
IgG)1,
IgG2a response against whole cell
antigen (WCA), outer
membrane protein (OMP), periplasmic
protein (PP), cytoplasmic
protein (CP), and crude Brucella
protein (CBP) of Brucella abortus in experimental
brucellosis induced with B. abortus biotype 1 in Sprague Dawley (SD) rats during a 17-week
infection period. Six- to 8-week-old SD rats (n = 44) were experimentally infected with 1 × 109 colony forming unit of B. abortus biotype 1 through the intraperitoneal route. Serial serum samples were collected from the rat at 0, 3, 7, 14, 21, 28, 35, 42, 60, 90, and 120 days after inoculation. The sera were tested by
enzyme linked
immunosorbent assay. We have noticed a very low level and short persistence of
IgA antibody in our experiment. The low level and short persistence of
IgA antibody suggest that this antibody isotype might not be protective against
brucellosis in rats. Both Th1 and Th2 specific immune responses were recorded in our study with the production of
IgG1 and
IgG2a antibody
isotopes, respectively. We noticed significant dominant
IgG2a antibody responses over
IgG1 responses throughout the experiment (p < 0.001) against WCA and OMP. The mixed Th1 and Th2 dominant immune responses mediated by
IgG2a and
IgG1 antibody isotypes were observed against CP, PP, and CBP. Data of our study suggest that
IgG2a dominant responses in the early stages of disease play the main role in conferring protection against
brucellosis and with the progress of disease
IgG1 dominant responses were elicited.