Defective influenza virus RNAsThe virulence of a virus – its capacity to cause disease – is determined by both viral and host factors. Even among healthy individuals, infection with a particular virus may have different outcomes ranging from benign to lethal. The study of influenza viruses that cause mild or fatal outcomes reveals that defective viral genomes play a role in determining viral virulence.

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By David Tuller, DrPH

Queen Mary University of London seems to have devised a fail-safe method of avoiding having to comply with more PACE-related freedom-of-information requests—just declare no one is around who can deal with it. Earlier this month, the U.K. Information Commissioner’s Office issued a decision in an appeal of QMUL’s rejection of a FOI request. The ICO found that QMUL had breached provisions of the FOI law–but that even so there was no way to order the university to produce the requested data.

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Scott Hensley joins the TWiVites to review the current influenza season and presence of the virus in exhaled breath of symptomatic cases.

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Scott Hensley of the University of Pennsylvania helps us summarize the current influenza season so far. Bottom line: it’s a very serious season with a great deal of morbidity and mortality. As usually, serious disease and deaths occur in unvaccinated individuals. Although there is a mismatch between the influenza vaccine and this year’s H3N2 strain, which is causing most of the infections, vaccination still reduces disease severity cause by this strain, as well as by the circulating H1N1 and influenza B viruses. Next we discuss an interesting study of symptomatic college students with influenza. The goal was to determine which mode of influenza transmission is likely to be important: contact, or aerosols produced by speaking, coughing, or sneezing. The results show that simple breathing leads to virus in the breath – small aerosols that can travel distances to infect others. Coughing, but not sneezing, was a major observed sign of infection, but neither was needed for infectious aerosol generation.

Gesundheit-II bio aerosol samplerInfluenza virus may be transmitted among humans in three ways: by direct contact with infected individuals; by contact with contaminated objects (called fomites, such as toys, doorknobs); and by inhalation of virus-laden aerosols. A recent study suggests that normal tidal breathing plays a substantial role in aerosol transmission.

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By David Tuller, DrPH

Last October, the British Journal of Sports Medicine published a short paper that was essentially a summary of Cochrane’s systematic review of graded exercise for chronic fatigue syndrome (as Cochrane calls the illness). This systematic review is problematic for a number of reasons—not least of which is that it includes the debunked PACE trial and other Oxford criteria studies.

The Oxford case definition does not require any symptoms besides fatigue for diagnosis—including the cardinal symptom of post-exertional malaise. Studies that rely on Oxford criteria samples do not represent the experiences of patients with more narrowly defined disease. Systematic reviews of flawed trials produce flawed results.

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The TWiVome explores induction of antiviral responses by repeating patterns of capsids, and a fungus in the mosquito gut that aids dengue virus replication.

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Show notes at microbe.tv/twiv

rhinovirus receptors

Rhinovirus receptors

An outbreak of respiratory disease in Ugandan chimpanzees provides insight into how virus infection can shape the genome and lead to differences in the cell receptor gene that regulate susceptibility to infection.

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By David Tuller, DrPH

Earlier today, Professor Racaniello e-mailed the following letter to Nick Brown, the editor-in-chief of Archives of Disease in Childhood, one of the journals from the BMJ Group. Archives recently published a study of the Lightning Process in kids with ME/CFS.

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Dear Dr. Brown:

In September, Archives of Disease in Childhood published a study called “Clinical and cost-effectiveness of the Lightning Process in addition to specialist medical care for paediatric chronic fatigue syndrome: randomised controlled trial” [1]. Like many studies of this illness, it was an open-label trial with self-reported outcomes—a study design known to be highly vulnerable to bias.

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The TWiV team explains how infectious horsepox virus – likely the ancestor of smallpox vaccines – was recovered from chemically synthesized DNA fragments.

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human papillomavirus

The human papillomavirus (HPV) vaccines save lives by preventing lethal cervical and anogenital cancers. If Henrietta Lacks had received an HPV vaccine, she would not have succumbed to cervical cancer. Yet not enough young men and women receive the vaccine. An obstacle to more widespread adoption of the HPV vaccine is that some parents and clinicians feel that it encourages risky sexual behavior. The results of a recent study indicate that such fears are unfounded.

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