RESUMO
Pentraxins are important molecules in innate defence and play a role in the acute phase response of both mammals and fish. Isolation of cod pentraxins by affinity chromatography using phosphorylcholine agarose revealed two pentraxin-like proteins, referred to as PI and PII proteins. These varied in their overall charge, pentameric and subunit molecular size, glycosylation and N-terminal amino acid sequences. The PI protein was homologous with the CRP-like pentraxin previously described in cod whereas the PII protein was a new CRP homologue, which was characterized by substantial individual heterogeneity with regard to subunit size and relative density. The results indicate considerable genetic variations in the cod pentraxins.
Assuntos
Proteína C-Reativa/isolamento & purificação , Proteínas de Peixes/isolamento & purificação , Gadus morhua/sangue , Gadus morhua/imunologia , Sequência de Aminoácidos , Animais , Anticorpos Monoclonais/metabolismo , Proteína C-Reativa/química , Proteína C-Reativa/ultraestrutura , Cromatografia de Afinidade , Cromatografia por Troca Iônica , Proteínas de Peixes/química , Proteínas de Peixes/ultraestrutura , Glicosilação , Ligantes , Dados de Sequência Molecular , Alinhamento de Sequência , Análise de Sequência de ProteínaRESUMO
Piscirickettsia salmonis is pathogenic for a variety of cultured marine fish species worldwide. The organism has been observed within host macrophages in natural disease outbreaks among coho salmon and European sea bass. In vitro studies, incorporating transmission electron microscopy (TEM) and ferritin loading of lysosomes, have confirmed that P. salmonis is capable of surviving and replicating in rainbow trout macrophages. Certain features of this intracellular survival underline its difference to other intracellular pathogens and suggest that a novel combination of defence mechanisms may be involved. Escape into the macrophage cytoplasm is not used as a means to avoid phago-lysosomal fusion and the organism remains at least partly enclosed within a vacuole membrane. While the piscirickettsial vacuole is often incomplete, survival and replication appear to require occupation of a complete, tightly-apposed, vacuolar membrane which does not fuse with lysosomes. Unlike some mammalian rickettsiae, actin-based motility (ABM) is not used as a means of intercellular spread. It is postulated that the presence of numerous small vesicles within vacuoles, and at gaps in the vacuolar membrane, may result from the blebbing of the piscirickettsial outer membrane seen early in the infection.