Viral Capsid Change upon Encapsulation of Double-Stranded DNA into an Infectious Hypodermal and Hematopoietic Necrosis Virus-like Particle

Wattana Weerachatyanukul; Pauline Kiatmetha; Ponlawoot Raksat; Supawich Boonkua; Orawan Thongsum; Pitchanee Jariyapong; Charoonroj Chotwiwatthanakun; Puey Ounjai; Zoltan Metlagel

doi:10.3390/v15010110

Viral Capsid Change upon Encapsulation of Double-Stranded DNA into an Infectious Hypodermal and Hematopoietic Necrosis Virus-like Particle

Viruses. 2022 Dec 30;15(1):110. doi: 10.3390/v15010110.

Authors

Wattana Weerachatyanukul¹, Pauline Kiatmetha¹, Ponlawoot Raksat², Supawich Boonkua¹, Orawan Thongsum¹, Pitchanee Jariyapong³, Charoonroj Chotwiwatthanakun⁴, Puey Ounjai², Zoltan Metlagel⁵

Affiliations

¹ Department of Anatomy, Faculty of Science, Mahidol University, Rama VI Rd., Ratchathewi, Bangkok 10400, Thailand.
² Department of Biology, Faculty of Science, Mahidol University, Ratchathewi, Bangkok 10400, Thailand.
³ Department of Medical Science, School of Medicine, Walailak University, Thasala District, Nakhonsrithammarat 80160, Thailand.
⁴ Academic and Curriculum Division, Nakhonsawan Campus, Mahidol University, Nakhonsawan 60130, Thailand.
⁵ Lawrence Berkeley National Laboratory, Molecular Biophysics and Integrated Bioimaging Division, University of California, Berkeley, CA 94720, USA.

Abstract

In this study, we aimed to encapsulate the sizable double-stranded DNA (dsDNA, 3.9 kbp) into a small-sized infectious hypodermal and hematopoietic necrosis virus-like particle (IHHNV-VLP; T = 1) and compared the changes in capsid structure between dsDNA-filled VLP and empty VLP. Based on our encapsulation protocol, IHHNV-VLP was able to load dsDNA at an efficiency of 30-40% (w/w) into its cavity. Structural analysis revealed two subclasses of IHHNV-VLP, so-called empty and dsDNA-filled VLPs. The three-dimensional (3D) structure of the empty VLP produced in E. coli was similar to that of the empty IHHNV-VLP produced in Sf9 insect cells. The size of the dsDNA-filled VLP was slightly bigger (50 Å) than its empty VLP counterpart; however, the capsid structure was drastically altered. The capsid was about 1.5-fold thicker due to the thickening of the capsid interior, presumably from DNA-capsid interaction evident from capsid protrusions or nodules on the interior surface. In addition, the morphological changes of the capsid exterior were particularly observed in the vicinity of the five-fold axes, where the counter-clockwise twisting of the "tripod" structure at the vertex of the five-fold channel was evident, resulting in a widening of the channel's opening. Whether these capsid changes are similar to virion capsid maturation in the host cells remains to be investigated. Nevertheless, the ability of IHHNV-VLP to encapsulate the sizable dsDNA has opened up the opportunity to package a dsDNA vector that can insert exogenous genes and target susceptible shrimp cells in order to halt viral infection.

Keywords: IHHNV; capsid maturation; dsDNA; encapsulation; virus-like particles.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Capsid Proteins / chemistry
Capsid* / chemistry
DNA, Viral / analysis
DNA, Viral / genetics
Densovirinae* / genetics
Escherichia coli / genetics

Substances

Capsid Proteins
DNA, Viral

Associated data

figshare/10.6084/m9.figshare.21507657

Grants and funding

This research was supported by the National Research Council of Thailand (NRCT: Grants No. NRCT5-RSA 63015-02), the Royal Golden Jubilee (RGJ) Ph.D. Program, and the Thailand Research Fund (Grant No. PHD/0195/2553). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.