Epitope-based vaccines with the Anaplasma marginale MSP1a functional motif induce a balanced humoral and cellular immune response in mice

PLoS One. 2013 Apr 8;8(4):e60311. doi: 10.1371/journal.pone.0060311. Print 2013.

Abstract

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 presents a protective humoral immune response; however, its efficacy is variable. Immunodominant epitopes seem to be a key-limiting factor for the adaptive immunity. We have successfully demonstrated that critical motifs of the MSP1a functional epitope are essential for antibody recognition of infected animal sera, but its protective immunity is yet to be tested. We have evaluated two synthetic vaccine formulations against A. marginale, using epitope-based approach in mice. Mice infection with bovine anaplasmosis was demonstrated by qPCR analysis of erythrocytes after 15-day exposure. A proof-of-concept was obtained in this murine model, in which peptides conjugated to bovine serum albumin were used for immunization in three 15-day intervals by intraperitoneal injections before challenging with live bacteria. Blood samples were analyzed for the presence of specific IgG2a and IgG1 antibodies, as well as for the rickettsemia analysis. A panel containing the cytokines' transcriptional profile for innate and adaptive immune responses was carried out through qPCR. Immunized BALB/c mice challenged with A. marginale presented stable body weight, reduced number of infected erythrocytes, and no mortality; and among control groups mortality rates ranged from 15% to 29%. Additionally, vaccines have significantly induced higher IgG2a than IgG1 response, followed by increased expression of pro-inflammatory cytokines. This is a successful demonstration of epitope-based vaccines, and protection against anaplasmosis may be associated with elicitation of effector functions of humoral and cellular immune responses in murine model.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs / immunology
  • Anaplasma marginale / immunology*
  • Anaplasmosis / immunology*
  • Anaplasmosis / prevention & control
  • Animals
  • Antibodies, Bacterial / blood
  • Antibodies, Bacterial / immunology
  • Bacterial Outer Membrane Proteins / chemistry
  • Bacterial Outer Membrane Proteins / immunology*
  • Bacterial Vaccines / immunology*
  • Cattle
  • Cytokines / genetics
  • Cytokines / immunology
  • Disease Models, Animal
  • Epitopes / genetics
  • Epitopes / immunology*
  • Erythrocytes / immunology
  • Erythrocytes / virology
  • Female
  • Immunity, Cellular*
  • Immunity, Humoral*
  • Immunization
  • Immunoglobulin G / blood
  • Immunoglobulin G / immunology
  • Inflammation Mediators / immunology
  • Mice
  • Peptides / chemical synthesis
  • Peptides / immunology
  • Spleen / cytology
  • Spleen / immunology
  • Transcription, Genetic

Substances

  • Antibodies, Bacterial
  • Bacterial Outer Membrane Proteins
  • Bacterial Vaccines
  • Cytokines
  • Epitopes
  • Immunoglobulin G
  • Inflammation Mediators
  • Peptides
  • major surface protein 1a, Anaplasma

Grants and funding

Funding provided by CNPq (National Agency for Scientific and Technological Development); MAPA (Ministry of Agriculture and Livestock Production); FAPEMIG (Minas Gerais State Agency for Research Development – PRONEX); CAPES (Brazilian Federal Agency for the Support and Evaluation of Graduate Education, Rede Nanobiotec/Brasil). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.