title: Administration of naloxone in combination with recombinant Plasmodium vivax AMA-1 in BALB/c mice induces mixed Th1/Th2 immune responses.
abstract: Naloxone (NLX) has the ability to shift the immune response to a Th1 profile. Therefore, the adjuvant efficacy of NLX with recombinant P. vivax apical membrane antigen-1(rPvAMA-1) in BALB/c mice was evaluated. Mice were immunized subcutaneously with purified rPvAMA-1 formulated with NLX (doses of 5 mg/kg body weight) alone or in combination with IFA. A significant increase in anti-PvAMA-1 IgG antibody after the second boost (mean OD490= 2·08 and 2·17, in groups received, rPvAMA-1/NLX and rPvAMA-1/NLX/IFA, respectively) was detected. IgG1 and IgG2b were the predominant isotypes in all immunized mouse groups. In immunized mice with rPvAMA-1/NLX (mean: 1036 pg/mL) and with rPvAMA-1/NLX/IFA (mean: 1024 pg/mL), IFN-γ was elicited in response to rPvAMA-1 after the second boost. No detectable IL-4 secretion was determined in all tested groups. In conclusion, the administration of NLX alone or NLX/IFA with rPvAMA-1 in BALB/c mice, which induced mixed Th1/Th2 immune responses, was comparable with that of the same recombinant antigen with CFA/IFA adjuvant. The results indicate that NLX alone may possibly not be considered as a potent Th1 adjuvant in PvAMA-1-based vaccine. However, in order to modulate immune responses from mixed Th1/Th2 to strong and protective Th1 response, further study is warranted on combination of NLX with other adjuvants such as CpG motifs or MPL in proper vaccine formulation. Additionally, dose-response study is necessary to determine the effect of different doses of antigen combined with NLX (at various doses) in Balb/c mice.
authors.affiliation: Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Tehran, Iran.|Department of Immunology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: M A
authors.initials: MA
authors.lastname: Someabozorg
authors.affiliation: Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Tehran, Iran.
authors.forename: S
authors.initials: S
authors.lastname: Mirkazemi
authors.affiliation: Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Tehran, Iran.
authors.forename: A A
authors.initials: AA
authors.lastname: Mehrizi
authors.affiliation: Department of Immunology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: F
authors.initials: F
authors.lastname: Shokri
authors.affiliation: Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Tehran, Iran.
authors.forename: N D
authors.initials: ND
authors.lastname: Djadid
authors.affiliation: Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Tehran, Iran.
authors.forename: S
authors.initials: S
authors.lastname: Zakeri
keywords: Apical membrane antigen 1; Plasmodium vivax; Th1/Th2 responses; naloxone; vaccine adjuvant