TWiV 322: Postcards from the edge of the membrane

On episode #322 of the science show This Week in Virology, the TWiVodes answer listener email about hantaviruses, antivirals, H1N1 vaccine and narcolepsy, credibility of peer review, Bourbon virus, influenza vaccine, careers in virology, and much more.

You can find TWiV #322 at

TWiV 213: Not bad for a hobby

On the final episode of the year of the science show This Week in Virology, the TWiV team reviews twelve cool virology stories from 2012.

You can find TWiV #213 at

Mumps in college

Morbidity and Mortality Weekly Report summarizes a mumps outbreak that occurred in 2011 on a university campus in California:

On September 29, 2011, the California Department of Public Health (CDPH) confirmed by polymerase chain reaction (PCR) three cases of mumps among students recently evaluated at their university’s student health services with symptoms suggestive of mumps. An investigation by CDPH, student health services, and the local health department identified 29 mumps cases. The presumed source patient was an unvaccinated student with a history of recent travel to Western Europe, where mumps is circulating. The student had mumps symptoms >28 days before the onset of symptoms among the patients confirmed on September 29. Recognizing that at least two generations of transmission had occurred before public health authorities were alerted, measles, mumps, and rubella (MMR) vaccine was provided as a control measure. This outbreak demonstrates the potential value of requiring MMR vaccination (including documentation of immunization or other evidence of immunity) before college enrollment, heightened clinical awareness, and timely reporting of suspected mumps patients to public health authorities.

All 29 cases were epidemiologically linked to the university. One of the cases was the source patient’s roommate who had received two doses of MMR (measles, mumps, rubella) vaccine. Other outbreaks of mumps have occurred in populations in which many individuals had received 2 doses of MMR.

Data collected during previous mumps outbreaks on college campuses indicate that extended person-to-person contact, in combination with waning vaccine-induced immunity, might make colleges and universities high-risk settings for outbreaks, even when 2-dose MMR vaccination coverage is high

CDC suggests that all colleges and universities consider requiring documentation that students have received 2 doses of MMR vaccine before matriculation.

The mumps vaccine was licensed in the US in 1967, resulting in a significant decline in the number of cases. However outbreaks continue to occur, even in immunized populations, when the virus is introduced by overseas travelers. The vaccine is included in national health programs of only 62% of countries, and immunization rates have declined in many European countries, leading to outbreaks of measles and mumps.

TWiV 183: Bats out of hell

On episode #183 of the science show This Week in Virology, Connor Bamford joins the TWiV team to discuss bats as hosts for major mammalian paramyxoviruses.

You can find TWiV #183 at

TWiV 172: Two can be as bad as one

On episode #172 of the podcast This Week in Virology, Vincent and Kathy discuss how a virus may cause disease distant from its replication site, then review a day in the life of a senior microbiology professor.

You can find TWiV #172 at

TWiV 166: Breaking and entering

npc1 ebolaHosts: Vincent Racaniello, Dickson DespommierRich Condit, and Alan Dove

Vincent, Dickson, Rich, and Alan review cell proteins essential for entry of hepatitis C, Ebola, and measles viruses.

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Links for this episode:

Weekly Science Picks

Dickson – What are you swimming with?
Rich –
Twelve monkeys
AlanKindle Touch
Vincent – Microbe news (thanks to Dave Winer)

Listener Pick of the Week

EricThe Nature of Things with David Suzuki
LanceTrials and Errors (Wired)

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

Virology lecture #20: Vaccines

Download: .wmv (314 MB) | .mp4 (82 MB)

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

TWiV 48: Outbreaks near you

twiv_aa_2001Hosts: Vincent Racaniello, Dick DespommierAlan Dove, and Rich Condit

On episode 48 of the podcast “This Week in Virology”, Vincent, Dick, Alan and Rich revisit a vaccinia virus lab accident and viral vaccines produced in plants, then talk about an iPhone app to track infectious diseases, flying foxes, and an inhaled measles vaccine.

Click the arrow above to play, or right-click to download TWiV #48 (58 MB .mp3, 79 minutes)

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Links for this episode:
Laboratory acquired vaccinia infection
Medicago (investor presentation, pdf) and Fraunhofer produce vaccines in plants
iPhone app Outbreaks near me
No culling of flying foxes in Australia
Inhaled powdered measles virus vaccine
Herpesvirus latency confers symbiotic protection from bacterial infection (thanks Juliet!)
Porcine circovirus vaccine
Swine flu vaccine and Guillain-Barré (thanks Tom!)
The Great Flu and blog post (thanks Swiss compass and Allison!)
Building semiconductors with DNA (thanks Duncan!)
Email on viral classification (thanks Rodney and Eliot!)

Weekly Science Picks
Rich Stumbling on Happiness by Daniel Gilbert
Dick Eliot Porter at the Carter Museum and bookstore at Amazon
Alan Dr. Clarke’s H1N1 rap at the HHS sponsored YouTube contest
Vincent Coast to Coast Bio Podcast

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

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Emerging viruses?

The term emerging virus was coined by scientists in the 1990s to describe the agent of a new or previously unrecognized infection. The term implies that emerging viruses are new; however this assumption is incorrect. New virus infections have been emerging for thousands of years, at least since the rise of agriculture 11,000 years ago. The development of agriculture and commerce provided the large populations needed to sustain human infections such as measles and smallpox.

Viruses probably (although we do not know for sure) appeared when living cells evolved, possibly even before. They subsequently infected multicellular forms of life and then mammals, which were present on the globe before humans. Humans then acquired virus infections from animals (an infection transmitted from animals to humans is a zoonosis). At some point the number of virus genomes and virion structures became established, and for the next millions of years, viruses evolved. It is unlikely that new viruses emerge de novo; rather they evolve from existing viruses.

Some examples serve to illustrate the origins of viruses. Comparisons of genome sequences of today’s members of the herpesvirus family has lead to the suggestion that these viruses arose 180-220 milllion years ago, possibly from ancestors of similar viruses that infect oysters and fish today. Smallpox virus may have emerged after an infection of humans with a gerbil poxvirus. Measles virus may have originated from infection of humans with an ancestor of a virus that today infects cows, rinderpest virus. It has been suggested that the virus ‘jumped’ from cows to humans about 5,000 years ago, when humans first began to domesticate cattle. Measles virus then spread throughout the Middle East and was then brought to the Americas by colonization and migration, where it had lethal effects on the Native Americans.

It is safe to say that all of the human viruses that exist today originated from a zoonotic infection. In some cases, related viruses still infect animals (e.g. measles and rinderpest virus). However, often the human virus has no known counterpart in animals. An example is the human pathogen, poliovirus. The ancestral poliovirus is not known, and there are currently no hosts for the virus other than humans. However, other members of the picornavirus family, of which poliovirus is a member, infect a variety of animals, and ancient versions of these viruses may have made the jump from animals to humans.

Two simple facts ensure that new human virus infections will continue to emerge from animal hosts. The first is the ability of viruses to produce huge numbers of progeny (billions and billions!) with a high level of diversity (mutation). The second is the fact that human and non-human animal populations continue to grow and interact. Put another way, humans are always finding new ways to acquire novel virus infections!

Viral evolution is a fascinating subject. A good place to start reading about it would be Principles of Virology, volume II, chapter 10.