TWiV 375: Zika and you will find

TWiVOn episode #375 of the science show This Week in Virology, the TWiVziks present everything you want to know about Zika virus, including association of infection with microcephaly and Guillain-Barré syndrome, transmission, epidemiology, and much more.

You can find TWiV #375 at microbe.tv/twiv.

TWiV 345: How a vaccine got the nod

On episode #345 of the science show This Week in Virology, the TWiVonauts review how the weather affects West Nile virus disease in the US, benefit of B cell depletion for ME/CFS patients, and an autoimmune reaction induced by influenza virus vaccine that leads to narcolepsy.

You can find TWiV #345 at www.microbe.tv/twiv.

TWiV 339: Herpes and the sashimi plot

On episode #339 of the science show This Week in Virology, tre TWiV amici present three snippets and a side of sashimi: how herpesvirus inhibits host cell gene expression by disrupting transcription termination.

You can find TWiV #339 at www.microbe.tv/twiv.

Sushi protects mosquitoes from lethal virus infections

mosquito brainAs far as I know, mosquitoes do not eat sushi. But mosquito cells have proteins with sushi repeat domains, and these proteins protect the brain from lethal virus infections.

Mosquitoes are vectors for the transmission of many human viral diseases, including yellow fever, West Nile disease, Japanese encephalitis, and dengue hemorrhagic fever. Many mosquito-borne viruses enter the human central nervous system and cause neurological disease. In contrast, these viruses replicate in many tissues of the mosquito, including the central nervous system, with little pathological effect and no alteration of behavior or lifespan. The defenses that allow such persistent infection of mosquitoes are slowly being unraveled.

A protein called Hikaru genki, or Hig, is crucial for controlling viral infections of the mosquito brain. Originally discovered in the fruit fly Drosophila, Hig is produced mainly in the brain of Aedes aegyptii, the natural vector for dengue and yellow fever viruses. Experimental reduction of Hig mRNA or protein in the mosquito leads to increased replication of dengue virus and Japanese encephalitis virus. This increase in viral replication is accompanied by more cell death in the mosquito brain, and decreased survival.

How does Hig protein impair virus replication? The Hig protein of A. aegyptii binds dengue virus particles via the E membrane glycoprotein. As Hig protein is located on the cell surface, binding to virus particles prevents virus entry into cells. Impairment of endocytosis is limited to insect cells – introduction of Hig into mammalian cells had no effect on virus replication. Clearly other components of insect cells must participate in the Hig-mediated antiviral mechanism.

The antiviral activity of Hig protein depends on the presence of sushi repeat domains, also known as complement control protein (CCP) domains. These consist of 60 amino acid repeats with four conserved cysteines and a tryptophan. The CCP domain is found in many proteins of the complement system, a collection of blood and cell surface proteins that is a major primary defense and a clearance component of innate and adaptive immune responses. The sushi domain mediates protein-protein interactions among complement components. Capturing the dengue and Japanese encephalitis viruses by the A. aegyptii Hig protein is just one example of the virus-binding ability of proteins with CCP domains. An insect scavenger receptor with two CCP domains is a pattern recognition receptor that recognizes dengue virus and recruits mosquito complement to limit viral replication. Some CCP containing proteins are virus receptors (complement receptor 2 binds Epstein-Barr virus, and membrane cofactor protein is a receptor tor measles virus).

Because the Hig antiviral machinery is largely limited to the mosquito brain, it is possible that it prolongs mosquito life to allow virus transmission to other hosts. Transmission of virus to other hosts requires replication in the salivary gland, which cannot take if the mosquito dies of neural infection. I wonder why humans do not have have similar mechanisms to protect their neural tissues from virus infections. Is neuroinvasion a less frequent event in humans, compared with mosquitoes, thereby providing less selective pressure for protective mechanisms to evolve?

TWiV 293: Virology Down Under

On episode #293 of the science show This Week in VirologyVincent visits Melbourne, Australia and speaks with Melissa, Alex, Gilda, and Paul about their work on HIV infection of the central nervous system, West Nile virus, microbicides for HIV, and the Koala retrovirus.

You can find TWiV #293 at www.microbe.tv/twiv.

Microbes After Hours: West Nile virus

This discussion of West Nile virus was recorded at the headquarters of the American Society for Microbiology during a “Microbes After Hours” event on May 6, 2013. The speakers are Dr. Lyle Petersen Lyle R. Petersen, M.D., M.P.H., director of the Division of Vector-Borne Diseases at CDC, and Dr. Roberta DeBiasi, MD, FIDSA, Associate Professor of Pediatrics at George Washington University School of Medicine, Acting Chief and Attending Physician in the Division of Pediatric Infectious Diseases at Children’s National Medical Center, and investigator at Children’s Research Institute in the Center for Translational Science in Washington, D.C.

MWV Episode 70 – Microbes After Hours – West Nile Virus from microbeworld on Vimeo.

TWiV 209: When the virus hits the fans

On episode #209 of the science show This Week in Virology, Vincent, Dickson, Alan, and Kathy answer listener email about deformed wing virus, West Nile virus, FluMist, influenza in Canada, viruses and the tree of life, and more.

You can find TWiV #209 at www.microbe.tv/twiv.

TWiV 129: We’ve got mail

rich unwindsHosts: Vincent Racaniello, Alan Dove, Dickson Despommier, and Rich Condit

Vincent, Alan, Dickson and Rich answer listener questions about XMRV, yellow fever vaccine, virus-like particles, West Nile virus, amyotrophic lateral sclerosis and human endogenous retroviruses, multiplicity of infection, and how to make a poxvirus.

Click the arrow above to play, or right-click to download TWiV #129 (67 MB .mp3, 93 minutes).

Subscribe to TWiV (free) in iTunes , at the Zune Marketplace, by the RSS feed, by email, or listen on your mobile device with the Microbeworld app.

Links for this episode:

Weekly Science Picks

Rich – Polyxeni Potter and EID covers
Dickson – American Museum of Natural History
Alan –
Moon Trees (EurekAlert! article)
Vincent – Infection Landscapes

Listener Picks of the Week

Didier  – The Vaccines (MySpace)
/Sven-Urban –
The Science of Discworld by Terry Pratchett
GarrenOmega Tau podcast

Send your virology questions and comments (email or mp3 file) to twiv@microbe.tv, or call them in to 908-312-0760. You can also post articles that you would like us to discuss at microbeworld.org and tag them with twiv.

Virology lecture #25: West Nile Story

In the final lecture of my virology course, Professor Dickson Despommier weaves a story about the arrival of West Nile virus to the United States in the summer of 1999. This is a special treat that you won’t want to miss, as Prof. Despommier is a wonderful storyteller.

Download: .wmv (422 MB) | .mp4 (108 MB)

Visit the virology W3310 home page for a complete list of course resources.

Virology lecture #17: Acute infections


Download: .wmv (322 MB) | .mp4 (91 MB)

Visit the virology W3310 home page for a complete list of course resources.