| Congresso Brasileiro de Microbiologia 2023 | Resumo: 951-2 | ||||
Resumo:Paracoccidioidomycosis presents a gamut of clinical manifestations, caused by both, the characteristics of the host response and to variability in virulence of the infecting Paracoccidioides brasiliensis strains. Severe forms of the disease are accompanied by the gradual loss of specific cellular immune responses and high titer of specific antibodies in contrast to the mild forms of the disease that course with maintained cellular immune responses and low levels of specific antibodies. Here we investigated the presence of circulating fungal antigens and specific antibodies in susceptible and resistant mice infected with Paracoccidioides brasiliensis isolates varying in virulence. Circulating Paracoccidioides brasiliensis antigens were quantified using a competitive ELISA and specific antibody titres were determined using a non-competitive ELISA, employing the same Paracoccidioides brasiliensis antigen. Higher frequency of positive reactions and higher levels of circulating Paracoccidioides brasiliensis antigen were observed when mice of either strain were infected with the virulent fungal isolate as compared to infection with the slightly virulent one. Antigen levels were low in the resistant mice during the course of infection with the virulent Paracoccidioides brasiliensis isolate, and progressively increased in the susceptible mice, reaching high and significant levels 16 weeks post-inoculation with this virulent isolate. Our data demonstrate that the presence of circulating Paracoccidioides brasiliensis antigens is a consequence of very severe disease, reflecting an infection caused by a highly virulent Paracoccidioides brasiliensis isolate in genetically susceptible mice. Thus, both the genetic background of the host, as well as the virulence of the infecting fungal isolate are determinant factors for the presence or absence of antigenemia. To our knowledge, this is the first time antigenemia is described as a parameter of disease severity in a controlled experimental model of paracoccidiodomycosis. The possible consequences of the presence of fungal antigens in circulation in immune modulation are discussed. Palavras-chave: antibody, antigenemia, Paracoccidioidomycosis, Paracoccidioides brasiliensis , susceptibility Agência de fomento:CNPq e FAPEMIG | |||||