THE REPERTOIRE OF ANAPLASMA-MARGINALE ANTIGENS RECOGNIZED BY CD4-LYMPHOCYTE CLONES FROM PROTECTIVELY IMMUNIZED CATTLE IS DIVERSE AND INCLUDES MAJOR SURFACE PROTEIN-2 (MSP-2) AND MSP-3( T)
Wc. Brown et al., THE REPERTOIRE OF ANAPLASMA-MARGINALE ANTIGENS RECOGNIZED BY CD4-LYMPHOCYTE CLONES FROM PROTECTIVELY IMMUNIZED CATTLE IS DIVERSE AND INCLUDES MAJOR SURFACE PROTEIN-2 (MSP-2) AND MSP-3( T), Infection and immunity (Print), 66(11), 1998, pp. 5414-5422
Major surface proteins of Anaplasma marginale are vaccine candidates.
We recently demonstrated that immunization of calves with outer membra
nes of the Florida strain of A. marginale resulted in protective immun
ity that correlated with a memory CD4(+) T-lymphocyte response specifi
c for major surface protein 1 (MSP-1), MSP-2, and MSP-3 (W. C. Brown,
V. Shkap, D. Zhu, T. C. McGuire, W. Tuo, T. F. McElwain, and G. H. Pal
mer, Infect. Immun. 66:5406-5413, 1998). As immunogens, these proteins
have been shown to induce complete or partial protection against homo
logous challenge. To further define the T helper (Th) cell response to
these and other A. marginale antigens and to determine conservation o
f Th cell epitopes among genetically distinct A. marginale strains, Th
cell clones obtained prior to challenge hen? three immunized calves w
ere characterized for antigen-specific responses. Nine distinct antige
nic profiles were defined by 11 Th cell clones derived by stimulation
with the Florida strain. Several clones responded to MSP-2, MSP-3, or
both. All of these MSP-2-or MSP-3-specific clones and the majority of
other clones that did not respond to MSPs recognized all bovine blood-
passaged strains of A. marginale. These results demonstrate conservati
on of certain Th cell epitopes between MSP-2 and MSP-3 and show that T
h cell epitopes in MSP-2, MSPs, and undefined antigens are conserved a
mong strains of A. marginale. Of seven clones that responded to the bl
ood-passaged Virginia strain, two did not recognize antigen prepared f
rom this strain cultured in tick cells, suggesting differences in the
antigenic composition between these stages. Analysis of the cytokines
expressed by the Th cells revealed that all clones expressed gamma int
erferon and tumor necrosis factor alpha, and most coexpressed interleu
kin-4. Our results provide a rationale for identifying Th cell epitope
s conserved among different strains of A. marginale for inclusion in a
nucleic acid or recombinant protein vaccine.