Genetic variability of Myzus persicae nicotianae densovirus based on partial NS and VP gene sequences

Abstract

We previously described a novel densovirus [Myzus persicae nicotianae densovirus (MpnDV)] infecting M. persicae nicotianae (Hemiptera: Aphididae) with 34% prevalence. This single-stranded DNA virus has a 5480-nucleotide ambisense genome and belongs to the Densovirinae subfamily within the family Parvoviridae. In the present study, we estimated the genetic diversity of MpnDV using partial nonstructural protein (NS) and capsid protein (VP) gene sequences from 10 locations in China. First, we identified MpnDV-positive samples by amplifying a 445-bp fragment with primers MpDVF/MpDVR. Subsequently, we amplified and sequenced COI genes with primers MpCOIF/ MpCOIR, and partial NS and VP sequences with primers MpnDVF1/MpnDVR1. The respective 655-, 1461-, and 423-bp COI, NS, and VP fragments were used to analyze the genetic diversity of MpnDV using MEGA 6.0 and DnaSP 5.0. The high level of identity shared by all COI sequences (>99%) suggested that the aphids sampled were of the same species, and indicated population homogeneity across the 10 locations investigated. The nucleotide diversity of MpnDV sequences (0.0020 ± 0.0025) was significantly higher than that of the COI genes (0.0002 ± 0.0005). The pairwise fixation index for MpnDV was 0.832, and the total gene flow was 0.05. Phylogenetic analysis revealed that the MpnDV haplotypes clustered according to geographical location, except for those from the Liaoning and Shanxi provinces. In conclusion, MpnDV demonstrated a low level of gene flow and high genetic diversity, suggesting that it is vertically transmitted, and implying that endosymbiotic viruses could be used as markers in studies of insect population genetics.

Exploring spatial and temporal patterns of viral infection across populations of the Melissa blue butterfly

“…On the other hand, our findings are in contrast with other studies of densoviruses that show high genetic diversity among host localities in regions of the capsid gene (Song et al, 2016), which is responsible for packaging and delivering the viral genome (Roos et al, 2007).…”

“…This confirms that the JcDV genome is highly conserved like other members of the Parvoviridae family (Tijssen & Bergoin, 1995). On the other hand, our findings are in contrast with other studies of densoviruses that show high genetic diversity among host localities in regions of the capsid gene (Song et al, 2016), which is responsible for packaging and delivering the viral genome (Roos et al, 2007). Although whole‐genome comparisons could be conducted in the future to further support this, it appears that genetic variation in JcDV is not dependent on L. melissa locality, at least not at the spatial scale encompassed by our study.…”

“…The study of emerging diseases in natural systems warrants pathogen genomic sequence comparisons, not only to confirm the identity of the pathogen but to potentially understand sources of variation in different host species and populations. Although other densoviruses are highly genetically conserved (Tijssen & Bergoin, 1995), we suspected diversity might be found in the viral capsid gene (Roos et al, 2007;Song et al, 2016). Therefore, we also compared JcDV capsid gene fragments among wild L. melissa localities to explore the possibility that variation in infection prevalence is explained by viral genetic variation between discrete host populations.…”