The structure of avian polyomavirus reveals variably sized capsids, non-conserved inter-capsomere interactions, and a possible location of the minor capsid protein VP4

Abstract

Avian polyomavirus (APV) causes a fatal, multi-organ disease among several bird species. Using cryogenic electron microscopy and other biochemical techniques, we investigated the structure of APV and compared it to that of mammalian polyomaviruses, particularly JC polyomavirus and simian virus 40. The structure of the pentameric major capsid protein (VP1) is mostly conserved; however, APV VP1 has a unique, truncated C-terminus that eliminates an intercapsomere-connecting β-hairpin observed in other polyomaviruses. We postulate that the terminal β-hairpin locks other polyomavirus capsids in a stable conformation and that absence of the hairpin leads to the observed capsid size variation in APV. Plug-like density features were observed at the base of the VP1 pentamers, consistent with the known location of minor capsid proteins VP2 and VP3. However, the plug density is more prominent in APV and may include VP4, a minor capsid protein unique to bird polyomaviruses.

Structural optimization of a retrograde trafficking inhibitor that protects cells from infections by human polyoma- and papillomaviruses

“…The Mad1-SVEΔ strain of JCPyV used in these experiments has previously been described. 24 Stocks of JCPyV were generated according to previously published studies 25 . HPV16 pseudovirus expressing the reporter HcRed was generated from the p16sheLL plasmid, which expresses HPV L1 and L2, and pCAG-HcRed were obtained from Addgene.…”

The Human Alpha Defensin HD5 Neutralizes JC Polyomavirus Infection by Reducing Endoplasmic Reticulum Traffic and Stabilizing the Viral Capsid

“…Defensins were purchased from Peptides International and reconstituted in water at a concentration of 100 M. Viral particles used in each experiment and the calculations used to determine these are as follows: for Virus propagation and labeling. JCPyV was propagated and purified as previously described (36). Briefly, 10 1,700-cm 2 roller bottles were seeded with SVG-A cells and infected with JCPyV (MOI ϭ 0.01 FFU per cell) for 14 days.…”

Structure of the Fab-Labeled “Breathing” State of Native Poliovirus

“…Frozen-hydrated specimens were prepared and imaged at 300 kV as described previously (27). An FEI Vitrobot (Hillsboro, OR) was used to vitrify the poliovirus-Fab sample and keep it at 37°C until it was plunged into liquid ethane.…”

“…An FEI Vitrobot (Hillsboro, OR) was used to vitrify the poliovirus-Fab sample and keep it at 37°C until it was plunged into liquid ethane. A 3D reconstruction was computed by the model-based, iterative process described previously (22,27), with previous reconstructions of native poliovirus (sedimentation coefficient,160S) (D. M. Belnap et al, unpublished data) and the cell entry intermediate (135S) particle (1) as the starting models. Despite differences in the starting models, the capsid structure, the Fab density location and volume, and the center slice of the two resulting maps were nearly identical.…”