Epidemiology Investigation, Amplification And Full-length Genome Sequence Analysis Of Torque Teno Sus Viru1 And 2 Of Swine In Jiangxi

Torque teno sus virus(TTSuV) is a non-enveloped virus which contains a negative sense, single-stranded circular DNA genome. The diameter of this virion is about 30-32 nm. In 1997, Torque teno virus was first discovered in a patient with Representational difference analysis by Nishizawa. TTSuV was first identified in America in1999 from domestic pigs. TTSuV infections are not restricted to human hosts and also identified in domesticated animals and wildlife. In recent twenty years, there are many emerging pathogens in swineey, especially some small DNA virus, which directly or indirectly caused economic losses to the pig industries.The objective of the study was to investigate the prevalence of the TTSuV1, TTSuV2 from 8 different districts in Jiangxi and analyze the genome property and phylogeny relationships of TTsuV with other reference strains.Swine blood serum samples(n=183) were collected from 8 cities of Jiangxi province. Nested polymerase chain reaction(nested PCR) established in our lab was performed to test the TTSuV1 and TTSuV2 infection prevalence. The epidemiology investigation results demonsrated that TTSuV1 infection rate was 40.4%, the TTSuV2 was 68.9%, and the co-infection rate was 36.1%.Two pairs of specific primer were designed based upon the published genomic sequence of TTSuV1(accession no. AB076001) and TTSuV2(accession no. AY823991). The complete genomes of six TTSuV1 strains and four TTSuV2 strains were amplified by PCR. The amplification products were purified, cloned, sequenced and assembled. The sequencing results showed that the complete genome length of these six TTSuv1 strains were 2879 bp, 2913 bp, 2860 bp, 2909 bp, 2894 bp, 2894 bp, respectively and the full length of these four TTSuV2 strains were 2800 bp, 2796 bp, 2795 bp and 2793 bp, respectively. Basic Local Alignment Search Tool(Blast) results showed that the nucleotide senquence identity between TTSuV1 and TTSuV2 was ranged from 75% to 97%. Based on the topology of phylogenetic tree, all the TTSuV1 and TTSuV2 strains were fell into two clades. The TSuV1-JX2 strain and HM633243(Beijing) strain shared one cluster, while TTSuV1-JX3 and GU188045(Germany), TTSuV1-JX4 and GU570198(Spain), TTSuV1-JX5 and TTSuV1-JX6 were divided into one group. The TTSuV2-JX1 and GU570206(Spain) were splitted into a same clades. The GU570207(Spain) together with other three isolated strains was grouped one cluster. To predict the ORF1 protein sequence and analyze the hydrophobicity, antigenicity, subcellular fraction of ORF1 protein, protein sequence was performed the TTSuV1 and TTSuV2 strains, and the results showed that ORF1 protein of TTSuV1-JX3 and TTSuV2-JX3 contained 639 and 623 amino acids, respectively. The epitopes of TTSuV1-JX3-ORF1 concentrated in areas of 8aa~39aa, 44aa~63aa, 88aa~115aa, 307aa~322aa, 590aa~627aa and the epitopes of TTSuV2-JX3-ORF1 locus in areas of 9aa~49aa, 179aa~202aa, 281aa~302aa, 570aa~581aa, 590aa~609aa.