|De Cunha, Ivo|
Submitted to: Brazilian Journal of Veterinary Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/15/2010
Publication Date: 12/17/2010
Citation: Igarashi, M., Zulpo, D.L., De Cunha, I.A., Barros, L., Pereira, V., Taroda, A., Navarro, I.T., Vidotto, O., Vidotto, M.C., Jenkins, M.C., Garcia, J.L. 2010. Toxoplasma gondii: humoral and cellular immune response of BALB/c mice immunized via intranasal route with rTgROP2. Brazilian Journal of Veterinary Parasitology. 19:210-216. Interpretive Summary: Toxoplasma gondii is a parasite that is a leading cause of birth defects in humans caused by an infectious agent. The parasite is transmitted after humans (and other warm-blooded animals) ingest either the oocyst stage (contaminating cat litter) or meat containing T. gondii cysts. A vaccine to prevent toxoplasmosis is desired as a way to prevent infection in humans and animals. A candidate vaccine comprised of an immunogenic T. gondii protein, namely TgROP2, was evaluated in the present study. Mice were vaccinated by nasal immunization with a recombinant TgROP2 protein that was produced in Escherichia coli using DNA cloning technology. Vaccinated mice produced antibodies specific for TgROP2. In addition, a cellular immune response to TgROP2 was observed in vaccinated mice. These data indicate that immunizing animals (and possibly humans) with recombinant TgROP2 protein via nasal route of administration may be a viable way to elicit protective immunity against toxoplasmosis. This information will be of interest to vaccine producers and health care workers in developing immunization strategies against Toxoplasmosis.
Technical Abstract: TgROP2 is an intracellular protein associated with rhoptries of Toxoplama gondii and an antigen component of a candidate vaccine for toxoplasmosis. The purpose of the present study was to evaluate the efficacy of rTgROP2 to stimulate humoral and cellular immune responses in BALB/c mice via intranasal injection. TgROP2 partial coding sequence was (196-561) amplified by PCR from genomic T. gondii RH strain DNA and cloned into the pTrcHis expression vector. Escherichia coli Rosetta 2 cells transformed with pTrcHis-TgROP2 showed high levels (1 mg/mL) of recombinant protein after 4 hours of IPTG induction. Recombinant TgROP2 exhibited an apparent Mr equal to 54 kDa. In order to test immunogenicity of the recombinant protein, 10 BALB/c mice received 10 ìg of rROP2 protein + 10 ìg of Quil-A via intranasal injection. Doses were administered at days 0, 21, and 42. Three animals were euthanized and used to evaluate cellular immune response on day 62. Five (50%) and two (20%) out of ten animals produced IgG (DO mean = 0.307; cut-off = 0.240) and IgA (DO mean = 0.133, cut-off = 0.101), respectively, by ELISA on day 62. The proliferation of splenocytes revealed high stimulation index (SI) when co-cultured with 5, 10 and 15 ug/mL of rTgROP2. These results indicate that intranasal immunization with recombinant protein ROP2 plus Quil-A can elicit both cellular and humoral immune responses in BALB/c mice.