HIV among US youth

The Centers for Disease Control and Prevention has released its latest estimates on the number of new HIV infections in the United States:

HIV remains a serious health problem, with an estimated 47,500 people becoming newly infected with the virus in the United States in 2010. Youth make up 7% of the more than 1 million people in the US living with HIV. About 12,000 youth were infected with HIV in 2010. The greatest number of infections occurred among gay and bisexual youth. Nearly half of all new infections among youth occur in African American males.

Included is this graph of at-risk populations:

At risk for HIV

Clearly awareness of HIV and how it is spread is not enough to prevent new infections. Would an effective HIV vaccine make a difference?

A pdf version of the factsheet is available for download.

Behind the scenes: TWiV 202 at the University of Nebraska

We recorded This Week in Virology #202 at the University of Nebraska in Lincoln, Nebraska on 5 October 2012, as part of the 12th Annual Symposium in Virology. Terence Dermody, Shou-Wei Ding, Grant McFadden and I spoke about our research, and then we recorded TWiV with University of Nebraska virologists James Van Etten, T. Jack Morris, and Charles Wood.

I was impressed by the fine virology being done at the Nebraska Center for Virology, as well as the collegiality of the virology community in Nebraska, Iowa, South Dakota, and Kansas – Symposium attendees were from all of those states! I met many young virologists at the poster session and I was touched by how many of them wanted to say hello and thank us for doing TWiV.

Many thanks to all the virologists who came to the Symposium and stayed to watch TWiV. Special thanks to Charles Wood, the Director of the Nebraska Center for Virology, who participated in TWiV #202 along with T. Jack Morris and James Van Etten.

Here are some behind the scenes photographs of this short but very informative visit.

TWiV 202: Huskers go viral

In episode #202 of the science show This Week in Virology, Vincent travels to the University of Nebraska to meet with members of the Nebraska Center for Virology and discuss their work on algal viruses, plant viruses, HIV and Kaposi’s sarcoma herpesvirus.

You can find TWiV #202 at www.microbe.tv/twiv.

TWiV 168: Super CalTech prophylaxis and ferret runny noses

adeno-associated virusHosts: Vincent Racaniello, Dickson DespommierRich ConditAlan Dove, and Welkin Johnson

Welkin joins the TWiV team for a discussion of HIV prophlaxis using vectored antibodies, and the influenza H5N1 virus studies in ferrets that were not redacted.

Click the arrow above to play, or right-click to download TWiV 168 (59 MB .mp3, 98 minutes).

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Links for this episode:

Weekly Science Picks

Welkin – Virtual PI (Nature)
DicksonDrain the Ocean
RichNova: To the Moon
Alan – Robert Falcon Scott on Twitter and the Terra Nova expedition
VincentHello, Mr. Chips (I, Cringely)

Listener Pick of the Week

CharlotteAnd the Band Played On

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.

TWiV 164: Six steps forward, four steps back

xmrvHosts: Vincent RacanielloRich Condit, and Alan Dove

Vincent, Alan, and Rich review ten compelling virology stories of 2011.

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Click the arrow above to play, or right-click to download TWiV 164 (60 MB .mp3, 99 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.

Ten virology stories of 2011:

  1. XMRV, CFS, and prostate cancer (TWiV 119, 123, 136, 150)
  2. Influenza H5N1, ferrets, and the NSABB (TWiV 159)
  3. The Panic Virus (TWiV 117)
  4. Polio eradication (TWiV 127, 149)
  5. Viral oncotherapy (TWiV 124, 131, 142, 156)
  6. Hepatitis C virus (TWiV 130, 137, 141)
  7. Zinc finger nuclease and HIV therapy (TWiV 144)
  8. Bacteria help viruses (TWiV 154)
  9. Human papillomaviruses (TWiV 126)
  10. Combating dengue with Wolbachia (TWiV 115, 147)

Links for this episode:

Weekly Science Picks

Rich – Fundamentals of Molecular Virology by Nicholas H. Acheson
AlanFetch, with Ruff Ruffman
Vincent – Year end reviews at Rule of 6ix and Contagions

Listener Pick of the Week

GarrenTrillion-frame-per-second video
Judi – iBioMagazine
Ricardo –
Brain Picking’s 11 best science books of 2011

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.

TWiV 146: Draco’s potion

dracoHosts: Vincent RacanielloRich Condit, and Abbie Smith

Vincent, Rich, and Abbie review a broad spectrum antiviral protein, and selective pressure applied by a failed HIV-1 vaccine.

Click the arrow above to play, or right-click to download TWiV 146 (78 MB .mp3, 107 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

Vincent – Hypothetical Risk: Cambridge City Council’s Hearings on Recombinant DNA Research
Rich –
Z Corporation 3-D printer (YouTube)

Listener Pick of the Week

JimDo-it-yourself DNA extraction (Citizen Scientist Quarterly)

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.

TWiV 144: HIV gets the (zinc) finger

zinc finger nucleaseHosts: Vincent Racaniello, Rich Condit, and Alan Dove

Vincent, Rich, and Alan discuss live blogging of scientific meetings, the current outbreak of Hendra virus is Australia, and using zinc finger nucleases to make HIV-resistant CD4 cells.

Click the arrow above to play, or right-click to download TWiV 144 (75 MB .mp3, 104 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

Alan – Bugscope
Rich –
Vaccine adverse events: Causal or coincidental? (Lancet)
Vincent – West Nile Story by Dickson Despommier (Kindle edition)

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.

TWiV 143: Live at ASV in Minneapolis

asv minneapolisHosts: Vincent Racaniello, Rich Condit, Julie Overbaugh, and Stacey Schultz-Cherry

Vincent, Rich, Julie and Stacey recorded TWiV at the 30th Annual Meeting of the American Society for Virology in Minneapolis, where they discussed the role of neutralizing antibodies in protection against HIV-1 infection, and astroviruses, agents of gastroenteritis.

Click the arrow above to play, or right-click to download TWiV 143 (48 MB .mp3, 66 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 – Iter – building a fusion reactor
Vincent – American girls sweep at Google science fair (NY Times)

Listener Pick of the Week

JingBees by Rudolph Steiner

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.

TWiV 140: An aptitude for microbicides

cd4 aptamer

Hosts: Vincent Racaniello, Alan Dove, Rich Condit, and Judy Lieberman

Vincent, Alan, Rich, and Judy Lieberman review the use of CD4 aptamer-siRNA chimeras to inhibit HIV transmission.

Click the arrow above to play, or right-click to download TWiV #140 (110 MB .mp3, 92 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

Alan – Inside insides
Rich – Rock stars of science
Vincent – A new open-access journal, and Francis Collins on NIH budget

Listener Pick of the Week

Kathy – Scientists and musicians compare notes (NPR)

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.

Not-so-similar fate of identical twins infected with HIV-1

identical twinsFor extra credit in my recently concluded virology course, I asked students to summarize a virology finding in the style of this blog. I received many excellent submissions which I plan to post here in the coming months.

by Amanda Carpenter

In 1983, identical twin boys simultaneously received a contaminated blood transfusion immediately after birth, and were subsequently diagnosed with HIV-1. Years later, one of the twins is faring very well and has a near normal immune system, while the other is in poor health and has experienced many complications. How could the same virus, infecting two individuals at the same time, with the same genetic background, yield such different clinical courses? This unfortunate natural experiment has allowed researchers to study viral evolution while holding host genetic make-up constant. Brigham Young University Chairman of Biology Keith Crandall has studied the virus in this interesting case and recently published his findings in BMC Evolutionary Biology.

Crandall’s team examined blood samples obtained from the twins when they were 15 years old. They collected nucleotide sequence data from several genes essential to the success of HIV infection, which allowed them to extrapolate rates of viral growth, recombination, and genetic diversity. They reported that the virus of the healthier twin exhibited generally higher growth rates, higher genetic diversity, and higher recombination rates than the virus of the sicker twin (2).

How is this possible? Infected individuals produce an estimated 1010 new HIV virions every day, with errors occurring at a rate of about 1 per 104 nucleotides incorporated (1). These frequent point mutations are a simple starting point to explain the divergence of a once identical virus. In addition, HIV virions are capable of exchanging their genetic material with a different strain of virus via a process called recombination. Recombination is likely a random event, but has important implications for the host immune system.

Part of the immune system’s response to HIV is the utilization of cytotoxic T lymphocytes (CD8+ cells), which target and kill virus-infected cells. These cells are very specific, and if a recombination event occurs, these cytotoxic cells may not be able to recognize the new viral strain as readily as the original. The immune system may adapt to the new strain, but the virus may recombine again and again, and the immune system will not be able to keep up. These recombinant strains are likely to become more prevalent through natural selection. If recombined strains are better at evading the immune system, and are therefore more detrimental to the host, does this mean they are more successful? Why would the virus that has higher genetic diversity, a growth rate, and a higher recombination rate cause less disease? Perhaps the answer lies in the immune system.

Once out of the womb, these twins no longer exist in identical environments. They are exposed to different pathogens, bacteria, and microbes, all of which affect the make-up of the immune system. The healthier twin’s immune system may be better able to fight the virus, and so the virus must grow, diversify, and recombine in order to propagate the infection. In other words, because the sicker twin has a more depressed immune system, the virus is replicating with less resistance, and there is less incentive for the virus to evolve. Divergent viral evolution in the case of these monozygotic twins is likely due to random mutation and recombination events, combined with antiviral pressure from the hosts, whose immune systems are not identical at all.

(1) Yang, O., Church, J., Kitchen, C., Kilpatrick, R., Ali, A., Geng, Y., Killian, M., Sabado, R., Ng, H., Suen, J., Bryson, Y., Jamieson, B., & Krogstad, P. (2005). Genetic and Stochastic Influences on the Interaction of Human Immunodeficiency Virus Type 1 and Cytotoxic T Lymphocytes in Identical Twins Journal of Virology, 79 (24), 15368-15375 DOI: 10.1128/JVI.79.24.15368-15375.2005

(2) Tazi L, Imamichi H, Hirschfeld S, Metcalf JA, Orsega S, Pérez-Losada M, Posada D, Lane HC, & Crandall KA (2011). HIV-1 infected monozygotic twins: a tale of two outcomes. BMC evolutionary biology, 11 PMID: 21385447