Paul Has Measles is a free children's book about viruses and vaccines available in 16 languages (link). Paul Stays Home is a free children's book about COVID-19 (link).

By David Tuller, DrPH

A few years ago, my friend and colleague Steven Lubet, a law professor and scholar at Northwestern University, wrote the following account of the start of his struggle with what was then largely called chronic fatigue syndrome. While his story does not directly relate to current events, Steve’s frustrations in his effort to seek a proper diagnosis will likely resonate with many in our pandemic era.

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Fatigue: An Adventure Story

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Daniel Griffin provides a clinical report on COVID-19, then Amy joins us to discuss the 2020 Chemistry Nobel Prize for gene editing using CRISPR/Cas9, continuing circulation of poliovirus in Afghanistan, inborn errors of interferon in patients with severe COVID-19, and listener questions.

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The 2020 Nobel Prize in Medicine has been awarded to Harvey Alter, Michael Houghton, and Charles Rice for their work leading to the discovery of hepatitis C virus. To me this prize makes a great deal of sense because each of the recipients produced key sequential discoveries, all of which were needed to find a new viral agent of hepatitis.

Transmissible liver disease has been known for thousands of years. One form was known to be transmitted by feces, and a viral etiology for this disease, subsequently called hepatitis A, was determined after WWII. The agent of a different form of hepatitis transmitted by blood and body fluids was identified in 1967 by Blumberg and colleagues and called hepatitis B virus. Blumberg received the 1976 Medicine Nobel Prize for this discovery.

Harvey Alter was studying hepatitis at the same time as Blumberg and observed that there were cases not caused by either hepatitis A or B virus. He showed that blood from these patients could transmit the disease to chimpanzees. By the mid-1980s studies of infected blood from patients with non-A, non-B (NANB) hepatitis showed the presence of small (less than 80 nm) enveloped particles, suggesting a viral etiology. However, the NANB agent could not be propagated in cell culture.

Identification of the agent of NANB was done by Michael Houghton, working at the Chiron Corporation. He and his colleagues produced a cDNA library from the plasma of an infected chimpanzee. The plasma had been first subjected to high speed centrifugation to enrich for virus particles. The cDNA library was inserted into a phage lambda expression vector designed to produced protein from cloned DNA (pictured; image credit). Plaques were then screened with serum from a chronic NANB patient. The idea was that antibodies to the virus in the serum would react with proteins produced in bacteria from the phage vector. One positive clone, called 5-1-1, was identified out of one million clones that were screened. Sequence analysis of the insert revealed the presence of a (+) strand RNA genome of a novel member of the Flaviviridae. This virus was subsequently named hepatitis C virus. One consequence of this work is that diagnostic reagents were then produced and revealed that many millions of people worldwide were infected with this virus.

Despite having cloned the viral genome, no one was able to recover infectious virus from cells transfected with cloned DNA or RNA transcripts.

Charles Rice and colleagues addressed this problem by producing multiple DNA clones of the viral genome from the serum of a patient with NANB hepatitis. After determining the nucleotide sequence of multiple DNA clones, a consensus genome was constructed that was thought to represent the correct sequence, including the authentic 5’- and 3’-termini. RNA transcripts of each of 10 different clones were inoculated into the liver of two chimpanzees, who subsequently developed hepatitis.

The work of these three groups led to the identification of hepatitis C virus. However, it was not until 2005 that the complete replication of hepatitis C virus was achieved in cells in culture. This work was done by Wakita and colleagues, and represented the last discovery needed to develop antiviral drugs to inhibit reproduction. Today patients treated with a mixture of two or three antiviral drugs can have their hepatitis C cured within months.

Kizzmekia Corbett joins TWiV to review her career and her work on respiratory syncytial virus, influenza virus, and coronaviruses and coronavirus vaccines, including her role in development and testing of a spike-encoding mRNA vaccine, and then we review the Nobel Prize for discovery of hepatitis C virus.

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By David Tuller, DrPH

*October is crowdfunding month at Berkeley. I conduct this project as a senior fellow in public health and journalism and the university’s Center for Global Public Health. If you would like to support the project, here’s the place: https://crowdfund.berkeley.edu/project/22602

The pandemic has played havoc with everything, including the timeline of the development process for the new ME/CFS guidance from the UK National Institute of Health and Care Excellence. Originally, a draft of the guidance was supposed to be released earlier this year. Following a period of public comment, NICE planned to issue the final version by December. Under the new schedule, the draft version is being released in November, with a six-week comment period to follow. The final version will be released next April.

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Daniel Griffin discusses President Trump’s case of COVID-19, including the clinical course, the medications he received and why, and expectations for the next few weeks.

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By David Tuller, DrPH

*October is crowdfunding month at Berkeley. I conduct this project as a senior fellow in public health and journalism and the university’s Center for Global Public Health. If you would like to support the project, here’s the place: https://crowdfund.berkeley.edu/project/22602

On September 24th, the Royal Society of Medicine hosted a webinar called “Long-COVID: Understanding the shadow of the virus.” In a previous post, I criticized one of the panelists, infectious disease expert Alastair Miller, on several grounds. He promoted graded exercise therapy, made unwarranted claims about recovery rates from CBT/GET treatments, and suggested that the PACE trial suffered only from “bad press” rather than methodological violations that appear to meet definitions of research misconduct.

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Tony Schountz joins TWiV to explain the work of his laboratory showing that deer mice can be infected with and transmit SARS-CoV-2, and how his colony of Jamaican fruit bats is being used to understand their response to virus infections.

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*October is crowdfunding month at Berkeley. I conduct this project as a senior fellow in public health and journalism and the university’s Center for Global Public Health. If you would like to support the project, here’s the place: https://crowdfund.berkeley.edu/project/22602

By David Tuller, DrPH

Proponents of cognitive behavior therapy and graded exercise therapy as treatments for CFS, ME, or their variants keep trotting out their favored interventions for patients suffering from persistent fatigue and other symptoms after acute Covid-19. Last week, the Royal Society of Medicine conducted an online webinar called “Long COVID: Understanding the shadow of the virus.” Three physicians participated: Alastair Miller, an infectious disease expert from Liverpool who used to run a local CFS/ME clinic; Carolyn Chew-Graham, a professor of general practice research at Keele University in Staffordshire; and Nisreen Alwan, an associate professor of public health at the University of Southampton.

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by Gertrud U. Rey

Antibodies are large proteins that are made by B cells of the adaptive immune system. Most people think that antibodies function only as a whole molecule, but some of the individual fragments of an antibody can also bind and neutralize antigens. 

An antibody consists of two heavy chains and two light chains that assemble into a Y-shaped structure (left side of Figure). The stem of the Y is known as the “fragment crystallizable” (Fc) portion and is composed of two heavy chains. The two arms of the Y are known as the “fragment antigen-binding” (Fab) portions and are each composed of one heavy chain and one light chain. As its name suggests, the top half of each Fab fragment is the antigen-binding region of the antibody, and it is variable – meaning that it varies between antibodies that are produced by different B cells. The bottom half of each Fab fragment and the entire Fc region are constant, meaning that they are identical in all antibodies of the same isotype, but differ in antibodies of different isotypes. For example, the constant regions are identical in all IgG antibodies but differ between IgG and IgA antibodies. 

In an effort to identify anti-SARS-CoV-2 antibodies suitable for preventing and treating SARS-CoV-2 infection, the authors of a recent publication screened 100 billion different anti-SARS-CoV-2 antibody candidates for their ability to bind and/or neutralize SARS-CoV-2. This eventually led to the discovery of “ab8,” an antibody fragment consisting of a variable heavy (VH) region and having particularly potent SARS-CoV-2 binding specificity and neutralization activity. To increase the binding avidity of ab8 (i.e., the stability of its interaction with an antigen) and extend its longevity in the human body, the authors fused this fragment to the Fc domain of human IgG1, an abundant and stable type of human antibody. This produced the molecule hereinafter referred to as “VH-Fc ab8” (right side of Figure).  

The authors found that VH-Fc ab8 can bind various conformations of the SARS-CoV-2 spike protein, including when the spike protein is bound to a cell surface. VH-Fc ab8 can also bind to and neutralize six different SARS-CoV-2 isolates having different amino acid changes in the receptor-binding domain, suggesting that it is broadly cross-reactive. Notably, it does not bind to human cells, meaning that it does not seem to interfere with normal cellular functions.

As a next step, the authors evaluated the ability of VH-Fc ab8 to prevent SARS-CoV-2 infection in mice. If given to mice before they were infected with SARS-CoV-2, VH-Fc ab8 inhibited viral replication at all doses tested, but it only neutralized virus at the highest dose of 36 mg/kg. Although these results were encouraging, it is often difficult to interpret data obtained in mice in terms of clinical relevance in humans, because mice don’t develop the COVID-19-related disease pathologies observed in humans. Hamsters more closely imitate human SARS-CoV-2 infection in the lung, suggesting that they could be a useful mammalian model for COVID-19. VH-Fc ab8 caused significantly reduced levels of infectious virus in the lung, nasal mucosa, and saliva of hamsters when administered one day before (i.e., “prophylactically”) or six hours after SARS-CoV-2 infection (i.e., “therapeutically”) compared to untreated control animals, suggesting that it could be used to both prevent and treat SARS-CoV-2 infection. Although VH-Fc ab8 led to greater reduction of virus levels when given prophylactically than when given therapeutically, therapeutic administration still led to significantly decreased viral loads in treated animals compared to untreated control animals, even at very low doses. VH-Fc ab8 not only alleviated pneumonia and reduced lung viral loads in hamsters, but it also reduced virus shedding in the upper airway, which could help with reducing transmission. 

The authors also found that when they gave hamsters the same dose of either VH-Fc ab8 or IgG1 ab1 – a full-sized version of the antibody, and then examined their concentrations in the serum five days later, levels of VH-Fc ab8 were significantly higher than those of the full-sized antibody. This suggests that the systemic distribution of VH-Fc ab8 is more long-lived than that of a full-sized antibody. 

Although small animal models can provide key insights into the pathogenic mechanisms of viral infections, they are often poor predictors of human disease outcomes. The therapeutic timeline followed in the hamster experiments (i.e., administration of VH-Fc ab8 six hours after infection) would also be difficult to reproduce in humans because therapeutic drugs are not usually administered until well after symptom onset. Therefore, it would be difficult to determine whether the therapeutic effect of VH-Fc ab8 observed in hamsters would be the same in humans. 

That being said, there are clear advantages to using antibody fragments instead of whole antibodies. Their small size allows them to penetrate more efficiently to sites of infection and bind antigens more easily and with more specificity. Smaller molecules also diffuse more easily through tissues, meaning that they could be administered by routes other than injection, such as by inhalation. Furthermore, because the molecular weight of VH-Fc ab8 is only about half that of a full-sized antibody, smaller quantities would be needed to obtain the same number of molecules, meaning that antibody fragment therapeutics could be more easily mass-produced. 

There is no question that we are in dire need of an effective therapeutic drug to treat SARS-CoV-2 infection. If the results observed in these animal experiments can be duplicated in humans, VH-Fc ab8 would be an attractive option for both treating and preventing SARS-CoV-2 infection.