VOLN27B: A New Head-Tailed Halovirus Isolated from an Underground Salt Crystal and Infecting Halorubrum.

Shaoxing Chen,Jingwen Liu,Xiangdong Chen,Peiyao Ruan,Fanjie Jin,Feilong Chen,Lu Li,Yongpei Dai,Shimin Zhang,Antonio Ventosa

doi:10.1155/2021/8271899

Shaoxing Chen, Jingwen Liu + Show 8 more

Open Access

https://doi.org/10.1155/2021/8271899

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Abstract

A novel halovirus, VOLN27B, was isolated from a drill core sample taken at a depth of approximately 430 m, from a layer formed during the Cretaceous period (Anhui, China). VOLN27B infects the halophilic archaeon Halorubrum sp. LN27 and has a head-tailed morphotype with a contractile tail, typical of myoviruses. The average head diameter is 64 ± 2.0 nm, and uncontracted tails are 15 ± 1.0 × 65 ± 2.0 nm. The latent period is about 10 h. The maturing time of VOLN27B in cells of Halorubrum sp. LN27 was nearly 8 h. The adsorption time of VOLN27B on cells of Halorubrum sp. LN27 was less than 1 min. Virus particles are unstable at pH values less than 5 or when the NaCl concentration is below 12% (w/v). VOLN27B and Halorubrum sp. LN27 were recovered from the same hypersaline environment and provide a new virus-host system in haloarchaea.

Highlights

Hypersaline environments, near salt saturation, are commonly found to harbor members of the extremely halophilic archaea, which are often the dominant cellular microorganisms and can grow to high cell densities (>107 cells per milliliter)
Viruses infecting haloarchaea are typically observed to be in much higher concentration than their host cell population, and direct examination of natural brines shows a number of different morphological types of virus-like particles (VLP), including spherical, spindle-shaped, and head-tail [1,2,3,4]
Head-tailed VLPs are a less-frequent morphotype observed in hypersaline environments, they are commonly isolated and show great diversity [7]

Summary

Introduction

Hypersaline environments, near salt saturation, are commonly found to harbor members of the extremely halophilic archaea (haloarchaea; Class Halobacteria), which are often the dominant cellular microorganisms and can grow to high cell densities (>107 cells per milliliter). Viruses infecting haloarchaea are typically observed to be in much higher concentration than their host cell population, and direct examination of natural brines shows a number of different morphological types of virus-like particles (VLP), including spherical, spindle-shaped, and head-tail [1,2,3,4]. In a comprehensive study of a salt lake in Senegal (Lake Retba), the morphotypes (and percentage) of VLPs were as follows: spindle-shaped/fusiform (43%), spherical (35%) particles, and head-tail (1%), while linear and various other, unusual morphological particles accounted for the remainder [3]. Head-tailed VLPs are a less-frequent morphotype observed in hypersaline environments, they are commonly isolated and show great diversity [7]. A brand new taxonomy of archaeal tailed viruses has been proposed that all genomesequenced archaeal tailed viruses were classified into three orders, i.e., Thumleimavirales, Kirjokansivirales, and Methanobavirales (https://talk.ictvonline.org/files/proposals/archaealviruses/m/ec-approved-awaiting-ictv-ratification)

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