Presence of Natural Antibodies in Broad-Snouted Caiman (Caiman latirostris) serum

SIROSKI, PABLO A.; LATORRE, MARÍA A.; MOLEÓN, SOLEDAD; POLETTA, GISELA L.; ORTEGA, HUGO H.

Lake Charles

Congreso; 23rd Working Meeting of the Crocodile Specialist Group; 2014

Presence of Natural Antibodies in Broad-Snouted Caiman (Caiman latirostris)serum Pablo A Siroski1,2,3, María A. Latorre2,3, Soledad Moleón1,2,3, Gisela L. Poletta2,3,4 and Hugo H. Ortega1,3 {1}Instituto de Ciencias Veterinarias del Litoral (ICiVet Litoral-UNL-CONICET). {2}Proyecto Yacaré-Lab. Zoología Aplicada: Anexo Vertebrados (FHUC-UNL/MASPyMA).{3}CONICET. {4}Cát Toxicol. y Bioq. Legal, FBCB-UNL. Crocodilians suffer serious injuries caused by different reasons but usually they do not show signs of diseases. Based on that, they have been objects of many studies, mainly related to innate immunity. This immunity, more ancestral than the acquired, provides the first-line of protection against pathogenic microbes where appear two interrelated humoral components: natural antibodies (NAbs) and complement system (CS). The CS has been characterized in many crocodilian species highlighting its remarkable ability to recognize and eliminate antigens. Additionally, NAbs are encoded directly by the germ-line genome and do not require somatic hypermutation and recombination during ontogenesis like occurs with the adaptive antibody repertoire. Natural antibodies have not been studied yet in any crocodilian or reptiles species. In the current study, we detected the presence of NAbs in Broad-snouted Caiman serum from different ages and nest, and characterized them under different laboratory conditions. Rabbit red blood cells were used in the hemagglutination assays and the titres of NAbs were measured. Results showed that neonates have 4 and 5 titres lower than one or two year old animals, and in both cases, temperature dependence was found. Although NAbs are the only immunoglobulins that do not require a previous contact with specific antigens, they always need a first exposure to antigens to put on work its mechanism of production, and this happen after hatching. This can explain the difference found in Nabs between neonate and juvenile caimans. These results allow us to propose NAbs as unspecific marker of the humoral immunocompetence.