Detection And Analysis Of Horizontal Gene Transfer In Baculovirus

Horizontal gene transfer (HGT) is one of the primary evolutionary forces in thegenomic evolution of viruses. It provides the viral genomes with an effective way toobtain new genetic materials. In co-evolution of viruses and hosts, horizontally trans-ferred genes play important roles in host defense, anti-apoptosis, immune escape andcontrol of the cell proliferation. The studies of horizontal gene transfer in viruses,which are essential to trace their evolutionary history and construct their phylogeneticrelations, can further the understanding of the mechanism of infection and immunity.Baculovirus is a kind of virus that infects invertebrates, which is widely usedgene vector and living insecticide. Nowadays an increasing number of whole ge-nomes of baculoviruses and their main host insects have been sequenced. Thus wecan apply them to the analysis of horizontal gene transfer. This paper attempted toadopt bioinformatical methods to predict the horizontally transferred genes from in-sects to baculoviruses, and to analyze the function of these genes and their evolutio-nary histories.In this study, the genomic characteristics of baculoviruses and insects were ge-neralized by k-mer oligonucleotide frequency, and a model was built by support vec- tor machine at first step. Then the genes in baculoviruses with atypical genomic cha-racteristics were predicted as putative horizontally transferred genes. The result ofcross validation showed the accuracy of this model is above98%. In the prediction,270genes in54baculovirus genomes were predicted as putative horizontally trans-ferred gene. The annotation of these genes by GO terms showed that these genes arecomponents of virons，membranes and cellular molecules, with function of structuralmolecular activity and DNA synthesis, which implied that these genes may took partin the mechanisms of viral entry and control of the cell proliferation. Furthermore,homologs of putative horizontally transferred genes were searched by blastp. And theorigins of horizontally transferred genes were deduced from the phylogenetic analysesof the homologs. Besides, synteny analyses were applied to the putative horizontallytransferred genes as additional evidence.