| Marek's Disease(MD)is a disease caused by Marek's Disease Virus(MDV)that causes tumorigenesis.It is clinically divided into four types: neurological and cutaneous.Visceral and eye type.The mortality rate of this disease is extremely high,and it spreads rapidly and is extremely harmful.The metabolism,immunity and health of the animal body are closely related to the horizontal and horizontal of the intestinal flora.The largest immune organ in the animal's body is the intestine.The intestinal flora and the animal's body are mutually beneficial.Only when the animal's intestinal flora is balanced,can the animal's healthy growth be maintained.In this study,MDV was used to infect SPF fowls,and tissue sections of fowls liver,spleen,jejunum and cecum were made by HE staining to observe the pathological changes of various tissues.MDV-infected fowls and control fowls were processed by high-throughput sequencing technology.The composition of microbial contents in the jejunum was analyzed to analyze the effects of MDV infection on the diversity of fowls jejunal flora.The lactic acid content and hyaluronic acid in serum and jejunum contents were detected by ELISA,colorimetry and microplate method.The content,lactate dehydrogenase activity and lactase activity were studied to study the effects of MDV infection on intestinal and blood biochemical parameters of fowls,and to explore the relationship between the changes and intestinal flora diversity.Histopathological examination showed that MDV infected fowl jejunum,cecum,spleen,liver and other tissues have bleeding,congestion and large areas of inflammatory infiltration.The results of high-throughput sequencing showed that there was a change in the diversity of jejunal flora in MDV-infected fowls compared with control fowls.There were 24 species with significant differences in genus levels,and 6 of them had extremely significant differences(P<0.01),there are 18 kinds of bacteria with significant difference(P<0.05),the pathogenic bacteria showed an upward trend,the beneficial bacteria(such as lactic acid bacteria)showed a downward trend,and the pathogenic bacteria(such as staphylococcus,actinomycetes,etc.)The pathogenic characteristics are closely related to MD,indicating that MDV infection can change the microbial diversity of jejunum and affect its species and quantity.This may be an important factor leading to the formation of clinical symptoms of intestinal and organ bleeding during the pathogenesis of MD.Analysis of lactic acid,lactate dehydrogenase,hyaluronic acid and lactase in fowl serum and jejunum contents of MDV-infected fowls showed that lactic acid content and hyaluronic acid in serum and jejunal contents of MDV-infected fowls compared with fowls in normal control group.The content wasup-regulated,the difference was extremely significant(P<0.01);the activity of lactate dehydrogenase was up-regulated,the difference was significant(P<0.05);the activity of lactase was down-regulated,and the difference was extremely significant(P<0.01).The results showed that MDV infection had significant or significant effects on blood and jejunal lactic acid content,hyaluronic acid content,lactase activity,lactate dehydrogenase activity,etc.,which may be due to changes in intestinal flora affecting the body.Metabolic pathway and related enzyme activity.This study shows that MDV infection can affect the blood biochemical parameters by affecting the intestinal flora diversity and intestinal metabolite components,which may be one of the factors causing MDV.The results of this study can provide reference for the development and clinical diagnosis of MD prevention and control drugs,laying a foundation for the healthy breeding of poultry. |
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