Comparative genome analysis of related Lymantria dispar nucleopolyhedrovirus isolates differing in virulence

Abstract

Motivation and Aim: Nucleopolyhedroviruses (NPVs, Baculoviridae) are specific viruses of insects that are used for pest control. High variation in virus virulence depends upon genetic factors [1]. Here we compare genomes of closely related genetic variants of Lymantria dispar multiple NPV (LdMNPV) that differ in virulence. Methods and Algorithms: Five viral genotypes, differing in virulence, were isolated from the standard strain of NPV in the biopesticide "Gypchek" [2]. Complete genomes of these five genotypes were sequenced using Illumina technology by paired end sequencing of fragment genomic libraries, and assembled by SPAdes 3.9.0 [3]. Initial assemblies consisted of 1-3 scaffolds with a total assembly length of 159-174 kbp. Genome coverage was in range of 200x-850x. Closing of scaffold gaps was performed by Sanger sequencing of amplicons. To determine genetic relatedness among studied LdMNPV variants a phylogenetic tree was reconstructed based on a set of core loci. Comparative analysis of candidate genes was performed to reveal genetic determinates of variation in virulence. Results: Phylogenetic analyses indicated recent divergence of LdMNPV-studied isolates from a common ancestor. We found a number of nonsynonymous nucleotide substitutions and indels in many genes. However, we could not find a locus that could be considered as the main effector of observed variation in virulence. This fact indicated a complex genetic nature of virulence variation among closely related virus isolates. Conclusion: Variation in virulence among related LdMNPV isolates can be explained by the complex effect of different loci. Acknowledgements: the study was supported by . References