Mixture of Alum - Naloxone and Alum - Naltrexone as a novel adjuvant elicits immune responses for Toxoplasma gondii lysate antigen in BALB /c mice

Toxoplasma gondii (T. gondii) is an obligate intracellular parasite. Treatment of the infection induced by
this parasite is not straightforward due to the toxic side effects of the available drugs. Vaccine development
could be a solution to this problem. In the present study, T.gondii Lysate Antigen (TLA), as a
model vaccine, in combination with the Alum-NLT (Aluminum phosphate-Naltrexone) and Alum-NLX
(Aluminum phosphate-Naloxone) were evaluated for immunization BALB/c. 147female BALB/c mice
which were divided into seven groups of 21, were allocated to immunization experiments. The first
group was selected as the negative control group, followed by the second, third, fourth, fifth, sixth and
seventh groups which were immunized with Vac, Vac-Alum, Vac-NLX, Vac-NLT, Vac-Alum-NLX, Vac-
Alum-NLT, respectively. Ten days after the final immunization, mice in all groups were divided into
three groups for evaluating cellular immune responses, measuring the delayed-type hypersensitivity
responses (DTHs) and evaluating survival. The DTH and cellular immune responses showed that in
mice immunized with the TLA vaccine combined with the Alum-NLT mixture, the efficacy improved by
increasing the production of Interleukin-5(IL-5) and Interferon gamma. This consequently shifted the
immune responses toward a Th1 profile by increasing the IFN-g/IL-5 ratios. In challenge experiments,
immunized mice with the Alum-NLT-Vac mixture survived for a longer period of time which indicated
an improvement in protective immunity against T. gondii. Administration of the Alum-NLT mixture