RESUMO
Immunoglobulin molecules play an important role in the immune defense system in all jawed vertebrates, by protecting the organism from a wide variety of pathogens. Nile tilapia (Oreochromis niloticus) is extensively cultivated worldwide, with a strong established market demand. It constitutes one of the model species for the study of fish immunology and its genome is currently fully sequenced. The presence of the immunoglobulin M gene in this species is well documented, as well as its major role in systemic immunity. To date, the IgT gene from O. niloticus has not been identified and, therefore, no information is available on the role of this immunoglobulin isotype in the immune response in tilapia. In the present work, novel secreted and membrane immunoglobulin T isotypes and a fragment of IgM were isolated from tilapia head kidney lymphocytes. Their transcriptional profiles were analyzed by quantitative PCR in larval development and in different tissues of healthy or lipopolysaccharide/Edwardsiella tarda-challenged tilapia adults. The presence of IgT and IgM were detected in early stages of larval development. Additionally, these genes exhibited differential expression profiles in basal conditions and after E. tarda infection in adult tilapia, in accord with the proposed effector functions of these immunoglobulins in the systemic and mucosal compartments. Our results suggest the potential involvement of this new Ig in mucosal immunity in tilapia.
Assuntos
Ciclídeos/imunologia , Doenças dos Peixes/imunologia , Proteínas de Peixes/imunologia , Imunidade nas Mucosas , Imunoglobulinas/imunologia , Animais , Biomarcadores , Edwardsiella tarda/imunologia , Infecções por Enterobacteriaceae/imunologia , Infecções por Enterobacteriaceae/veterinária , Infecções por Enterobacteriaceae/virologia , Doenças dos Peixes/microbiologia , Proteínas de Peixes/genética , Proteínas de Peixes/isolamento & purificação , Perfilação da Expressão Gênica , Rim Cefálico/citologia , Imunoglobulinas/genética , Imunoglobulinas/isolamento & purificação , Larva/imunologia , Lipopolissacarídeos/imunologia , Linfócitos/metabolismo , FilogeniaRESUMO
Vibrio anguillarum and Edwardsiella tarda are severe aquaculture pathogens shared similar epidemiological characteristics and susceptible to flounder (Paralichthys olivaceus). In our previous studies, recombinant(r) protein heat shock protein 33 (rHsp33) from V. anguillarum and outer membrane protein C (rOmpC) from E. tarda were proved to have protection against V. anguillarum and E. tarda, respectively. In this paper, the cross protection of rHsp33 against E. tarda and rOmpC against V. anguillarum, and the protection of divalent vaccine candidate (rHsp33 + rOmpC, rHC) against both V. anguillarum and E. tarda were evaluated. RHC, rHsp33, and rOmpC were vaccinated to flounder, respectively, and the percentages of surface immunoglobulin-positive (sIg+) cells in peripheral blood lymphocytes (PBLs), serum IgM, specific antibodies against V. anguillarum or E. tarda, specific antibodies against rHsp33, rOmpC or rHC, the expression of immune-related genes and relative percent survival (RPS) against V. anguillarum or E. tarda were measured. The results showed that: RHC could induced the enhancement of sIg + cells and high levels of specific antibodies against both V. anguillarm and E. tarda; Also a significant increase of specific antibodies against rHsp33, rOmpC or rHC, and up-regulation of gene expression of CD3, CD4-1, CD4-2, CD8α, CD8ß and IgM in spleen, head-kidney, and hindgut, RPS of 70⯱â¯3.45% against V. anguillarum and 60⯱â¯1.48% against E. tarda, respectively. In addition, rHsp33 induced specific antibodies against E. tarda and rOmpC, and had a RPS of 43.3⯱â¯3.73% against E. tarda; rOmpC could evoke specific antibodies against V. anguillarum and rHsp33, and had a RPS of 44⯱â¯1.27% against V. anguillarm; The results demonstrated that there was cross protection of rHsp33 against E. tarda and rOmpC against V. anguillarum, rHC as a divalent vaccine can induce significant immune response and efficient protection against both E. tarda and V. anguillarum in flounder.
Assuntos
Proteínas de Bactérias/imunologia , Vacinas Bacterianas/farmacologia , Edwardsiella tarda/imunologia , Doenças dos Peixes/prevenção & controle , Linguados , Vibrio/imunologia , Animais , Infecções por Enterobacteriaceae/prevenção & controle , Proteínas de Choque Térmico/imunologia , Porinas/imunologia , Proteínas Recombinantes/imunologia , Vibrioses/prevenção & controleRESUMO
The histological lesions caused by Edwardsiella tarda in a variety of fish species, including tilapia, have been well characterized. There are apparent differences in the type of inflammatory response manifested by these different species, which may be due to the fish species itself, the phase of infection, or the virulence factors produced by different strains of E. tarda. In catfish, systemic abscesses involving muscles of the flank or caudal peduncle are the most common lesions. By contrast, infection in tilapia and red sea bream is more likely to be associated with granulomatous inflammation. Necrotic meningitis, encephalitis, and vasculitis with fibrinoid necrosis of the blood vessels walls, as well as the formation of a plaque-like structure in the brain, are described in the current study. The presence of E. tarda was confirmed by microbiological isolation and a positive nested polymerase chain reaction in paraffin wax-embedded tilapia tissues.