TWiV 63: Melting pot virus

marseillevirus_genomeHosts: Vincent Racaniello, Alan Dove, and Rich Condit

On episode 63 of the podcast This Week in Virology, Vincent, Alan, and Rich talk about US government contract for freeze-dried smallpox vaccine, red squirrels in the UK threatened by poxvirus, and Marseillevirus, another DNA virus from amoebae built for comfort and speed.

Click the arrow above to play, or right-click to download TWiV #63 (64 MB .mp3, 89 minutes)

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Links for this episode:

Weekly Science Picks
Rich Infectious Awearables
Alan Darwine
Vincent Microbial Art

Send your virology questions and comments (email or mp3 file) to twiv@microbe.tv or leave voicemail at Skype: twivpodcast. You can also post articles that you would like us to discuss at microbeworld.org and tag them with twiv.

TWiV 60: Making viral RNA

TWiV_AA_200Hosts: Vincent Racaniello and Dickson Despommier

Vincent and Dick continue Virology 101 with a discussion of how RNA viruses produce mRNA and replicate their genomes.

Click the arrow above to play, or right-click to download TWiV #60 (51 MB .mp3, 71 minutes)

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Links for this episode:

Weekly Science Picks
Dick The Double Helix by James D. Watson
Vincent
Worms and Germs Blog

Send your virology questions and comments (email or mp3 file) to twiv@microbe.tv or leave voicemail at Skype: twivpodcast. You can also send articles that you would like us to discuss to delicious and tag them with to:twivpodcast.

Below is a video of TWiV 60, which highlights the diagrams I referred to during the podcast.

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Download TWiV 60 video. These videos are slightly larger (800 x 512) than the flash version shown above

186 MB .mov video file

584 MB .wmv video file

TWiV 59: Dog bites virus

TWiV_AA_200Hosts: Vincent Racaniello, Alan Dove, Rich Condit, Gustavo Palacios, and Mady Hornig

A TWiV panel of five considers the finding of Streptococcus pneumoniae in fatal H1N1 cases in Argentina, hysteria in the Ukraine over pandemic influenza, and human vaccinia infection after contact with a raccoon rabies vaccine bait.

Click the arrow above to play, or right-click to download TWiV #59 (58 MB .mp3, 80 minutes)

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Links for this episode:

Weekly Science Picks
Rich Longitude by Dava Sobel
Alan Heil Pro Set Media Headset (for a good price, order from a ham radio store)
Vincent
MicrobeWorld app for iPhone and iTouch (iTunes or MicrobeWorld)

Send your virology questions and comments (email or mp3 file) to twiv@microbe.tv or leave voicemail at Skype: twivpodcast. You can also send articles that you would like us to discuss to delicious and tag them with to:twivpodcast.

TWiV 42: Bats and ticks

twiv-200Hosts: Vincent Racaniello, Dick DespommierAlan Dove, and Delthia Ricks

In episode #42 of the podcast “This Week in Virology”, Vincent, Dick, Alan, and Delthia Ricks discuss a new influenza virus-like particle vaccine, dog flu, ultrasensitive pen-sized virus detector, imported rabies in the US, Crimean-Congo hemorrhagic fever, and next season’s flu vaccines.

Click the arrow above to play, or right-click to download TWiV #42 (40 MB .mp3, 58 minutes)

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Links for this episode:
Trivalent virus-like particle vaccine
Canine flu virus vaccine
Ultrasensitive virus detector
Rabies imported into the US
Crimean-Congo hemorrhagic fever in Kazakhstan
FDA approves seasonal flu vaccine for fall
Yields of 2009 H1N1 vaccine are low
FDA may fast-track approval of 2009 H1N1 vaccine

Weekly Science Picks
Delthia 100 questions and answers about influenza by Delthia Ricks
Alan
Tinychat
Dick
Mythbusters
Vincent Effect Measure

Send your virology questions and comments (email or mp3 file) to twiv@microbe.tv or leave voicemail at Skype: twivpodcast

TWiV 41: Fish flu

TWiV_AA_200Hosts: Vincent Racaniello, Dick DespommierAlan Dove, and Rich Condit

On episode #41 of the podcast “This Week in Virology”, Vincent, Dick, Alan and Rich Condit chat about infectious salmon anemia virus, virus-resistant grapevines, virulence of pandemic H1N1 influenza virus, origin of 1918 influenza virus, holy water ban to halt influenza, frequency of human WU and KI polyomavirus infection, rabies in China, and host species of sin nombre virus.

Click the arrow above to play, or right-click to download TWiV #41 (51 MB .mp3, 73 minutes)

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Links for this episode:
Wal-Mart stops buying Chile salmon on virus outbreak
Virus-resistant grapevines
Virulence of H1N1 pandemic influenza virus in animal models
Did 1918 influenza virus originate in birds or not?
Holy water ban to halt swine flu
Frequent Human Infection with WU and KI Polyomaviruses
Rabies in China
Increased Host Species Diversity and Decreased Prevalence of Sin Nombre Virus
Fast, cheap PCR for crime scenes (thanks Jim!)

Weekly Science Picks
Alan For Love of Insects by Thomas Eisner
Rich Making of the Atomic Bomb by Richard Rhodes
Dick
Origin of Species by Charles Darwin
Vincent Gallileoscope (thanks Zach!)

Send your virology questions and comments (email or mp3 file) to twiv@microbe.tv or leave voicemail at Skype: twivpodcast

TWiV 38: Measles

twiv-200Hosts: Vincent Racaniello and Glenn Rall

On episode #38 of the podcast “This Week in Virology”, Vincent and Glenn Rall chat about koi herpesvirus, H1N1 influenza vaccine produced in insect cells, attack by a rabid raccoon, and measles.

Click the arrow above to play, or right-click to download TWiV #38 (63 MB .mp3, 91 minutes)

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Links for this episode:
Virus suspected in carp die-off: koi herpesvirus
H1N1 influenza vaccine produced in insect cells with baculovirus vectors
Outbreak of measles in Wales
Production of influenza vaccines in cell cultures: MDCKVeroPER.C6EB66insect (thanks Peter!)

Weekly Science Picks
Glenn Riddled with Life by Marlene Zuk
Vincent All the Virology on the WWW

Send your virology questions and comments (email or mp3 file) to twiv@microbe.tv or leave voicemail at Skype: twivpodcast

TWiV #27: Leaving latency

twiv_aa_2001On episode #27 of the podcast “This Week in Virology”, Vincent, Dick, Alan, and Saul Silverstein revisit an ebolavirus needlestick accident, and discuss the role of TLR3 in formation of Negri bodies, a New England college closed by norovirus gastroenteritis, hand, foot, and mouth disease outbreak in China, and the exit of herpes simplex virus from latency by synthesis of VP16.

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Negri bodies and rabies

rabies-encephalitis-negri_bodies1Viral replication frequently leads to the accumulation of intracellular masses of virions or unassembled viral components in the cytoplasm or nucleus of the cell. These inclusion bodies often bear the name of the individual who discovered them – such as Guarnieri bodies in the cytoplasm of poxvirus infected cells, intranuclear Cowdry bodies in herpesvirus infected cells, and Negri bodies in cells infected with rabies virus. Before molecular diagnostic techniques were developed, inclusion bodies were important for identifying the agent of a viral disease – but do they have an important role in viral replication?

Toll-like receptor 3 (TLR3) is one of many cellular proteins that can ‘sense’ when a cell is infected by a virus. The protein recognizes RNA that is produced during viral infection, and then signals the cell to produce interferons (IFN).  IFNs in turn induce the synthesis of many other cell proteins which have antiviral activities. TLRs and IFN are components of the innate immune system, the earliest defense against microbial invaders.

Normally a membrane protein, in cells infected with rabies virus TLR3 is relocated to Negri bodies, which also contain viral proteins and viral RNA. When levels of TLR3 are reduced in rabies-virus infected cells by RNA silencing, Negri bodies do not form, and viral yields are reduced. Therefore TLR3 is required for the formation of Negri bodies. Furthermore, mice lacking TLR3 are less susceptible to rabies virus infection. This result is somewhat counterintuitive, considering the role of TLR3 in detecting RNA virus infections and turning on the IFN system. However, it makes sense because rabies virus replication is reduced in the absence of TLR3.

Why would rabies virus replication depend upon TLR3? One possibility is that Negri bodies are essential ‘factories’ for the assembly of new virions. When Negri body formation is blocked by depleting TLR3, levels of virus production decrease. Sequestration of TLR3 in Negri bodies might also be a mechanism to prevent the protein from inducing the synthesis of IFN. Therefore the presence of TLR3 in Negri bodies has at least two important roles in rabies virus infection.

Negri bodies were first described in 1903 by Adelchi Negri, an Italian pathologist and microbiologist. He would be amazed to learn the important role played by these eponymous bodies in rabies virus replication.

Ménager, P., Roux, P., Mégret, F., Bourgeois, J., Le Sourd, A., Danckaert, A., Lafage, M., Préhaud, C., & Lafon, M. (2009). Toll-Like Receptor 3 (TLR3) Plays a Major Role in the Formation of Rabies Virus Negri Bodies PLoS Pathogens, 5 (2) DOI: 10.1371/journal.ppat.1000315

TWiV #25: Viral evolution

twiv_aa_2001In episode #25 of the podcast This Week in Virology, Vincent, Alan, and Luis Villarreal talk about rabies in Viet Nam and Angola, needle-stick infections with ebolavirus and West Nile virus, and viral evolution.

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