Early high avidity specific IgG production in experimental hamster visceral leishmaniasis

Author(s)

de Carvalho, Camila Aparecida ^{[1, 2]} ; Ferrao, Thiago Fidelis ^[1] ; Cavalcante, Fernanda Siqueira ^[1] ; Novais de Freitas, Flavia Regina ^[1] ; Meireles, Luciana Regina ^[1] ; de Andrade Junior, Heitor Franco ^[1]

Affiliation

^[1] Univ Sao Paulo, Inst Med Trop, Fac Med, Sao Paulo - Brazil

^[2] Inst Med Trop Sao Paulo, Protozool Lab, Ave Doutor Eneas Carvalho Aguiar 470, BR-05403000 Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: Parasitology Research; v. 119, n. 11 AUG 2020.
• Web of Science Citations: 0

Abstract

Visceral leishmaniasis (VL) byLeishmania (Leishmania) infantumis epidemic in Brazil. Hypergammaglobulinemia appears early in patients with VL and is ineffective. Usually, high-affinity IgG B cells are selected during most infections, a critical step for an effective humoral response. The avidity of IgG antibodies in VL is unexplored due to the absence of temporal parameters in most patients, associated to low clinical significance. Experimental infection models overcome this fact, allowing the monitoring of the disease temporal evolution. In this study, the avidity of IgG antibodies was evaluated in experimental models, in infection in hamsters, and in immunization in rabbits. Specific IgG antibodies were detected by ELISA, using chaotropic solution to determine avidity, as reported for viral infections. The levels of IgG antibodies correlated with the progression of experimental infection in hamsters or antigenic stimulation in immunized rabbits. However, IgG avidity was high early in infected animals, even in early periods (> 80%), while in immunized rabbits, they had early antibodies of low avidity with progressive maturation, similar as other infections. These data suggest that the affinity maturation of the avidity of anti-LeishmaniaIgG antibodies promoted at an early stage, influencing the appropriate interaction between antigens and affecting the disease progression. This fact could be associated to monovalent immune complexes, as reported in human and experimental VL. This scenario may be related to an independent process of immune cell activation by the parasite but absent in antigen preparation used as immunogens. (AU)

• FAPESP's process: 17/26558-9 - Haptens in visceral leishmaniasis. Development of solid phase assays for diagnosis and its immunology in experimental models.
• Grantee: Heitor Franco de Andrade Junior
• Support Opportunities: Regular Research Grants
• FAPESP's process: 17/14675-0 - Humoral immune response to haptens of L. (L.) infantum chagasi by detection of specific and natural antibodies in experimental and natural visceral leishmaniasis
• Grantee: Camila Aparecida de Carvalho
• Support Opportunities: Scholarships in Brazil - Post-Doctoral