Monday, October 13, 2014

Seeing EBV!


Hi there virophiles!

We've learned a bit about herpesviruses in class so far; Epstein-Barr virus is one within this family, most commonly recognized as the cause of infectious Hi mononucleosis (Mono). While there has been much research in the past about structure, putting together these atomic-resolution images to develop a clear view of the detailed structure of herpesvirus has proved to be very challenging. This is challenging because herpesviruses are so large that they don't fit within the field of view of an electron microscope.

On October 7, a group of researchers at UCLA, headed by Dr. Z. Hong Zhou published a paper  in Structure with clarifying details about the structure of herpesviruses. According to an article by Scientific American, this is the first time that anyone has been able to focus the structure of the herpesvirus' capsid. This study was done on the rhesus monkey rhadinovirus (RRV), a type of gammaherpesvirus, which is one of three subfamilies under Herpesviridae

Based on their analysis, there is a pattern of "interlocking protein rings" resembling chain mail, which explains why these viruses can sustain long infection periods. The pattern is similar to the structure of bacteriophages; this finding was surprising, suggesting an evolutionary similar (perhaps a common origin) between herpesviruses and bacteriophages. According to Dr. Johnson from The Scripps Research Institute, the genomic sequence alone would not have revealed this similarity, underscoring the need to study viral structure. 

This research is also important because understanding capsid structure can help in development of antivirals. This four-level "chain mail" structure improves the stability of the viral molecule, making herpesviruses more difficult to break apart. The DNA, packed tightly within these viruses, exerts very large internal pressure on the capsid wall, creating the need for this strong capsid structure. Present antivirals that neutralize viruses are unable to "pull apart" the capsid structure of herpesvirus, complicating vaccine development. This research is exciting and opens up new possibilities for herpesvirus research.


If you're interested in reading the paper, if you do a Lane Medical Library search using the title of the paper ("Four Levels of Hierarchical Organization, Including Noncovalent Chainmail, Brace the Mature Tumor Herpesvirus Capsid against Pressurization"), you'll be able to access the paper and learn more about the specifics of the paper. 



Sources:

  • http://virus.chem.ucla.edu/
  • http://www.scientificamerican.com/article/the-epstein-barr-virus-wears-chain-mail/ 
  • http://www.ncbi.nlm.nih.gov/pubmed/25220471
  • Image (from Lane medical library - copy of paper in Structure) http://origin-ars.els-cdn.com.laneproxy.stanford.edu/content/image/1-s2.0-S0969212614002494-gr2.jpg
- Nicole Dalal

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