Equine Herpesvirus Type 1 (EHV-1)

Products of sequential degradation

 

Steven K. Vernon*

WHRI, Wyeth-Ayerst Research, Radnor, Pa.

vernons@war.wyeth.com

 

 

All samples were negatively stained with uranyl acetate or sodium phosphotungstate.

    

Page 1: Deenvelopment of viral nucleocapsids

 

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Enveloped virions of EHV-1. At times, stain penetrates the particles sufficiently to provide faint outlines of the nucleocapsids.

 

 

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Enveloped EHV-1. In three of the four virions shown, the envelopes have been penetrated by negative stain, permitting observation of the icosahedral capsids and the tegument surrounding them. Surface glycoproteins give the envelopes a "fuzzy" appearance.

 

 

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The virion envelope can be removed with surfactants. One of these two deenveloped nucleocapsids retains its overlying tegument.

 

 

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Deenveloped nucleocapsids with adherent tegument. The fragile tegument is easily damaged during dehydration after staining, but some remains attached to capsids. Images such as these suggest that the tegument could be attached at or near capsid vertices.

 

 

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Deenveloped EHV-1 nucleocapsids after residual tegument has been removed during centrifugation.

 

 

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Three vertex capsomers (pentamers) are marked on the intact EHV-1 nucleocapsid on the left. The pentamers define one triangular facet of the T=16 icosahedral capsid. On the right is a capsid whose pentamers have been removed by treatment with trypsin.

 

 

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Sheets of capsomers from dehydrated, flattened capsids. The arrows indicate pentamers that remain in the sheets.

 

To Page 2: Exposure of viral cores


The morphology of herpesvirus particles and the principles of icosahedral capsid structure are described at other sites:

| Virus structure | Herpesvirus morphology | Herpesvirus capsid structure |