Study On The Role Of Duck Galectin-1 In Host Anti-duck Virus Infection

Galectin is a member of the lectin family.It contains 15 carbohydrate binding proteins and is highly conserved in animal evolution.Already 15 mammalian galectins have been identified,and animal galectin is part of a S-type lectin with a conserved CRD that protects against certain bacteria,fungi and viruses in animals.Many galectins have a variety of biological functions that play a role in inflammatory responses,cell growth,cell trafficking,and antiviral responses.As a homodimer,the prototype galectin-1 can be widely present in a variety of immune-related cells,such as thymic epithelial cells,T cells,macrophages,and stimulated B cells.Besides,Galectin-1 can be found as an important regulator of T cells.Many different organs and cells can express galectin,including muscle,heart,liver,kidney,prostate,lymph nodes,spleen,thymus,placenta,retina,and in other immune and non-immune cells.Studies have found that galectin-1 can alter neuroinflammation,and like other galectin,it regulates the interaction between host and pathogen.Although galectin-1 has been extensively studied in mammals,studies on poultry have been relatively rare.Thus,the biological function of galectin-1 in Cherry Valley ducks and its relationship with the innate immune response to duck plague virus were systematically studied for the first time in this study.In this study,the Cherry Valley Duck was used as an experimental animal.The research content mainly includes three parts:Part ? The Cloning and Sequence Identification of Galectin-1 from Cherry Valley duck.The specific primers were designed according to the predicted conserved region of duck galectin-1 gene,and the cDNA obtained by reverse transcription of healthy Cherry Valley ducks' spleen was used as a template,and amplified with specific primer(duGal-1-F1 / R1).The target fragment was sequenced and found that the protein coding region consisted of 405 bp,encoding 135 amino acids.Its molecular weight is about 14.8 kDa.The results of SMART and other software analysis showed that galectin-1contained no specific signal peptide.According to the results of phylogenetic tree,the galectin-1 sequence cloned in this study hadthe highest homology with Anas platyrhynchos,the homology was 98.8%,and the homology with chicken was 87.2%.The galectin-1 amino acid sequence has higher amino acid sequence similarity to other bird galectin,and has lower amino acid sequence similarity to reptiles and mammalians galectin.Part ? The distribution of galectin-1 in various tissues of Cherry Valley DuckTotal RNA was extracted from the heart,liver,spleen,lung,kidney,brain,cerebellum,brainstem,thymus,pancreas,bursa,trachea,esophagus,musculature and glandular stomach of healthy cherry valley duck to determine the distribution of galectin-1 in various tissues.Using fluorescent quantitative PCR,it was found that the expression level of galectin-1 in the healthy cherry valley duck was higher in the trachea,lung and skin,and the highest in the heart.It is weakly expressed in the liver,spleen,kidney,thymus,ileum,thymus,duodenum and jejunum.After the cherry valley duck was infected with duck plague virus,the expression level of galectin-1 was detected to be up-regulated.Galectin-1 in the liver of the challenge group increased 4.5-fold at 1 dpi,2.8-fold at 3 dpi,and 1.7-fold at 4 dpi compared to the untreated group.In the spleen,the expression level of galectin-1 was greatly increased in a short time: 8.2 times at 1 dpi and 4.3 times at 2 dpi.In the brain,the expression level of galectin-1 was significantly up-regulated at 1 dpi and 2 dpi,but decreased at 3 and 4 dpi.Part ? Detection of related cytokines induced by galectin-1In order to study the innate immune response mediated by galectin-1,the relationship between the expression of galectin-1 and the expression of related cytokines was studied by interfering RNA and overexpressing galectin-1.Studies have shown that after overexpression of galectin-1,the expression levels of ISGs(Mx,PKR,OAS)and some cytokines such as IL-2,IL-1?,IFN-? are up-regulated to varying degrees,Mx up 8.4 times,OAS up 6.8 times.The inflammatory cytokines IL-1?,IL-2 increased to varying degrees,and the expression of IFN-? was significantly up-regulated.In contrast,the expression of galectin was knocked down by interfering RNA,and it was found that the expression levels of ISGs and some inflammatory cytokines were down-regulated,for example,at 24 hpi,Mx is down-regulated by 4.2-fold and IL-1? is down-regulated by 4.5-fold,The results indicate that galectin-1 can up-regulate the expression of ISGs and other cytokines and mediate the host's antiviral immune response.After overexpressing duGal-1or interfering with galectin-1,the viral loadwas detected,and the results showed that galectin-1 had a significant inhibitory effect on the early stage replication of duck plague virus.This experiment provides a possibility for further analysis of the signaling pathway of galectin-1 in innate immune response and its inhibition on duck plague virus replication in the future.