INTRODUCTION: Red blood cells (RBCs), also known as erythrocytes, are underestimated in their role in the immune system. In mammals, erythrocytes undergo maturation that involves the loss of nuclei, resulting in limited transcription and protein synthesis capabilities. However, the nucleated nature of non-mammalian RBCs is challenging this conventional understanding of RBCs. Notably, in bony fishes, research indicates that RBCs are not only susceptible to pathogen attacks but express immune receptors and effector molecules. However, given the abundance of RBCs and their interaction with every physiological system, we postulate that they act in surveillance as sentinels, rapid responders, and messengers. METHODS: We performed a series of in vitro experiments with Cyprinus carpio RBCs exposed to Aeromonas hydrophila, as well as in vivo laboratory infections using different concentrations of bacteria. RESULTS: qPCR revealed that RBCs express genes of several inflammatory cytokines. Using cyprinid-specific antibodies, we confirmed that RBCs secreted tumor necrosis factor alpha (TNFα) and interferon gamma (IFNγ). In contrast to these indirect immune mechanisms, we observed that RBCs produce reactive oxygen species and, through transmission electron and confocal microscopy, that RBCs can engulf particles. Finally, RBCs expressed and upregulated several putative toll-like receptors, including tlr4 and tlr9, in response to A. hydrophila infection in vivo. DISCUSSION: Overall, the RBC repertoire of pattern recognition receptors, their secretion of effector molecules, and their swift response make them immune sentinels capable of rapidly detecting and signaling the presence of foreign pathogens. By studying the interaction between a bacterium and erythrocytes, we provide novel insights into how the latter may contribute to overall innate and adaptive immune responses of teleost fishes.

• MeSH
• Aeromonas hydrophila * imunologie   MeSH
• cytokiny * metabolismus   imunologie   MeSH
• erytrocyty * imunologie   metabolismus   MeSH
• fagocytóza imunologie   MeSH
• gramnegativní bakteriální infekce * imunologie   MeSH
• kapři * imunologie   mikrobiologie   MeSH
• nemoci ryb * imunologie   mikrobiologie   MeSH
• PAMP struktury imunologie   MeSH
• přirozená imunita MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

INTRODUCTION: Carp edema virus (CEV) is a fish poxvirus that primarily infects the gills of common carp. CEV causes koi sleepy disease (KSD), which is highly contagious and can result in mortality of up to 100%. METHODS: In the present study, we analyzed the stress and immune responses during KSD in two strains of common carp with different resistance to CEV: susceptible koi and resistant Amur sazan. Experiments were performed at two temperatures: 12°C and 18°C. In the case of koi carp, we also analyzed the effect of supplementation of 0.6% NaCl into tank water, which prevents mortality of the CEV-infected fish (salt rescue model). RESULTS: We found that CEV-infected koi kept at 18°C had the highest viral load, which correlated with the most severe histopathological changes in the gills. CEV infection resulted in the activation of stress response reflected by the upregulated expression of genes involved in stress response in the stress axis organs and increased levels of cortisol and glucose in the blood plasma. These changes were the most pronounced in CEV-infected koi kept at 18°C. At both temperatures, the activation of antiviral immune response was observed in koi kept under freshwater and NaCl conditions upon CEV infection. Interestingly, a clear downregulation of the expression of adaptive immune genes was observed in CEV-infected koi kept under freshwater at 18°C. CONCLUSION: CEV induces a stress response and modulates adaptive immune response in koi, and this is correlated with the level of viral load and disease development.

• MeSH
• chlorid sodný MeSH
• edém MeSH
• imunita MeSH
• infekce vyvolané poxviry * MeSH
• kapři * MeSH
• nemoci ryb * MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH