immunology of infectious and parasitic diseases - XXXVII Congress ...

Critical motifs of the Anaplasma marginale MSP1a functional epitope
protect mice by balancing humoral and cellular immune response
PAULA DE SOUZA SANTOS (1); ANGELA APARECIDA SERVINO DE SENA
(1); RAFAEL NASCIMENTO (1); THAISE GONÇALVES ARAÚJO (1); MIRIAN
MACHADO MENDES (1); TIAGO WILSON PATRIARCA MINEO (1); LUIZ
RICARDO GOULART (1)
(1). Federal University of Uberlândia
Introduction: Bovine anaplasmosis is a hemoparasitic disease that causes
considerable economic loss to the dairy and beef industries. Cattle immunized
with the Anaplasma marginale MSP1 outer membrane protein complex present
a protective humoral immune response; however, the efficacy of these vaccines
is variable. The immunodominance of epitopes seems to be a key-limiting factor
for the adaptive immunity. We have successfully demonstrated that a critical
motif of the MSP1a functional epitope is essential for antibody recognition of
infected animal sera (PLoS One 7(3):e33045, 2012) , but its potential to induce
protective immunity is yet to be tested.
Methods and Results: We have evaluated two synthetic vaccine formulations
(Am1 and Am2) against A. marginale, using epitope-based approach. The
experiments were carried out in murine model, which were immunized with
peptides conjugated to bovine serum albumin in three 15-day interval
intraperitoneal injections before challenge with live bacteria. Blood samples
were analyzed for the presence of specific IgG antibodies, along with IgG2a and
IgG1 antibodies, as well as for the rickettsemia analysis. Additionally, a panel
containing the transcription of innate and adaptive immune responses‟
cytokines was carried out through qPCR. After challenge with A. marginale, it
was observed that mice immunized with synthetic peptides presented stable
body weight and no mortality, along with reduced number of infected
erythrocytes (75%). In addition, the immunization process induced significantly
higher production of specific IgG2a than IgG1 antibodies, along with an
increased in situ expression of pro-inflammatory cytokines.
Conclusion: we have demonstrated that the two synthetic peptides obtained
from critical motifs within the MSP1a functional epitope were able to induce an
effective immune response in mice, associated with the upregulation of effector
functions of humoral and cellular immune responses, reinforcing the use of
synthetic epitopes as vaccine targets against bovine anaplasmosis, aiming
bacterial clearance and diminished pathogenesis.
Financial Support: CNPq, FAPEMIG and CAPES.