Initial characterization of Vaccinia Virus B4 suggests a role in virus spread

Abstract

Currently, little is known about the ankyrin/F-box protein B4. Here, we report that B4R-null viruses exhibited reduced plaque size in tissue culture, and decreased ability to spread, as assessed by multiple-step growth analysis. Electron microscopy indicated that B4R-null viruses still formed mature and extracellular virions; however, there was a slight decrease of virions released into the media following deletion of B4R. Deletion of B4R did not affect the ability of the virus to rearrange actin; however, VACV811, a large vaccinia virus deletion mutant missing 55 open reading frames, had decreased ability to produce actin tails. Using ectromelia virus, a natural mouse pathogen, we demonstrated that virus devoid of EVM154, the B4R homolog, showed decreased spread to organs and was attenuated during infection. This initial characterization suggests that B4 may play a role in virus spread, and that other unidentified mediators of actin tail formation may exist in vaccinia virus.

Redundancy complicates the definition of essential genes for vaccinia virus

“…1. Consistent with previous reports (Burles et al, 2014;Sumner et al, 2014), vP811 produced only very small foci on monolayers of BS-C-1 cells, but the plaques formed by vP759 were also significantly smaller than VACV Copenhagen (Fig. 2).…”

“…Furthermore, in single-step growth curves, vP811 replicates as well as Copenhagen in BGMK and A549 cells, but forms smaller plaques than Copenhagen on BS-C-1, A549 and BGMK cells (Burles et al, 2014;Sumner et al, 2014). Poor replication in a multiple-step growth curve in BGMK cells, a small plaque phenotype and an observation of fewer actin tails all suggested that whilst viable in culture, vP811 has a defect in virus spread (Burles et al, 2014).…”

Establishing normal metabolism and differentiation in hepatocellular carcinoma cells by culturing in adult human serum

“…#353180, BD Biosciences, Canada), in order to obtain perpendicular sections of cells on the membrane surface. Cells were then prepared for electron microscopic analysis as described before 48 with minor modifications: 2x conventional TEM fixative (mixture of glutaraldehyde (4%), paraformaldehyde (2%), sucrose (0.2 M) and CaCl 2 (4 mM), in 0.16 M sodium cacodylate buffer, pH 7.4) was added to the cell media to make optimally diluted fixative. Pre-fixation was performed at 37 °C for 1 hour.…”

LINE-1 retrotransposons facilitate horizontal gene transfer into poxviruses

“…Non-essential (Child et al, 1990, Gammon et al, 2010 HGT6 D1R Essential (Hassett et al, 1997) HGT7 A40R Non-essential (Wilcock et al, 1999) HGT8 A9L Essential (Yeh et al, 2000) HGT9 and HGT10 D9R Non-essential (Parrish and Moss, 2006) HGT11 B4R Non-essential (Burles et al, 2014) HGT12…”