Genetic Variation And Transmitting Rule Of Cryptosporidium Parvum From Dairy Cattle In Concentrated Animal Feeding Operations

Cryptosporidium is an important intestinal pathogen that causes diarrhea in animals and humans.Among them,Cryptosporidium parvum can cause moderate or severe diarrhea and even death in young ruminants.Cryptosporidiosis has an impact on the growth and development of young ruminants,and also has a serious impact on the economy of animal husbandry.Nowadays,intensive farming has become a trend in the development of global animal husbandry.However,intensive farming,while increasing the economy of animal husbandry,has also promoted the emergence of new zoonotic diseases.Intensive farming has accelerated the genetic variation of pathogens and accelerated the spread of pathogens in the animal population.The purpose of this study was to study the genetic variation of C.parvum from dairy cattle under the background of intensive farming,and the transmission mechanism of C.parvum in China.This provides the basis and basis for the effective prevention and control of Cryptosporidium.The specific research contents are as follows:1.A random effects model was used to conduct a meta-analysis of the global prevalence and risk factors of C.parvum in dairy cattle.A pooled effect statistic was estimated for the global prevalence of C.parvum in dairy cattle(21.9%;95% CI: 19.9-23.9%;7755/42890).C.parvum infection was high in pre-weaned dairy calves(24.9%,6706/29,753)and diarrhea dairy calves(33.6%,1637/6077).In countries with low dairy stocking density(<10cows/farm),the prevalence of C.parvum in dairy calves was also relatively low(15.2%,1960/16,584).The results showed that age and intensive culture were two important risk factors affecting C.parvum infection in dairy cattle.Risk factors do provide a basis for dairy farm managers to develop cryptosporidiosis control measures.2.The random forest and multiple correspondence analysis were used to analyze 1834gp60 gene sequences from all over the world,and factors such as the degree of intensive culture,geographical climate and transportation capacity were included in the analysis.The results showed that the degree of intensive culture affected the distribution of C.parvum subtype and the base mutation rate.This study also quantified the relationship between dairy cattle stocking density and the base mutation rate of gp60 locus of C.parvum and the probability of IIa occurrence.It was found that the higher the dairy cattle stocking density,the higher the base mutation rate of gp60 locus of C.parvum,the higher the probability of IIa,and the Logistic curve relationship between the dairy cattle stocking density and the base mutation rate of gp60 locus of C.parvum.This study shows the potential application of machine learning modeling in the prevention and control of C.parvum genetic variation.It provides a new idea for the precise prevention and control of cryptosporidiosis.3.A strategy of single oocyst whole genome amplification and long-read sequencing was used to obtain high-quality genome assembly of C.parvum IId A19G1 subtype isolated from pre-weaning diarrhea calves.The assembled gene is 9.13 Mb long and includes eight chromosomes,six of which are covered by telomere sequences at one or both ends.A total of3915 protein-coding genes were predicted,of which the single copy of BUSCO gene was98.2% complete.The present study was the first to assemble C.parvum genome to the chromosomal level through a combination of whole genome amplification and long-read sequencing in a single oocyst.This high-quality genome assembly and established sequencing strategy provides a valuable resource for comparative genomics and evolutionary analysis of Cryptosporidium evolutionary clades.4.The whole genome resequencing data of C.parvum in dairy cattle in some areas of China were obtained by high-throughput whole genome sequencing technology.Genome resequencing data of 117 C.parvum isolates from 8 provinces in China were analyzed.Phylogenetic analysis,principal component analysis,and gene flow analysis were used to explore the evolution of C.parvum in China at the genome level.The results show that gene flow tends to flow from western China to central and eastern China.The results provide a basis for effectively blocking the transmission of C.parvum in China.In summary,this study focuses on the background of intensive farming,using mathematical statistics to mine published molecular epidemiological data,combined with pathogen genome sequencing and bioinformatics analysis,to study the subtype distribution,genetic variation and transmission of C.parvum in dairy cattle.The results provide a reference for the prevention and control of Cryptosporidium in dairy farms,and provide a basis for the healthy and sustainable development of animal husbandry.