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Pick of the Coronavirus Papers: A Comparison Finds Subtle Differences Between Tests For The COVID-19 Virus

Nature wades through the literature on COVID-19 so you don’t have to.

Fresh findings about SARS-CoV-2 and the disease it causes.

6 April — A comparison finds subtle differences between tests for the COVID-19 virus

Doctors rely on a test called quantitative reverse-transcription polymerase chain reaction (qRT-PCR) to determine whether a person is infected with SARS-CoV-2. A team led by Nathan Grubaugh at Yale School of Public Health in New Haven, Connecticut, compared nine widely used versions of the test and found that all of them reliably detect the virus (C. B. F. Vogels et al. Preprint at medRxiv; 2020).

But the researchers also found that some tests — including one made by the US Centers for Disease Control and Prevention, another developed at Hong Kong University, and a third from Charité–Universitätsmedizin Berlin — performed best when it came to detecting low levels of the virus in samples.

5 April — Bats harbour a pool of coronaviruses related to pandemic culprit

Viruses closely related to SARS-CoV-2, the virus causing the COVID-19 pandemic, have been circulating in horseshoe bats, ready to jump to humans, for decades — and maybe even longer.

David Robertson at the University of Glasgow, UK, and his colleagues analysed the RNA of 68 coronaviruses, including SARS-CoV-2 and the virus that causes severe acute respiratory syndrome, or SARS (M. F. Boni et al. Preprint at bioRxiv; 2020). This analysis shows that horseshoe bats (Rhinolophus spp.) host an expanding lineage of viruses that, like SARS-CoV-2, can infect humans. The team estimates that the ancestor of SARS-CoV-2 split 40 to 70 years ago from the closely related bat virus RaTG13. Though the two viruses are highly similar genetically, RaTG13 doesn’t infect humans.

The analysis also suggests that viruses in the lineage are ready to jump to humans directly from bats. But SARS-CoV-2 might have first hopped to another species that humans are more exposed to, rather than spreading straight from bat to human.

3 April — Masks could cut spread of COVID-19 virus

Surgical face masks effectively block the spread of seasonal coronaviruses in respiratory droplets, suggesting that masks could prevent transmission of SARS-CoV-2.

Seasonal coronaviruses are one cause of the common cold. Benjamin Cowling at the University of Hong Kong and his colleagues had ill volunteers who were infected with seasonal coronaviruses sit in an enclosed booth and place their faces in a sampling device, called the Gesundheit-II, that captures airborne particles (N. H. L. Leung et al. Nat. Med.; 2020).

The scientists detected coronavirus RNA in both coarse droplets and finer ‘aerosol’ droplets emitted by volunteers who were not wearing masks. Mask reduced detection of viral RNA in both types of droplet. Larger particles are carried by sneezes and coughs, whereas exhaled breath can spread aerosol droplets, which have a diameter of five micrometres or less.

The authors say that surgical masks reduce transmission of not only seasonal coronaviruses, but also influenza.

Correction: An earlier version of this article said masks reduced detection of viral DNA.

1 April — Antibodies from llamas help to foil the COVID-19 virus

Antibodies from llamas (Lama glama) could help in the fight against several coronaviruses that infect humans.

A team led by Bert Schepens and Xavier Saelens of the VIB life-sciences institute in Ghent, Belgium, and Jason McLellan of the University of Texas at Austin has isolated two llama antibodies that bind the ‘spike’ proteins that coronaviruses use to enter cells (D. Wrapp et al. Preprint at bioRxiv; 2020). One antibody neutralized the coronavirus responsible for Middle East respiratory syndrome (MERS); the second mopped up the severe acute respiratory syndrome (SARS) coronavirus.

Fusing the SARS antibody from a llama with an antibody from a human yielded a hybrid that neutralized the virus responsible for COVID-19. The data suggest that such antibodies could be useful in combating coronavirus epidemics.

30 March — Debilitated patients rally after dose of survivors’ blood

People seriously ill with COVID-19 experienced striking improvement after receiving infusions of blood from disease survivors, according to two separate research teams.

Both teams extracted antibody-laden plasma — a component of blood — from people who’d recovered from COVID-19.

Xiaoming Yang at the National Engineering Technology Research Center for Combined Vaccines in Wuhan, China, and his colleagues gave the plasma to ten severely ill people. By the sixth day after the treatment, the virus that causes COVID-19 was undetectable in seven of the ten. The recipients experienced no significant side effects (K. Duan et al. Preprint at medRxiv; 2020).

A group led by Lei Liu at Shenzhen Third People’s Hospital in China gave survivors’ plasma to five “critically ill” people (C. Shen et alJ. Am. Med. Assoc; 2020). Symptoms dwindled in all five; within ten days of receiving the plasma, three recipients no longer needed ventilators.

Other researchers would like to try such transfusions to treat health workers who have been directly exposed.

27 March — Viral proteins point to potential treatments

A list of the human proteins affected by the SARS-CoV-2 virus offers a guide to potential treatments for infected people.

A team led by Nevan Krogan at the University of California, San Francisco, engineered human cells to produce one of 26 proteins made by the coronavirus (D. E. Gordon et al. Preprint at bioRxiv; 2020). This allowed the researchers to identify human proteins that physically interact with coronavirus proteins.

Out of 332 interactions between human and viral proteins, the authors identified 67 that existing or candidate drugs could potentially disrupt. The researchers and their collaborators are now testing some of these compounds for antiviral activity — and urge others to do the same.


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