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Protective effect of prior immunization on ocular paracoccidioidomycosis in guinea pigs
A Kamegasawa1, R M Viero, M T Rezkallah-Iwasso
1Disciplina de Oftalmologia da Faculdade de Medicina, UNESP, Campus de Botucatu, S. Paulo, Brazil.
Abstract:
The present study reproduced the experimental model of ocular paracoccidioidomycosis in guinea pigs, by the intracardiac inoculation of yeast-forms of P. brasiliensis. Ocular involvement was observed in 80% of the infected animals. The uvea, ciliary body, choroid, iris, lids and the conjunctiva were the structures most commonly affected. To protect the animals against the infection, an immunization protocol was standardized utilizing a P. brasiliensis soluble antigen in Freund's complete adjuvant, administered weekly, during 3 weeks, by the subcutaneous route. Two weeks later, previously immunized guinea pigs were challenged by the intracardiac route with yeast-forms of P. brasiliensis (vaccinated group). When compared with a control group (infection in the absence of prior immunization), the vaccinated animals developed higher levels of anti-P. brasiliensis cellular and humoral immune response and a three times lower frequency of ocular involvement (85.7% vs 28.5%). In addition, the ocular lesions were significantly more localized and contained less fungal cells. The data demonstrated that the subcutaneous immunization was effective in decreasing the frequency and extent of ocular lesions, as well as in blocking fungal multiplication.
Insights
This study developed an immunization strategy against ocular paracoccidioidomycosis in guinea pigs. Vaccination significantly reduced eye infections and fungal load, demonstrating its protective efficacy.
Area of Science:
- Ophthalmology
- Mycology
- Immunology
Background:
- Ocular paracoccidioidomycosis is a significant clinical manifestation of Paracoccidioides brasiliensis infection.
- Experimental models are crucial for understanding disease pathogenesis and developing therapeutic strategies.
Purpose of the Study:
- To establish and validate an experimental model of ocular paracoccidioidomycosis in guinea pigs.
- To evaluate the efficacy of a P. brasiliensis soluble antigen-based immunization protocol in preventing ocular disease.
Main Methods:
- Guinea pigs were inoculated intracardiac with P. brasiliensis yeast-forms to induce ocular infection.
- An immunization protocol involved subcutaneous administration of P. brasiliensis antigen with Freund's complete adjuvant over three weeks.
- Vaccinated and control groups were challenged with P. brasiliensis, and ocular involvement was assessed.
Main Results:
- Ocular involvement was observed in 80% of infected guinea pigs, affecting structures like the uvea, ciliary body, and conjunctiva.
- Vaccinated animals exhibited higher anti-P. brasiliensis cellular and humoral immune responses.
- Vaccination reduced the frequency of ocular involvement by three times (85.7% vs. 28.5%) and decreased fungal load in lesions.
Conclusions:
- Subcutaneous immunization with P. brasiliensis antigen effectively protects against experimental ocular paracoccidioidomycosis.
- The immunization protocol decreases the incidence and severity of ocular lesions and inhibits fungal proliferation.
- This study provides a foundation for developing preventative strategies against Paracoccidioides brasiliensis-induced eye infections.