The course of infection with Toxoplasma gondii RH strain in mice pre-vaccinated with gamma irradiated tachyzoites

Toxoplasma gondii is a ubiquitous protozoan of major medical and veterinary importance. Its treatment is difficult since the available drugs have severe side effects and reactivation may occur anytime. Vaccination with irradiated parasites exhibits ideal characteristics for vaccine development. In o...

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Bibliographic Details
Published in:Experimental parasitology 2019-10, Vol.205, p.107733-107733, Article 107733
Main Authors: Gomaa, Ahmed M., El-Tantawy, Nora L., Elsawey, Aliaa M., Abdelsalam, Ramy A., Azab, Manar S.
Format: Article
Language:English
Subjects:
Gamma irradiation
Mice
Toxoplasma
Vaccine
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Summary:Toxoplasma gondii is a ubiquitous protozoan of major medical and veterinary importance. Its treatment is difficult since the available drugs have severe side effects and reactivation may occur anytime. Vaccination with irradiated parasites exhibits ideal characteristics for vaccine development. In our experimental mice model, the protection against challenge with the virulent RH strain was assessed, using 255Gy irradiated tachyzoites. Eighty mice were allocated into 3 groups: naive control group, challenged with virulent RH tachyzoites group and a third group which is challenged with 1 × 106 irradiated tachyzoites, administered as two biweekly doses intraperitoneally. Protection was tested by challenging vaccinated mice with the virulent type RH tachyzoites 30 days after the 2nd vaccination dose. The assessment was built on qualitative clinical, quantitative parasitological, histopathological parameters and measurement of serum Nitric Oxide (NO). The results showed prolonged survival rate, absence of tachyzoites in the peritoneal aspirate by counting, absence of tachyzoites in all examined organs by impression smears, amelioration of histopathological changes in the liver, spleen, brain and lung specimens and increase of the serum NO level in the vaccinated group. Therefore, we propose that irradiated Toxoplasma tachyzoites confer protection for challenged mice and could be an alternative immunization schedule for vaccine development especially for who are at risk of severe immunosuppression. [Display omitted] •There is a need for development of anti-Toxoplasma vaccine due to its fatal sequels besides the absence of efficient treatment.•Gamma irradiated tachyzoites provokes cellular immunity and cytokine responses as natural infection.•The survival rate, clinical assessment and histopathological changes events are improved in immunized mice with gamma irradiated RH tachyzoites.•Re-challenge of the immunized mice with RH Toxoplasma tachyzoites after long period (3–5 months) proved the development of memory immunity as the mice appeared healthy and survived.
ISSN:0014-4894
1090-2449
DOI:10.1016/j.exppara.2019.107733