Complete Genome Sequence Analysis Of PPV7 Anhui Strains And The Establishment Of SYBR Green ? Detection Method

Porcine parvovirus 7(PPV 7)has first been found in commercial pig herds in the United States in 2016.Subsequently,infection cases of PPV7 have been reported by Sweden,Poland,South Korea and other countries.In 2017,the Chinese scholars has detected PPV7 by PCR method in the pig farms in Guangdong province,indicating the existence of PPV7 infection in Chinese pig herds.Due to the fact that the epidemic rule of the new pathogen PPV7 has not been discovered yet,and the detection methods have not been set widely,it needs further studying by all scholars and scientists.First of all,a pair of detection primers were designed according to the Cap gene of PPV7.The clinical samples of suspected PPV7 from some areas of Anhui province were detected.In the meantime,7 pairs of specific primers were designed to amplify the whole genome of the virus in the positive samples.A total of three PPV7 isolates from Anhui were successfully amplified,named respectively as PPV7/China/AHbz,PPV7/China/Ahhf and PPV7/China/AHmas,and the gene sequences were uploaded to Gen Bank database.The genetic evolution analysis showed that the genomic sequences of all the three strains obtained in this study and the reference strain PPV7 were in the same big branch.Among them,PPV7/China/AHmas was closely related to PPV7-GX35 in Guangxi,which demonstrated that they may have originated from the same strain.Secondly,bioinformatic analysis such as basic physical and chemical properties,structural and functional properties of NS1 and Cap proteins of PPV7 were analyzed.Bioinformatics analysis showed that NS1 protein was composed of 673 amino acids with a size of 73 k Da.It is a hydrophilic stable protein with more ?-helix and irregular crimp in its secondary structure.The size of Cap protein is 54 k Da,and there are many irregular curls in the secondary structure.This structure is easy to combine with antibody molecules to form dominant epitopes.There were 12 B cell epitopes and 5 T cell epitopes.Finally,this study established a SYBR Green I fluorescence quantitative PCR method for the detection on PPV7.The method has high specificity,good repeatability and is more stable,which is suitable for clinical detection.In this study,the whole genome of PPV7 in some areas of Anhui Province was amplified for the first time,its genetic evolution was analyzed,and bioinformatics analysis was carried out.Ultimately,a fluorescence quantitative PCR detection method for SYBR Green I was established,which provided a certain support for further understanding and mastering the law of genetic evolution,molecular characteristics,as well as rapid and accurate diagnosis of PPV7.